From: Paul Moore paul@paul-moore.com
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
--- security/selinux/hooks.c | 69 ++++++++++++++++++++++++++++++----------------- 1 file changed, 45 insertions(+), 24 deletions(-)
--- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -4791,38 +4791,59 @@ static int selinux_tun_dev_open(void *se
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) { - printk(KERN_WARNING - "SELinux: unrecognized netlink message:" - " protocol=%hu nlmsg_type=%hu sclass=%s\n", - sk->sk_protocol, nlh->nlmsg_type, - secclass_map[sksec->sclass - 1].name); - if (!selinux_enforcing || security_get_allow_unknown()) - err = 0; + /* 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(current, 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" + " pid=%d comm=%s\n", + sk->sk_protocol, nlh->nlmsg_type, + secclass_map[sclass - 1].name, + task_pid_nr(current), current->comm); + if (selinux_enforcing && !security_get_allow_unknown()) + 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(current, sk, perm); -out: - return err; + return rc; }
#ifdef CONFIG_NETFILTER