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-rw-r--r--net/ipv6/exthdrs_core.c282
1 files changed, 282 insertions, 0 deletions
diff --git a/net/ipv6/exthdrs_core.c b/net/ipv6/exthdrs_core.c
new file mode 100644
index 000000000..49e31e4ae
--- /dev/null
+++ b/net/ipv6/exthdrs_core.c
@@ -0,0 +1,282 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * IPv6 library code, needed by static components when full IPv6 support is
+ * not configured or static.
+ */
+#include <linux/export.h>
+#include <net/ipv6.h>
+
+/*
+ * find out if nexthdr is a well-known extension header or a protocol
+ */
+
+bool ipv6_ext_hdr(u8 nexthdr)
+{
+ /*
+ * find out if nexthdr is an extension header or a protocol
+ */
+ return (nexthdr == NEXTHDR_HOP) ||
+ (nexthdr == NEXTHDR_ROUTING) ||
+ (nexthdr == NEXTHDR_FRAGMENT) ||
+ (nexthdr == NEXTHDR_AUTH) ||
+ (nexthdr == NEXTHDR_NONE) ||
+ (nexthdr == NEXTHDR_DEST);
+}
+EXPORT_SYMBOL(ipv6_ext_hdr);
+
+/*
+ * Skip any extension headers. This is used by the ICMP module.
+ *
+ * Note that strictly speaking this conflicts with RFC 2460 4.0:
+ * ...The contents and semantics of each extension header determine whether
+ * or not to proceed to the next header. Therefore, extension headers must
+ * be processed strictly in the order they appear in the packet; a
+ * receiver must not, for example, scan through a packet looking for a
+ * particular kind of extension header and process that header prior to
+ * processing all preceding ones.
+ *
+ * We do exactly this. This is a protocol bug. We can't decide after a
+ * seeing an unknown discard-with-error flavour TLV option if it's a
+ * ICMP error message or not (errors should never be send in reply to
+ * ICMP error messages).
+ *
+ * But I see no other way to do this. This might need to be reexamined
+ * when Linux implements ESP (and maybe AUTH) headers.
+ * --AK
+ *
+ * This function parses (probably truncated) exthdr set "hdr".
+ * "nexthdrp" initially points to some place,
+ * where type of the first header can be found.
+ *
+ * It skips all well-known exthdrs, and returns pointer to the start
+ * of unparsable area i.e. the first header with unknown type.
+ * If it is not NULL *nexthdr is updated by type/protocol of this header.
+ *
+ * NOTES: - if packet terminated with NEXTHDR_NONE it returns NULL.
+ * - it may return pointer pointing beyond end of packet,
+ * if the last recognized header is truncated in the middle.
+ * - if packet is truncated, so that all parsed headers are skipped,
+ * it returns NULL.
+ * - First fragment header is skipped, not-first ones
+ * are considered as unparsable.
+ * - Reports the offset field of the final fragment header so it is
+ * possible to tell whether this is a first fragment, later fragment,
+ * or not fragmented.
+ * - ESP is unparsable for now and considered like
+ * normal payload protocol.
+ * - Note also special handling of AUTH header. Thanks to IPsec wizards.
+ *
+ * --ANK (980726)
+ */
+
+int ipv6_skip_exthdr(const struct sk_buff *skb, int start, u8 *nexthdrp,
+ __be16 *frag_offp)
+{
+ u8 nexthdr = *nexthdrp;
+
+ *frag_offp = 0;
+
+ while (ipv6_ext_hdr(nexthdr)) {
+ struct ipv6_opt_hdr _hdr, *hp;
+ int hdrlen;
+
+ if (nexthdr == NEXTHDR_NONE)
+ return -1;
+ hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr);
+ if (!hp)
+ return -1;
+ if (nexthdr == NEXTHDR_FRAGMENT) {
+ __be16 _frag_off, *fp;
+ fp = skb_header_pointer(skb,
+ start+offsetof(struct frag_hdr,
+ frag_off),
+ sizeof(_frag_off),
+ &_frag_off);
+ if (!fp)
+ return -1;
+
+ *frag_offp = *fp;
+ if (ntohs(*frag_offp) & ~0x7)
+ break;
+ hdrlen = 8;
+ } else if (nexthdr == NEXTHDR_AUTH)
+ hdrlen = ipv6_authlen(hp);
+ else
+ hdrlen = ipv6_optlen(hp);
+
+ nexthdr = hp->nexthdr;
+ start += hdrlen;
+ }
+
+ *nexthdrp = nexthdr;
+ return start;
+}
+EXPORT_SYMBOL(ipv6_skip_exthdr);
+
+int ipv6_find_tlv(const struct sk_buff *skb, int offset, int type)
+{
+ const unsigned char *nh = skb_network_header(skb);
+ int packet_len = skb_tail_pointer(skb) - skb_network_header(skb);
+ struct ipv6_opt_hdr *hdr;
+ int len;
+
+ if (offset + 2 > packet_len)
+ goto bad;
+ hdr = (struct ipv6_opt_hdr *)(nh + offset);
+ len = ((hdr->hdrlen + 1) << 3);
+
+ if (offset + len > packet_len)
+ goto bad;
+
+ offset += 2;
+ len -= 2;
+
+ while (len > 0) {
+ int opttype = nh[offset];
+ int optlen;
+
+ if (opttype == type)
+ return offset;
+
+ switch (opttype) {
+ case IPV6_TLV_PAD1:
+ optlen = 1;
+ break;
+ default:
+ if (len < 2)
+ goto bad;
+ optlen = nh[offset + 1] + 2;
+ if (optlen > len)
+ goto bad;
+ break;
+ }
+ offset += optlen;
+ len -= optlen;
+ }
+ /* not_found */
+ bad:
+ return -1;
+}
+EXPORT_SYMBOL_GPL(ipv6_find_tlv);
+
+/*
+ * find the offset to specified header or the protocol number of last header
+ * if target < 0. "last header" is transport protocol header, ESP, or
+ * "No next header".
+ *
+ * Note that *offset is used as input/output parameter, and if it is not zero,
+ * then it must be a valid offset to an inner IPv6 header. This can be used
+ * to explore inner IPv6 header, eg. ICMPv6 error messages.
+ *
+ * If target header is found, its offset is set in *offset and return protocol
+ * number. Otherwise, return -1.
+ *
+ * If the first fragment doesn't contain the final protocol header or
+ * NEXTHDR_NONE it is considered invalid.
+ *
+ * Note that non-1st fragment is special case that "the protocol number
+ * of last header" is "next header" field in Fragment header. In this case,
+ * *offset is meaningless and fragment offset is stored in *fragoff if fragoff
+ * isn't NULL.
+ *
+ * if flags is not NULL and it's a fragment, then the frag flag
+ * IP6_FH_F_FRAG will be set. If it's an AH header, the
+ * IP6_FH_F_AUTH flag is set and target < 0, then this function will
+ * stop at the AH header. If IP6_FH_F_SKIP_RH flag was passed, then this
+ * function will skip all those routing headers, where segements_left was 0.
+ */
+int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
+ int target, unsigned short *fragoff, int *flags)
+{
+ unsigned int start = skb_network_offset(skb) + sizeof(struct ipv6hdr);
+ u8 nexthdr = ipv6_hdr(skb)->nexthdr;
+ bool found;
+
+ if (fragoff)
+ *fragoff = 0;
+
+ if (*offset) {
+ struct ipv6hdr _ip6, *ip6;
+
+ ip6 = skb_header_pointer(skb, *offset, sizeof(_ip6), &_ip6);
+ if (!ip6 || (ip6->version != 6))
+ return -EBADMSG;
+ start = *offset + sizeof(struct ipv6hdr);
+ nexthdr = ip6->nexthdr;
+ }
+
+ do {
+ struct ipv6_opt_hdr _hdr, *hp;
+ unsigned int hdrlen;
+ found = (nexthdr == target);
+
+ if ((!ipv6_ext_hdr(nexthdr)) || nexthdr == NEXTHDR_NONE) {
+ if (target < 0 || found)
+ break;
+ return -ENOENT;
+ }
+
+ hp = skb_header_pointer(skb, start, sizeof(_hdr), &_hdr);
+ if (!hp)
+ return -EBADMSG;
+
+ if (nexthdr == NEXTHDR_ROUTING) {
+ struct ipv6_rt_hdr _rh, *rh;
+
+ rh = skb_header_pointer(skb, start, sizeof(_rh),
+ &_rh);
+ if (!rh)
+ return -EBADMSG;
+
+ if (flags && (*flags & IP6_FH_F_SKIP_RH) &&
+ rh->segments_left == 0)
+ found = false;
+ }
+
+ if (nexthdr == NEXTHDR_FRAGMENT) {
+ unsigned short _frag_off;
+ __be16 *fp;
+
+ if (flags) /* Indicate that this is a fragment */
+ *flags |= IP6_FH_F_FRAG;
+ fp = skb_header_pointer(skb,
+ start+offsetof(struct frag_hdr,
+ frag_off),
+ sizeof(_frag_off),
+ &_frag_off);
+ if (!fp)
+ return -EBADMSG;
+
+ _frag_off = ntohs(*fp) & ~0x7;
+ if (_frag_off) {
+ if (target < 0 &&
+ ((!ipv6_ext_hdr(hp->nexthdr)) ||
+ hp->nexthdr == NEXTHDR_NONE)) {
+ if (fragoff)
+ *fragoff = _frag_off;
+ return hp->nexthdr;
+ }
+ if (!found)
+ return -ENOENT;
+ if (fragoff)
+ *fragoff = _frag_off;
+ break;
+ }
+ hdrlen = 8;
+ } else if (nexthdr == NEXTHDR_AUTH) {
+ if (flags && (*flags & IP6_FH_F_AUTH) && (target < 0))
+ break;
+ hdrlen = ipv6_authlen(hp);
+ } else
+ hdrlen = ipv6_optlen(hp);
+
+ if (!found) {
+ nexthdr = hp->nexthdr;
+ start += hdrlen;
+ }
+ } while (!found);
+
+ *offset = start;
+ return nexthdr;
+}
+EXPORT_SYMBOL(ipv6_find_hdr);
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-02 03:22:04 +0000