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Fix for CVE-2013-0198 (checking of TCP connection interfaces)

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Resolves: rhbz#901555
Signed-off-by: Tomas Hozza <thozza@redhat.com>
This commit is contained in:
Tomas Hozza 2013-01-22 17:40:49 +01:00
parent 89b8fd1a70
commit 837eefae26
2 changed files with 198 additions and 1 deletions
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189
dnsmasq-2.65-Correct-behaviour-for-TCP-queries-to-allowed-address.patch Normal file
View File

@ -0,0 +1,189 @@
diff -up dnsmasq-2.65/src/dnsmasq.c.CVE-2013-0198 dnsmasq-2.65/src/dnsmasq.c
--- dnsmasq-2.65/src/dnsmasq.c.CVE-2013-0198 2012-12-14 12:48:26.000000000 +0100
+++ dnsmasq-2.65/src/dnsmasq.c 2013-01-22 16:32:30.387640907 +0100
@@ -1384,7 +1384,7 @@ static void check_dns_listeners(fd_set *
if (listener->tcpfd != -1 && FD_ISSET(listener->tcpfd, set))
{
- int confd;
+ int confd, client_ok = 1;
struct irec *iface = NULL;
pid_t p;
union mysockaddr tcp_addr;
@@ -1395,25 +1395,49 @@ static void check_dns_listeners(fd_set *
if (confd == -1 ||
getsockname(confd, (struct sockaddr *)&tcp_addr, &tcp_len) == -1)
continue;
-
- if (option_bool(OPT_NOWILD) || option_bool(OPT_CLEVERBIND))
+
+ if (option_bool(OPT_NOWILD))
iface = listener->iface; /* May be NULL */
- else
- {
- /* Check for allowed interfaces when binding the wildcard address:
- we do this by looking for an interface with the same address as
- the local address of the TCP connection, then looking to see if that's
- an allowed interface. As a side effect, we get the netmask of the
- interface too, for localisation. */
-
- /* interface may be new since startup */
- if (enumerate_interfaces())
- for (iface = daemon->interfaces; iface; iface = iface->next)
- if (sockaddr_isequal(&iface->addr, &tcp_addr))
- break;
- }
-
- if (!iface && !(option_bool(OPT_NOWILD) || option_bool(OPT_CLEVERBIND)))
+ else
+ {
+ int if_index;
+
+ /* In full wildcard mode, need to refresh interface list.
+ This happens automagically in CLEVERBIND */
+ if (!option_bool(OPT_CLEVERBIND))
+ enumerate_interfaces();
+
+ /* if we can find the arrival interface, check it's one that's allowed */
+ if ((if_index = tcp_interface(confd, tcp_addr.sa.sa_family)) != 0)
+ {
+ for (iface = daemon->interfaces; iface; iface = iface->next)
+ if (iface->index == if_index)
+ break;
+
+ if (!iface)
+ client_ok = 0;
+ }
+
+ if (option_bool(OPT_CLEVERBIND))
+ iface = listener->iface; /* May be NULL */
+ else
+ {
+ /* Check for allowed interfaces when binding the wildcard address:
+ we do this by looking for an interface with the same address as
+ the local address of the TCP connection, then looking to see if that's
+ an allowed interface. As a side effect, we get the netmask of the
+ interface too, for localisation. */
+
+ for (iface = daemon->interfaces; iface; iface = iface->next)
+ if (sockaddr_isequal(&iface->addr, &tcp_addr))
+ break;
+
+ if (!iface)
+ client_ok = 0;
+ }
+ }
+
+ if (!client_ok)
{
shutdown(confd, SHUT_RDWR);
close(confd);
diff -up dnsmasq-2.65/src/dnsmasq.h.CVE-2013-0198 dnsmasq-2.65/src/dnsmasq.h
--- dnsmasq-2.65/src/dnsmasq.h.CVE-2013-0198 2012-12-14 12:48:26.000000000 +0100
+++ dnsmasq-2.65/src/dnsmasq.h 2013-01-22 16:32:30.387640907 +0100
@@ -412,7 +412,7 @@ struct server {
struct irec {
union mysockaddr addr;
struct in_addr netmask; /* only valid for IPv4 */
- int tftp_ok, dhcp_ok, mtu, done, dad;
+ int tftp_ok, dhcp_ok, mtu, done, dad, index;
char *name;
struct irec *next;
};
@@ -955,6 +955,7 @@ void create_bound_listeners(int die);
int is_dad_listeners(void);
int iface_check(int family, struct all_addr *addr, char *name);
int fix_fd(int fd);
+int tcp_interface(int fd, int af);
struct in_addr get_ifaddr(char *intr);
#ifdef HAVE_IPV6
int set_ipv6pktinfo(int fd);
diff -up dnsmasq-2.65/src/network.c.CVE-2013-0198 dnsmasq-2.65/src/network.c
--- dnsmasq-2.65/src/network.c.CVE-2013-0198 2012-12-14 12:48:26.000000000 +0100
+++ dnsmasq-2.65/src/network.c 2013-01-22 17:33:00.349128334 +0100
@@ -239,6 +239,7 @@ static int iface_allowed(struct irec **i
iface->mtu = mtu;
iface->dad = dad;
iface->done = 0;
+ iface->index = if_index;
if ((iface->name = whine_malloc(strlen(ifr.ifr_name)+1)))
{
strcpy(iface->name, ifr.ifr_name);
@@ -420,6 +421,77 @@ int set_ipv6pktinfo(int fd)
return 0;
}
#endif
+
+
+/* Find the interface on which a TCP connection arrived, if possible, or zero otherwise. */
+int tcp_interface(int fd, int af)
+{
+ int if_index = 0;
+
+#ifdef HAVE_LINUX_NETWORK
+ int opt = 1;
+ struct cmsghdr *cmptr;
+ struct msghdr msg;
+
+ /* use mshdr do that the CMSDG_* macros are available */
+ msg.msg_control = daemon->packet;
+ msg.msg_controllen = daemon->packet_buff_sz;
+
+ /* we overwrote the buffer... */
+ daemon->srv_save = NULL;
+
+ if (af == AF_INET)
+ {
+ if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &opt, sizeof(opt)) != -1 &&
+ getsockopt(fd, IPPROTO_IP, IP_PKTOPTIONS, msg.msg_control, (socklen_t *)&msg.msg_controllen) != -1)
+ for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr))
+ if (cmptr->cmsg_level == IPPROTO_IP && cmptr->cmsg_type == IP_PKTINFO)
+ {
+ union {
+ unsigned char *c;
+ struct in_pktinfo *p;
+ } p;
+
+ p.c = CMSG_DATA(cmptr);
+ if_index = p.p->ipi_ifindex;
+ }
+ }
+#ifdef HAVE_IPV6
+ else
+ {
+ /* Only the RFC-2292 API has the ability to find the interface for TCP connections,
+ it was removed in RFC-3542 !!!!
+
+ Fortunately, Linux kept the 2292 ABI when it moved to 3542. The following code always
+ uses the old ABI, and should work with pre- and post-3542 kernel headers */
+
+#ifdef IPV6_2292PKTOPTIONS
+# define PKTOPTIONS IPV6_2292PKTOPTIONS
+#else
+# define PKTOPTIONS IPV6_PKTOPTIONS
+#endif
+
+ if (set_ipv6pktinfo(fd) &&
+ getsockopt(fd, IPPROTO_IPV6, PKTOPTIONS, msg.msg_control, (socklen_t *)&msg.msg_controllen) != -1)
+ {
+ for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr))
+ if (cmptr->cmsg_level == IPPROTO_IPV6 && cmptr->cmsg_type == daemon->v6pktinfo)
+ {
+ union {
+ unsigned char *c;
+ struct in6_pktinfo *p;
+ } p;
+ p.c = CMSG_DATA(cmptr);
+
+ if_index = p.p->ipi6_ifindex;
+ }
+ }
+ }
+#endif /* IPV6 */
+#endif /* Linux */
+
+ return if_index;
+}
static struct listener *create_listeners(union mysockaddr *addr, int do_tftp, int dienow)
{

10
dnsmasq.spec
View File

@ -11,7 +11,7 @@
Name: dnsmasq
Version: 2.65
Release: 1%{?extraversion}%{?dist}
Release: 2%{?extraversion}%{?dist}
Summary: A lightweight DHCP/caching DNS server
Group: System Environment/Daemons
@ -20,6 +20,9 @@ URL: http://www.thekelleys.org.uk/dnsmasq/
Source0: http://www.thekelleys.org.uk/dnsmasq/%{?extrapath}%{name}-%{version}%{?extraversion}.tar.gz
Source1: %{name}.service
# http://www.thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commit;h=22ce550e5346947a12a781ed0959a7b1165d0dc6
Patch0: %{name}-2.65-Correct-behaviour-for-TCP-queries-to-allowed-address.patch
BuildRoot: %{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)
BuildRequires: dbus-devel
@ -53,6 +56,8 @@ query/remove a DHCP server's leases.
%prep
%setup -q -n %{name}-%{version}%{?extraversion}
%patch0 -p1 -b .CVE-2013-0198
# use /var/lib/dnsmasq instead of /var/lib/misc
for file in dnsmasq.conf.example man/dnsmasq.8 man/es/dnsmasq.8 src/config.h; do
sed -i 's|/var/lib/misc/dnsmasq.leases|/var/lib/dnsmasq/dnsmasq.leases|g' "$file"
@ -131,6 +136,9 @@ rm -rf $RPM_BUILD_ROOT
%{_mandir}/man1/dhcp_*
%changelog
* Tue Jan 22 2013 Tomas Hozza <thozza@redhat.com> - 2.65-2
- Fix for CVE-2013-0198 (checking of TCP connection interfaces) (#901555)
* Sat Dec 15 2012 Tomas Hozza <thozza@redhat.com> - 2.65-1
- new version 2.65