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[SRU,OEM-6.0,3/3] tap: tap_open(): correctly initialize socket uid

Message ID 20230824110603.1266826-4-cengiz.can@canonical.com
State New
Headers show
Series CVE-2023-1076 | expand

Commit Message

Cengiz Can Aug. 24, 2023, 11:06 a.m. UTC 
From: Pietro Borrello <borrello@diag.uniroma1.it>

sock_init_data() assumes that the `struct socket` passed in input is
contained in a `struct socket_alloc` allocated with sock_alloc().
However, tap_open() passes a `struct socket` embedded in a `struct
tap_queue` allocated with sk_alloc().
This causes a type confusion when issuing a container_of() with
SOCK_INODE() in sock_init_data() which results in assigning a wrong
sk_uid to the `struct sock` in input.
On default configuration, the type confused field overlaps with
padding bytes between `int vnet_hdr_sz` and `struct tap_dev __rcu
*tap` in `struct tap_queue`, which makes the uid of all tap sockets 0,
i.e., the root one.
Fix the assignment by using sock_init_data_uid().

Fixes: 86741ec25462 ("net: core: Add a UID field to struct sock.")
Signed-off-by: Pietro Borrello <borrello@diag.uniroma1.it>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 66b2c338adce580dfce2199591e65e2bab889cff)
CVE-2023-1076
Signed-off-by: Cengiz Can <cengiz.can@canonical.com>
---
 drivers/net/tap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index 9e75ed3f08ce..760d8d1b6cba 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -533,7 +533,7 @@  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(&q->sock, &q->sk);
+	sock_init_data_uid(&q->sock, &q->sk, inode->i_uid);
 	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;