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| author | Laszlo Ersek <lersek@redhat.com> | 2023-07-31 18:42:37 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-08-11 11:53:59 +0200 |
| commit | 1202deb153d68d569439a4d1772eba20daa95589 (patch) | |
| tree | fa5800ebdabeaea145a8dcd4dcdeaefda1b77562 | |
| parent | 1d53ea776760097186258ced06d468bf26adb437 (diff) | |
| download | linux-stable-1202deb153d68d569439a4d1772eba20daa95589.tar.gz linux-stable-1202deb153d68d569439a4d1772eba20daa95589.tar.bz2 linux-stable-1202deb153d68d569439a4d1772eba20daa95589.zip | |
net: tap_open(): set sk_uid from current_fsuid()
commit 5c9241f3ceab3257abe2923a59950db0dc8bb737 upstream.
Commit 66b2c338adce initializes the "sk_uid" field in the protocol socket
(struct sock) from the "/dev/tapX" device node's owner UID. Per original
commit 86741ec25462 ("net: core: Add a UID field to struct sock.",
2016-11-04), that's wrong: the idea is to cache the UID of the userspace
process that creates the socket. Commit 86741ec25462 mentions socket() and
accept(); with "tap", the action that creates the socket is
open("/dev/tapX").
Therefore the device node's owner UID is irrelevant. In most cases,
"/dev/tapX" will be owned by root, so in practice, commit 66b2c338adce has
no observable effect:
- before, "sk_uid" would be zero, due to undefined behavior
(CVE-2023-1076),
- after, "sk_uid" would be zero, due to "/dev/tapX" being owned by root.
What matters is the (fs)UID of the process performing the open(), so cache
that in "sk_uid".
Cc: Eric Dumazet <edumazet@google.com>
Cc: Lorenzo Colitti <lorenzo@google.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Pietro Borrello <borrello@diag.uniroma1.it>
Cc: netdev@vger.kernel.org
Cc: stable@vger.kernel.org
Fixes: 66b2c338adce ("tap: tap_open(): correctly initialize socket uid")
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2173435
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/net/tap.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/net/tap.c b/drivers/net/tap.c index 574c17aa4b09..c299faaf4b2d 100644 --- a/drivers/net/tap.c +++ b/drivers/net/tap.c @@ -525,7 +525,7 @@ static int tap_open(struct inode *inode, struct file *file) q->sock.state = SS_CONNECTED; q->sock.file = file; q->sock.ops = &tap_socket_ops; - sock_init_data_uid(&q->sock, &q->sk, inode->i_uid); + sock_init_data_uid(&q->sock, &q->sk, current_fsuid()); q->sk.sk_write_space = tap_sock_write_space; q->sk.sk_destruct = tap_sock_destruct; q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP; |