| Message ID | 1548209986-83527-7-git-send-email-maowenan@huawei.com |
|---|---|
| State | Not Applicable |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | fix FragmentSmack in stable branch (CVE-2018-5391) | expand |
On Wed, Jan 23, 2019 at 10:19:41AM +0800, Mao Wenan wrote: > From: Florian Westphal <fw@strlen.de> > > [ Upstream commit 0ed4229b08c13c84a3c301a08defdc9e7f4467e6 ] > > don't bother with pathological cases, they only waste cycles. > IPv6 requires a minimum MTU of 1280 so we should never see fragments > smaller than this (except last frag). > > v3: don't use awkward "-offset + len" > v2: drop IPv4 part, which added same check w. IPV4_MIN_MTU (68). > There were concerns that there could be even smaller frags > generated by intermediate nodes, e.g. on radio networks. > > Cc: Peter Oskolkov <posk@google.com> > Cc: Eric Dumazet <edumazet@google.com> > Signed-off-by: Florian Westphal <fw@strlen.de> > Signed-off-by: David S. Miller <davem@davemloft.net> > Signed-off-by: Mao Wenan <maowenan@huawei.com> > --- > net/ipv6/netfilter/nf_conntrack_reasm.c | 4 ++++ > net/ipv6/reassembly.c | 4 ++++ > 2 files changed, 8 insertions(+) > > diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c > index 9cd8863..c5033a2 100644 > --- a/net/ipv6/netfilter/nf_conntrack_reasm.c > +++ b/net/ipv6/netfilter/nf_conntrack_reasm.c > @@ -602,6 +602,10 @@ struct sk_buff *nf_ct_frag6_gather(struct net *net, struct sk_buff *skb, u32 use > hdr = ipv6_hdr(clone); > fhdr = (struct frag_hdr *)skb_transport_header(clone); > > + if (skb->len - skb_network_offset(skb) < IPV6_MIN_MTU && > + fhdr->frag_off & htons(IP6_MF)) > + return -EINVAL; This backport is incorrect, you should be returning a pointer, right? How did you test this? This should have blown up under test :( I'm going to drop this whole series. Please fix it up and test it properly and then resend. thanks, greg k-h
On 2019/1/25 2:31, Greg KH wrote: > On Wed, Jan 23, 2019 at 10:19:41AM +0800, Mao Wenan wrote: >> From: Florian Westphal <fw@strlen.de> >> >> [ Upstream commit 0ed4229b08c13c84a3c301a08defdc9e7f4467e6 ] >> >> don't bother with pathological cases, they only waste cycles. >> IPv6 requires a minimum MTU of 1280 so we should never see fragments >> smaller than this (except last frag). >> >> v3: don't use awkward "-offset + len" >> v2: drop IPv4 part, which added same check w. IPV4_MIN_MTU (68). >> There were concerns that there could be even smaller frags >> generated by intermediate nodes, e.g. on radio networks. >> >> Cc: Peter Oskolkov <posk@google.com> >> Cc: Eric Dumazet <edumazet@google.com> >> Signed-off-by: Florian Westphal <fw@strlen.de> >> Signed-off-by: David S. Miller <davem@davemloft.net> >> Signed-off-by: Mao Wenan <maowenan@huawei.com> >> --- >> net/ipv6/netfilter/nf_conntrack_reasm.c | 4 ++++ >> net/ipv6/reassembly.c | 4 ++++ >> 2 files changed, 8 insertions(+) >> >> diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c >> index 9cd8863..c5033a2 100644 >> --- a/net/ipv6/netfilter/nf_conntrack_reasm.c >> +++ b/net/ipv6/netfilter/nf_conntrack_reasm.c >> @@ -602,6 +602,10 @@ struct sk_buff *nf_ct_frag6_gather(struct net *net, struct sk_buff *skb, u32 use >> hdr = ipv6_hdr(clone); >> fhdr = (struct frag_hdr *)skb_transport_header(clone); >> >> + if (skb->len - skb_network_offset(skb) < IPV6_MIN_MTU && >> + fhdr->frag_off & htons(IP6_MF)) >> + return -EINVAL; > > This backport is incorrect, you should be returning a pointer, right? Thank you for correcting me, the return value should be a pointer, I will fix it and test all of patches again, then resend v2. sorry for my mistake. > > How did you test this? This should have blown up under test :( > > I'm going to drop this whole series. Please fix it up and test it > properly and then resend. > > thanks, > > greg k-h > > . >
diff --git a/net/ipv6/netfilter/nf_conntrack_reasm.c b/net/ipv6/netfilter/nf_conntrack_reasm.c index 9cd8863..c5033a2 100644 --- a/net/ipv6/netfilter/nf_conntrack_reasm.c +++ b/net/ipv6/netfilter/nf_conntrack_reasm.c @@ -602,6 +602,10 @@ struct sk_buff *nf_ct_frag6_gather(struct net *net, struct sk_buff *skb, u32 use hdr = ipv6_hdr(clone); fhdr = (struct frag_hdr *)skb_transport_header(clone); + if (skb->len - skb_network_offset(skb) < IPV6_MIN_MTU && + fhdr->frag_off & htons(IP6_MF)) + return -EINVAL; + skb_orphan(skb); fq = fq_find(net, fhdr->identification, user, &hdr->saddr, &hdr->daddr, skb->dev ? skb->dev->ifindex : 0, ip6_frag_ecn(hdr)); diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c index adc7512..44c7f4c 100644 --- a/net/ipv6/reassembly.c +++ b/net/ipv6/reassembly.c @@ -549,6 +549,10 @@ static int ipv6_frag_rcv(struct sk_buff *skb) return 1; } + if (skb->len - skb_network_offset(skb) < IPV6_MIN_MTU && + fhdr->frag_off & htons(IP6_MF)) + goto fail_hdr; + fq = fq_find(net, fhdr->identification, &hdr->saddr, &hdr->daddr, skb->dev ? skb->dev->ifindex : 0, ip6_frag_ecn(hdr)); if (fq) {