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Code Issues Releases Wiki Activity

bpf: support BPF_PROG_QUERY for progs attached to sockmap

Browse source 
Right now there is no way to query whether BPF programs are
attached to a sockmap or not.

we can use the standard interface in libbpf to query, such as:
bpf_prog_query(mapFd, BPF_SK_SKB_STREAM_PARSER, 0, NULL, ...);
the mapFd is the fd of sockmap.

Signed-off-by: Di Zhu <zhudi2@huawei.com>
Acked-by: Yonghong Song <yhs@fb.com>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/r/20220119014005.1209-1-zhudi2@huawei.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Di Zhu 2022-01-19 09:40:04 +08:00 committed by Alexei Starovoitov
parent 3f712d4691
commit 748cd5729a
3 changed files with 84 additions and 7 deletions
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9
include/linux/bpf.h
View file

@ -2069,6 +2069,9 @@ int bpf_prog_test_run_syscall(struct bpf_prog *prog,
int sock_map_get_from_fd(const union bpf_attr *attr, struct bpf_prog *prog);
int sock_map_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype);
int sock_map_update_elem_sys(struct bpf_map *map, void *key, void *value, u64 flags);
int sock_map_bpf_prog_query(const union bpf_attr *attr,
union bpf_attr __user *uattr);
void sock_map_unhash(struct sock *sk);
void sock_map_close(struct sock *sk, long timeout);
#else
@ -2122,6 +2125,12 @@ static inline int sock_map_update_elem_sys(struct bpf_map *map, void *key, void
{
return -EOPNOTSUPP;
}
static inline int sock_map_bpf_prog_query(const union bpf_attr *attr,
union bpf_attr __user *uattr)
{
return -EINVAL;
}
#endif /* CONFIG_BPF_SYSCALL */
#endif /* CONFIG_NET && CONFIG_BPF_SYSCALL */

5
kernel/bpf/syscall.c
View file

@ -3318,6 +3318,11 @@ static int bpf_prog_query(const union bpf_attr *attr,
case BPF_FLOW_DISSECTOR:
case BPF_SK_LOOKUP:
return netns_bpf_prog_query(attr, uattr);
case BPF_SK_SKB_STREAM_PARSER:
case BPF_SK_SKB_STREAM_VERDICT:
case BPF_SK_MSG_VERDICT:
case BPF_SK_SKB_VERDICT:
return sock_map_bpf_prog_query(attr, uattr);
default:
return -EINVAL;
}

77
net/core/sock_map.c
View file

@ -1416,38 +1416,50 @@ static struct sk_psock_progs *sock_map_progs(struct bpf_map *map)
return NULL;
}
static int sock_map_prog_update(struct bpf_map *map, struct bpf_prog *prog,
struct bpf_prog *old, u32 which)
static int sock_map_prog_lookup(struct bpf_map *map, struct bpf_prog ***pprog,
u32 which)
{
struct sk_psock_progs *progs = sock_map_progs(map);
struct bpf_prog **pprog;
if (!progs)
return -EOPNOTSUPP;
switch (which) {
case BPF_SK_MSG_VERDICT:
pprog = &progs->msg_parser;
*pprog = &progs->msg_parser;
break;
#if IS_ENABLED(CONFIG_BPF_STREAM_PARSER)
case BPF_SK_SKB_STREAM_PARSER:
pprog = &progs->stream_parser;
*pprog = &progs->stream_parser;
break;
#endif
case BPF_SK_SKB_STREAM_VERDICT:
if (progs->skb_verdict)
return -EBUSY;
pprog = &progs->stream_verdict;
*pprog = &progs->stream_verdict;
break;
case BPF_SK_SKB_VERDICT:
if (progs->stream_verdict)
return -EBUSY;
pprog = &progs->skb_verdict;
*pprog = &progs->skb_verdict;
break;
default:
return -EOPNOTSUPP;
}
return 0;
}
static int sock_map_prog_update(struct bpf_map *map, struct bpf_prog *prog,
struct bpf_prog *old, u32 which)
{
struct bpf_prog **pprog;
int ret;
ret = sock_map_prog_lookup(map, &pprog, which);
if (ret)
return ret;
if (old)
return psock_replace_prog(pprog, prog, old);
@ -1455,6 +1467,57 @@ static int sock_map_prog_update(struct bpf_map *map, struct bpf_prog *prog,
return 0;
}
int sock_map_bpf_prog_query(const union bpf_attr *attr,
union bpf_attr __user *uattr)
{
__u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
u32 prog_cnt = 0, flags = 0, ufd = attr->target_fd;
struct bpf_prog **pprog;
struct bpf_prog *prog;
struct bpf_map *map;
struct fd f;
u32 id = 0;
int ret;
if (attr->query.query_flags)
return -EINVAL;
f = fdget(ufd);
map = __bpf_map_get(f);
if (IS_ERR(map))
return PTR_ERR(map);
rcu_read_lock();
ret = sock_map_prog_lookup(map, &pprog, attr->query.attach_type);
if (ret)
goto end;
prog = *pprog;
prog_cnt = !prog ? 0 : 1;
if (!attr->query.prog_cnt || !prog_ids || !prog_cnt)
goto end;
/* we do not hold the refcnt, the bpf prog may be released
* asynchronously and the id would be set to 0.
*/
id = data_race(prog->aux->id);
if (id == 0)
prog_cnt = 0;
end:
rcu_read_unlock();
if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)) ||
(id != 0 && copy_to_user(prog_ids, &id, sizeof(u32))) ||
copy_to_user(&uattr->query.prog_cnt, &prog_cnt, sizeof(prog_cnt)))
ret = -EFAULT;
fdput(f);
return ret;
}
static void sock_map_unlink(struct sock *sk, struct sk_psock_link *link)
{
switch (link->map->map_type) {