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![Alexander Aring](/assets/img/avatar_default.png)
This patch makes it impossible that cmpri or cmpre values are set to the value 16 which is not possible, because these are 4 bit values. We currently run in an overflow when assigning the value 16 to it. According to the standard a value of 16 can be interpreted as a full elided address which isn't possible to set as compression value. A reason why this cannot be set is that the current ipv6 header destination address should never show up inside the segments of the rpl header. In this case we run in a overflow and the address will have no compression at all. Means cmpri or compre is set to 0. As we handle cmpri and cmpre sometimes as unsigned char or 4 bit value inside the rpl header the current behaviour ends in an invalid header format. This patch simple use the best compression method if we ever run into the case that the destination address is showed up inside the rpl segments. We avoid the overflow handling and the rpl header is still valid, even when we have the destination address inside the rpl segments. Signed-off-by: Alexander Aring <alex.aring@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
124 lines
3.2 KiB
C
124 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/**
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* Authors:
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* (C) 2020 Alexander Aring <alex.aring@gmail.com>
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*/
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#include <net/ipv6.h>
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#include <net/rpl.h>
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#define IPV6_PFXTAIL_LEN(x) (sizeof(struct in6_addr) - (x))
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#define IPV6_RPL_BEST_ADDR_COMPRESSION 15
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static void ipv6_rpl_addr_decompress(struct in6_addr *dst,
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const struct in6_addr *daddr,
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const void *post, unsigned char pfx)
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{
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memcpy(dst, daddr, pfx);
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memcpy(&dst->s6_addr[pfx], post, IPV6_PFXTAIL_LEN(pfx));
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}
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static void ipv6_rpl_addr_compress(void *dst, const struct in6_addr *addr,
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unsigned char pfx)
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{
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memcpy(dst, &addr->s6_addr[pfx], IPV6_PFXTAIL_LEN(pfx));
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}
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static void *ipv6_rpl_segdata_pos(const struct ipv6_rpl_sr_hdr *hdr, int i)
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{
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return (void *)&hdr->rpl_segdata[i * IPV6_PFXTAIL_LEN(hdr->cmpri)];
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}
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size_t ipv6_rpl_srh_size(unsigned char n, unsigned char cmpri,
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unsigned char cmpre)
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{
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return (n * IPV6_PFXTAIL_LEN(cmpri)) + IPV6_PFXTAIL_LEN(cmpre);
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}
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void ipv6_rpl_srh_decompress(struct ipv6_rpl_sr_hdr *outhdr,
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const struct ipv6_rpl_sr_hdr *inhdr,
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const struct in6_addr *daddr, unsigned char n)
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{
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int i;
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outhdr->nexthdr = inhdr->nexthdr;
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outhdr->hdrlen = (((n + 1) * sizeof(struct in6_addr)) >> 3);
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outhdr->pad = 0;
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outhdr->type = inhdr->type;
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outhdr->segments_left = inhdr->segments_left;
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outhdr->cmpri = 0;
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outhdr->cmpre = 0;
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for (i = 0; i < n; i++)
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ipv6_rpl_addr_decompress(&outhdr->rpl_segaddr[i], daddr,
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ipv6_rpl_segdata_pos(inhdr, i),
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inhdr->cmpri);
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ipv6_rpl_addr_decompress(&outhdr->rpl_segaddr[n], daddr,
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ipv6_rpl_segdata_pos(inhdr, n),
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inhdr->cmpre);
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}
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static unsigned char ipv6_rpl_srh_calc_cmpri(const struct ipv6_rpl_sr_hdr *inhdr,
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const struct in6_addr *daddr,
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unsigned char n)
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{
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unsigned char plen;
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int i;
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for (plen = 0; plen < sizeof(*daddr); plen++) {
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for (i = 0; i < n; i++) {
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if (daddr->s6_addr[plen] !=
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inhdr->rpl_segaddr[i].s6_addr[plen])
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return plen;
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}
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}
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return IPV6_RPL_BEST_ADDR_COMPRESSION;
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}
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static unsigned char ipv6_rpl_srh_calc_cmpre(const struct in6_addr *daddr,
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const struct in6_addr *last_segment)
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{
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unsigned int plen;
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for (plen = 0; plen < sizeof(*daddr); plen++) {
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if (daddr->s6_addr[plen] != last_segment->s6_addr[plen])
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return plen;
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}
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return IPV6_RPL_BEST_ADDR_COMPRESSION;
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}
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void ipv6_rpl_srh_compress(struct ipv6_rpl_sr_hdr *outhdr,
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const struct ipv6_rpl_sr_hdr *inhdr,
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const struct in6_addr *daddr, unsigned char n)
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{
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unsigned char cmpri, cmpre;
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size_t seglen;
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int i;
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cmpri = ipv6_rpl_srh_calc_cmpri(inhdr, daddr, n);
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cmpre = ipv6_rpl_srh_calc_cmpre(daddr, &inhdr->rpl_segaddr[n]);
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outhdr->nexthdr = inhdr->nexthdr;
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seglen = (n * IPV6_PFXTAIL_LEN(cmpri)) + IPV6_PFXTAIL_LEN(cmpre);
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outhdr->hdrlen = seglen >> 3;
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if (seglen & 0x7) {
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outhdr->hdrlen++;
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outhdr->pad = 8 - (seglen & 0x7);
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} else {
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outhdr->pad = 0;
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}
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outhdr->type = inhdr->type;
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outhdr->segments_left = inhdr->segments_left;
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outhdr->cmpri = cmpri;
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outhdr->cmpre = cmpre;
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for (i = 0; i < n; i++)
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ipv6_rpl_addr_compress(ipv6_rpl_segdata_pos(outhdr, i),
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&inhdr->rpl_segaddr[i], cmpri);
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ipv6_rpl_addr_compress(ipv6_rpl_segdata_pos(outhdr, n),
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&inhdr->rpl_segaddr[n], cmpre);
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}
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