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authorTom Gundersen <teg@jklm.no>2015-11-23 15:59:58 +0100
committerTom Gundersen <teg@jklm.no>2015-11-25 18:30:31 +0100
commitcddf4d81eacfc81cf761619fcb67bc07a744a6d1 (patch)
tree5ad00fafa1d883eee418fd5cd048cc8c5b49d0c8
parent6d06ac1faa1b06a9fb5793c970bccd5b47825d07 (diff)
sd-ndisc: better validate RA packets
Verify the hoplimit and that the received packet is large enough for the RA header. See <http://tools.ietf.org/html/rfc4861#section-6.1.2>.
-rw-r--r--src/libsystemd-network/icmp6-util.c24
-rw-r--r--src/libsystemd-network/sd-ndisc.c58
2 files changed, 58 insertions, 24 deletions
diff --git a/src/libsystemd-network/icmp6-util.c b/src/libsystemd-network/icmp6-util.c
index 03505fc47b..acad9d7d6a 100644
--- a/src/libsystemd-network/icmp6-util.c
+++ b/src/libsystemd-network/icmp6-util.c
@@ -47,17 +47,15 @@ int icmp6_bind_router_solicitation(int index) {
.ipv6mr_interface = index,
};
_cleanup_close_ int s = -1;
- int r, zero = 0, hops = 255;
+ int r, zero = 0, one = 1, hops = 255;
- s = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC | SOCK_NONBLOCK,
- IPPROTO_ICMPV6);
+ s = socket(AF_INET6, SOCK_RAW | SOCK_CLOEXEC | SOCK_NONBLOCK, IPPROTO_ICMPV6);
if (s < 0)
return -errno;
ICMP6_FILTER_SETBLOCKALL(&filter);
ICMP6_FILTER_SETPASS(ND_ROUTER_ADVERT, &filter);
- r = setsockopt(s, IPPROTO_ICMPV6, ICMP6_FILTER, &filter,
- sizeof(filter));
+ r = setsockopt(s, IPPROTO_ICMPV6, ICMP6_FILTER, &filter, sizeof(filter));
if (r < 0)
return -errno;
@@ -65,23 +63,23 @@ int icmp6_bind_router_solicitation(int index) {
IPV6_PKTINFO socket option also applies for ICMPv6 multicast.
Empirical experiments indicates otherwise and therefore an
IPV6_MULTICAST_IF socket option is used here instead */
- r = setsockopt(s, IPPROTO_IPV6, IPV6_MULTICAST_IF, &index,
- sizeof(index));
+ r = setsockopt(s, IPPROTO_IPV6, IPV6_MULTICAST_IF, &index, sizeof(index));
if (r < 0)
return -errno;
- r = setsockopt(s, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &zero,
- sizeof(zero));
+ r = setsockopt(s, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &zero, sizeof(zero));
if (r < 0)
return -errno;
- r = setsockopt(s, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &hops,
- sizeof(hops));
+ r = setsockopt(s, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &hops, sizeof(hops));
if (r < 0)
return -errno;
- r = setsockopt(s, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mreq,
- sizeof(mreq));
+ r = setsockopt(s, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mreq, sizeof(mreq));
+ if (r < 0)
+ return -errno;
+
+ r = setsockopt(s, SOL_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
if (r < 0)
return -errno;
diff --git a/src/libsystemd-network/sd-ndisc.c b/src/libsystemd-network/sd-ndisc.c
index 249586f048..f2bce3b99f 100644
--- a/src/libsystemd-network/sd-ndisc.c
+++ b/src/libsystemd-network/sd-ndisc.c
@@ -418,8 +418,7 @@ static int ndisc_prefix_update(sd_ndisc *nd, ssize_t len,
return 0;
}
-static int ndisc_ra_parse(sd_ndisc *nd, struct nd_router_advert *ra,
- ssize_t len) {
+static int ndisc_ra_parse(sd_ndisc *nd, struct nd_router_advert *ra, ssize_t len) {
void *opt;
struct nd_opt_hdr *opt_hdr;
@@ -482,12 +481,25 @@ static int ndisc_ra_parse(sd_ndisc *nd, struct nd_router_advert *ra,
static int ndisc_router_advertisment_recv(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
_cleanup_free_ struct nd_router_advert *ra = NULL;
sd_ndisc *nd = userdata;
- int r, buflen = 0, pref, stateful;
- union sockaddr_union router = {};
- socklen_t router_len = sizeof(router);
+ union {
+ struct cmsghdr cmsghdr;
+ uint8_t buf[CMSG_LEN(sizeof(int))];
+ } control = {};
+ struct iovec iov = {};
+ union sockaddr_union sa = {};
+ struct msghdr msg = {
+ .msg_name = &sa.sa,
+ .msg_namelen = sizeof(sa),
+ .msg_iov = &iov,
+ .msg_iovlen = 1,
+ .msg_control = &control,
+ .msg_controllen = sizeof(control),
+ };
+ struct cmsghdr *cmsg;
struct in6_addr *gw;
unsigned lifetime;
ssize_t len;
+ int r, pref, stateful, buflen = 0;
assert(s);
assert(nd);
@@ -500,24 +512,48 @@ static int ndisc_router_advertisment_recv(sd_event_source *s, int fd, uint32_t r
/* This really should not happen */
return -EIO;
- ra = malloc(buflen);
+ iov.iov_len = buflen;
+
+ ra = malloc(iov.iov_len);
if (!ra)
return -ENOMEM;
- len = recvfrom(fd, ra, buflen, 0, &router.sa, &router_len);
+ iov.iov_base = ra;
+
+ len = recvmsg(fd, &msg, 0);
if (len < 0) {
if (errno == EAGAIN || errno == EINTR)
return 0;
log_ndisc(nd, "Could not receive message from ICMPv6 socket: %m");
return -errno;
- } else if (router_len == 0)
+ } else if ((size_t)len < sizeof(struct nd_router_advert)) {
+ return 0;
+ } else if (msg.msg_namelen == 0)
gw = NULL; /* only happens when running the test-suite over a socketpair */
- else if (router_len != sizeof(router.in6)) {
- log_ndisc(nd, "Received invalid source address size from ICMPv6 socket: %zu bytes", (size_t)router_len);
+ else if (msg.msg_namelen != sizeof(sa.in6)) {
+ log_ndisc(nd, "Received invalid source address size from ICMPv6 socket: %zu bytes", (size_t)msg.msg_namelen);
return 0;
} else
- gw = &router.in6.sin6_addr;
+ gw = &sa.in6.sin6_addr;
+
+ assert(!(msg.msg_flags & MSG_CTRUNC));
+ assert(!(msg.msg_flags & MSG_TRUNC));
+
+ CMSG_FOREACH(cmsg, &msg) {
+ if (cmsg->cmsg_level == SOL_IPV6 &&
+ cmsg->cmsg_type == IPV6_HOPLIMIT &&
+ cmsg->cmsg_len == CMSG_LEN(sizeof(int))) {
+ int hops = *(int*)CMSG_DATA(cmsg);
+
+ if (hops != 255) {
+ log_ndisc(nd, "Received RA with invalid hop limit %d. Ignoring.", hops);
+ return 0;
+ }
+
+ break;
+ }
+ }
if (gw && !in_addr_is_link_local(AF_INET6, (const union in_addr_union*) gw)) {
_cleanup_free_ char *addr = NULL;