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authorPaul Moore <paul@paul-moore.com>2020-04-28 09:59:02 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-05-06 08:15:17 +0200
commiteeef0d9fd40df3c033dca68bca8249e5951660ac (patch)
treeef3a6a0d55a4a3f9bcda95ad72c9e204bc77f1b7
parent1de07eb54ab75bd475e73f80339f40dfbc67e3bc (diff)
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selinux: properly handle multiple messages in selinux_netlink_send()
commit fb73974172ffaaf57a7c42f35424d9aece1a5af6 upstream. Fix the SELinux netlink_send hook to properly handle multiple netlink messages in a single sk_buff; each message is parsed and subject to SELinux access control. Prior to this patch, SELinux only inspected the first message in the sk_buff. Cc: stable@vger.kernel.org Reported-by: Dmitry Vyukov <dvyukov@google.com> Reviewed-by: Stephen Smalley <stephen.smalley.work@gmail.com> Signed-off-by: Paul Moore <paul@paul-moore.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--security/selinux/hooks.c70
1 files changed, 45 insertions, 25 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 39410913a694..552e73d90fd2 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -5521,40 +5521,60 @@ static int selinux_tun_dev_open(void *security)
static int selinux_nlmsg_perm(struct sock *sk, struct sk_buff *skb)
{
- int err = 0;
- u32 perm;
+ int rc = 0;
+ unsigned int msg_len;
+ unsigned int data_len = skb->len;
+ unsigned char *data = skb->data;
struct nlmsghdr *nlh;
struct sk_security_struct *sksec = sk->sk_security;
+ u16 sclass = sksec->sclass;
+ u32 perm;
- if (skb->len < NLMSG_HDRLEN) {
- err = -EINVAL;
- goto out;
- }
- nlh = nlmsg_hdr(skb);
+ while (data_len >= nlmsg_total_size(0)) {
+ nlh = (struct nlmsghdr *)data;
+
+ /* NOTE: the nlmsg_len field isn't reliably set by some netlink
+ * users which means we can't reject skb's with bogus
+ * length fields; our solution is to follow what
+ * netlink_rcv_skb() does and simply skip processing at
+ * messages with length fields that are clearly junk
+ */
+ if (nlh->nlmsg_len < NLMSG_HDRLEN || nlh->nlmsg_len > data_len)
+ return 0;
- err = selinux_nlmsg_lookup(sksec->sclass, nlh->nlmsg_type, &perm);
- if (err) {
- if (err == -EINVAL) {
+ rc = selinux_nlmsg_lookup(sclass, nlh->nlmsg_type, &perm);
+ if (rc == 0) {
+ rc = sock_has_perm(sk, perm);
+ if (rc)
+ return rc;
+ } else if (rc == -EINVAL) {
+ /* -EINVAL is a missing msg/perm mapping */
pr_warn_ratelimited("SELinux: unrecognized netlink"
- " message: protocol=%hu nlmsg_type=%hu sclass=%s"
- " pig=%d comm=%s\n",
- sk->sk_protocol, nlh->nlmsg_type,
- secclass_map[sksec->sclass - 1].name,
- task_pid_nr(current), current->comm);
- if (!enforcing_enabled(&selinux_state) ||
- security_get_allow_unknown(&selinux_state))
- err = 0;
+ " message: protocol=%hu nlmsg_type=%hu sclass=%s"
+ " pid=%d comm=%s\n",
+ sk->sk_protocol, nlh->nlmsg_type,
+ secclass_map[sclass - 1].name,
+ task_pid_nr(current), current->comm);
+ if (enforcing_enabled(&selinux_state) &&
+ !security_get_allow_unknown(&selinux_state))
+ return rc;
+ rc = 0;
+ } else if (rc == -ENOENT) {
+ /* -ENOENT is a missing socket/class mapping, ignore */
+ rc = 0;
+ } else {
+ return rc;
}
- /* Ignore */
- if (err == -ENOENT)
- err = 0;
- goto out;
+ /* move to the next message after applying netlink padding */
+ msg_len = NLMSG_ALIGN(nlh->nlmsg_len);
+ if (msg_len >= data_len)
+ return 0;
+ data_len -= msg_len;
+ data += msg_len;
}
- err = sock_has_perm(sk, perm);
-out:
- return err;
+ return rc;
}
#ifdef CONFIG_NETFILTER