forked from luck/tmp_suning_uos_patched
218d952160
1772 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Alexei Starovoitov
|
218d952160 |
bpf: Adjust BTF log size limit.
[ Upstream commit c5a2d43e998a821701029f23e25b62f9188e93ff ] Make BTF log size limit to be the same as the verifier log size limit. Otherwise tools that progressively increase log size and use the same log for BTF loading and program loading will be hitting hard to debug EINVAL. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20211201181040.23337-7-alexei.starovoitov@gmail.com Signed-off-by: Sasha Levin <sashal@kernel.org> |
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Daniel Borkmann
|
35ab8c9085 |
bpf: Fix out of bounds access from invalid *_or_null type verification
[ no upstream commit given implicitly fixed through the larger refactoring in c25b2ae136039ffa820c26138ed4a5e5f3ab3841 ] While auditing some other code, I noticed missing checks inside the pointer arithmetic simulation, more specifically, adjust_ptr_min_max_vals(). Several *_OR_NULL types are not rejected whereas they are _required_ to be rejected given the expectation is that they get promoted into a 'real' pointer type for the success case, that is, after an explicit != NULL check. One case which stands out and is accessible from unprivileged (iff enabled given disabled by default) is BPF ring buffer. From crafting a PoC, the NULL check can be bypassed through an offset, and its id marking will then lead to promotion of mem_or_null to a mem type. bpf_ringbuf_reserve() helper can trigger this case through passing of reserved flags, for example. func#0 @0 0: R1=ctx(id=0,off=0,imm=0) R10=fp0 0: (7a) *(u64 *)(r10 -8) = 0 1: R1=ctx(id=0,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm 1: (18) r1 = 0x0 3: R1_w=map_ptr(id=0,off=0,ks=0,vs=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm 3: (b7) r2 = 8 4: R1_w=map_ptr(id=0,off=0,ks=0,vs=0,imm=0) R2_w=invP8 R10=fp0 fp-8_w=mmmmmmmm 4: (b7) r3 = 0 5: R1_w=map_ptr(id=0,off=0,ks=0,vs=0,imm=0) R2_w=invP8 R3_w=invP0 R10=fp0 fp-8_w=mmmmmmmm 5: (85) call bpf_ringbuf_reserve#131 6: R0_w=mem_or_null(id=2,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 6: (bf) r6 = r0 7: R0_w=mem_or_null(id=2,ref_obj_id=2,off=0,imm=0) R6_w=mem_or_null(id=2,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 7: (07) r0 += 1 8: R0_w=mem_or_null(id=2,ref_obj_id=2,off=1,imm=0) R6_w=mem_or_null(id=2,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 8: (15) if r0 == 0x0 goto pc+4 R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 9: R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 9: (62) *(u32 *)(r6 +0) = 0 R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 10: R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 10: (bf) r1 = r6 11: R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R1_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 11: (b7) r2 = 0 12: R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R1_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R2_w=invP0 R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2 12: (85) call bpf_ringbuf_submit#132 13: R6=invP(id=0) R10=fp0 fp-8=mmmmmmmm 13: (b7) r0 = 0 14: R0_w=invP0 R6=invP(id=0) R10=fp0 fp-8=mmmmmmmm 14: (95) exit from 8 to 13: safe processed 15 insns (limit 1000000) max_states_per_insn 0 total_states 1 peak_states 1 mark_read 0 OK All three commits, that is |
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Daniel Borkmann
|
8c15bfb36a |
bpf: Add kconfig knob for disabling unpriv bpf by default
commit 08389d888287c3823f80b0216766b71e17f0aba5 upstream.
Add a kconfig knob which allows for unprivileged bpf to be disabled by default.
If set, the knob sets /proc/sys/kernel/unprivileged_bpf_disabled to value of 2.
This still allows a transition of 2 -> {0,1} through an admin. Similarly,
this also still keeps 1 -> {1} behavior intact, so that once set to permanently
disabled, it cannot be undone aside from a reboot.
We've also added extra2 with max of 2 for the procfs handler, so that an admin
still has a chance to toggle between 0 <-> 2.
Either way, as an additional alternative, applications can make use of CAP_BPF
that we added a while ago.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/74ec548079189e4e4dffaeb42b8987bb3c852eee.1620765074.git.daniel@iogearbox.net
Cc: Salvatore Bonaccorso <carnil@debian.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Daniel Borkmann
|
279e0bf80d |
bpf: Make 32->64 bounds propagation slightly more robust
commit e572ff80f05c33cd0cb4860f864f5c9c044280b6 upstream. Make the bounds propagation in __reg_assign_32_into_64() slightly more robust and readable by aligning it similarly as we did back in the __reg_combine_64_into_32() counterpart. Meaning, only propagate or pessimize them as a smin/smax pair. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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Daniel Borkmann
|
e2aad0b5f2 |
bpf: Fix signed bounds propagation after mov32
commit 3cf2b61eb06765e27fec6799292d9fb46d0b7e60 upstream.
For the case where both s32_{min,max}_value bounds are positive, the
__reg_assign_32_into_64() directly propagates them to their 64 bit
counterparts, otherwise it pessimises them into [0,u32_max] universe and
tries to refine them later on by learning through the tnum as per comment
in mentioned function. However, that does not always happen, for example,
in mov32 operation we call zext_32_to_64(dst_reg) which invokes the
__reg_assign_32_into_64() as is without subsequent bounds update as
elsewhere thus no refinement based on tnum takes place.
Thus, not calling into the __update_reg_bounds() / __reg_deduce_bounds() /
__reg_bound_offset() triplet as we do, for example, in case of ALU ops via
adjust_scalar_min_max_vals(), will lead to more pessimistic bounds when
dumping the full register state:
Before fix:
0: (b4) w0 = -1
1: R0_w=invP4294967295
(id=0,imm=ffffffff,
smin_value=4294967295,smax_value=4294967295,
umin_value=4294967295,umax_value=4294967295,
var_off=(0xffffffff; 0x0),
s32_min_value=-1,s32_max_value=-1,
u32_min_value=-1,u32_max_value=-1)
1: (bc) w0 = w0
2: R0_w=invP4294967295
(id=0,imm=ffffffff,
smin_value=0,smax_value=4294967295,
umin_value=4294967295,umax_value=4294967295,
var_off=(0xffffffff; 0x0),
s32_min_value=-1,s32_max_value=-1,
u32_min_value=-1,u32_max_value=-1)
Technically, the smin_value=0 and smax_value=4294967295 bounds are not
incorrect, but given the register is still a constant, they break assumptions
about const scalars that smin_value == smax_value and umin_value == umax_value.
After fix:
0: (b4) w0 = -1
1: R0_w=invP4294967295
(id=0,imm=ffffffff,
smin_value=4294967295,smax_value=4294967295,
umin_value=4294967295,umax_value=4294967295,
var_off=(0xffffffff; 0x0),
s32_min_value=-1,s32_max_value=-1,
u32_min_value=-1,u32_max_value=-1)
1: (bc) w0 = w0
2: R0_w=invP4294967295
(id=0,imm=ffffffff,
smin_value=4294967295,smax_value=4294967295,
umin_value=4294967295,umax_value=4294967295,
var_off=(0xffffffff; 0x0),
s32_min_value=-1,s32_max_value=-1,
u32_min_value=-1,u32_max_value=-1)
Without the smin_value == smax_value and umin_value == umax_value invariant
being intact for const scalars, it is possible to leak out kernel pointers
from unprivileged user space if the latter is enabled. For example, when such
registers are involved in pointer arithmtics, then adjust_ptr_min_max_vals()
will taint the destination register into an unknown scalar, and the latter
can be exported and stored e.g. into a BPF map value.
Fixes:
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Bui Quang Minh
|
613725436e |
bpf: Fix integer overflow in argument calculation for bpf_map_area_alloc
commit 7dd5d437c258bbf4cc15b35229e5208b87b8b4e0 upstream.
In 32-bit architecture, the result of sizeof() is a 32-bit integer so
the expression becomes the multiplication between 2 32-bit integer which
can potentially leads to integer overflow. As a result,
bpf_map_area_alloc() allocates less memory than needed.
Fix this by casting 1 operand to u64.
Fixes: 0d2c4f964050 ("bpf: Eliminate rlimit-based memory accounting for sockmap and sockhash maps")
Fixes:
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Maxim Mikityanskiy
|
349e83c0cf |
bpf: Fix the off-by-two error in range markings
commit 2fa7d94afc1afbb4d702760c058dc2d7ed30f226 upstream.
The first commit cited below attempts to fix the off-by-one error that
appeared in some comparisons with an open range. Due to this error,
arithmetically equivalent pieces of code could get different verdicts
from the verifier, for example (pseudocode):
// 1. Passes the verifier:
if (data + 8 > data_end)
return early
read *(u64 *)data, i.e. [data; data+7]
// 2. Rejected by the verifier (should still pass):
if (data + 7 >= data_end)
return early
read *(u64 *)data, i.e. [data; data+7]
The attempted fix, however, shifts the range by one in a wrong
direction, so the bug not only remains, but also such piece of code
starts failing in the verifier:
// 3. Rejected by the verifier, but the check is stricter than in #1.
if (data + 8 >= data_end)
return early
read *(u64 *)data, i.e. [data; data+7]
The change performed by that fix converted an off-by-one bug into
off-by-two. The second commit cited below added the BPF selftests
written to ensure than code chunks like #3 are rejected, however,
they should be accepted.
This commit fixes the off-by-two error by adjusting new_range in the
right direction and fixes the tests by changing the range into the
one that should actually fail.
Fixes:
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Daniel Borkmann
|
33fe044f6a |
bpf: Fix toctou on read-only map's constant scalar tracking
commit 353050be4c19e102178ccc05988101887c25ae53 upstream. Commit |
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Alexei Starovoitov
|
4a50bc0084 |
bpf: Fix propagation of signed bounds from 64-bit min/max into 32-bit.
[ Upstream commit 388e2c0b978339dee9b0a81a2e546f8979e021e2 ]
Similar to unsigned bounds propagation fix signed bounds.
The 'Fixes' tag is a hint. There is no security bug here.
The verifier was too conservative.
Fixes:
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Alexei Starovoitov
|
84dde8c8c9 |
bpf: Fix propagation of bounds from 64-bit min/max into 32-bit and var_off.
[ Upstream commit b9979db8340154526d9ab38a1883d6f6ba9b6d47 ]
Before this fix:
166: (b5) if r2 <= 0x1 goto pc+22
from 166 to 189: R2=invP(id=1,umax_value=1,var_off=(0x0; 0xffffffff))
After this fix:
166: (b5) if r2 <= 0x1 goto pc+22
from 166 to 189: R2=invP(id=1,umax_value=1,var_off=(0x0; 0x1))
While processing BPF_JLE the reg_set_min_max() would set true_reg->umax_value = 1
and call __reg_combine_64_into_32(true_reg).
Without the fix it would not pass the condition:
if (__reg64_bound_u32(reg->umin_value) && __reg64_bound_u32(reg->umax_value))
since umin_value == 0 at this point.
Before commit 10bf4e83167c the umin was incorrectly ingored.
The commit 10bf4e83167c fixed the correctness issue, but pessimized
propagation of 64-bit min max into 32-bit min max and corresponding var_off.
Fixes: 10bf4e83167c ("bpf: Fix propagation of 32 bit unsigned bounds from 64 bit bounds")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211101222153.78759-1-alexei.starovoitov@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
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Lorenz Bauer
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b92ac0a9ca |
bpf: Prevent increasing bpf_jit_limit above max
[ Upstream commit fadb7ff1a6c2c565af56b4aacdd086b067eed440 ] Restrict bpf_jit_limit to the maximum supported by the arch's JIT. Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211014142554.53120-4-lmb@cloudflare.com Signed-off-by: Sasha Levin <sashal@kernel.org> |
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Xu Kuohai
|
ee4908f909 |
bpf: Fix error usage of map_fd and fdget() in generic_map_update_batch()
commit fda7a38714f40b635f5502ec4855602c6b33dad2 upstream.
1. The ufd in generic_map_update_batch() should be read from batch.map_fd;
2. A call to fdget() should be followed by a symmetric call to fdput().
Fixes:
|
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Toke Høiland-Jørgensen
|
dd2260ec64 |
bpf: Fix potential race in tail call compatibility check
commit 54713c85f536048e685258f880bf298a74c3620d upstream.
Lorenzo noticed that the code testing for program type compatibility of
tail call maps is potentially racy in that two threads could encounter a
map with an unset type simultaneously and both return true even though they
are inserting incompatible programs.
The race window is quite small, but artificially enlarging it by adding a
usleep_range() inside the check in bpf_prog_array_compatible() makes it
trivial to trigger from userspace with a program that does, essentially:
map_fd = bpf_create_map(BPF_MAP_TYPE_PROG_ARRAY, 4, 4, 2, 0);
pid = fork();
if (pid) {
key = 0;
value = xdp_fd;
} else {
key = 1;
value = tc_fd;
}
err = bpf_map_update_elem(map_fd, &key, &value, 0);
While the race window is small, it has potentially serious ramifications in
that triggering it would allow a BPF program to tail call to a program of a
different type. So let's get rid of it by protecting the update with a
spinlock. The commit in the Fixes tag is the last commit that touches the
code in question.
v2:
- Use a spinlock instead of an atomic variable and cmpxchg() (Alexei)
v3:
- Put lock and the members it protects into an embedded 'owner' struct (Daniel)
Fixes:
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Tatsuhiko Yasumatsu
|
064faa8e8a |
bpf: Fix integer overflow in prealloc_elems_and_freelist()
[ Upstream commit 30e29a9a2bc6a4888335a6ede968b75cd329657a ]
In prealloc_elems_and_freelist(), the multiplication to calculate the
size passed to bpf_map_area_alloc() could lead to an integer overflow.
As a result, out-of-bounds write could occur in pcpu_freelist_populate()
as reported by KASAN:
[...]
[ 16.968613] BUG: KASAN: slab-out-of-bounds in pcpu_freelist_populate+0xd9/0x100
[ 16.969408] Write of size 8 at addr ffff888104fc6ea0 by task crash/78
[ 16.970038]
[ 16.970195] CPU: 0 PID: 78 Comm: crash Not tainted 5.15.0-rc2+ #1
[ 16.970878] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
[ 16.972026] Call Trace:
[ 16.972306] dump_stack_lvl+0x34/0x44
[ 16.972687] print_address_description.constprop.0+0x21/0x140
[ 16.973297] ? pcpu_freelist_populate+0xd9/0x100
[ 16.973777] ? pcpu_freelist_populate+0xd9/0x100
[ 16.974257] kasan_report.cold+0x7f/0x11b
[ 16.974681] ? pcpu_freelist_populate+0xd9/0x100
[ 16.975190] pcpu_freelist_populate+0xd9/0x100
[ 16.975669] stack_map_alloc+0x209/0x2a0
[ 16.976106] __sys_bpf+0xd83/0x2ce0
[...]
The possibility of this overflow was originally discussed in [0], but
was overlooked.
Fix the integer overflow by changing elem_size to u64 from u32.
[0] https://lore.kernel.org/bpf/728b238e-a481-eb50-98e9-b0f430ab01e7@gmail.com/
Fixes:
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Lorenz Bauer
|
59efda5073 |
bpf: Exempt CAP_BPF from checks against bpf_jit_limit
[ Upstream commit 8a98ae12fbefdb583a7696de719a1d57e5e940a2 ]
When introducing CAP_BPF, bpf_jit_charge_modmem() was not changed to treat
programs with CAP_BPF as privileged for the purpose of JIT memory allocation.
This means that a program without CAP_BPF can block a program with CAP_BPF
from loading a program.
Fix this by checking bpf_capable() in bpf_jit_charge_modmem().
Fixes:
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Hou Tao
|
d93f65586c |
bpf: Handle return value of BPF_PROG_TYPE_STRUCT_OPS prog
[ Upstream commit 356ed64991c6847a0c4f2e8fa3b1133f7a14f1fc ]
Currently if a function ptr in struct_ops has a return value, its
caller will get a random return value from it, because the return
value of related BPF_PROG_TYPE_STRUCT_OPS prog is just dropped.
So adding a new flag BPF_TRAMP_F_RET_FENTRY_RET to tell bpf trampoline
to save and return the return value of struct_ops prog if ret_size of
the function ptr is greater than 0. Also restricting the flag to be
used alone.
Fixes:
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Bixuan Cui
|
6345a0bee8 |
bpf: Add oversize check before call kvcalloc()
[ Upstream commit 0e6491b559704da720f6da09dd0a52c4df44c514 ]
Commit 7661809d493b ("mm: don't allow oversized kvmalloc() calls") add the
oversize check. When the allocation is larger than what kmalloc() supports,
the following warning triggered:
WARNING: CPU: 0 PID: 8408 at mm/util.c:597 kvmalloc_node+0x108/0x110 mm/util.c:597
Modules linked in:
CPU: 0 PID: 8408 Comm: syz-executor221 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:kvmalloc_node+0x108/0x110 mm/util.c:597
Call Trace:
kvmalloc include/linux/mm.h:806 [inline]
kvmalloc_array include/linux/mm.h:824 [inline]
kvcalloc include/linux/mm.h:829 [inline]
check_btf_line kernel/bpf/verifier.c:9925 [inline]
check_btf_info kernel/bpf/verifier.c:10049 [inline]
bpf_check+0xd634/0x150d0 kernel/bpf/verifier.c:13759
bpf_prog_load kernel/bpf/syscall.c:2301 [inline]
__sys_bpf+0x11181/0x126e0 kernel/bpf/syscall.c:4587
__do_sys_bpf kernel/bpf/syscall.c:4691 [inline]
__se_sys_bpf kernel/bpf/syscall.c:4689 [inline]
__x64_sys_bpf+0x78/0x90 kernel/bpf/syscall.c:4689
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
Reported-by: syzbot+f3e749d4c662818ae439@syzkaller.appspotmail.com
Signed-off-by: Bixuan Cui <cuibixuan@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210911005557.45518-1-cuibixuan@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
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Andrey Ignatov
|
b0491ab7d4 |
bpf: Fix possible out of bound write in narrow load handling
[ Upstream commit d7af7e497f0308bc97809cc48b58e8e0f13887e1 ]
Fix a verifier bug found by smatch static checker in [0].
This problem has never been seen in prod to my best knowledge. Fixing it
still seems to be a good idea since it's hard to say for sure whether
it's possible or not to have a scenario where a combination of
convert_ctx_access() and a narrow load would lead to an out of bound
write.
When narrow load is handled, one or two new instructions are added to
insn_buf array, but before it was only checked that
cnt >= ARRAY_SIZE(insn_buf)
And it's safe to add a new instruction to insn_buf[cnt++] only once. The
second try will lead to out of bound write. And this is what can happen
if `shift` is set.
Fix it by making sure that if the BPF_RSH instruction has to be added in
addition to BPF_AND then there is enough space for two more instructions
in insn_buf.
The full report [0] is below:
kernel/bpf/verifier.c:12304 convert_ctx_accesses() warn: offset 'cnt' incremented past end of array
kernel/bpf/verifier.c:12311 convert_ctx_accesses() warn: offset 'cnt' incremented past end of array
kernel/bpf/verifier.c
12282
12283 insn->off = off & ~(size_default - 1);
12284 insn->code = BPF_LDX | BPF_MEM | size_code;
12285 }
12286
12287 target_size = 0;
12288 cnt = convert_ctx_access(type, insn, insn_buf, env->prog,
12289 &target_size);
12290 if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) ||
^^^^^^^^^^^^^^^^^^^^^^^^^^^
Bounds check.
12291 (ctx_field_size && !target_size)) {
12292 verbose(env, "bpf verifier is misconfigured\n");
12293 return -EINVAL;
12294 }
12295
12296 if (is_narrower_load && size < target_size) {
12297 u8 shift = bpf_ctx_narrow_access_offset(
12298 off, size, size_default) * 8;
12299 if (ctx_field_size <= 4) {
12300 if (shift)
12301 insn_buf[cnt++] = BPF_ALU32_IMM(BPF_RSH,
^^^^^
increment beyond end of array
12302 insn->dst_reg,
12303 shift);
--> 12304 insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg,
^^^^^
out of bounds write
12305 (1 << size * 8) - 1);
12306 } else {
12307 if (shift)
12308 insn_buf[cnt++] = BPF_ALU64_IMM(BPF_RSH,
12309 insn->dst_reg,
12310 shift);
12311 insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg,
^^^^^^^^^^^^^^^
Same.
12312 (1ULL << size * 8) - 1);
12313 }
12314 }
12315
12316 new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
12317 if (!new_prog)
12318 return -ENOMEM;
12319
12320 delta += cnt - 1;
12321
12322 /* keep walking new program and skip insns we just inserted */
12323 env->prog = new_prog;
12324 insn = new_prog->insnsi + i + delta;
12325 }
12326
12327 return 0;
12328 }
[0] https://lore.kernel.org/bpf/20210817050843.GA21456@kili/
v1->v2:
- clarify that problem was only seen by static checker but not in prod;
Fixes:
|
||
|
He Fengqing
|
389dfd1147 |
bpf: Fix potential memleak and UAF in the verifier.
[ Upstream commit 75f0fc7b48ad45a2e5736bcf8de26c8872fe8695 ]
In bpf_patch_insn_data(), we first use the bpf_patch_insn_single() to
insert new instructions, then use adjust_insn_aux_data() to adjust
insn_aux_data. If the old env->prog have no enough room for new inserted
instructions, we use bpf_prog_realloc to construct new_prog and free the
old env->prog.
There have two errors here. First, if adjust_insn_aux_data() return
ENOMEM, we should free the new_prog. Second, if adjust_insn_aux_data()
return ENOMEM, bpf_patch_insn_data() will return NULL, and env->prog has
been freed in bpf_prog_realloc, but we will use it in bpf_check().
So in this patch, we make the adjust_insn_aux_data() never fails. In
bpf_patch_insn_data(), we first pre-malloc memory for the new
insn_aux_data, then call bpf_patch_insn_single() to insert new
instructions, at last call adjust_insn_aux_data() to adjust
insn_aux_data.
Fixes:
|
||
|
Yonghong Song
|
0c9a876f28 |
bpf: Fix potentially incorrect results with bpf_get_local_storage()
commit a2baf4e8bb0f306fbed7b5e6197c02896a638ab5 upstream.
Commit b910eaaaa4b8 ("bpf: Fix NULL pointer dereference in bpf_get_local_storage()
helper") fixed a bug for bpf_get_local_storage() helper so different tasks
won't mess up with each other's percpu local storage.
The percpu data contains 8 slots so it can hold up to 8 contexts (same or
different tasks), for 8 different program runs, at the same time. This in
general is sufficient. But our internal testing showed the following warning
multiple times:
[...]
warning: WARNING: CPU: 13 PID: 41661 at include/linux/bpf-cgroup.h:193
__cgroup_bpf_run_filter_sock_ops+0x13e/0x180
RIP: 0010:__cgroup_bpf_run_filter_sock_ops+0x13e/0x180
<IRQ>
tcp_call_bpf.constprop.99+0x93/0xc0
tcp_conn_request+0x41e/0xa50
? tcp_rcv_state_process+0x203/0xe00
tcp_rcv_state_process+0x203/0xe00
? sk_filter_trim_cap+0xbc/0x210
? tcp_v6_inbound_md5_hash.constprop.41+0x44/0x160
tcp_v6_do_rcv+0x181/0x3e0
tcp_v6_rcv+0xc65/0xcb0
ip6_protocol_deliver_rcu+0xbd/0x450
ip6_input_finish+0x11/0x20
ip6_input+0xb5/0xc0
ip6_sublist_rcv_finish+0x37/0x50
ip6_sublist_rcv+0x1dc/0x270
ipv6_list_rcv+0x113/0x140
__netif_receive_skb_list_core+0x1a0/0x210
netif_receive_skb_list_internal+0x186/0x2a0
gro_normal_list.part.170+0x19/0x40
napi_complete_done+0x65/0x150
mlx5e_napi_poll+0x1ae/0x680
__napi_poll+0x25/0x120
net_rx_action+0x11e/0x280
__do_softirq+0xbb/0x271
irq_exit_rcu+0x97/0xa0
common_interrupt+0x7f/0xa0
</IRQ>
asm_common_interrupt+0x1e/0x40
RIP: 0010:bpf_prog_1835a9241238291a_tw_egress+0x5/0xbac
? __cgroup_bpf_run_filter_skb+0x378/0x4e0
? do_softirq+0x34/0x70
? ip6_finish_output2+0x266/0x590
? ip6_finish_output+0x66/0xa0
? ip6_output+0x6c/0x130
? ip6_xmit+0x279/0x550
? ip6_dst_check+0x61/0xd0
[...]
Using drgn [0] to dump the percpu buffer contents showed that on this CPU
slot 0 is still available, but slots 1-7 are occupied and those tasks in
slots 1-7 mostly don't exist any more. So we might have issues in
bpf_cgroup_storage_unset().
Further debugging confirmed that there is a bug in bpf_cgroup_storage_unset().
Currently, it tries to unset "current" slot with searching from the start.
So the following sequence is possible:
1. A task is running and claims slot 0
2. Running BPF program is done, and it checked slot 0 has the "task"
and ready to reset it to NULL (not yet).
3. An interrupt happens, another BPF program runs and it claims slot 1
with the *same* task.
4. The unset() in interrupt context releases slot 0 since it matches "task".
5. Interrupt is done, the task in process context reset slot 0.
At the end, slot 1 is not reset and the same process can continue to occupy
slots 2-7 and finally, when the above step 1-5 is repeated again, step 3 BPF
program won't be able to claim an empty slot and a warning will be issued.
To fix the issue, for unset() function, we should traverse from the last slot
to the first. This way, the above issue can be avoided.
The same reverse traversal should also be done in bpf_get_local_storage() helper
itself. Otherwise, incorrect local storage may be returned to BPF program.
[0] https://github.com/osandov/drgn
Fixes: b910eaaaa4b8 ("bpf: Fix NULL pointer dereference in bpf_get_local_storage() helper")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210810010413.1976277-1-yhs@fb.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
||
|
Yonghong Song
|
d81ddadabd |
bpf: Fix NULL pointer dereference in bpf_get_local_storage() helper
commit b910eaaaa4b89976ef02e5d6448f3f73dc671d91 upstream.
Jiri Olsa reported a bug ([1]) in kernel where cgroup local
storage pointer may be NULL in bpf_get_local_storage() helper.
There are two issues uncovered by this bug:
(1). kprobe or tracepoint prog incorrectly sets cgroup local storage
before prog run,
(2). due to change from preempt_disable to migrate_disable,
preemption is possible and percpu storage might be overwritten
by other tasks.
This issue (1) is fixed in [2]. This patch tried to address issue (2).
The following shows how things can go wrong:
task 1: bpf_cgroup_storage_set() for percpu local storage
preemption happens
task 2: bpf_cgroup_storage_set() for percpu local storage
preemption happens
task 1: run bpf program
task 1 will effectively use the percpu local storage setting by task 2
which will be either NULL or incorrect ones.
Instead of just one common local storage per cpu, this patch fixed
the issue by permitting 8 local storages per cpu and each local
storage is identified by a task_struct pointer. This way, we
allow at most 8 nested preemption between bpf_cgroup_storage_set()
and bpf_cgroup_storage_unset(). The percpu local storage slot
is released (calling bpf_cgroup_storage_unset()) by the same task
after bpf program finished running.
bpf_test_run() is also fixed to use the new bpf_cgroup_storage_set()
interface.
The patch is tested on top of [2] with reproducer in [1].
Without this patch, kernel will emit error in 2-3 minutes.
With this patch, after one hour, still no error.
[1] https://lore.kernel.org/bpf/CAKH8qBuXCfUz=w8L+Fj74OaUpbosO29niYwTki7e3Ag044_aww@mail.gmail.com/T
[2] https://lore.kernel.org/bpf/20210309185028.3763817-1-yhs@fb.com
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Roman Gushchin <guro@fb.com>
Link: https://lore.kernel.org/bpf/20210323055146.3334476-1-yhs@fb.com
Cc: <stable@vger.kernel.org> # 5.10.x
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
||
|
Daniel Borkmann
|
9dd6f6d896 |
bpf: Fix ringbuf helper function compatibility
commit 5b029a32cfe4600f5e10e36b41778506b90fd4de upstream. Commit |
||
|
Ilya Leoshkevich
|
585ff7344e |
bpf: Clear zext_dst of dead insns
[ Upstream commit 45c709f8c71b525b51988e782febe84ce933e7e0 ] "access skb fields ok" verifier test fails on s390 with the "verifier bug. zext_dst is set, but no reg is defined" message. The first insns of the test prog are ... 0: 61 01 00 00 00 00 00 00 ldxw %r0,[%r1+0] 8: 35 00 00 01 00 00 00 00 jge %r0,0,1 10: 61 01 00 08 00 00 00 00 ldxw %r0,[%r1+8] ... and the 3rd one is dead (this does not look intentional to me, but this is a separate topic). sanitize_dead_code() converts dead insns into "ja -1", but keeps zext_dst. When opt_subreg_zext_lo32_rnd_hi32() tries to parse such an insn, it sees this discrepancy and bails. This problem can be seen only with JITs whose bpf_jit_needs_zext() returns true. Fix by clearning dead insns' zext_dst. The commits that contributed to this problem are: 1. |
||
|
Tatsuhiko Yasumatsu
|
e95620c3bd |
bpf: Fix integer overflow involving bucket_size
[ Upstream commit c4eb1f403243fc7bbb7de644db8587c03de36da6 ]
In __htab_map_lookup_and_delete_batch(), hash buckets are iterated
over to count the number of elements in each bucket (bucket_size).
If bucket_size is large enough, the multiplication to calculate
kvmalloc() size could overflow, resulting in out-of-bounds write
as reported by KASAN:
[...]
[ 104.986052] BUG: KASAN: vmalloc-out-of-bounds in __htab_map_lookup_and_delete_batch+0x5ce/0xb60
[ 104.986489] Write of size 4194224 at addr ffffc9010503be70 by task crash/112
[ 104.986889]
[ 104.987193] CPU: 0 PID: 112 Comm: crash Not tainted 5.14.0-rc4 #13
[ 104.987552] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
[ 104.988104] Call Trace:
[ 104.988410] dump_stack_lvl+0x34/0x44
[ 104.988706] print_address_description.constprop.0+0x21/0x140
[ 104.988991] ? __htab_map_lookup_and_delete_batch+0x5ce/0xb60
[ 104.989327] ? __htab_map_lookup_and_delete_batch+0x5ce/0xb60
[ 104.989622] kasan_report.cold+0x7f/0x11b
[ 104.989881] ? __htab_map_lookup_and_delete_batch+0x5ce/0xb60
[ 104.990239] kasan_check_range+0x17c/0x1e0
[ 104.990467] memcpy+0x39/0x60
[ 104.990670] __htab_map_lookup_and_delete_batch+0x5ce/0xb60
[ 104.990982] ? __wake_up_common+0x4d/0x230
[ 104.991256] ? htab_of_map_free+0x130/0x130
[ 104.991541] bpf_map_do_batch+0x1fb/0x220
[...]
In hashtable, if the elements' keys have the same jhash() value, the
elements will be put into the same bucket. By putting a lot of elements
into a single bucket, the value of bucket_size can be increased to
trigger the integer overflow.
Triggering the overflow is possible for both callers with CAP_SYS_ADMIN
and callers without CAP_SYS_ADMIN.
It will be trivial for a caller with CAP_SYS_ADMIN to intentionally
reach this overflow by enabling BPF_F_ZERO_SEED. As this flag will set
the random seed passed to jhash() to 0, it will be easy for the caller
to prepare keys which will be hashed into the same value, and thus put
all the elements into the same bucket.
If the caller does not have CAP_SYS_ADMIN, BPF_F_ZERO_SEED cannot be
used. However, it will be still technically possible to trigger the
overflow, by guessing the random seed value passed to jhash() (32bit)
and repeating the attempt to trigger the overflow. In this case,
the probability to trigger the overflow will be low and will take
a very long time.
Fix the integer overflow by calling kvmalloc_array() instead of
kvmalloc() to allocate memory.
Fixes:
|
||
|
Daniel Borkmann
|
be561c0154 |
bpf: Fix pointer arithmetic mask tightening under state pruning
commit e042aa532c84d18ff13291d00620502ce7a38dda upstream.
In 7fedb63a8307 ("bpf: Tighten speculative pointer arithmetic mask") we
narrowed the offset mask for unprivileged pointer arithmetic in order to
mitigate a corner case where in the speculative domain it is possible to
advance, for example, the map value pointer by up to value_size-1 out-of-
bounds in order to leak kernel memory via side-channel to user space.
The verifier's state pruning for scalars leaves one corner case open
where in the first verification path R_x holds an unknown scalar with an
aux->alu_limit of e.g. 7, and in a second verification path that same
register R_x, here denoted as R_x', holds an unknown scalar which has
tighter bounds and would thus satisfy range_within(R_x, R_x') as well as
tnum_in(R_x, R_x') for state pruning, yielding an aux->alu_limit of 3:
Given the second path fits the register constraints for pruning, the final
generated mask from aux->alu_limit will remain at 7. While technically
not wrong for the non-speculative domain, it would however be possible
to craft similar cases where the mask would be too wide as in 7fedb63a8307.
One way to fix it is to detect the presence of unknown scalar map pointer
arithmetic and force a deeper search on unknown scalars to ensure that
we do not run into a masking mismatch.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
||
|
Lorenz Bauer
|
ffb9d5c48b |
bpf: verifier: Allocate idmap scratch in verifier env
commit c9e73e3d2b1eb1ea7ff068e05007eec3bd8ef1c9 upstream. func_states_equal makes a very short lived allocation for idmap, probably because it's too large to fit on the stack. However the function is called quite often, leading to a lot of alloc / free churn. Replace the temporary allocation with dedicated scratch space in struct bpf_verifier_env. Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Edward Cree <ecree.xilinx@gmail.com> Link: https://lore.kernel.org/bpf/20210429134656.122225-4-lmb@cloudflare.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
||
|
Daniel Borkmann
|
a11ca29c65 |
bpf: Remove superfluous aux sanitation on subprog rejection
commit 59089a189e3adde4cf85f2ce479738d1ae4c514d upstream.
Follow-up to fe9a5ca7e370 ("bpf: Do not mark insn as seen under speculative
path verification"). The sanitize_insn_aux_data() helper does not serve a
particular purpose in today's code. The original intention for the helper
was that if function-by-function verification fails, a given program would
be cleared from temporary insn_aux_data[], and then its verification would
be re-attempted in the context of the main program a second time.
However, a failure in do_check_subprogs() will skip do_check_main() and
propagate the error to the user instead, thus such situation can never occur.
Given its interaction is not compatible to the Spectre v1 mitigation (due to
comparing aux->seen with env->pass_cnt), just remove sanitize_insn_aux_data()
to avoid future bugs in this area.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
||
|
Daniel Borkmann
|
0e9280654a |
bpf: Fix leakage due to insufficient speculative store bypass mitigation
[ Upstream commit 2039f26f3aca5b0e419b98f65dd36481337b86ee ] Spectre v4 gadgets make use of memory disambiguation, which is a set of techniques that execute memory access instructions, that is, loads and stores, out of program order; Intel's optimization manual, section 2.4.4.5: A load instruction micro-op may depend on a preceding store. Many microarchitectures block loads until all preceding store addresses are known. The memory disambiguator predicts which loads will not depend on any previous stores. When the disambiguator predicts that a load does not have such a dependency, the load takes its data from the L1 data cache. Eventually, the prediction is verified. If an actual conflict is detected, the load and all succeeding instructions are re-executed. |
||
|
Daniel Borkmann
|
bea9e2fd18 |
bpf: Introduce BPF nospec instruction for mitigating Spectre v4
[ Upstream commit f5e81d1117501546b7be050c5fbafa6efd2c722c ] In case of JITs, each of the JIT backends compiles the BPF nospec instruction /either/ to a machine instruction which emits a speculation barrier /or/ to /no/ machine instruction in case the underlying architecture is not affected by Speculative Store Bypass or has different mitigations in place already. This covers both x86 and (implicitly) arm64: In case of x86, we use 'lfence' instruction for mitigation. In case of arm64, we rely on the firmware mitigation as controlled via the ssbd kernel parameter. Whenever the mitigation is enabled, it works for all of the kernel code with no need to provide any additional instructions here (hence only comment in arm64 JIT). Other archs can follow as needed. The BPF nospec instruction is specifically targeting Spectre v4 since i) we don't use a serialization barrier for the Spectre v1 case, and ii) mitigation instructions for v1 and v4 might be different on some archs. The BPF nospec is required for a future commit, where the BPF verifier does annotate intermediate BPF programs with speculation barriers. Co-developed-by: Piotr Krysiuk <piotras@gmail.com> Co-developed-by: Benedict Schlueter <benedict.schlueter@rub.de> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Piotr Krysiuk <piotras@gmail.com> Signed-off-by: Benedict Schlueter <benedict.schlueter@rub.de> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> |
||
|
Daniel Borkmann
|
39f1735c81 |
bpf: Fix tail_call_reachable rejection for interpreter when jit failed
[ Upstream commit 5dd0a6b8582ffbfa88351949d50eccd5b6694ade ]
During testing of f263a81451c1 ("bpf: Track subprog poke descriptors correctly
and fix use-after-free") under various failure conditions, for example, when
jit_subprogs() fails and tries to clean up the program to be run under the
interpreter, we ran into the following freeze:
[...]
#127/8 tailcall_bpf2bpf_3:FAIL
[...]
[ 92.041251] BUG: KASAN: slab-out-of-bounds in ___bpf_prog_run+0x1b9d/0x2e20
[ 92.042408] Read of size 8 at addr ffff88800da67f68 by task test_progs/682
[ 92.043707]
[ 92.044030] CPU: 1 PID: 682 Comm: test_progs Tainted: G O 5.13.0-53301-ge6c08cb33a30-dirty #87
[ 92.045542] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014
[ 92.046785] Call Trace:
[ 92.047171] ? __bpf_prog_run_args64+0xc0/0xc0
[ 92.047773] ? __bpf_prog_run_args32+0x8b/0xb0
[ 92.048389] ? __bpf_prog_run_args64+0xc0/0xc0
[ 92.049019] ? ktime_get+0x117/0x130
[...] // few hundred [similar] lines more
[ 92.659025] ? ktime_get+0x117/0x130
[ 92.659845] ? __bpf_prog_run_args64+0xc0/0xc0
[ 92.660738] ? __bpf_prog_run_args32+0x8b/0xb0
[ 92.661528] ? __bpf_prog_run_args64+0xc0/0xc0
[ 92.662378] ? print_usage_bug+0x50/0x50
[ 92.663221] ? print_usage_bug+0x50/0x50
[ 92.664077] ? bpf_ksym_find+0x9c/0xe0
[ 92.664887] ? ktime_get+0x117/0x130
[ 92.665624] ? kernel_text_address+0xf5/0x100
[ 92.666529] ? __kernel_text_address+0xe/0x30
[ 92.667725] ? unwind_get_return_address+0x2f/0x50
[ 92.668854] ? ___bpf_prog_run+0x15d4/0x2e20
[ 92.670185] ? ktime_get+0x117/0x130
[ 92.671130] ? __bpf_prog_run_args64+0xc0/0xc0
[ 92.672020] ? __bpf_prog_run_args32+0x8b/0xb0
[ 92.672860] ? __bpf_prog_run_args64+0xc0/0xc0
[ 92.675159] ? ktime_get+0x117/0x130
[ 92.677074] ? lock_is_held_type+0xd5/0x130
[ 92.678662] ? ___bpf_prog_run+0x15d4/0x2e20
[ 92.680046] ? ktime_get+0x117/0x130
[ 92.681285] ? __bpf_prog_run32+0x6b/0x90
[ 92.682601] ? __bpf_prog_run64+0x90/0x90
[ 92.683636] ? lock_downgrade+0x370/0x370
[ 92.684647] ? mark_held_locks+0x44/0x90
[ 92.685652] ? ktime_get+0x117/0x130
[ 92.686752] ? lockdep_hardirqs_on+0x79/0x100
[ 92.688004] ? ktime_get+0x117/0x130
[ 92.688573] ? __cant_migrate+0x2b/0x80
[ 92.689192] ? bpf_test_run+0x2f4/0x510
[ 92.689869] ? bpf_test_timer_continue+0x1c0/0x1c0
[ 92.690856] ? rcu_read_lock_bh_held+0x90/0x90
[ 92.691506] ? __kasan_slab_alloc+0x61/0x80
[ 92.692128] ? eth_type_trans+0x128/0x240
[ 92.692737] ? __build_skb+0x46/0x50
[ 92.693252] ? bpf_prog_test_run_skb+0x65e/0xc50
[ 92.693954] ? bpf_prog_test_run_raw_tp+0x2d0/0x2d0
[ 92.694639] ? __fget_light+0xa1/0x100
[ 92.695162] ? bpf_prog_inc+0x23/0x30
[ 92.695685] ? __sys_bpf+0xb40/0x2c80
[ 92.696324] ? bpf_link_get_from_fd+0x90/0x90
[ 92.697150] ? mark_held_locks+0x24/0x90
[ 92.698007] ? lockdep_hardirqs_on_prepare+0x124/0x220
[ 92.699045] ? finish_task_switch+0xe6/0x370
[ 92.700072] ? lockdep_hardirqs_on+0x79/0x100
[ 92.701233] ? finish_task_switch+0x11d/0x370
[ 92.702264] ? __switch_to+0x2c0/0x740
[ 92.703148] ? mark_held_locks+0x24/0x90
[ 92.704155] ? __x64_sys_bpf+0x45/0x50
[ 92.705146] ? do_syscall_64+0x35/0x80
[ 92.706953] ? entry_SYSCALL_64_after_hwframe+0x44/0xae
[...]
Turns out that the program rejection from
|
||
|
John Fastabend
|
a9f36bf361 |
bpf: Track subprog poke descriptors correctly and fix use-after-free
commit f263a81451c12da5a342d90572e317e611846f2c upstream. Subprograms are calling map_poke_track(), but on program release there is no hook to call map_poke_untrack(). However, on program release, the aux memory (and poke descriptor table) is freed even though we still have a reference to it in the element list of the map aux data. When we run map_poke_run(), we then end up accessing free'd memory, triggering KASAN in prog_array_map_poke_run(): [...] [ 402.824689] BUG: KASAN: use-after-free in prog_array_map_poke_run+0xc2/0x34e [ 402.824698] Read of size 4 at addr ffff8881905a7940 by task hubble-fgs/4337 [ 402.824705] CPU: 1 PID: 4337 Comm: hubble-fgs Tainted: G I 5.12.0+ #399 [ 402.824715] Call Trace: [ 402.824719] dump_stack+0x93/0xc2 [ 402.824727] print_address_description.constprop.0+0x1a/0x140 [ 402.824736] ? prog_array_map_poke_run+0xc2/0x34e [ 402.824740] ? prog_array_map_poke_run+0xc2/0x34e [ 402.824744] kasan_report.cold+0x7c/0xd8 [ 402.824752] ? prog_array_map_poke_run+0xc2/0x34e [ 402.824757] prog_array_map_poke_run+0xc2/0x34e [ 402.824765] bpf_fd_array_map_update_elem+0x124/0x1a0 [...] The elements concerned are walked as follows: for (i = 0; i < elem->aux->size_poke_tab; i++) { poke = &elem->aux->poke_tab[i]; [...] The access to size_poke_tab is a 4 byte read, verified by checking offsets in the KASAN dump: [ 402.825004] The buggy address belongs to the object at ffff8881905a7800 which belongs to the cache kmalloc-1k of size 1024 [ 402.825008] The buggy address is located 320 bytes inside of 1024-byte region [ffff8881905a7800, ffff8881905a7c00) The pahole output of bpf_prog_aux: struct bpf_prog_aux { [...] /* --- cacheline 5 boundary (320 bytes) --- */ u32 size_poke_tab; /* 320 4 */ [...] In general, subprograms do not necessarily manage their own data structures. For example, BTF func_info and linfo are just pointers to the main program structure. This allows reference counting and cleanup to be done on the latter which simplifies their management a bit. The aux->poke_tab struct, however, did not follow this logic. The initial proposed fix for this use-after-free bug further embedded poke data tracking into the subprogram with proper reference counting. However, Daniel and Alexei questioned why we were treating these objects special; I agree, its unnecessary. The fix here removes the per subprogram poke table allocation and map tracking and instead simply points the aux->poke_tab pointer at the main programs poke table. This way, map tracking is simplified to the main program and we do not need to manage them per subprogram. This also means, bpf_prog_free_deferred(), which unwinds the program reference counting and kfrees objects, needs to ensure that we don't try to double free the poke_tab when free'ing the subprog structures. This is easily solved by NULL'ing the poke_tab pointer. The second detail is to ensure that per subprogram JIT logic only does fixups on poke_tab[] entries it owns. To do this, we add a pointer in the poke structure to point at the subprogram value so JITs can easily check while walking the poke_tab structure if the current entry belongs to the current program. The aux pointer is stable and therefore suitable for such comparison. On the jit_subprogs() error path, we omit cleaning up the poke->aux field because these are only ever referenced from the JIT side, but on error we will never make it to the JIT, so its fine to leave them dangling. Removing these pointers would complicate the error path for no reason. However, we do need to untrack all poke descriptors from the main program as otherwise they could race with the freeing of JIT memory from the subprograms. Lastly, |
||
|
Rustam Kovhaev
|
a61af01141 |
bpf: Fix false positive kmemleak report in bpf_ringbuf_area_alloc()
[ Upstream commit ccff81e1d028bbbf8573d3364a87542386c707bf ]
kmemleak scans struct page, but it does not scan the page content. If we
allocate some memory with kmalloc(), then allocate page with alloc_page(),
and if we put kmalloc pointer somewhere inside that page, kmemleak will
report kmalloc pointer as a false positive.
We can instruct kmemleak to scan the memory area by calling kmemleak_alloc()
and kmemleak_free(), but part of struct bpf_ringbuf is mmaped to user space,
and if struct bpf_ringbuf changes we would have to revisit and review size
argument in kmemleak_alloc(), because we do not want kmemleak to scan the
user space memory. Let's simplify things and use kmemleak_not_leak() here.
For posterity, also adding additional prior analysis from Andrii:
I think either kmemleak or syzbot are misreporting this. I've added a
bunch of printks around all allocations performed by BPF ringbuf. [...]
On repro side I get these two warnings:
[vmuser@archvm bpf]$ sudo ./repro
BUG: memory leak
unreferenced object 0xffff88810d538c00 (size 64):
comm "repro", pid 2140, jiffies 4294692933 (age 14.540s)
hex dump (first 32 bytes):
00 af 19 04 00 ea ff ff c0 ae 19 04 00 ea ff ff ................
80 ae 19 04 00 ea ff ff c0 29 2e 04 00 ea ff ff .........)......
backtrace:
[<0000000077bfbfbd>] __bpf_map_area_alloc+0x31/0xc0
[<00000000587fa522>] ringbuf_map_alloc.cold.4+0x48/0x218
[<0000000044d49e96>] __do_sys_bpf+0x359/0x1d90
[<00000000f601d565>] do_syscall_64+0x2d/0x40
[<0000000043d3112a>] entry_SYSCALL_64_after_hwframe+0x44/0xae
BUG: memory leak
unreferenced object 0xffff88810d538c80 (size 64):
comm "repro", pid 2143, jiffies 4294699025 (age 8.448s)
hex dump (first 32 bytes):
80 aa 19 04 00 ea ff ff 00 ab 19 04 00 ea ff ff ................
c0 ab 19 04 00 ea ff ff 80 44 28 04 00 ea ff ff .........D(.....
backtrace:
[<0000000077bfbfbd>] __bpf_map_area_alloc+0x31/0xc0
[<00000000587fa522>] ringbuf_map_alloc.cold.4+0x48/0x218
[<0000000044d49e96>] __do_sys_bpf+0x359/0x1d90
[<00000000f601d565>] do_syscall_64+0x2d/0x40
[<0000000043d3112a>] entry_SYSCALL_64_after_hwframe+0x44/0xae
Note that both reported leaks (ffff88810d538c80 and ffff88810d538c00)
correspond to pages array bpf_ringbuf is allocating and tracking properly
internally. Note also that syzbot repro doesn't close FD of created BPF
ringbufs, and even when ./repro itself exits with error, there are still
two forked processes hanging around in my system. So clearly ringbuf maps
are alive at that point. So reporting any memory leak looks weird at that
point, because that memory is being used by active referenced BPF ringbuf.
It's also a question why repro doesn't clean up its forks. But if I do a
`pkill repro`, I do see that all the allocated memory is /properly/ cleaned
up [and the] "leaks" are deallocated properly.
BTW, if I add close() right after bpf() syscall in syzbot repro, I see that
everything is immediately deallocated, like designed. And no memory leak
is reported. So I don't think the problem is anywhere in bpf_ringbuf code,
rather in the leak detection and/or repro itself.
Reported-by: syzbot+5d895828587f49e7fe9b@syzkaller.appspotmail.com
Signed-off-by: Rustam Kovhaev <rkovhaev@gmail.com>
[ Daniel: also included analysis from Andrii to the commit log ]
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: syzbot+5d895828587f49e7fe9b@syzkaller.appspotmail.com
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/CAEf4BzYk+dqs+jwu6VKXP-RttcTEGFe+ySTGWT9CRNkagDiJVA@mail.gmail.com
Link: https://lore.kernel.org/lkml/YNTAqiE7CWJhOK2M@nuc10
Link: https://lore.kernel.org/lkml/20210615101515.GC26027@arm.com
Link: https://syzkaller.appspot.com/bug?extid=5d895828587f49e7fe9b
Link: https://lore.kernel.org/bpf/20210626181156.1873604-1-rkovhaev@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
||
|
Daniel Borkmann
|
2e66c36f13 |
bpf: Fix up register-based shifts in interpreter to silence KUBSAN
[ Upstream commit 28131e9d933339a92f78e7ab6429f4aaaa07061c ] syzbot reported a shift-out-of-bounds that KUBSAN observed in the interpreter: [...] UBSAN: shift-out-of-bounds in kernel/bpf/core.c:1420:2 shift exponent 255 is too large for 64-bit type 'long long unsigned int' CPU: 1 PID: 11097 Comm: syz-executor.4 Not tainted 5.12.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x141/0x1d7 lib/dump_stack.c:120 ubsan_epilogue+0xb/0x5a lib/ubsan.c:148 __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:327 ___bpf_prog_run.cold+0x19/0x56c kernel/bpf/core.c:1420 __bpf_prog_run32+0x8f/0xd0 kernel/bpf/core.c:1735 bpf_dispatcher_nop_func include/linux/bpf.h:644 [inline] bpf_prog_run_pin_on_cpu include/linux/filter.h:624 [inline] bpf_prog_run_clear_cb include/linux/filter.h:755 [inline] run_filter+0x1a1/0x470 net/packet/af_packet.c:2031 packet_rcv+0x313/0x13e0 net/packet/af_packet.c:2104 dev_queue_xmit_nit+0x7c2/0xa90 net/core/dev.c:2387 xmit_one net/core/dev.c:3588 [inline] dev_hard_start_xmit+0xad/0x920 net/core/dev.c:3609 __dev_queue_xmit+0x2121/0x2e00 net/core/dev.c:4182 __bpf_tx_skb net/core/filter.c:2116 [inline] __bpf_redirect_no_mac net/core/filter.c:2141 [inline] __bpf_redirect+0x548/0xc80 net/core/filter.c:2164 ____bpf_clone_redirect net/core/filter.c:2448 [inline] bpf_clone_redirect+0x2ae/0x420 net/core/filter.c:2420 ___bpf_prog_run+0x34e1/0x77d0 kernel/bpf/core.c:1523 __bpf_prog_run512+0x99/0xe0 kernel/bpf/core.c:1737 bpf_dispatcher_nop_func include/linux/bpf.h:644 [inline] bpf_test_run+0x3ed/0xc50 net/bpf/test_run.c:50 bpf_prog_test_run_skb+0xabc/0x1c50 net/bpf/test_run.c:582 bpf_prog_test_run kernel/bpf/syscall.c:3127 [inline] __do_sys_bpf+0x1ea9/0x4f00 kernel/bpf/syscall.c:4406 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae [...] Generally speaking, KUBSAN reports from the kernel should be fixed. However, in case of BPF, this particular report caused concerns since the large shift is not wrong from BPF point of view, just undefined. In the verifier, K-based shifts that are >= {64,32} (depending on the bitwidth of the instruction) are already rejected. The register-based cases were not given their content might not be known at verification time. Ideas such as verifier instruction rewrite with an additional AND instruction for the source register were brought up, but regularly rejected due to the additional runtime overhead they incur. As Edward Cree rightly put it: Shifts by more than insn bitness are legal in the BPF ISA; they are implementation-defined behaviour [of the underlying architecture], rather than UB, and have been made legal for performance reasons. Each of the JIT backends compiles the BPF shift operations to machine instructions which produce implementation-defined results in such a case; the resulting contents of the register may be arbitrary but program behaviour as a whole remains defined. Guard checks in the fast path (i.e. affecting JITted code) will thus not be accepted. The case of division by zero is not truly analogous here, as division instructions on many of the JIT-targeted architectures will raise a machine exception / fault on division by zero, whereas (to the best of my knowledge) none will do so on an out-of-bounds shift. Given the KUBSAN report only affects the BPF interpreter, but not JITs, one solution is to add the ANDs with 63 or 31 into ___bpf_prog_run(). That would make the shifts defined, and thus shuts up KUBSAN, and the compiler would optimize out the AND on any CPU that interprets the shift amounts modulo the width anyway (e.g., confirmed from disassembly that on x86-64 and arm64 the generated interpreter code is the same before and after this fix). The BPF interpreter is slow path, and most likely compiled out anyway as distros select BPF_JIT_ALWAYS_ON to avoid speculative execution of BPF instructions by the interpreter. Given the main argument was to avoid sacrificing performance, the fact that the AND is optimized away from compiler for mainstream archs helps as well as a solution moving forward. Also add a comment on LSH/RSH/ARSH translation for JIT authors to provide guidance when they see the ___bpf_prog_run() interpreter code and use it as a model for a new JIT backend. Reported-by: syzbot+bed360704c521841c85d@syzkaller.appspotmail.com Reported-by: Kurt Manucredo <fuzzybritches0@gmail.com> Signed-off-by: Eric Biggers <ebiggers@kernel.org> Co-developed-by: Eric Biggers <ebiggers@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Tested-by: syzbot+bed360704c521841c85d@syzkaller.appspotmail.com Cc: Edward Cree <ecree.xilinx@gmail.com> Link: https://lore.kernel.org/bpf/0000000000008f912605bd30d5d7@google.com Link: https://lore.kernel.org/bpf/bac16d8d-c174-bdc4-91bd-bfa62b410190@gmail.com Signed-off-by: Sasha Levin <sashal@kernel.org> |
||
|
John Fastabend
|
f97b9c4c07 |
bpf: Fix null ptr deref with mixed tail calls and subprogs
[ Upstream commit 7506d211b932870155bcb39e3dd9e39fab45a7c7 ]
The sub-programs prog->aux->poke_tab[] is populated in jit_subprogs() and
then used when emitting 'BPF_JMP|BPF_TAIL_CALL' insn->code from the
individual JITs. The poke_tab[] to use is stored in the insn->imm by
the code adding it to that array slot. The JIT then uses imm to find the
right entry for an individual instruction. In the x86 bpf_jit_comp.c
this is done by calling emit_bpf_tail_call_direct with the poke_tab[]
of the imm value.
However, we observed the below null-ptr-deref when mixing tail call
programs with subprog programs. For this to happen we just need to
mix bpf-2-bpf calls and tailcalls with some extra calls or instructions
that would be patched later by one of the fixup routines. So whats
happening?
Before the fixup_call_args() -- where the jit op is done -- various
code patching is done by do_misc_fixups(). This may increase the
insn count, for example when we patch map_lookup_up using map_gen_lookup
hook. This does two things. First, it means the instruction index,
insn_idx field, of a tail call instruction will move by a 'delta'.
In verifier code,
struct bpf_jit_poke_descriptor desc = {
.reason = BPF_POKE_REASON_TAIL_CALL,
.tail_call.map = BPF_MAP_PTR(aux->map_ptr_state),
.tail_call.key = bpf_map_key_immediate(aux),
.insn_idx = i + delta,
};
Then subprog start values subprog_info[i].start will be updated
with the delta and any poke descriptor index will also be updated
with the delta in adjust_poke_desc(). If we look at the adjust
subprog starts though we see its only adjusted when the delta
occurs before the new instructions,
/* NOTE: fake 'exit' subprog should be updated as well. */
for (i = 0; i <= env->subprog_cnt; i++) {
if (env->subprog_info[i].start <= off)
continue;
Earlier subprograms are not changed because their start values
are not moved. But, adjust_poke_desc() does the offset + delta
indiscriminately. The result is poke descriptors are potentially
corrupted.
Then in jit_subprogs() we only populate the poke_tab[]
when the above insn_idx is less than the next subprogram start. From
above we corrupted our insn_idx so we might incorrectly assume a
poke descriptor is not used in a subprogram omitting it from the
subprogram. And finally when the jit runs it does the deref of poke_tab
when emitting the instruction and crashes with below. Because earlier
step omitted the poke descriptor.
The fix is straight forward with above context. Simply move same logic
from adjust_subprog_starts() into adjust_poke_descs() and only adjust
insn_idx when needed.
[ 82.396354] bpf_testmod: version magic '5.12.0-rc2alu+ SMP preempt mod_unload ' should be '5.12.0+ SMP preempt mod_unload '
[ 82.623001] loop10: detected capacity change from 0 to 8
[ 88.487424] ==================================================================
[ 88.487438] BUG: KASAN: null-ptr-deref in do_jit+0x184a/0x3290
[ 88.487455] Write of size 8 at addr 0000000000000008 by task test_progs/5295
[ 88.487471] CPU: 7 PID: 5295 Comm: test_progs Tainted: G I 5.12.0+ #386
[ 88.487483] Hardware name: Dell Inc. Precision 5820 Tower/002KVM, BIOS 1.9.2 01/24/2019
[ 88.487490] Call Trace:
[ 88.487498] dump_stack+0x93/0xc2
[ 88.487515] kasan_report.cold+0x5f/0xd8
[ 88.487530] ? do_jit+0x184a/0x3290
[ 88.487542] do_jit+0x184a/0x3290
...
[ 88.487709] bpf_int_jit_compile+0x248/0x810
...
[ 88.487765] bpf_check+0x3718/0x5140
...
[ 88.487920] bpf_prog_load+0xa22/0xf10
Fixes:
|
||
|
Daniel Borkmann
|
8c82c52d1d |
bpf: Do not mark insn as seen under speculative path verification
[ Upstream commit fe9a5ca7e370e613a9a75a13008a3845ea759d6e ] ... in such circumstances, we do not want to mark the instruction as seen given the goal is still to jmp-1 rewrite/sanitize dead code, if it is not reachable from the non-speculative path verification. We do however want to verify it for safety regardless. With the patch as-is all the insns that have been marked as seen before the patch will also be marked as seen after the patch (just with a potentially different non-zero count). An upcoming patch will also verify paths that are unreachable in the non-speculative domain, hence this extension is needed. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: John Fastabend <john.fastabend@gmail.com> Reviewed-by: Benedict Schlueter <benedict.schlueter@rub.de> Reviewed-by: Piotr Krysiuk <piotras@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> |
||
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Daniel Borkmann
|
e9d271731d |
bpf: Inherit expanded/patched seen count from old aux data
[ Upstream commit d203b0fd863a2261e5d00b97f3d060c4c2a6db71 ] Instead of relying on current env->pass_cnt, use the seen count from the old aux data in adjust_insn_aux_data(), and expand it to the new range of patched instructions. This change is valid given we always expand 1:n with n>=1, so what applies to the old/original instruction needs to apply for the replacement as well. Not relying on env->pass_cnt is a prerequisite for a later change where we want to avoid marking an instruction seen when verified under speculative execution path. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: John Fastabend <john.fastabend@gmail.com> Reviewed-by: Benedict Schlueter <benedict.schlueter@rub.de> Reviewed-by: Piotr Krysiuk <piotras@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> |
||
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Daniel Borkmann
|
5fc6ed1831 |
bpf: Fix leakage under speculation on mispredicted branches
[ Upstream commit 9183671af6dbf60a1219371d4ed73e23f43b49db ]
The verifier only enumerates valid control-flow paths and skips paths that
are unreachable in the non-speculative domain. And so it can miss issues
under speculative execution on mispredicted branches.
For example, a type confusion has been demonstrated with the following
crafted program:
// r0 = pointer to a map array entry
// r6 = pointer to readable stack slot
// r9 = scalar controlled by attacker
1: r0 = *(u64 *)(r0) // cache miss
2: if r0 != 0x0 goto line 4
3: r6 = r9
4: if r0 != 0x1 goto line 6
5: r9 = *(u8 *)(r6)
6: // leak r9
Since line 3 runs iff r0 == 0 and line 5 runs iff r0 == 1, the verifier
concludes that the pointer dereference on line 5 is safe. But: if the
attacker trains both the branches to fall-through, such that the following
is speculatively executed ...
r6 = r9
r9 = *(u8 *)(r6)
// leak r9
... then the program will dereference an attacker-controlled value and could
leak its content under speculative execution via side-channel. This requires
to mistrain the branch predictor, which can be rather tricky, because the
branches are mutually exclusive. However such training can be done at
congruent addresses in user space using different branches that are not
mutually exclusive. That is, by training branches in user space ...
A: if r0 != 0x0 goto line C
B: ...
C: if r0 != 0x0 goto line D
D: ...
... such that addresses A and C collide to the same CPU branch prediction
entries in the PHT (pattern history table) as those of the BPF program's
lines 2 and 4, respectively. A non-privileged attacker could simply brute
force such collisions in the PHT until observing the attack succeeding.
Alternative methods to mistrain the branch predictor are also possible that
avoid brute forcing the collisions in the PHT. A reliable attack has been
demonstrated, for example, using the following crafted program:
// r0 = pointer to a [control] map array entry
// r7 = *(u64 *)(r0 + 0), training/attack phase
// r8 = *(u64 *)(r0 + 8), oob address
// [...]
// r0 = pointer to a [data] map array entry
1: if r7 == 0x3 goto line 3
2: r8 = r0
// crafted sequence of conditional jumps to separate the conditional
// branch in line 193 from the current execution flow
3: if r0 != 0x0 goto line 5
4: if r0 == 0x0 goto exit
5: if r0 != 0x0 goto line 7
6: if r0 == 0x0 goto exit
[...]
187: if r0 != 0x0 goto line 189
188: if r0 == 0x0 goto exit
// load any slowly-loaded value (due to cache miss in phase 3) ...
189: r3 = *(u64 *)(r0 + 0x1200)
// ... and turn it into known zero for verifier, while preserving slowly-
// loaded dependency when executing:
190: r3 &= 1
191: r3 &= 2
// speculatively bypassed phase dependency
192: r7 += r3
193: if r7 == 0x3 goto exit
194: r4 = *(u8 *)(r8 + 0)
// leak r4
As can be seen, in training phase (phase != 0x3), the condition in line 1
turns into false and therefore r8 with the oob address is overridden with
the valid map value address, which in line 194 we can read out without
issues. However, in attack phase, line 2 is skipped, and due to the cache
miss in line 189 where the map value is (zeroed and later) added to the
phase register, the condition in line 193 takes the fall-through path due
to prior branch predictor training, where under speculation, it'll load the
byte at oob address r8 (unknown scalar type at that point) which could then
be leaked via side-channel.
One way to mitigate these is to 'branch off' an unreachable path, meaning,
the current verification path keeps following the is_branch_taken() path
and we push the other branch to the verification stack. Given this is
unreachable from the non-speculative domain, this branch's vstate is
explicitly marked as speculative. This is needed for two reasons: i) if
this path is solely seen from speculative execution, then we later on still
want the dead code elimination to kick in in order to sanitize these
instructions with jmp-1s, and ii) to ensure that paths walked in the
non-speculative domain are not pruned from earlier walks of paths walked in
the speculative domain. Additionally, for robustness, we mark the registers
which have been part of the conditional as unknown in the speculative path
given there should be no assumptions made on their content.
The fix in here mitigates type confusion attacks described earlier due to
i) all code paths in the BPF program being explored and ii) existing
verifier logic already ensuring that given memory access instruction
references one specific data structure.
An alternative to this fix that has also been looked at in this scope was to
mark aux->alu_state at the jump instruction with a BPF_JMP_TAKEN state as
well as direction encoding (always-goto, always-fallthrough, unknown), such
that mixing of different always-* directions themselves as well as mixing of
always-* with unknown directions would cause a program rejection by the
verifier, e.g. programs with constructs like 'if ([...]) { x = 0; } else
{ x = 1; }' with subsequent 'if (x == 1) { [...] }'. For unprivileged, this
would result in only single direction always-* taken paths, and unknown taken
paths being allowed, such that the former could be patched from a conditional
jump to an unconditional jump (ja). Compared to this approach here, it would
have two downsides: i) valid programs that otherwise are not performing any
pointer arithmetic, etc, would potentially be rejected/broken, and ii) we are
required to turn off path pruning for unprivileged, where both can be avoided
in this work through pushing the invalid branch to the verification stack.
The issue was originally discovered by Adam and Ofek, and later independently
discovered and reported as a result of Benedict and Piotr's research work.
Fixes:
|
||
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Jiri Olsa
|
584b2c7ce2 |
bpf: Forbid trampoline attach for functions with variable arguments
[ Upstream commit 31379397dcc364a59ce764fabb131b645c43e340 ] We can't currently allow to attach functions with variable arguments. The problem is that we should save all the registers for arguments, which is probably doable, but if caller uses more than 6 arguments, we need stack data, which will be wrong, because of the extra stack frame we do in bpf trampoline, so we could crash. Also currently there's malformed trampoline code generated for such functions at the moment as described in: https://lore.kernel.org/bpf/20210429212834.82621-1-jolsa@kernel.org/ Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210505132529.401047-1-jolsa@kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org> |
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Daniel Borkmann
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ff5039ec75 |
bpf, lockdown, audit: Fix buggy SELinux lockdown permission checks
[ Upstream commit ff40e51043af63715ab413995ff46996ecf9583f ] Commit |
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Tobias Klauser
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cdf3f6db1a |
bpf: Simplify cases in bpf_base_func_proto
[ Upstream commit 61ca36c8c4eb3bae35a285b1ae18c514cde65439 ] !perfmon_capable() is checked before the last switch(func_id) in bpf_base_func_proto. Thus, the cases BPF_FUNC_trace_printk and BPF_FUNC_snprintf_btf can be moved to that last switch(func_id) to omit the inline !perfmon_capable() checks. Signed-off-by: Tobias Klauser <tklauser@distanz.ch> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20210127174615.3038-1-tklauser@distanz.ch Signed-off-by: Sasha Levin <sashal@kernel.org> |
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Yinjun Zhang
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24cb8bb7f6 |
bpf, offload: Reorder offload callback 'prepare' in verifier
[ Upstream commit ceb11679d9fcf3fdb358a310a38760fcbe9b63ed ] Commit |
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Daniel Borkmann
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27acfd11ba |
bpf: No need to simulate speculative domain for immediates
commit a7036191277f9fa68d92f2071ddc38c09b1e5ee5 upstream.
In 801c6058d14a ("bpf: Fix leakage of uninitialized bpf stack under
speculation") we replaced masking logic with direct loads of immediates
if the register is a known constant. Given in this case we do not apply
any masking, there is also no reason for the operation to be truncated
under the speculative domain.
Therefore, there is also zero reason for the verifier to branch-off and
simulate this case, it only needs to do it for unknown but bounded scalars.
As a side-effect, this also enables few test cases that were previously
rejected due to simulation under zero truncation.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Piotr Krysiuk <piotras@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Daniel Borkmann
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c87ef240a8 |
bpf: Fix mask direction swap upon off reg sign change
commit bb01a1bba579b4b1c5566af24d95f1767859771e upstream.
Masking direction as indicated via mask_to_left is considered to be
calculated once and then used to derive pointer limits. Thus, this
needs to be placed into bpf_sanitize_info instead so we can pass it
to sanitize_ptr_alu() call after the pointer move. Piotr noticed a
corner case where the off reg causes masking direction change which
then results in an incorrect final aux->alu_limit.
Fixes: 7fedb63a8307 ("bpf: Tighten speculative pointer arithmetic mask")
Reported-by: Piotr Krysiuk <piotras@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Piotr Krysiuk <piotras@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Daniel Borkmann
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4e2c7b2974 |
bpf: Wrap aux data inside bpf_sanitize_info container
commit 3d0220f6861d713213b015b582e9f21e5b28d2e0 upstream. Add a container structure struct bpf_sanitize_info which holds the current aux info, and update call-sites to sanitize_ptr_alu() to pass it in. This is needed for passing in additional state later on. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Piotr Krysiuk <piotras@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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Andrii Nakryiko
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00d9f429af |
bpf: Prevent writable memory-mapping of read-only ringbuf pages
commit 04ea3086c4d73da7009de1e84962a904139af219 upstream.
Only the very first page of BPF ringbuf that contains consumer position
counter is supposed to be mapped as writeable by user-space. Producer
position is read-only and can be modified only by the kernel code. BPF ringbuf
data pages are read-only as well and are not meant to be modified by
user-code to maintain integrity of per-record headers.
This patch allows to map only consumer position page as writeable and
everything else is restricted to be read-only. remap_vmalloc_range()
internally adds VM_DONTEXPAND, so all the established memory mappings can't be
extended, which prevents any future violations through mremap()'ing.
Fixes:
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Thadeu Lima de Souza Cascardo
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1ca284f086 |
bpf, ringbuf: Deny reserve of buffers larger than ringbuf
commit 4b81ccebaeee885ab1aa1438133f2991e3a2b6ea upstream.
A BPF program might try to reserve a buffer larger than the ringbuf size.
If the consumer pointer is way ahead of the producer, that would be
successfully reserved, allowing the BPF program to read or write out of
the ringbuf allocated area.
Reported-by: Ryota Shiga (Flatt Security)
Fixes:
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Daniel Borkmann
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282bfc8848 |
bpf: Fix alu32 const subreg bound tracking on bitwise operations
commit 049c4e13714ecbca567b4d5f6d563f05d431c80e upstream.
Fix a bug in the verifier's scalar32_min_max_*() functions which leads to
incorrect tracking of 32 bit bounds for the simulation of and/or/xor bitops.
When both the src & dst subreg is a known constant, then the assumption is
that scalar_min_max_*() will take care to update bounds correctly. However,
this is not the case, for example, consider a register R2 which has a tnum
of 0xffffffff00000000, meaning, lower 32 bits are known constant and in this
case of value 0x00000001. R2 is then and'ed with a register R3 which is a
64 bit known constant, here, 0x100000002.
What can be seen in line '10:' is that 32 bit bounds reach an invalid state
where {u,s}32_min_value > {u,s}32_max_value. The reason is scalar32_min_max_*()
delegates 32 bit bounds updates to scalar_min_max_*(), however, that really
only takes place when both the 64 bit src & dst register is a known constant.
Given scalar32_min_max_*() is intended to be designed as closely as possible
to scalar_min_max_*(), update the 32 bit bounds in this situation through
__mark_reg32_known() which will set all {u,s}32_{min,max}_value to the correct
constant, which is 0x00000000 after the fix (given 0x00000001 & 0x00000002 in
32 bit space). This is possible given var32_off already holds the final value
as dst_reg->var_off is updated before calling scalar32_min_max_*().
Before fix, invalid tracking of R2:
[...]
9: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,smin_value=-9223372036854775807 (0x8000000000000001),smax_value=9223372032559808513 (0x7fffffff00000001),umin_value=1,umax_value=0xffffffff00000001,var_off=(0x1; 0xffffffff00000000),s32_min_value=1,s32_max_value=1,u32_min_value=1,u32_max_value=1) R3_w=inv4294967298 R10=fp0
9: (5f) r2 &= r3
10: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,smin_value=0,smax_value=4294967296 (0x100000000),umin_value=0,umax_value=0x100000000,var_off=(0x0; 0x100000000),s32_min_value=1,s32_max_value=0,u32_min_value=1,u32_max_value=0) R3_w=inv4294967298 R10=fp0
[...]
After fix, correct tracking of R2:
[...]
9: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,smin_value=-9223372036854775807 (0x8000000000000001),smax_value=9223372032559808513 (0x7fffffff00000001),umin_value=1,umax_value=0xffffffff00000001,var_off=(0x1; 0xffffffff00000000),s32_min_value=1,s32_max_value=1,u32_min_value=1,u32_max_value=1) R3_w=inv4294967298 R10=fp0
9: (5f) r2 &= r3
10: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,smin_value=0,smax_value=4294967296 (0x100000000),umin_value=0,umax_value=0x100000000,var_off=(0x0; 0x100000000),s32_min_value=0,s32_max_value=0,u32_min_value=0,u32_max_value=0) R3_w=inv4294967298 R10=fp0
[...]
Fixes:
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Daniel Borkmann
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4394be0a18 |
bpf: Fix propagation of 32 bit unsigned bounds from 64 bit bounds
[ Upstream commit 10bf4e83167cc68595b85fd73bb91e8f2c086e36 ] Similarly as |
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Daniel Borkmann
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2fa15d61e4 |
bpf: Fix leakage of uninitialized bpf stack under speculation
commit 801c6058d14a82179a7ee17a4b532cac6fad067f upstream.
The current implemented mechanisms to mitigate data disclosure under
speculation mainly address stack and map value oob access from the
speculative domain. However, Piotr discovered that uninitialized BPF
stack is not protected yet, and thus old data from the kernel stack,
potentially including addresses of kernel structures, could still be
extracted from that 512 bytes large window. The BPF stack is special
compared to map values since it's not zero initialized for every
program invocation, whereas map values /are/ zero initialized upon
their initial allocation and thus cannot leak any prior data in either
domain. In the non-speculative domain, the verifier ensures that every
stack slot read must have a prior stack slot write by the BPF program
to avoid such data leaking issue.
However, this is not enough: for example, when the pointer arithmetic
operation moves the stack pointer from the last valid stack offset to
the first valid offset, the sanitation logic allows for any intermediate
offsets during speculative execution, which could then be used to
extract any restricted stack content via side-channel.
Given for unprivileged stack pointer arithmetic the use of unknown
but bounded scalars is generally forbidden, we can simply turn the
register-based arithmetic operation into an immediate-based arithmetic
operation without the need for masking. This also gives the benefit
of reducing the needed instructions for the operation. Given after
the work in 7fedb63a8307 ("bpf: Tighten speculative pointer arithmetic
mask"), the aux->alu_limit already holds the final immediate value for
the offset register with the known scalar. Thus, a simple mov of the
immediate to AX register with using AX as the source for the original
instruction is sufficient and possible now in this case.
Reported-by: Piotr Krysiuk <piotras@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Piotr Krysiuk <piotras@gmail.com>
Reviewed-by: Piotr Krysiuk <piotras@gmail.com>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Daniel Borkmann
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2cfa537674 |
bpf: Fix masking negation logic upon negative dst register
commit b9b34ddbe2076ade359cd5ce7537d5ed019e9807 upstream.
The negation logic for the case where the off_reg is sitting in the
dst register is not correct given then we cannot just invert the add
to a sub or vice versa. As a fix, perform the final bitwise and-op
unconditionally into AX from the off_reg, then move the pointer from
the src to dst and finally use AX as the source for the original
pointer arithmetic operation such that the inversion yields a correct
result. The single non-AX mov in between is possible given constant
blinding is retaining it as it's not an immediate based operation.
Fixes:
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