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authorNeil Horman <nhorman@tuxdriver.com>2009-10-28 08:59:47 +0000
committerDavid S. Miller <davem@davemloft.net>2009-10-29 01:09:58 -0700
commit55888dfb6ba7e318bb3d6a44d25009906206bf6a (patch)
treef78100527fdc2aa7d9626fd1c2475f0a8ee7a342
parentf552ce5fc2df5504f2feb0087e8a3e61b694ad67 (diff)
downloadvexpress-lsk-55888dfb6ba7e318bb3d6a44d25009906206bf6a.tar.gz
AF_RAW: Augment raw_send_hdrinc to expand skb to fit iphdr->ihl (v2)
Augment raw_send_hdrinc to correct for incorrect ip header length values A series of oopses was reported to me recently. Apparently when using AF_RAW sockets to send data to peers that were reachable via ipsec encapsulation, people could panic or BUG halt their systems. I've tracked the problem down to user space sending an invalid ip header over an AF_RAW socket with IP_HDRINCL set to 1. Basically what happens is that userspace sends down an ip frame that includes only the header (no data), but sets the ip header ihl value to a large number, one that is larger than the total amount of data passed to the sendmsg call. In raw_send_hdrincl, we allocate an skb based on the size of the data in the msghdr that was passed in, but assume the data is all valid. Later during ipsec encapsulation, xfrm4_tranport_output moves the entire frame back in the skbuff to provide headroom for the ipsec headers. During this operation, the skb->transport_header is repointed to a spot computed by skb->network_header + the ip header length (ihl). Since so little data was passed in relative to the value of ihl provided by the raw socket, we point transport header to an unknown location, resulting in various crashes. This fix for this is pretty straightforward, simply validate the value of of iph->ihl when sending over a raw socket. If (iph->ihl*4U) > user data buffer size, drop the frame and return -EINVAL. I just confirmed this fixes the reported crashes. Signed-off-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/raw.c24
1 files changed, 17 insertions, 7 deletions
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 757c9171e7c..ab996f9c0fe 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -352,13 +352,24 @@ static int raw_send_hdrinc(struct sock *sk, void *from, size_t length,
skb->ip_summed = CHECKSUM_NONE;
skb->transport_header = skb->network_header;
- err = memcpy_fromiovecend((void *)iph, from, 0, length);
- if (err)
- goto error_fault;
+ err = -EFAULT;
+ if (memcpy_fromiovecend((void *)iph, from, 0, length))
+ goto error_free;
- /* We don't modify invalid header */
iphlen = iph->ihl * 4;
- if (iphlen >= sizeof(*iph) && iphlen <= length) {
+
+ /*
+ * We don't want to modify the ip header, but we do need to
+ * be sure that it won't cause problems later along the network
+ * stack. Specifically we want to make sure that iph->ihl is a
+ * sane value. If ihl points beyond the length of the buffer passed
+ * in, reject the frame as invalid
+ */
+ err = -EINVAL;
+ if (iphlen > length)
+ goto error_free;
+
+ if (iphlen >= sizeof(*iph)) {
if (!iph->saddr)
iph->saddr = rt->rt_src;
iph->check = 0;
@@ -381,8 +392,7 @@ static int raw_send_hdrinc(struct sock *sk, void *from, size_t length,
out:
return 0;
-error_fault:
- err = -EFAULT;
+error_free:
kfree_skb(skb);
error:
IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);