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From: David Gibson <david@gibson.dropbear.id.au>
To: passt-dev@passt.top, Stefano Brivio <sbrivio@redhat.com>
Cc: Paul Holzinger <pholzing@redhat.com>,
	David Gibson <david@gibson.dropbear.id.au>
Subject: [PATCH v2 07/23] conf: Move DNS array bounds checks into add_dns[46]
Date: Wed, 21 Aug 2024 14:20:03 +1000	[thread overview]
Message-ID: <20240821042020.718422-8-david@gibson.dropbear.id.au> (raw)
In-Reply-To: <20240821042020.718422-1-david@gibson.dropbear.id.au>

Every time we call add_dns[46] we need to first check if there's space in
the c->ip[46].dns array for the new entry.  We might as well make that
check in add_dns[46]() itself.

In fact it looks like the calls in get_dns() had an off by one error, not
allowing the last entry of the array to be filled.  So, that bug is also
fixed by the change.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 conf.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/conf.c b/conf.c
index d19013c1..dfe417b4 100644
--- a/conf.c
+++ b/conf.c
@@ -363,6 +363,9 @@ static unsigned add_dns4(struct ctx *c, const struct in_addr *addr,
 {
 	unsigned added = 0;
 
+	if (idx >= ARRAY_SIZE(c->ip4.dns))
+		return 0;
+
 	/* Guest or container can only access local addresses via redirect */
 	if (IN4_IS_ADDR_LOOPBACK(addr)) {
 		if (!c->no_map_gw) {
@@ -395,6 +398,9 @@ static unsigned add_dns6(struct ctx *c, struct in6_addr *addr, unsigned idx)
 {
 	unsigned added = 0;
 
+	if (idx >= ARRAY_SIZE(c->ip6.dns))
+		return 0;
+
 	/* Guest or container can only access local addresses via redirect */
 	if (IN6_IS_ADDR_LOOPBACK(addr)) {
 		if (!c->no_map_gw) {
@@ -453,12 +459,10 @@ static void get_dns(struct ctx *c)
 			if (end)
 				*end = 0;
 
-			if (!dns4_set && dns4_idx < ARRAY_SIZE(c->ip4.dns) - 1
-			    && inet_pton(AF_INET, p + 1, &dns4_tmp))
+			if (!dns4_set && inet_pton(AF_INET, p + 1, &dns4_tmp))
 				dns4_idx += add_dns4(c, &dns4_tmp, dns4_idx);
 
-			if (!dns6_set && dns6_idx < ARRAY_SIZE(c->ip6.dns) - 1
-			    && inet_pton(AF_INET6, p + 1, &dns6_tmp))
+			if (!dns6_set && inet_pton(AF_INET6, p + 1, &dns6_tmp))
 				dns6_idx += add_dns6(c, &dns6_tmp, dns6_idx);
 		} else if (!dnss_set && strstr(line, "search ") == line &&
 			   s == c->dns_search) {
@@ -1682,14 +1686,12 @@ void conf(struct ctx *c, int argc, char **argv)
 
 			c->no_dns = 0;
 
-			if (dns4_idx < ARRAY_SIZE(c->ip4.dns) &&
-			    inet_pton(AF_INET, optarg, &dns4_tmp)) {
+			if (inet_pton(AF_INET, optarg, &dns4_tmp)) {
 				dns4_idx += add_dns4(c, &dns4_tmp, dns4_idx);
 				continue;
 			}
 
-			if (dns6_idx < ARRAY_SIZE(c->ip6.dns) &&
-			    inet_pton(AF_INET6, optarg, &dns6_tmp)) {
+			if (inet_pton(AF_INET6, optarg, &dns6_tmp)) {
 				dns6_idx += add_dns6(c, &dns6_tmp, dns6_idx);
 				continue;
 			}
-- 
@@ -363,6 +363,9 @@ static unsigned add_dns4(struct ctx *c, const struct in_addr *addr,
 {
 	unsigned added = 0;
 
+	if (idx >= ARRAY_SIZE(c->ip4.dns))
+		return 0;
+
 	/* Guest or container can only access local addresses via redirect */
 	if (IN4_IS_ADDR_LOOPBACK(addr)) {
 		if (!c->no_map_gw) {
@@ -395,6 +398,9 @@ static unsigned add_dns6(struct ctx *c, struct in6_addr *addr, unsigned idx)
 {
 	unsigned added = 0;
 
+	if (idx >= ARRAY_SIZE(c->ip6.dns))
+		return 0;
+
 	/* Guest or container can only access local addresses via redirect */
 	if (IN6_IS_ADDR_LOOPBACK(addr)) {
 		if (!c->no_map_gw) {
@@ -453,12 +459,10 @@ static void get_dns(struct ctx *c)
 			if (end)
 				*end = 0;
 
-			if (!dns4_set && dns4_idx < ARRAY_SIZE(c->ip4.dns) - 1
-			    && inet_pton(AF_INET, p + 1, &dns4_tmp))
+			if (!dns4_set && inet_pton(AF_INET, p + 1, &dns4_tmp))
 				dns4_idx += add_dns4(c, &dns4_tmp, dns4_idx);
 
-			if (!dns6_set && dns6_idx < ARRAY_SIZE(c->ip6.dns) - 1
-			    && inet_pton(AF_INET6, p + 1, &dns6_tmp))
+			if (!dns6_set && inet_pton(AF_INET6, p + 1, &dns6_tmp))
 				dns6_idx += add_dns6(c, &dns6_tmp, dns6_idx);
 		} else if (!dnss_set && strstr(line, "search ") == line &&
 			   s == c->dns_search) {
@@ -1682,14 +1686,12 @@ void conf(struct ctx *c, int argc, char **argv)
 
 			c->no_dns = 0;
 
-			if (dns4_idx < ARRAY_SIZE(c->ip4.dns) &&
-			    inet_pton(AF_INET, optarg, &dns4_tmp)) {
+			if (inet_pton(AF_INET, optarg, &dns4_tmp)) {
 				dns4_idx += add_dns4(c, &dns4_tmp, dns4_idx);
 				continue;
 			}
 
-			if (dns6_idx < ARRAY_SIZE(c->ip6.dns) &&
-			    inet_pton(AF_INET6, optarg, &dns6_tmp)) {
+			if (inet_pton(AF_INET6, optarg, &dns6_tmp)) {
 				dns6_idx += add_dns6(c, &dns6_tmp, dns6_idx);
 				continue;
 			}
-- 
2.46.0


  parent reply	other threads:[~2024-08-21  4:20 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-08-21  4:19 [PATCH v2 00/23] Allow configuration of special case NATs David Gibson
2024-08-21  4:19 ` [PATCH v2 01/23] treewide: Use "our address" instead of "forwarding address" David Gibson
2024-08-21  4:19 ` [PATCH v2 02/23] util: Helper for formatting MAC addresses David Gibson
2024-08-21  4:19 ` [PATCH v2 03/23] treewide: Rename MAC address fields for clarity David Gibson
2024-08-21  4:20 ` [PATCH v2 04/23] treewide: Use struct assignment instead of memcpy() for IP addresses David Gibson
2024-08-21  4:20 ` [PATCH v2 05/23] conf: Use array indices rather than pointers for DNS array slots David Gibson
2024-08-21  4:20 ` [PATCH v2 06/23] conf: More accurately count entries added in get_dns() David Gibson
2024-08-21  4:20 ` David Gibson [this message]
2024-08-21  4:20 ` [PATCH v2 08/23] conf: Move adding of a nameserver from resolv.conf into subfunction David Gibson
2024-08-21  4:20 ` [PATCH v2 09/23] conf: Correct setting of dns_match address in add_dns6() David Gibson
2024-08-21  4:20 ` [PATCH v2 10/23] conf: Treat --dns addresses as guest visible addresses David Gibson
2024-08-21  4:20 ` [PATCH v2 11/23] conf: Remove incorrect initialisation of addr_ll_seen David Gibson
2024-08-21  4:20 ` [PATCH v2 12/23] util: Correct sock_l4() binding for link local addresses David Gibson
2024-08-21  4:20 ` [PATCH v2 13/23] treewide: Change misleading 'addr_ll' name David Gibson
2024-08-21  4:20 ` [PATCH v2 14/23] Clarify which addresses in ip[46]_ctx are meaningful where David Gibson
2024-08-21  4:20 ` [PATCH v2 15/23] Initialise our_tap_ll to ip6.gw when suitable David Gibson
2024-08-21  4:20 ` [PATCH v2 16/23] fwd: Helpers to clarify what host addresses aren't guest accessible David Gibson
2024-08-21  4:20 ` [PATCH v2 17/23] fwd: Split notion of "our tap address" from gateway for IPv4 David Gibson
2024-08-21  4:20 ` [PATCH v2 18/23] Don't take "our" MAC address from the host David Gibson
2024-08-21  4:20 ` [PATCH v2 19/23] conf, fwd: Split notion of gateway/router from guest-visible host address David Gibson
2024-08-21  4:20 ` [PATCH v2 20/23] test: Reconfigure IPv6 address after changing MTU David Gibson
2024-08-21  4:20 ` [PATCH v2 21/23] conf: Allow address remapped to host to be configured David Gibson
2024-08-21  4:20 ` [PATCH v2 22/23] fwd: Distinguish translatable from untranslatable addresses on inbound David Gibson
2024-08-21  4:20 ` [PATCH v2 23/23] fwd, conf: Allow NAT of the guest's assigned address David Gibson
2024-08-21 10:38 ` [PATCH v2 00/23] Allow configuration of special case NATs Stefano Brivio

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