From: John Fastabend <john.fastabend@gmail.com>
To: ast@kernel.org, daniel@iogearbox.net
Cc: netdev@vger.kernel.org
Subject: [bpf PATCH v2] bpf: avoid misuse of psock when TCP_ULP_BPF collides with another ULP
Date: Thu, 30 Aug 2018 21:25:02 -0700 [thread overview]
Message-ID: <20180831042502.15257.35453.stgit@john-Precision-Tower-5810> (raw)
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>
---
kernel/bpf/sockmap.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
index ce63e58..488ef96 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;
next reply other threads:[~2018-08-31 8:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-31 4:25 John Fastabend [this message]
2018-09-02 20:40 ` [bpf PATCH v2] bpf: avoid misuse of psock when TCP_ULP_BPF collides with another ULP Daniel Borkmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180831042502.15257.35453.stgit@john-Precision-Tower-5810 \
--to=john.fastabend@gmail.com \
--cc=ast@kernel.org \
--cc=daniel@iogearbox.net \
--cc=netdev@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.