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bpf: Allow bpf_map_lookup_elem() on an xskmap

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Currently, the AF_XDP code uses a separate map in order to
determine if an xsk is bound to a queue.  Instead of doing this,
have bpf_map_lookup_elem() return a xdp_sock.

Rearrange some xdp_sock members to eliminate structure holes.

Remove selftest - will be added back in later patch.

Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Jonathan Lemon 2019-06-06 13:59:40 -07:00 committed by Alexei Starovoitov
parent 4ecabd55c9
commit fada7fdc83
7 changed files with 85 additions and 19 deletions
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8
include/linux/bpf.h
View File

@ -280,6 +280,7 @@ enum bpf_reg_type {
PTR_TO_TCP_SOCK, /* reg points to struct tcp_sock */
PTR_TO_TCP_SOCK_OR_NULL, /* reg points to struct tcp_sock or NULL */
PTR_TO_TP_BUFFER, /* reg points to a writable raw tp's buffer */
PTR_TO_XDP_SOCK, /* reg points to struct xdp_sock */
};
/* The information passed from prog-specific *_is_valid_access
@ -727,6 +728,13 @@ void __cpu_map_insert_ctx(struct bpf_map *map, u32 index);
void __cpu_map_flush(struct bpf_map *map);
int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu, struct xdp_buff *xdp,
struct net_device *dev_rx);
bool bpf_xdp_sock_is_valid_access(int off, int size, enum bpf_access_type type,
struct bpf_insn_access_aux *info);
u32 bpf_xdp_sock_convert_ctx_access(enum bpf_access_type type,
const struct bpf_insn *si,
struct bpf_insn *insn_buf,
struct bpf_prog *prog,
u32 *target_size);
/* Return map's numa specified by userspace */
static inline int bpf_map_attr_numa_node(const union bpf_attr *attr)

4
include/net/xdp_sock.h
View File

@ -58,11 +58,11 @@ struct xdp_sock {
struct xdp_umem *umem;
struct list_head flush_node;
u16 queue_id;
struct xsk_queue *tx ____cacheline_aligned_in_smp;
struct list_head list;
bool zc;
/* Protects multiple processes in the control path */
struct mutex mutex;
struct xsk_queue *tx ____cacheline_aligned_in_smp;
struct list_head list;
/* Mutual exclusion of NAPI TX thread and sendmsg error paths
* in the SKB destructor callback.
*/

4
include/uapi/linux/bpf.h
View File

@ -3083,6 +3083,10 @@ struct bpf_sock_tuple {
};
};
struct bpf_xdp_sock {
__u32 queue_id;
};
#define XDP_PACKET_HEADROOM 256
/* User return codes for XDP prog type.

26
kernel/bpf/verifier.c
View File

@ -334,7 +334,8 @@ static bool type_is_sk_pointer(enum bpf_reg_type type)
{
return type == PTR_TO_SOCKET ||
type == PTR_TO_SOCK_COMMON ||
type == PTR_TO_TCP_SOCK;
type == PTR_TO_TCP_SOCK ||
type == PTR_TO_XDP_SOCK;
}
static bool reg_type_may_be_null(enum bpf_reg_type type)
@ -406,6 +407,7 @@ static const char * const reg_type_str[] = {
[PTR_TO_TCP_SOCK] = "tcp_sock",
[PTR_TO_TCP_SOCK_OR_NULL] = "tcp_sock_or_null",
[PTR_TO_TP_BUFFER] = "tp_buffer",
[PTR_TO_XDP_SOCK] = "xdp_sock",
};
static char slot_type_char[] = {
@ -1363,6 +1365,7 @@ static bool is_spillable_regtype(enum bpf_reg_type type)
case PTR_TO_SOCK_COMMON_OR_NULL:
case PTR_TO_TCP_SOCK:
case PTR_TO_TCP_SOCK_OR_NULL:
case PTR_TO_XDP_SOCK:
return true;
default:
return false;
@ -1843,6 +1846,9 @@ static int check_sock_access(struct bpf_verifier_env *env, int insn_idx,
case PTR_TO_TCP_SOCK:
valid = bpf_tcp_sock_is_valid_access(off, size, t, &info);
break;
case PTR_TO_XDP_SOCK:
valid = bpf_xdp_sock_is_valid_access(off, size, t, &info);
break;
default:
valid = false;
}
@ -2007,6 +2013,9 @@ static int check_ptr_alignment(struct bpf_verifier_env *env,
case PTR_TO_TCP_SOCK:
pointer_desc = "tcp_sock ";
break;
case PTR_TO_XDP_SOCK:
pointer_desc = "xdp_sock ";
break;
default:
break;
}
@ -2905,10 +2914,14 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
* appear.
*/
case BPF_MAP_TYPE_CPUMAP:
case BPF_MAP_TYPE_XSKMAP:
if (func_id != BPF_FUNC_redirect_map)
goto error;
break;
case BPF_MAP_TYPE_XSKMAP:
if (func_id != BPF_FUNC_redirect_map &&
func_id != BPF_FUNC_map_lookup_elem)
goto error;
break;
case BPF_MAP_TYPE_ARRAY_OF_MAPS:
case BPF_MAP_TYPE_HASH_OF_MAPS:
if (func_id != BPF_FUNC_map_lookup_elem)
@ -3799,6 +3812,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
case PTR_TO_SOCK_COMMON_OR_NULL:
case PTR_TO_TCP_SOCK:
case PTR_TO_TCP_SOCK_OR_NULL:
case PTR_TO_XDP_SOCK:
verbose(env, "R%d pointer arithmetic on %s prohibited\n",
dst, reg_type_str[ptr_reg->type]);
return -EACCES;
@ -5038,6 +5052,9 @@ static void mark_ptr_or_null_reg(struct bpf_func_state *state,
if (reg->map_ptr->inner_map_meta) {
reg->type = CONST_PTR_TO_MAP;
reg->map_ptr = reg->map_ptr->inner_map_meta;
} else if (reg->map_ptr->map_type ==
BPF_MAP_TYPE_XSKMAP) {
reg->type = PTR_TO_XDP_SOCK;
} else {
reg->type = PTR_TO_MAP_VALUE;
}
@ -6299,6 +6316,7 @@ static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur,
case PTR_TO_SOCK_COMMON_OR_NULL:
case PTR_TO_TCP_SOCK:
case PTR_TO_TCP_SOCK_OR_NULL:
case PTR_TO_XDP_SOCK:
/* Only valid matches are exact, which memcmp() above
* would have accepted
*/
@ -6693,6 +6711,7 @@ static bool reg_type_mismatch_ok(enum bpf_reg_type type)
case PTR_TO_SOCK_COMMON_OR_NULL:
case PTR_TO_TCP_SOCK:
case PTR_TO_TCP_SOCK_OR_NULL:
case PTR_TO_XDP_SOCK:
return false;
default:
return true;
@ -7826,6 +7845,9 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
case PTR_TO_TCP_SOCK:
convert_ctx_access = bpf_tcp_sock_convert_ctx_access;
break;
case PTR_TO_XDP_SOCK:
convert_ctx_access = bpf_xdp_sock_convert_ctx_access;
break;
default:
continue;
}

7
kernel/bpf/xskmap.c
View File

@ -151,6 +151,12 @@ void __xsk_map_flush(struct bpf_map *map)
}
static void *xsk_map_lookup_elem(struct bpf_map *map, void *key)
{
WARN_ON_ONCE(!rcu_read_lock_held());
return __xsk_map_lookup_elem(map, *(u32 *)key);
}
static void *xsk_map_lookup_elem_sys_only(struct bpf_map *map, void *key)
{
return ERR_PTR(-EOPNOTSUPP);
}
@ -218,6 +224,7 @@ const struct bpf_map_ops xsk_map_ops = {
.map_free = xsk_map_free,
.map_get_next_key = xsk_map_get_next_key,
.map_lookup_elem = xsk_map_lookup_elem,
.map_lookup_elem_sys_only = xsk_map_lookup_elem_sys_only,
.map_update_elem = xsk_map_update_elem,
.map_delete_elem = xsk_map_delete_elem,
.map_check_btf = map_check_no_btf,

40
net/core/filter.c
View File

@ -5680,6 +5680,46 @@ BPF_CALL_1(bpf_skb_ecn_set_ce, struct sk_buff *, skb)
return INET_ECN_set_ce(skb);
}
bool bpf_xdp_sock_is_valid_access(int off, int size, enum bpf_access_type type,
struct bpf_insn_access_aux *info)
{
if (off < 0 || off >= offsetofend(struct bpf_xdp_sock, queue_id))
return false;
if (off % size != 0)
return false;
switch (off) {
default:
return size == sizeof(__u32);
}
}
u32 bpf_xdp_sock_convert_ctx_access(enum bpf_access_type type,
const struct bpf_insn *si,
struct bpf_insn *insn_buf,
struct bpf_prog *prog, u32 *target_size)
{
struct bpf_insn *insn = insn_buf;
#define BPF_XDP_SOCK_GET(FIELD) \
do { \
BUILD_BUG_ON(FIELD_SIZEOF(struct xdp_sock, FIELD) > \
FIELD_SIZEOF(struct bpf_xdp_sock, FIELD)); \
*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct xdp_sock, FIELD),\
si->dst_reg, si->src_reg, \
offsetof(struct xdp_sock, FIELD)); \
} while (0)
switch (si->off) {
case offsetof(struct bpf_xdp_sock, queue_id):
BPF_XDP_SOCK_GET(queue_id);
break;
}
return insn - insn_buf;
}
static const struct bpf_func_proto bpf_skb_ecn_set_ce_proto = {
.func = bpf_skb_ecn_set_ce,
.gpl_only = false,

15
tools/testing/selftests/bpf/verifier/prevent_map_lookup.c
View File

@ -28,21 +28,6 @@
.errstr = "cannot pass map_type 18 into func bpf_map_lookup_elem",
.prog_type = BPF_PROG_TYPE_SOCK_OPS,
},
{
"prevent map lookup in xskmap",
.insns = {
BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
BPF_LD_MAP_FD(BPF_REG_1, 0),
BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
BPF_EXIT_INSN(),
},
.fixup_map_xskmap = { 3 },
.result = REJECT,
.errstr = "cannot pass map_type 17 into func bpf_map_lookup_elem",
.prog_type = BPF_PROG_TYPE_XDP,
},
{
"prevent map lookup in stack trace",
.insns = {