From 5845a145808162560293cf4f7c55bbb5afc8dce7 Mon Sep 17 00:00:00 2001

From: Phil Sutter <psutter@redhat.com>

Date: Thu, 21 Feb 2019 14:38:57 +0100

Subject: [PATCH] ip-route: Fix segfault with many nexthops

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1624656

Upstream Status: iproute2.git commit bd59e5b1517b0

Conflicts: Context changes due to missing other commits.

commit bd59e5b1517b09b6f26d59f38fe6077d953c2396

Author: Phil Sutter <phil@nwl.cc>

Date:   Thu Sep 6 15:31:51 2018 +0200

    ip-route: Fix segfault with many nexthops

    It was possible to crash ip-route by adding an IPv6 route with 37

    nexthop statements. A simple reproducer is:

    | for i in `seq 37`; do

    |       nhs="nexthop via 1111::$i "$nhs

    | done

    | ip -6 route add 3333::/64 $nhs

    The related code was broken in multiple ways:

    * parse_one_nh() assumed that rta points to 4kB of storage but caller

      provided just 1kB. Fixed by passing 'len' parameter with the correct

      value.

    * Error checking of rta_addattr*() calls in parse_one_nh() and called

      functions was completely absent, so with above fix in place output

      flood would occur due to parser looping forever.

    While being at it, increase message buffer sizes to 4k. This allows for

    at most 144 nexthops.

    Signed-off-by: Phil Sutter <phil@nwl.cc>

    Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

---

 ip/iproute.c          | 43 +++++++++++++++++++++--------------

 ip/iproute_lwtunnel.c | 63 ++++++++++++++++++++++++++++++++-------------------

 2 files changed, 66 insertions(+), 40 deletions(-)

diff --git a/ip/iproute.c b/ip/iproute.c

index 759032d..d4db035 100644

--- a/ip/iproute.c

+++ b/ip/iproute.c

@@ -721,7 +721,7 @@ int print_route(const struct sockaddr_nl *who, struct nlmsghdr *n, void *arg)

 }

 static int parse_one_nh(struct nlmsghdr *n, struct rtmsg *r,

-			struct rtattr *rta, struct rtnexthop *rtnh,

+			struct rtattr *rta, size_t len, struct rtnexthop *rtnh,

 			int *argcp, char ***argvp)

 {

 	int argc = *argcp;

@@ -742,11 +742,16 @@ static int parse_one_nh(struct nlmsghdr *n, struct rtmsg *r,

 			if (r->rtm_family == AF_UNSPEC)

 				r->rtm_family = addr.family;

 			if (addr.family == r->rtm_family) {

-				rta_addattr_l(rta, 4096, RTA_GATEWAY, &addr.data, addr.bytelen);

-				rtnh->rtnh_len += sizeof(struct rtattr) + addr.bytelen;

+				if (rta_addattr_l(rta, len, RTA_GATEWAY,

+						  &addr.data, addr.bytelen))

+					return -1;

+				rtnh->rtnh_len += sizeof(struct rtattr)

+						  + addr.bytelen;

 			} else {

-				rta_addattr_l(rta, 4096, RTA_VIA, &addr.family, addr.bytelen+2);

-				rtnh->rtnh_len += RTA_SPACE(addr.bytelen+2);

+				if (rta_addattr_l(rta, len, RTA_VIA,

+						  &addr.family, addr.bytelen + 2))

+					return -1;

+				rtnh->rtnh_len += RTA_SPACE(addr.bytelen + 2);

 			}

 		} else if (strcmp(*argv, "dev") == 0) {

 			NEXT_ARG();

@@ -769,13 +774,15 @@ static int parse_one_nh(struct nlmsghdr *n, struct rtmsg *r,

 			NEXT_ARG();

 			if (get_rt_realms_or_raw(&realm, *argv))

 				invarg("\"realm\" value is invalid\n", *argv);

-			rta_addattr32(rta, 4096, RTA_FLOW, realm);

+			if (rta_addattr32(rta, len, RTA_FLOW, realm))

+				return -1;

 			rtnh->rtnh_len += sizeof(struct rtattr) + 4;

 		} else if (strcmp(*argv, "encap") == 0) {

-			int len = rta->rta_len;

+			int old_len = rta->rta_len;

-			lwt_parse_encap(rta, 4096, &argc, &argv);

-			rtnh->rtnh_len += rta->rta_len - len;

+			if (lwt_parse_encap(rta, len, &argc, &argv))

+				return -1;

+			rtnh->rtnh_len += rta->rta_len - old_len;

 		} else if (strcmp(*argv, "as") == 0) {

 			inet_prefix addr;

@@ -783,8 +790,9 @@ static int parse_one_nh(struct nlmsghdr *n, struct rtmsg *r,

 			if (strcmp(*argv, "to") == 0)

 				NEXT_ARG();

 			get_addr(&addr, *argv, r->rtm_family);

-			rta_addattr_l(rta, 4096, RTA_NEWDST, &addr.data,

-				      addr.bytelen);

+			if (rta_addattr_l(rta, len, RTA_NEWDST,

+					  &addr.data, addr.bytelen))

+				return -1;

 			rtnh->rtnh_len += sizeof(struct rtattr) + addr.bytelen;

 		} else

 			break;

@@ -797,7 +805,7 @@ static int parse_one_nh(struct nlmsghdr *n, struct rtmsg *r,

 static int parse_nexthops(struct nlmsghdr *n, struct rtmsg *r,

 			  int argc, char **argv)

 {

-	char buf[1024];

+	char buf[4096];

 	struct rtattr *rta = (void *)buf;

 	struct rtnexthop *rtnh;

@@ -817,7 +825,7 @@ static int parse_nexthops(struct nlmsghdr *n, struct rtmsg *r,

 		memset(rtnh, 0, sizeof(*rtnh));

 		rtnh->rtnh_len = sizeof(*rtnh);

 		rta->rta_len += rtnh->rtnh_len;

-		if (parse_one_nh(n, r, rta, rtnh, &argc, &argv)) {

+		if (parse_one_nh(n, r, rta, 4096, rtnh, &argc, &argv)) {

 			fprintf(stderr, "Error: cannot parse nexthop\n");

 			exit(-1);

 		}

@@ -825,7 +833,8 @@ static int parse_nexthops(struct nlmsghdr *n, struct rtmsg *r,

 	}

 	if (rta->rta_len > RTA_LENGTH(0))

-		addattr_l(n, 1024, RTA_MULTIPATH, RTA_DATA(rta), RTA_PAYLOAD(rta));

+		return addattr_l(n, 4096, RTA_MULTIPATH,

+				 RTA_DATA(rta), RTA_PAYLOAD(rta));

 	return 0;

 }

@@ -834,7 +843,7 @@ static int iproute_modify(int cmd, unsigned int flags, int argc, char **argv)

 	struct {

 		struct nlmsghdr	n;

 		struct rtmsg		r;

-		char			buf[1024];

+		char			buf[4096];

 	} req = {

 		.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg)),

 		.n.nlmsg_flags = NLM_F_REQUEST | flags,

@@ -1238,8 +1247,8 @@ static int iproute_modify(int cmd, unsigned int flags, int argc, char **argv)

 		addattr_l(&req.n, sizeof(req), RTA_METRICS, RTA_DATA(mxrta), RTA_PAYLOAD(mxrta));

 	}

-	if (nhs_ok)

-		parse_nexthops(&req.n, &req.r, argc, argv);

+	if (nhs_ok && parse_nexthops(&req.n, &req.r, argc, argv))

+		return -1;

 	if (req.r.rtm_family == AF_UNSPEC)

 		req.r.rtm_family = AF_INET;

diff --git a/ip/iproute_lwtunnel.c b/ip/iproute_lwtunnel.c

index 0fa1cab..1a68912 100644

--- a/ip/iproute_lwtunnel.c

+++ b/ip/iproute_lwtunnel.c

@@ -255,8 +255,9 @@ static int parse_encap_mpls(struct rtattr *rta, size_t len,

 		exit(1);

 	}

-	rta_addattr_l(rta, len, MPLS_IPTUNNEL_DST, &addr.data,

-		      addr.bytelen);

+	if (rta_addattr_l(rta, len, MPLS_IPTUNNEL_DST,

+			  &addr.data, addr.bytelen))

+		return -1;

 	*argcp = argc;

 	*argvp = argv;

@@ -270,6 +271,7 @@ static int parse_encap_ip(struct rtattr *rta, size_t len,

 	int id_ok = 0, dst_ok = 0, tos_ok = 0, ttl_ok = 0;

 	char **argv = *argvp;

 	int argc = *argcp;

+	int ret = 0;

 	while (argc > 0) {

 		if (strcmp(*argv, "id") == 0) {

@@ -280,7 +282,7 @@ static int parse_encap_ip(struct rtattr *rta, size_t len,

 				duparg2("id", *argv);

 			if (get_be64(&id, *argv, 0))

 				invarg("\"id\" value is invalid\n", *argv);

-			rta_addattr64(rta, len, LWTUNNEL_IP_ID, id);

+			ret = rta_addattr64(rta, len, LWTUNNEL_IP_ID, id);

 		} else if (strcmp(*argv, "dst") == 0) {

 			inet_prefix addr;

@@ -288,8 +290,8 @@ static int parse_encap_ip(struct rtattr *rta, size_t len,

 			if (dst_ok++)

 				duparg2("dst", *argv);

 			get_addr(&addr, *argv, AF_INET);

-			rta_addattr_l(rta, len, LWTUNNEL_IP_DST,

-				      &addr.data, addr.bytelen);

+			ret = rta_addattr_l(rta, len, LWTUNNEL_IP_DST,

+					    &addr.data, addr.bytelen);

 		} else if (strcmp(*argv, "tos") == 0) {

 			__u32 tos;

@@ -298,7 +300,7 @@ static int parse_encap_ip(struct rtattr *rta, size_t len,

 				duparg2("tos", *argv);

 			if (rtnl_dsfield_a2n(&tos, *argv))

 				invarg("\"tos\" value is invalid\n", *argv);

-			rta_addattr8(rta, len, LWTUNNEL_IP_TOS, tos);

+			ret = rta_addattr8(rta, len, LWTUNNEL_IP_TOS, tos);

 		} else if (strcmp(*argv, "ttl") == 0) {

 			__u8 ttl;

@@ -307,10 +309,12 @@ static int parse_encap_ip(struct rtattr *rta, size_t len,

 				duparg2("ttl", *argv);

 			if (get_u8(&ttl, *argv, 0))

 				invarg("\"ttl\" value is invalid\n", *argv);

-			rta_addattr8(rta, len, LWTUNNEL_IP_TTL, ttl);

+			ret = rta_addattr8(rta, len, LWTUNNEL_IP_TTL, ttl);

 		} else {

 			break;

 		}

+		if (ret)

+			break;

 		argc--; argv++;

 	}

@@ -321,7 +325,7 @@ static int parse_encap_ip(struct rtattr *rta, size_t len,

 	*argcp = argc + 1;

 	*argvp = argv - 1;

-	return 0;

+	return ret;

 }

 static int parse_encap_ila(struct rtattr *rta, size_t len,

@@ -330,6 +334,7 @@ static int parse_encap_ila(struct rtattr *rta, size_t len,

 	__u64 locator;

 	int argc = *argcp;

 	char **argv = *argvp;

+	int ret = 0;

 	if (get_addr64(&locator, *argv) < 0) {

 		fprintf(stderr, "Bad locator: %s\n", *argv);

@@ -338,7 +343,8 @@ static int parse_encap_ila(struct rtattr *rta, size_t len,

 	argc--; argv++;

-	rta_addattr64(rta, 1024, ILA_ATTR_LOCATOR, locator);

+	if (rta_addattr64(rta, 1024, ILA_ATTR_LOCATOR, locator))

+		return -1;

 	while (argc > 0) {

 		if (strcmp(*argv, "csum-mode") == 0) {

@@ -351,12 +357,15 @@ static int parse_encap_ila(struct rtattr *rta, size_t len,

 				invarg("\"csum-mode\" value is invalid\n",

 				       *argv);

-			rta_addattr8(rta, 1024, ILA_ATTR_CSUM_MODE, csum_mode);

+			ret = rta_addattr8(rta, 1024, ILA_ATTR_CSUM_MODE,

+					   (__u8)csum_mode);

 			argc--; argv++;

 		} else {

 			break;

 		}

+		if (ret)

+			break;

 	}

 	/* argv is currently the first unparsed argument,

@@ -366,7 +375,7 @@ static int parse_encap_ila(struct rtattr *rta, size_t len,

 	*argcp = argc + 1;

 	*argvp = argv - 1;

-	return 0;

+	return ret;

 }

 static int parse_encap_ip6(struct rtattr *rta, size_t len,

@@ -375,6 +384,7 @@ static int parse_encap_ip6(struct rtattr *rta, size_t len,

 	int id_ok = 0, dst_ok = 0, tos_ok = 0, ttl_ok = 0;

 	char **argv = *argvp;

 	int argc = *argcp;

+	int ret = 0;

 	while (argc > 0) {

 		if (strcmp(*argv, "id") == 0) {

@@ -385,7 +395,7 @@ static int parse_encap_ip6(struct rtattr *rta, size_t len,

 				duparg2("id", *argv);

 			if (get_be64(&id, *argv, 0))

 				invarg("\"id\" value is invalid\n", *argv);

-			rta_addattr64(rta, len, LWTUNNEL_IP6_ID, id);

+			ret = rta_addattr64(rta, len, LWTUNNEL_IP6_ID, id);

 		} else if (strcmp(*argv, "dst") == 0) {

 			inet_prefix addr;

@@ -393,8 +403,8 @@ static int parse_encap_ip6(struct rtattr *rta, size_t len,

 			if (dst_ok++)

 				duparg2("dst", *argv);

 			get_addr(&addr, *argv, AF_INET6);

-			rta_addattr_l(rta, len, LWTUNNEL_IP6_DST,

-				      &addr.data, addr.bytelen);

+			ret = rta_addattr_l(rta, len, LWTUNNEL_IP6_DST,

+					    &addr.data, addr.bytelen);

 		} else if (strcmp(*argv, "tc") == 0) {

 			__u32 tc;

@@ -403,7 +413,7 @@ static int parse_encap_ip6(struct rtattr *rta, size_t len,

 				duparg2("tc", *argv);

 			if (rtnl_dsfield_a2n(&tc, *argv))

 				invarg("\"tc\" value is invalid\n", *argv);

-			rta_addattr8(rta, len, LWTUNNEL_IP6_TC, tc);

+			ret = rta_addattr8(rta, len, LWTUNNEL_IP6_TC, tc);

 		} else if (strcmp(*argv, "hoplimit") == 0) {

 			__u8 hoplimit;

@@ -413,10 +423,13 @@ static int parse_encap_ip6(struct rtattr *rta, size_t len,

 			if (get_u8(&hoplimit, *argv, 0))

 				invarg("\"hoplimit\" value is invalid\n",

 				       *argv);

-			rta_addattr8(rta, len, LWTUNNEL_IP6_HOPLIMIT, hoplimit);

+			ret = rta_addattr8(rta, len, LWTUNNEL_IP6_HOPLIMIT,

+					   hoplimit);

 		} else {

 			break;

 		}

+		if (ret)

+			break;

 		argc--; argv++;

 	}

@@ -427,7 +440,7 @@ static int parse_encap_ip6(struct rtattr *rta, size_t len,

 	*argcp = argc + 1;

 	*argvp = argv - 1;

-	return 0;

+	return ret;

 }

 struct lwt_x {

@@ -542,6 +555,7 @@ int lwt_parse_encap(struct rtattr *rta, size_t len, int *argcp, char ***argvp)

 	int argc = *argcp;

 	char **argv = *argvp;

 	__u16 type;

+	int ret = 0;

 	NEXT_ARG();

 	type = read_encap_type(*argv);

@@ -558,16 +572,16 @@ int lwt_parse_encap(struct rtattr *rta, size_t len, int *argcp, char ***argvp)

 	nest = rta_nest(rta, 1024, RTA_ENCAP);

 	switch (type) {

 	case LWTUNNEL_ENCAP_MPLS:

-		parse_encap_mpls(rta, len, &argc, &argv);

+		ret = parse_encap_mpls(rta, len, &argc, &argv);

 		break;

 	case LWTUNNEL_ENCAP_IP:

-		parse_encap_ip(rta, len, &argc, &argv);

+		ret = parse_encap_ip(rta, len, &argc, &argv);

 		break;

 	case LWTUNNEL_ENCAP_ILA:

-		parse_encap_ila(rta, len, &argc, &argv);

+		ret = parse_encap_ila(rta, len, &argc, &argv);

 		break;

 	case LWTUNNEL_ENCAP_IP6:

-		parse_encap_ip6(rta, len, &argc, &argv);

+		ret = parse_encap_ip6(rta, len, &argc, &argv);

 		break;

 	case LWTUNNEL_ENCAP_BPF:

 		if (parse_encap_bpf(rta, len, &argc, &argv) < 0)

@@ -577,12 +591,15 @@ int lwt_parse_encap(struct rtattr *rta, size_t len, int *argcp, char ***argvp)

 		fprintf(stderr, "Error: unsupported encap type\n");

 		break;

 	}

+	if (ret)

+		return ret;

+

 	rta_nest_end(rta, nest);

-	rta_addattr16(rta, 1024, RTA_ENCAP_TYPE, type);

+	ret = rta_addattr16(rta, 1024, RTA_ENCAP_TYPE, type);

 	*argcp = argc;

 	*argvp = argv;

-	return 0;

+	return ret;

 }

-- 

1.8.3.1