From 584f3742890e966d2f0a1f3c418c9ead70b2d99e Mon Sep 17 00:00:00 2001 From: Pietro Borrello Date: Sat, 4 Feb 2023 17:39:20 +0000 Subject: net: add sock_init_data_uid() Add sock_init_data_uid() to explicitly initialize the socket uid. To initialise the socket uid, sock_init_data() assumes a the struct socket* sock is always embedded in a struct socket_alloc, used to access the corresponding inode uid. This may not be true. Examples are sockets created in tun_chr_open() and tap_open(). Fixes: 86741ec25462 ("net: core: Add a UID field to struct sock.") Signed-off-by: Pietro Borrello Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- include/net/sock.h | 7 ++++++- net/core/sock.c | 15 ++++++++++++--- 2 files changed, 18 insertions(+), 4 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index dcd72e6285b2..937e842dc930 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1956,7 +1956,12 @@ void sk_common_release(struct sock *sk); * Default socket callbacks and setup code */ -/* Initialise core socket variables */ +/* Initialise core socket variables using an explicit uid. */ +void sock_init_data_uid(struct socket *sock, struct sock *sk, kuid_t uid); + +/* Initialise core socket variables. + * Assumes struct socket *sock is embedded in a struct socket_alloc. + */ void sock_init_data(struct socket *sock, struct sock *sk); /* diff --git a/net/core/sock.c b/net/core/sock.c index f08b76acde9b..208634b01df5 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -3383,7 +3383,7 @@ void sk_stop_timer_sync(struct sock *sk, struct timer_list *timer) } EXPORT_SYMBOL(sk_stop_timer_sync); -void sock_init_data(struct socket *sock, struct sock *sk) +void sock_init_data_uid(struct socket *sock, struct sock *sk, kuid_t uid) { sk_init_common(sk); sk->sk_send_head = NULL; @@ -3403,11 +3403,10 @@ void sock_init_data(struct socket *sock, struct sock *sk) sk->sk_type = sock->type; RCU_INIT_POINTER(sk->sk_wq, &sock->wq); sock->sk = sk; - sk->sk_uid = SOCK_INODE(sock)->i_uid; } else { RCU_INIT_POINTER(sk->sk_wq, NULL); - sk->sk_uid = make_kuid(sock_net(sk)->user_ns, 0); } + sk->sk_uid = uid; rwlock_init(&sk->sk_callback_lock); if (sk->sk_kern_sock) @@ -3466,6 +3465,16 @@ void sock_init_data(struct socket *sock, struct sock *sk) refcount_set(&sk->sk_refcnt, 1); atomic_set(&sk->sk_drops, 0); } +EXPORT_SYMBOL(sock_init_data_uid); + +void sock_init_data(struct socket *sock, struct sock *sk) +{ + kuid_t uid = sock ? + SOCK_INODE(sock)->i_uid : + make_kuid(sock_net(sk)->user_ns, 0); + + sock_init_data_uid(sock, sk, uid); +} EXPORT_SYMBOL(sock_init_data); void lock_sock_nested(struct sock *sk, int subclass) -- cgit v1.2.3 From a096ccca6e503a5c575717ff8a36ace27510ab0a Mon Sep 17 00:00:00 2001 From: Pietro Borrello Date: Sat, 4 Feb 2023 17:39:21 +0000 Subject: tun: tun_chr_open(): correctly initialize socket uid 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 Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- drivers/net/tun.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index a7d17c680f4a..745131b2d6db 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -3448,7 +3448,7 @@ 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; -- cgit v1.2.3 From 66b2c338adce580dfce2199591e65e2bab889cff Mon Sep 17 00:00:00 2001 From: Pietro Borrello Date: Sat, 4 Feb 2023 17:39:22 +0000 Subject: tap: tap_open(): correctly initialize socket uid 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 Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- drivers/net/tap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/tap.c b/drivers/net/tap.c index a2be1994b389..8941aa199ea3 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; -- cgit v1.2.3