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implemented more validation checks about incoming responses per RFC2080, and one additional heuristic check for safer operation.

Browse source 
Obtained from: KAME
MFC after: 1 week
This commit is contained in:
SUZUKI Shinsuke 2006-11-16 19:03:03 +00:00
parent 3bea4efeb1
commit 5e5792a887
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=164339
1 changed files with 78 additions and 4 deletions
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82
usr.sbin/route6d/route6d.c
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@ -656,6 +656,20 @@ init()
}
#endif
#ifdef IPV6_RECVPKTINFO
if (setsockopt(ripsock, IPPROTO_IPV6, IPV6_RECVHOPLIMIT,
&int1, sizeof(int1)) < 0) {
fatal("rip IPV6_RECVHOPLIMIT");
/*NOTREACHED*/
}
#else /* old adv. API */
if (setsockopt(ripsock, IPPROTO_IPV6, IPV6_HOPLIMIT,
&int1, sizeof(int1)) < 0) {
fatal("rip IPV6_HOPLIMIT");
/*NOTREACHED*/
}
#endif
memset(&hints, 0, sizeof(hints));
hints.ai_family = PF_INET6;
hints.ai_socktype = SOCK_DGRAM;
@ -1082,7 +1096,8 @@ riprecv()
struct cmsghdr *cm;
struct iovec iov[2];
u_char cmsgbuf[256];
struct in6_pktinfo *pi;
struct in6_pktinfo *pi = NULL;
int *hlimp = NULL;
struct iff *iffp;
struct in6_addr ia;
int ok;
@ -1107,11 +1122,26 @@ riprecv()
for (cm = (struct cmsghdr *)CMSG_FIRSTHDR(&m);
cm;
cm = (struct cmsghdr *)CMSG_NXTHDR(&m, cm)) {
if (cm->cmsg_level == IPPROTO_IPV6 &&
cm->cmsg_type == IPV6_PKTINFO) {
if (cm->cmsg_level != IPPROTO_IPV6)
continue;
switch (cm->cmsg_type) {
case IPV6_PKTINFO:
if (cm->cmsg_len != CMSG_LEN(sizeof(*pi))) {
trace(1,
"invalid cmsg length for IPV6_PKTINFO\n");
return;
}
pi = (struct in6_pktinfo *)(CMSG_DATA(cm));
idx = pi->ipi6_ifindex;
break;
case IPV6_HOPLIMIT:
if (cm->cmsg_len != CMSG_LEN(sizeof(int))) {
trace(1,
"invalid cmsg length for IPV6_HOPLIMIT\n");
return;
}
hlimp = (int *)CMSG_DATA(cm);
break;
}
}
if (idx && IN6_IS_ADDR_LINKLOCAL(&fsock.sin6_addr))
@ -1122,6 +1152,18 @@ riprecv()
return;
}
if (pi == NULL || hlimp == NULL) {
/*
* This can happen when the kernel failed to allocate memory
* for the ancillary data. Although we might be able to handle
* some cases without this info, those are minor and not so
* important, so it's better to discard the packet for safer
* operation.
*/
trace(1, "IPv6 packet information cannot be retrieved\n");
return;
}
nh = fsock.sin6_addr;
nn = (len - sizeof(struct rip6) + sizeof(struct netinfo6)) /
sizeof(struct netinfo6);
@ -1143,10 +1185,42 @@ riprecv()
}
if (!IN6_IS_ADDR_LINKLOCAL(&fsock.sin6_addr)) {
trace(1, "Packets from non-ll addr: %s\n",
trace(1, "Response from non-ll addr: %s\n",
inet6_n2p(&fsock.sin6_addr));
return; /* Ignore packets from non-link-local addr */
}
if (ntohs(fsock.sin6_port) != RIP6_PORT) {
trace(1, "Response from non-rip port from %s\n",
inet6_n2p(&fsock.sin6_addr));
return;
}
if (IN6_IS_ADDR_MULTICAST(&pi->ipi6_addr) && *hlimp != 255) {
trace(1,
"Response packet with a smaller hop limit (%d) from %s\n",
*hlimp, inet6_n2p(&fsock.sin6_addr));
return;
}
/*
* Further validation: since this program does not send off-link
* requests, an incoming response must always come from an on-link
* node. Although this is normally ensured by the source address
* check above, it may not 100% be safe because there are router
* implementations that (invalidly) allow a packet with a link-local
* source address to be forwarded to a different link.
* So we also check whether the destination address is a link-local
* address or the hop limit is 255. Note that RFC2080 does not require
* the specific hop limit for a unicast response, so we cannot assume
* the limitation.
*/
if (!IN6_IS_ADDR_LINKLOCAL(&pi->ipi6_addr) && *hlimp != 255) {
trace(1,
"Response packet possibly from an off-link node: "
"from %s to %s hlim=%d\n",
inet6_n2p(&fsock.sin6_addr),
inet6_n2p(&pi->ipi6_addr), *hlimp);
return;
}
idx = IN6_LINKLOCAL_IFINDEX(fsock.sin6_addr);
ifcp = (idx < nindex2ifc) ? index2ifc[idx] : NULL;
if (!ifcp) {