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bpf: Bpf_{g,s}etsockopt for struct bpf_sock_addr

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Currently, bpf_getsockopt and bpf_setsockopt helpers operate on the
'struct bpf_sock_ops' context in BPF_PROG_TYPE_SOCK_OPS program.
Let's generalize them and make them available for 'struct bpf_sock_addr'.
That way, in the future, we can allow those helpers in more places.

As an example, let's expose those 'struct bpf_sock_addr' based helpers to
BPF_CGROUP_INET{4,6}_CONNECT hooks. That way we can override CC before the
connection is made.

v3:
* Expose custom helpers for bpf_sock_addr context instead of doing
  generic bpf_sock argument (as suggested by Daniel). Even with
  try_socket_lock that doesn't sleep we have a problem where context sk
  is already locked and socket lock is non-nestable.

v2:
* s/BPF_PROG_TYPE_CGROUP_SOCKOPT/BPF_PROG_TYPE_SOCK_OPS/

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200430233152.199403-1-sdf@google.com
This commit is contained in:
Stanislav Fomichev 2020-04-30 16:31:52 -07:00 committed by Alexei Starovoitov
parent 3dbb5b5040
commit beecf11bc2
5 changed files with 166 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
include/uapi/linux/bpf.h
View File

@ -1587,7 +1587,7 @@ union bpf_attr {
* Return
* 0
*
* int bpf_setsockopt(struct bpf_sock_ops *bpf_socket, int level, int optname, void *optval, int optlen)
* int bpf_setsockopt(void *bpf_socket, int level, int optname, void *optval, int optlen)
* Description
* Emulate a call to **setsockopt()** on the socket associated to
* *bpf_socket*, which must be a full socket. The *level* at
@ -1595,6 +1595,11 @@ union bpf_attr {
* must be specified, see **setsockopt(2)** for more information.
* The option value of length *optlen* is pointed by *optval*.
*
* *bpf_socket* should be one of the following:
* * **struct bpf_sock_ops** for **BPF_PROG_TYPE_SOCK_OPS**.
* * **struct bpf_sock_addr** for **BPF_CGROUP_INET4_CONNECT**
* and **BPF_CGROUP_INET6_CONNECT**.
*
* This helper actually implements a subset of **setsockopt()**.
* It supports the following *level*\ s:
*
@ -1789,7 +1794,7 @@ union bpf_attr {
* Return
* 0 on success, or a negative error in case of failure.
*
* int bpf_getsockopt(struct bpf_sock_ops *bpf_socket, int level, int optname, void *optval, int optlen)
* int bpf_getsockopt(void *bpf_socket, int level, int optname, void *optval, int optlen)
* Description
* Emulate a call to **getsockopt()** on the socket associated to
* *bpf_socket*, which must be a full socket. The *level* at
@ -1798,6 +1803,11 @@ union bpf_attr {
* The retrieved value is stored in the structure pointed by
* *opval* and of length *optlen*.
*
* *bpf_socket* should be one of the following:
* * **struct bpf_sock_ops** for **BPF_PROG_TYPE_SOCK_OPS**.
* * **struct bpf_sock_addr** for **BPF_CGROUP_INET4_CONNECT**
* and **BPF_CGROUP_INET6_CONNECT**.
*
* This helper actually implements a subset of **getsockopt()**.
* It supports the following *level*\ s:
*

118
net/core/filter.c
View File

@ -4194,16 +4194,19 @@ static const struct bpf_func_proto bpf_get_socket_uid_proto = {
.arg1_type = ARG_PTR_TO_CTX,
};
BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock,
int, level, int, optname, char *, optval, int, optlen)
#define SOCKOPT_CC_REINIT (1 << 0)
static int _bpf_setsockopt(struct sock *sk, int level, int optname,
char *optval, int optlen, u32 flags)
{
struct sock *sk = bpf_sock->sk;
int ret = 0;
int val;
if (!sk_fullsock(sk))
return -EINVAL;
sock_owned_by_me(sk);
if (level == SOL_SOCKET) {
if (optlen != sizeof(int))
return -EINVAL;
@ -4298,7 +4301,7 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock,
sk->sk_prot->setsockopt == tcp_setsockopt) {
if (optname == TCP_CONGESTION) {
char name[TCP_CA_NAME_MAX];
bool reinit = bpf_sock->op > BPF_SOCK_OPS_NEEDS_ECN;
bool reinit = flags & SOCKOPT_CC_REINIT;
strncpy(name, optval, min_t(long, optlen,
TCP_CA_NAME_MAX-1));
@ -4345,24 +4348,14 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_sock_ops_kern *, bpf_sock,
return ret;
}
static const struct bpf_func_proto bpf_setsockopt_proto = {
.func = bpf_setsockopt,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_ANYTHING,
.arg3_type = ARG_ANYTHING,
.arg4_type = ARG_PTR_TO_MEM,
.arg5_type = ARG_CONST_SIZE,
};
BPF_CALL_5(bpf_getsockopt, struct bpf_sock_ops_kern *, bpf_sock,
int, level, int, optname, char *, optval, int, optlen)
static int _bpf_getsockopt(struct sock *sk, int level, int optname,
char *optval, int optlen)
{
struct sock *sk = bpf_sock->sk;
if (!sk_fullsock(sk))
goto err_clear;
sock_owned_by_me(sk);
#ifdef CONFIG_INET
if (level == SOL_TCP && sk->sk_prot->getsockopt == tcp_getsockopt) {
struct inet_connection_sock *icsk;
@ -4428,8 +4421,71 @@ BPF_CALL_5(bpf_getsockopt, struct bpf_sock_ops_kern *, bpf_sock,
return -EINVAL;
}
static const struct bpf_func_proto bpf_getsockopt_proto = {
.func = bpf_getsockopt,
BPF_CALL_5(bpf_sock_addr_setsockopt, struct bpf_sock_addr_kern *, ctx,
int, level, int, optname, char *, optval, int, optlen)
{
u32 flags = 0;
return _bpf_setsockopt(ctx->sk, level, optname, optval, optlen,
flags);
}
static const struct bpf_func_proto bpf_sock_addr_setsockopt_proto = {
.func = bpf_sock_addr_setsockopt,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_ANYTHING,
.arg3_type = ARG_ANYTHING,
.arg4_type = ARG_PTR_TO_MEM,
.arg5_type = ARG_CONST_SIZE,
};
BPF_CALL_5(bpf_sock_addr_getsockopt, struct bpf_sock_addr_kern *, ctx,
int, level, int, optname, char *, optval, int, optlen)
{
return _bpf_getsockopt(ctx->sk, level, optname, optval, optlen);
}
static const struct bpf_func_proto bpf_sock_addr_getsockopt_proto = {
.func = bpf_sock_addr_getsockopt,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_ANYTHING,
.arg3_type = ARG_ANYTHING,
.arg4_type = ARG_PTR_TO_UNINIT_MEM,
.arg5_type = ARG_CONST_SIZE,
};
BPF_CALL_5(bpf_sock_ops_setsockopt, struct bpf_sock_ops_kern *, bpf_sock,
int, level, int, optname, char *, optval, int, optlen)
{
u32 flags = 0;
if (bpf_sock->op > BPF_SOCK_OPS_NEEDS_ECN)
flags |= SOCKOPT_CC_REINIT;
return _bpf_setsockopt(bpf_sock->sk, level, optname, optval, optlen,
flags);
}
static const struct bpf_func_proto bpf_sock_ops_setsockopt_proto = {
.func = bpf_sock_ops_setsockopt,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
.arg2_type = ARG_ANYTHING,
.arg3_type = ARG_ANYTHING,
.arg4_type = ARG_PTR_TO_MEM,
.arg5_type = ARG_CONST_SIZE,
};
BPF_CALL_5(bpf_sock_ops_getsockopt, struct bpf_sock_ops_kern *, bpf_sock,
int, level, int, optname, char *, optval, int, optlen)
{
return _bpf_getsockopt(bpf_sock->sk, level, optname, optval, optlen);
}
static const struct bpf_func_proto bpf_sock_ops_getsockopt_proto = {
.func = bpf_sock_ops_getsockopt,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
@ -6043,6 +6099,22 @@ sock_addr_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_sk_storage_get_proto;
case BPF_FUNC_sk_storage_delete:
return &bpf_sk_storage_delete_proto;
case BPF_FUNC_setsockopt:
switch (prog->expected_attach_type) {
case BPF_CGROUP_INET4_CONNECT:
case BPF_CGROUP_INET6_CONNECT:
return &bpf_sock_addr_setsockopt_proto;
default:
return NULL;
}
case BPF_FUNC_getsockopt:
switch (prog->expected_attach_type) {
case BPF_CGROUP_INET4_CONNECT:
case BPF_CGROUP_INET6_CONNECT:
return &bpf_sock_addr_getsockopt_proto;
default:
return NULL;
}
default:
return bpf_base_func_proto(func_id);
}
@ -6261,9 +6333,9 @@ sock_ops_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{
switch (func_id) {
case BPF_FUNC_setsockopt:
return &bpf_setsockopt_proto;
return &bpf_sock_ops_setsockopt_proto;
case BPF_FUNC_getsockopt:
return &bpf_getsockopt_proto;
return &bpf_sock_ops_getsockopt_proto;
case BPF_FUNC_sock_ops_cb_flags_set:
return &bpf_sock_ops_cb_flags_set_proto;
case BPF_FUNC_sock_map_update:

14
tools/include/uapi/linux/bpf.h
View File

@ -1587,7 +1587,7 @@ union bpf_attr {
* Return
* 0
*
* int bpf_setsockopt(struct bpf_sock_ops *bpf_socket, int level, int optname, void *optval, int optlen)
* int bpf_setsockopt(void *bpf_socket, int level, int optname, void *optval, int optlen)
* Description
* Emulate a call to **setsockopt()** on the socket associated to
* *bpf_socket*, which must be a full socket. The *level* at
@ -1595,6 +1595,11 @@ union bpf_attr {
* must be specified, see **setsockopt(2)** for more information.
* The option value of length *optlen* is pointed by *optval*.
*
* *bpf_socket* should be one of the following:
* * **struct bpf_sock_ops** for **BPF_PROG_TYPE_SOCK_OPS**.
* * **struct bpf_sock_addr** for **BPF_CGROUP_INET4_CONNECT**
* and **BPF_CGROUP_INET6_CONNECT**.
*
* This helper actually implements a subset of **setsockopt()**.
* It supports the following *level*\ s:
*
@ -1789,7 +1794,7 @@ union bpf_attr {
* Return
* 0 on success, or a negative error in case of failure.
*
* int bpf_getsockopt(struct bpf_sock_ops *bpf_socket, int level, int optname, void *optval, int optlen)
* int bpf_getsockopt(void *bpf_socket, int level, int optname, void *optval, int optlen)
* Description
* Emulate a call to **getsockopt()** on the socket associated to
* *bpf_socket*, which must be a full socket. The *level* at
@ -1798,6 +1803,11 @@ union bpf_attr {
* The retrieved value is stored in the structure pointed by
* *opval* and of length *optlen*.
*
* *bpf_socket* should be one of the following:
* * **struct bpf_sock_ops** for **BPF_PROG_TYPE_SOCK_OPS**.
* * **struct bpf_sock_addr** for **BPF_CGROUP_INET4_CONNECT**
* and **BPF_CGROUP_INET6_CONNECT**.
*
* This helper actually implements a subset of **getsockopt()**.
* It supports the following *level*\ s:
*

1
tools/testing/selftests/bpf/config
View File

@ -37,3 +37,4 @@ CONFIG_IPV6_SIT=m
CONFIG_BPF_JIT=y
CONFIG_BPF_LSM=y
CONFIG_SECURITY=y
CONFIG_TCP_CONG_DCTCP=y

46
tools/testing/selftests/bpf/progs/connect4_prog.c
View File

@ -8,6 +8,7 @@
#include <linux/in.h>
#include <linux/in6.h>
#include <sys/socket.h>
#include <netinet/tcp.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>
@ -16,6 +17,10 @@
#define DST_REWRITE_IP4 0x7f000001U
#define DST_REWRITE_PORT4 4444
#ifndef TCP_CA_NAME_MAX
#define TCP_CA_NAME_MAX 16
#endif
int _version SEC("version") = 1;
__attribute__ ((noinline))
@ -33,6 +38,43 @@ int do_bind(struct bpf_sock_addr *ctx)
return 1;
}
static __inline int verify_cc(struct bpf_sock_addr *ctx,
char expected[TCP_CA_NAME_MAX])
{
char buf[TCP_CA_NAME_MAX];
int i;
if (bpf_getsockopt(ctx, SOL_TCP, TCP_CONGESTION, &buf, sizeof(buf)))
return 1;
for (i = 0; i < TCP_CA_NAME_MAX; i++) {
if (buf[i] != expected[i])
return 1;
if (buf[i] == 0)
break;
}
return 0;
}
static __inline int set_cc(struct bpf_sock_addr *ctx)
{
char dctcp[TCP_CA_NAME_MAX] = "dctcp";
char cubic[TCP_CA_NAME_MAX] = "cubic";
if (bpf_setsockopt(ctx, SOL_TCP, TCP_CONGESTION, &dctcp, sizeof(dctcp)))
return 1;
if (verify_cc(ctx, dctcp))
return 1;
if (bpf_setsockopt(ctx, SOL_TCP, TCP_CONGESTION, &cubic, sizeof(cubic)))
return 1;
if (verify_cc(ctx, cubic))
return 1;
return 0;
}
SEC("cgroup/connect4")
int connect_v4_prog(struct bpf_sock_addr *ctx)
{
@ -66,6 +108,10 @@ int connect_v4_prog(struct bpf_sock_addr *ctx)
bpf_sk_release(sk);
/* Rewrite congestion control. */
if (ctx->type == SOCK_STREAM && set_cc(ctx))
return 0;
/* Rewrite destination. */
ctx->user_ip4 = bpf_htonl(DST_REWRITE_IP4);
ctx->user_port = bpf_htons(DST_REWRITE_PORT4);