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selinux: properly handle multiple messages in selinux_netlink_send()

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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>
This commit is contained in:
Paul Moore 2020-04-28 09:59:02 -04:00 committed by Greg Kroah-Hartman
parent 87cb81e69b
commit 23075857ad
1 changed files with 45 additions and 25 deletions
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70
security/selinux/hooks.c
View file

@ -5595,40 +5595,60 @@ 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;
err = selinux_nlmsg_lookup(sksec->sclass, nlh->nlmsg_type, &perm);
if (err) {
if (err == -EINVAL) {
/* 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;
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