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bpf: sockmap: Require attach_bpf_fd when detaching a program

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The sockmap code currently ignores the value of attach_bpf_fd when
detaching a program. This is contrary to the usual behaviour of
checking that attach_bpf_fd represents the currently attached
program.

Ensure that attach_bpf_fd is indeed the currently attached
program. It turns out that all sockmap selftests already do this,
which indicates that this is unlikely to cause breakage.

Fixes: 604326b41a ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200629095630.7933-5-lmb@cloudflare.com
This commit is contained in:
Lorenz Bauer 2020-06-29 10:56:28 +01:00 committed by Alexei Starovoitov
parent 9b2b09717e
commit bb0de3131f
4 changed files with 70 additions and 8 deletions
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13
include/linux/bpf.h
View File

@ -1543,13 +1543,16 @@ static inline void bpf_map_offload_map_free(struct bpf_map *map)
#endif /* CONFIG_NET && CONFIG_BPF_SYSCALL */
#if defined(CONFIG_BPF_STREAM_PARSER)
int sock_map_prog_update(struct bpf_map *map, struct bpf_prog *prog, u32 which);
int sock_map_prog_update(struct bpf_map *map, struct bpf_prog *prog,
struct bpf_prog *old, u32 which);
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);
void sock_map_unhash(struct sock *sk);
void sock_map_close(struct sock *sk, long timeout);
#else
static inline int sock_map_prog_update(struct bpf_map *map,
struct bpf_prog *prog, u32 which)
struct bpf_prog *prog,
struct bpf_prog *old, u32 which)
{
return -EOPNOTSUPP;
}
@ -1559,6 +1562,12 @@ static inline int sock_map_get_from_fd(const union bpf_attr *attr,
{
return -EINVAL;
}
static inline int sock_map_prog_detach(const union bpf_attr *attr,
enum bpf_prog_type ptype)
{
return -EOPNOTSUPP;
}
#endif /* CONFIG_BPF_STREAM_PARSER */
#if defined(CONFIG_INET) && defined(CONFIG_BPF_SYSCALL)

13
include/linux/skmsg.h
View File

@ -430,6 +430,19 @@ static inline void psock_set_prog(struct bpf_prog **pprog,
bpf_prog_put(prog);
}
static inline int psock_replace_prog(struct bpf_prog **pprog,
struct bpf_prog *prog,
struct bpf_prog *old)
{
if (cmpxchg(pprog, old, prog) != old)
return -ENOENT;
if (old)
bpf_prog_put(old);
return 0;
}
static inline void psock_progs_drop(struct sk_psock_progs *progs)
{
psock_set_prog(&progs->msg_parser, NULL);

2
kernel/bpf/syscall.c
View File

@ -2893,7 +2893,7 @@ static int bpf_prog_detach(const union bpf_attr *attr)
switch (ptype) {
case BPF_PROG_TYPE_SK_MSG:
case BPF_PROG_TYPE_SK_SKB:
return sock_map_get_from_fd(attr, NULL);
return sock_map_prog_detach(attr, ptype);
case BPF_PROG_TYPE_LIRC_MODE2:
return lirc_prog_detach(attr);
case BPF_PROG_TYPE_FLOW_DISSECTOR:

50
net/core/sock_map.c
View File

@ -77,7 +77,42 @@ int sock_map_get_from_fd(const union bpf_attr *attr, struct bpf_prog *prog)
map = __bpf_map_get(f);
if (IS_ERR(map))
return PTR_ERR(map);
ret = sock_map_prog_update(map, prog, attr->attach_type);
ret = sock_map_prog_update(map, prog, NULL, attr->attach_type);
fdput(f);
return ret;
}
int sock_map_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype)
{
u32 ufd = attr->target_fd;
struct bpf_prog *prog;
struct bpf_map *map;
struct fd f;
int ret;
if (attr->attach_flags || attr->replace_bpf_fd)
return -EINVAL;
f = fdget(ufd);
map = __bpf_map_get(f);
if (IS_ERR(map))
return PTR_ERR(map);
prog = bpf_prog_get(attr->attach_bpf_fd);
if (IS_ERR(prog)) {
ret = PTR_ERR(prog);
goto put_map;
}
if (prog->type != ptype) {
ret = -EINVAL;
goto put_prog;
}
ret = sock_map_prog_update(map, NULL, prog, attr->attach_type);
put_prog:
bpf_prog_put(prog);
put_map:
fdput(f);
return ret;
}
@ -1206,27 +1241,32 @@ static struct sk_psock_progs *sock_map_progs(struct bpf_map *map)
}
int sock_map_prog_update(struct bpf_map *map, struct bpf_prog *prog,
u32 which)
struct bpf_prog *old, 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:
psock_set_prog(&progs->msg_parser, prog);
pprog = &progs->msg_parser;
break;
case BPF_SK_SKB_STREAM_PARSER:
psock_set_prog(&progs->skb_parser, prog);
pprog = &progs->skb_parser;
break;
case BPF_SK_SKB_STREAM_VERDICT:
psock_set_prog(&progs->skb_verdict, prog);
pprog = &progs->skb_verdict;
break;
default:
return -EOPNOTSUPP;
}
if (old)
return psock_replace_prog(pprog, prog, old);
psock_set_prog(pprog, prog);
return 0;
}