From 013e8167899d389075160412a8c0c5e0581e1f13 Mon Sep 17 00:00:00 2001 From: David Lebrun Date: Thu, 2 Feb 2017 11:29:38 +0100 Subject: [PATCH] ipv6: sr: remove cleanup flag and fix HMAC computation In the latest version of the IPv6 Segment Routing IETF draft [1] the cleanup flag is removed and the flags field length is shrunk from 16 bits to 8 bits. As a consequence, the input of the HMAC computation is modified in a non-backward compatible way by covering the whole octet of flags instead of only the cleanup bit. As such, if an implementation compatible with the latest draft computes the HMAC of an SRH who has other flags set to 1, then the HMAC result would differ from the current implementation. This patch carries those modifications to prevent conflict with other implementations of IPv6 SR. [1] https://tools.ietf.org/html/draft-ietf-6man-segment-routing-header-05 Signed-off-by: David Lebrun Signed-off-by: David S. Miller --- include/uapi/linux/seg6.h | 9 +++------ net/ipv6/exthdrs.c | 31 +++---------------------------- net/ipv6/seg6_hmac.c | 8 ++++---- 3 files changed, 10 insertions(+), 38 deletions(-) diff --git a/include/uapi/linux/seg6.h b/include/uapi/linux/seg6.h index c396a80..052799e 100644 --- a/include/uapi/linux/seg6.h +++ b/include/uapi/linux/seg6.h @@ -23,14 +23,12 @@ struct ipv6_sr_hdr { __u8 type; __u8 segments_left; __u8 first_segment; - __u8 flag_1; - __u8 flag_2; - __u8 reserved; + __u8 flags; + __u16 reserved; struct in6_addr segments[0]; }; -#define SR6_FLAG1_CLEANUP (1 << 7) #define SR6_FLAG1_PROTECTED (1 << 6) #define SR6_FLAG1_OAM (1 << 5) #define SR6_FLAG1_ALERT (1 << 4) @@ -42,8 +40,7 @@ struct ipv6_sr_hdr { #define SR6_TLV_PADDING 4 #define SR6_TLV_HMAC 5 -#define sr_has_cleanup(srh) ((srh)->flag_1 & SR6_FLAG1_CLEANUP) -#define sr_has_hmac(srh) ((srh)->flag_1 & SR6_FLAG1_HMAC) +#define sr_has_hmac(srh) ((srh)->flags & SR6_FLAG1_HMAC) struct sr6_tlv { __u8 type; diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c index e419850..275cac6 100644 --- a/net/ipv6/exthdrs.c +++ b/net/ipv6/exthdrs.c @@ -327,7 +327,6 @@ static int ipv6_srh_rcv(struct sk_buff *skb) struct ipv6_sr_hdr *hdr; struct inet6_dev *idev; struct in6_addr *addr; - bool cleanup = false; int accept_seg6; hdr = (struct ipv6_sr_hdr *)skb_transport_header(skb); @@ -351,11 +350,7 @@ static int ipv6_srh_rcv(struct sk_buff *skb) #endif looped_back: - if (hdr->segments_left > 0) { - if (hdr->nexthdr != NEXTHDR_IPV6 && hdr->segments_left == 1 && - sr_has_cleanup(hdr)) - cleanup = true; - } else { + if (hdr->segments_left == 0) { if (hdr->nexthdr == NEXTHDR_IPV6) { int offset = (hdr->hdrlen + 1) << 3; @@ -418,21 +413,6 @@ looped_back: ipv6_hdr(skb)->daddr = *addr; - if (cleanup) { - int srhlen = (hdr->hdrlen + 1) << 3; - int nh = hdr->nexthdr; - - skb_pull_rcsum(skb, sizeof(struct ipv6hdr) + srhlen); - memmove(skb_network_header(skb) + srhlen, - skb_network_header(skb), - (unsigned char *)hdr - skb_network_header(skb)); - skb->network_header += srhlen; - ipv6_hdr(skb)->nexthdr = nh; - ipv6_hdr(skb)->payload_len = htons(skb->len - - sizeof(struct ipv6hdr)); - skb_push_rcsum(skb, sizeof(struct ipv6hdr)); - } - skb_dst_drop(skb); ip6_route_input(skb); @@ -453,13 +433,8 @@ looped_back: } ipv6_hdr(skb)->hop_limit--; - /* be sure that srh is still present before reinjecting */ - if (!cleanup) { - skb_pull(skb, sizeof(struct ipv6hdr)); - goto looped_back; - } - skb_set_transport_header(skb, sizeof(struct ipv6hdr)); - IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr); + skb_pull(skb, sizeof(struct ipv6hdr)); + goto looped_back; } dst_input(skb); diff --git a/net/ipv6/seg6_hmac.c b/net/ipv6/seg6_hmac.c index 03a0648..6ef3dfb 100644 --- a/net/ipv6/seg6_hmac.c +++ b/net/ipv6/seg6_hmac.c @@ -174,7 +174,7 @@ int seg6_hmac_compute(struct seg6_hmac_info *hinfo, struct ipv6_sr_hdr *hdr, * hash function (RadioGatun) with up to 1216 bits */ - /* saddr(16) + first_seg(1) + cleanup(1) + keyid(4) + seglist(16n) */ + /* saddr(16) + first_seg(1) + flags(1) + keyid(4) + seglist(16n) */ plen = 16 + 1 + 1 + 4 + (hdr->first_segment + 1) * 16; /* this limit allows for 14 segments */ @@ -186,7 +186,7 @@ int seg6_hmac_compute(struct seg6_hmac_info *hinfo, struct ipv6_sr_hdr *hdr, * * 1. Source IPv6 address (128 bits) * 2. first_segment value (8 bits) - * 3. cleanup flag (8 bits: highest bit is cleanup value, others are 0) + * 3. Flags (8 bits) * 4. HMAC Key ID (32 bits) * 5. All segments in the segments list (n * 128 bits) */ @@ -202,8 +202,8 @@ int seg6_hmac_compute(struct seg6_hmac_info *hinfo, struct ipv6_sr_hdr *hdr, /* first_segment value */ *off++ = hdr->first_segment; - /* cleanup flag */ - *off++ = !!(sr_has_cleanup(hdr)) << 7; + /* flags */ + *off++ = hdr->flags; /* HMAC Key ID */ memcpy(off, &hmackeyid, 4); -- 2.7.4