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authorPhil Sutter <phil@nwl.cc>2023-12-05 21:58:12 +0100
committerPablo Neira Ayuso <pablo@netfilter.org>2023-12-06 17:52:15 +0100
commit7ae836a3d630e146b732fe8ef7d86b243748751f (patch)
treee7de314a4b70b89d256168aa8fb078de3c7117aa /net
parentf6e1532a2697b81da00bfb184e99d15e01e9d98c (diff)
netfilter: xt_owner: Fix for unsafe access of sk->sk_socket
A concurrently running sock_orphan() may NULL the sk_socket pointer in between check and deref. Follow other users (like nft_meta.c for instance) and acquire sk_callback_lock before dereferencing sk_socket. Fixes: 0265ab44bacc ("[NETFILTER]: merge ipt_owner/ip6t_owner in xt_owner") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Phil Sutter <phil@nwl.cc> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/xt_owner.c16
1 files changed, 12 insertions, 4 deletions
diff --git a/net/netfilter/xt_owner.c b/net/netfilter/xt_owner.c
index e85ce69924ae..50332888c8d2 100644
--- a/net/netfilter/xt_owner.c
+++ b/net/netfilter/xt_owner.c
@@ -76,18 +76,23 @@ owner_mt(const struct sk_buff *skb, struct xt_action_param *par)
*/
return false;
- filp = sk->sk_socket->file;
- if (filp == NULL)
+ read_lock_bh(&sk->sk_callback_lock);
+ filp = sk->sk_socket ? sk->sk_socket->file : NULL;
+ if (filp == NULL) {
+ read_unlock_bh(&sk->sk_callback_lock);
return ((info->match ^ info->invert) &
(XT_OWNER_UID | XT_OWNER_GID)) == 0;
+ }
if (info->match & XT_OWNER_UID) {
kuid_t uid_min = make_kuid(net->user_ns, info->uid_min);
kuid_t uid_max = make_kuid(net->user_ns, info->uid_max);
if ((uid_gte(filp->f_cred->fsuid, uid_min) &&
uid_lte(filp->f_cred->fsuid, uid_max)) ^
- !(info->invert & XT_OWNER_UID))
+ !(info->invert & XT_OWNER_UID)) {
+ read_unlock_bh(&sk->sk_callback_lock);
return false;
+ }
}
if (info->match & XT_OWNER_GID) {
@@ -112,10 +117,13 @@ owner_mt(const struct sk_buff *skb, struct xt_action_param *par)
}
}
- if (match ^ !(info->invert & XT_OWNER_GID))
+ if (match ^ !(info->invert & XT_OWNER_GID)) {
+ read_unlock_bh(&sk->sk_callback_lock);
return false;
+ }
}
+ read_unlock_bh(&sk->sk_callback_lock);
return true;
}