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authorJohn Fastabend <john.fastabend@gmail.com>2018-08-30 21:25:02 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2018-09-02 22:31:10 +0200
commit597222f72a94118f593e4f32bf58ae7e049a0df1 (patch)
tree846e0e8c6a168acc8c4e6e7fe570b95e7e702699 /kernel
parent97911e0ccb54c7478b9dac77e6c54c01b449e3a7 (diff)
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/sockmap.c12
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;