| Message ID | 20210130115452.19192-2-acj@cisco.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [stable,v5.4,1/2] ICMPv6: Add ICMPv6 Parameter Problem, code 3 definition | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Guessing tree name failed - patch did not apply |
On Sat, Jan 30, 2021 at 05:24:52PM +0530, Aviraj CJ wrote: > From: Hangbin Liu <liuhangbin@gmail.com> > > commit 2efdaaaf883a143061296467913c01aa1ff4b3ce upstream. > > Based on RFC 8200, Section 4.5 Fragment Header: > > - If the first fragment does not include all headers through an > Upper-Layer header, then that fragment should be discarded and > an ICMP Parameter Problem, Code 3, message should be sent to > the source of the fragment, with the Pointer field set to zero. > > Checking each packet header in IPv6 fast path will have performance impact, > so I put the checking in ipv6_frag_rcv(). > > As the packet may be any kind of L4 protocol, I only checked some common > protocols' header length and handle others by (offset + 1) > skb->len. > Also use !(frag_off & htons(IP6_OFFSET)) to catch atomic fragments > (fragmented packet with only one fragment). > > When send ICMP error message, if the 1st truncated fragment is ICMP message, > icmp6_send() will break as is_ineligible() return true. So I added a check > in is_ineligible() to let fragment packet with nexthdr ICMP but no ICMP header > return false. > > Signed-off-by: Hangbin Liu <liuhangbin@gmail.com> > Signed-off-by: Jakub Kicinski <kuba@kernel.org> > Signed-off-by: Aviraj CJ <acj@cisco.com> > --- > net/ipv6/icmp.c | 8 +++++++- > net/ipv6/reassembly.c | 33 ++++++++++++++++++++++++++++++++- > 2 files changed, 39 insertions(+), 2 deletions(-) Both now queued up, thanks. greg k-h
diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c index 7d3a3894f785..e9bb89131e02 100644 --- a/net/ipv6/icmp.c +++ b/net/ipv6/icmp.c @@ -158,7 +158,13 @@ static bool is_ineligible(const struct sk_buff *skb) tp = skb_header_pointer(skb, ptr+offsetof(struct icmp6hdr, icmp6_type), sizeof(_type), &_type); - if (!tp || !(*tp & ICMPV6_INFOMSG_MASK)) + + /* Based on RFC 8200, Section 4.5 Fragment Header, return + * false if this is a fragment packet with no icmp header info. + */ + if (!tp && frag_off != 0) + return false; + else if (!tp || !(*tp & ICMPV6_INFOMSG_MASK)) return true; } return false; diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c index 1f5d4d196dcc..c8cf1bbad74a 100644 --- a/net/ipv6/reassembly.c +++ b/net/ipv6/reassembly.c @@ -42,6 +42,8 @@ #include <linux/skbuff.h> #include <linux/slab.h> #include <linux/export.h> +#include <linux/tcp.h> +#include <linux/udp.h> #include <net/sock.h> #include <net/snmp.h> @@ -322,7 +324,9 @@ static int ipv6_frag_rcv(struct sk_buff *skb) struct frag_queue *fq; const struct ipv6hdr *hdr = ipv6_hdr(skb); struct net *net = dev_net(skb_dst(skb)->dev); - int iif; + __be16 frag_off; + int iif, offset; + u8 nexthdr; if (IP6CB(skb)->flags & IP6SKB_FRAGMENTED) goto fail_hdr; @@ -351,6 +355,33 @@ static int ipv6_frag_rcv(struct sk_buff *skb) return 1; } + /* RFC 8200, Section 4.5 Fragment Header: + * If the first fragment does not include all headers through an + * Upper-Layer header, then that fragment should be discarded and + * an ICMP Parameter Problem, Code 3, message should be sent to + * the source of the fragment, with the Pointer field set to zero. + */ + nexthdr = hdr->nexthdr; + offset = ipv6_skip_exthdr(skb, skb_transport_offset(skb), &nexthdr, &frag_off); + if (offset >= 0) { + /* Check some common protocols' header */ + if (nexthdr == IPPROTO_TCP) + offset += sizeof(struct tcphdr); + else if (nexthdr == IPPROTO_UDP) + offset += sizeof(struct udphdr); + else if (nexthdr == IPPROTO_ICMPV6) + offset += sizeof(struct icmp6hdr); + else + offset += 1; + + if (!(frag_off & htons(IP6_OFFSET)) && offset > skb->len) { + __IP6_INC_STATS(net, __in6_dev_get_safely(skb->dev), + IPSTATS_MIB_INHDRERRORS); + icmpv6_param_prob(skb, ICMPV6_HDR_INCOMP, 0); + return -1; + } + } + iif = skb->dev ? skb->dev->ifindex : 0; fq = fq_find(net, fhdr->identification, hdr, iif); if (fq) {