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author | John Fastabend <john.fastabend@gmail.com> | 2018-08-30 21:25:02 -0700 |
---|---|---|
committer | Daniel Borkmann <daniel@iogearbox.net> | 2018-09-02 22:31:10 +0200 |
commit | 597222f72a94118f593e4f32bf58ae7e049a0df1 (patch) | |
tree | 846e0e8c6a168acc8c4e6e7fe570b95e7e702699 | |
parent | 97911e0ccb54c7478b9dac77e6c54c01b449e3a7 (diff) | |
download | linux-597222f72a94118f593e4f32bf58ae7e049a0df1.tar.gz linux-597222f72a94118f593e4f32bf58ae7e049a0df1.tar.bz2 linux-597222f72a94118f593e4f32bf58ae7e049a0df1.zip |
bpf: avoid misuse of psock when TCP_ULP_BPF collides with another ULP
Currently we check sk_user_data is non NULL to determine if the sk
exists in a map. However, this is not sufficient to ensure the psock
or the ULP ops are not in use by another user, such as kcm or TLS. To
avoid this when adding a sock to a map also verify it is of the
correct ULP type. Additionally, when releasing a psock verify that
it is the TCP_ULP_BPF type before releasing the ULP. The error case
where we abort an update due to ULP collision can cause this error
path.
For example,
__sock_map_ctx_update_elem()
[...]
err = tcp_set_ulp_id(sock, TCP_ULP_BPF) <- collides with TLS
if (err) <- so err out here
goto out_free
[...]
out_free:
smap_release_sock() <- calling tcp_cleanup_ulp releases the
TLS ULP incorrectly.
Fixes: 2f857d04601a ("bpf: sockmap, remove STRPARSER map_flags and add multi-map support")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
-rw-r--r-- | kernel/bpf/sockmap.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c index ce63e5801746..488ef9663c01 100644 --- a/kernel/bpf/sockmap.c +++ b/kernel/bpf/sockmap.c @@ -1462,10 +1462,16 @@ static void smap_destroy_psock(struct rcu_head *rcu) schedule_work(&psock->gc_work); } +static bool psock_is_smap_sk(struct sock *sk) +{ + return inet_csk(sk)->icsk_ulp_ops == &bpf_tcp_ulp_ops; +} + static void smap_release_sock(struct smap_psock *psock, struct sock *sock) { if (refcount_dec_and_test(&psock->refcnt)) { - tcp_cleanup_ulp(sock); + if (psock_is_smap_sk(sock)) + tcp_cleanup_ulp(sock); write_lock_bh(&sock->sk_callback_lock); smap_stop_sock(psock, sock); write_unlock_bh(&sock->sk_callback_lock); @@ -1892,6 +1898,10 @@ static int __sock_map_ctx_update_elem(struct bpf_map *map, * doesn't update user data. */ if (psock) { + if (!psock_is_smap_sk(sock)) { + err = -EBUSY; + goto out_progs; + } if (READ_ONCE(psock->bpf_parse) && parse) { err = -EBUSY; goto out_progs; |