diff mbox series

[SRU,OEM-6.0,2/3] tun: tun_chr_open(): correctly initialize socket uid

Message ID 20230824110603.1266826-3-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, tun_chr_open() passes a `struct socket` embedded in a `struct
tun_file` 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 the
high 4 bytes of `struct tun_struct __rcu *tun` of `struct tun_file`,
NULL at the time of call, which makes the uid of all tun 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 a096ccca6e503a5c575717ff8a36ace27510ab0a)
CVE-2023-1076
Signed-off-by: Cengiz Can <cengiz.can@canonical.com>
---
 drivers/net/tun.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 3387074a2bdb..7fd539387e80 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -3447,7 +3447,7 @@  static int tun_chr_open(struct inode *inode, struct file * file)
 	tfile->socket.file = file;
 	tfile->socket.ops = &tun_socket_ops;
 
-	sock_init_data(&tfile->socket, &tfile->sk);
+	sock_init_data_uid(&tfile->socket, &tfile->sk, inode->i_uid);
 
 	tfile->sk.sk_write_space = tun_sock_write_space;
 	tfile->sk.sk_sndbuf = INT_MAX;