Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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);