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| author | Laszlo Ersek <lersek@redhat.com> | 2023-07-31 18:42:36 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-08-11 11:53:59 +0200 |
| commit | 1d53ea776760097186258ced06d468bf26adb437 (patch) | |
| tree | ed0e12f05ae15a4b35886f78d65a020afcadb7ba | |
| parent | ae9cf40873d351cf5076ef3bca1227ec998848a7 (diff) | |
| download | linux-stable-1d53ea776760097186258ced06d468bf26adb437.tar.gz linux-stable-1d53ea776760097186258ced06d468bf26adb437.tar.bz2 linux-stable-1d53ea776760097186258ced06d468bf26adb437.zip | |
net: tun_chr_open(): set sk_uid from current_fsuid()
commit 9bc3047374d5bec163e83e743709e23753376f0c upstream.
Commit a096ccca6e50 initializes the "sk_uid" field in the protocol socket
(struct sock) from the "/dev/net/tun" 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 "tun", the action that creates the socket is
open("/dev/net/tun").
Therefore the device node's owner UID is irrelevant. In most cases,
"/dev/net/tun" will be owned by root, so in practice, commit a096ccca6e50
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/net/tun" 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: a096ccca6e50 ("tun: tun_chr_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/tun.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index a4e44f98fbc3..309a0dd16bdc 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -3534,7 +3534,7 @@ static int tun_chr_open(struct inode *inode, struct file * file) tfile->socket.file = file; tfile->socket.ops = &tun_socket_ops; - sock_init_data_uid(&tfile->socket, &tfile->sk, inode->i_uid); + sock_init_data_uid(&tfile->socket, &tfile->sk, current_fsuid()); tfile->sk.sk_write_space = tun_sock_write_space; tfile->sk.sk_sndbuf = INT_MAX; |