Attachment 311434 Details for Bug 454566 – Proposed backported patch for RHEL-2.1

[patch] Proposed backported patch for RHEL-2.1

rhel2u1-UDP-Randomize-port-selection.patch (text/plain), 6.91 KB, created by Eugene Teo (Security Response) on 2008-07-10 02:28:11 UTC

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Creator: Eugene Teo (Security Response)

Created: 2008-07-10 02:28:11 UTC

Size: 6.91 KB

patch

obsolete

>[RHEL2.1 PATCH] BZ#454567 kernel: randomize udp port allocation
>
>This is for Bugzilla bug #454567.
>
>Backport of upstream commit 32c1da70810017a98aa6c431a5494a302b6b9a30
>
>This patch causes UDP port allocation to be randomized like TCP. The
>earlier code would always choose same port (ie first empty list).
>
>Implementing this would mitigate CVE-2008-1447 as applied to the glibc
>stub resolver.
>
>Signed-off-by: Eugene Teo <eteo@redhat.com>
>---
> include/net/udp.h |    2 -
> net/ipv4/udp.c    |   67 ++++++++++++++++++++++++++----------------------------
> net/ipv6/udp.c    |   64 ++++++++++++++++++++++++++-------------------------
> net/netsyms.c     |    2 -
> 4 files changed, 66 insertions(+), 69 deletions(-)
>
>diff -Naur linux.default/include/net/udp.h linux/include/net/udp.h
>--- linux.default/include/net/udp.h	2001-08-16 05:26:33.000000000 +0800
>+++ linux/include/net/udp.h	2008-07-10 08:22:27.000000000 +0800
>@@ -34,8 +34,6 @@
> extern struct sock *udp_hash[UDP_HTABLE_SIZE];
> extern rwlock_t udp_hash_lock;
> 
>-extern int udp_port_rover;
>-
> static inline int udp_lport_inuse(u16 num)
> {
> 	struct sock *sk = udp_hash[num & (UDP_HTABLE_SIZE - 1)];
>diff -Naur linux.default/net/ipv4/udp.c linux/net/ipv4/udp.c
>--- linux.default/net/ipv4/udp.c	2008-07-09 23:24:48.000000000 +0800
>+++ linux/net/ipv4/udp.c	2008-07-10 08:18:54.000000000 +0800
>@@ -103,54 +103,53 @@
> struct sock *udp_hash[UDP_HTABLE_SIZE];
> rwlock_t udp_hash_lock = RW_LOCK_UNLOCKED;
> 
>-/* Shared by v4/v6 udp. */
>-int udp_port_rover;
>-
> static int udp_v4_get_port(struct sock *sk, unsigned short snum)
> {
> 	write_lock_bh(&udp_hash_lock);
>-	if (snum == 0) {
>-		int best_size_so_far, best, result, i;
>+	if (!snum) {
>+		int i, remaining;
>+		int low = sysctl_local_port_range[0];
>+		int high = sysctl_local_port_range[1];
>+		unsigned rover, best, best_size_so_far;
>+
>+		remaining = (high - low) + 1;
>+		best_size_so_far = UINT_MAX;
>+		best = rover = net_random() % remaining + low;
> 
>-		if (udp_port_rover > sysctl_local_port_range[1] ||
>-		    udp_port_rover < sysctl_local_port_range[0])
>-			udp_port_rover = sysctl_local_port_range[0];
>-		best_size_so_far = 32767;
>-		best = result = udp_port_rover;
>-		for (i = 0; i < UDP_HTABLE_SIZE; i++, result++) {
>+		/* 1st pass: look for empty (or shortest) hash chain */
>+		for (i = 0; i < UDP_HTABLE_SIZE; i++) {
> 			struct sock *sk;
>-			int size;
>+			int size = 0;
> 
>-			sk = udp_hash[result & (UDP_HTABLE_SIZE - 1)];
>-			if (!sk) {
>-				if (result > sysctl_local_port_range[1])
>-					result = sysctl_local_port_range[0] +
>-						((result - sysctl_local_port_range[0]) &
>-						 (UDP_HTABLE_SIZE - 1));
>+			sk = udp_hash[rover & (UDP_HTABLE_SIZE - 1)];
>+			if (!sk)
> 				goto gotit;
>-			}
>-			size = 0;
> 			do {
> 				if (++size >= best_size_so_far)
> 					goto next;
> 			} while ((sk = sk->next) != NULL);
> 			best_size_so_far = size;
>-			best = result;
>-		next:;
>-		}
>-		result = best;
>-		for(i = 0; i < (1 << 16) / UDP_HTABLE_SIZE; i++, result += UDP_HTABLE_SIZE) {
>-			if (result > sysctl_local_port_range[1])
>-				result = sysctl_local_port_range[0]
>-					+ ((result - sysctl_local_port_range[0]) &
>-					   (UDP_HTABLE_SIZE - 1));
>-			if (!udp_lport_inuse(result))
>-				break;
>+			best = rover;
>+		next:
>+			/* fold back if end of range */
>+			if (++rover > high)
>+				rover = low + ((rover - low)
>+				            & (UDP_HTABLE_SIZE - 1));
>+		}
>+		/* 2nd pass: find hole in shortest hash chain */
>+		rover = best;
>+		for (i = 0; i < (1 << 16) / UDP_HTABLE_SIZE; i++) {
>+			if (!udp_lport_inuse(rover))
>+				goto gotit;
>+			rover += UDP_HTABLE_SIZE;
>+			if (rover > high)
>+				rover = low + ((rover - low)
>+				            & (UDP_HTABLE_SIZE - 1));
> 		}
>-		if (i >= (1 << 16) / UDP_HTABLE_SIZE)
>-			goto fail;
>+		/* All ports in use! */
>+		goto fail;
> gotit:
>-		udp_port_rover = snum = result;
>+		snum = rover;
> 	} else {
> 		struct sock *sk2;
> 
>diff -Naur linux.default/net/ipv6/udp.c linux/net/ipv6/udp.c
>--- linux.default/net/ipv6/udp.c	2008-07-09 23:24:48.000000000 +0800
>+++ linux/net/ipv6/udp.c	2008-07-10 08:22:04.000000000 +0800
>@@ -56,48 +56,50 @@
> static int udp_v6_get_port(struct sock *sk, unsigned short snum)
> {
> 	write_lock_bh(&udp_hash_lock);
>-	if (snum == 0) {
>-		int best_size_so_far, best, result, i;
>+	if (!snum) {
>+		int i, remaining;
>+		int low = sysctl_local_port_range[0];
>+		int high = sysctl_local_port_range[1];
>+		unsigned rover, best, best_size_so_far;
>+
>+		remaining = (high - low) + 1;
>+		best_size_so_far = UINT_MAX;
>+		best = rover = net_random() % remaining + low;
> 
>-		if (udp_port_rover > sysctl_local_port_range[1] ||
>-		    udp_port_rover < sysctl_local_port_range[0])
>-			udp_port_rover = sysctl_local_port_range[0];
>-		best_size_so_far = 32767;
>-		best = result = udp_port_rover;
>-		for (i = 0; i < UDP_HTABLE_SIZE; i++, result++) {
>+		/* 1st pass: look for empty (or shortest) hash chain */
>+		for (i = 0; i < UDP_HTABLE_SIZE; i++) {
> 			struct sock *sk;
>-			int size;
>+			int size = 0;
> 
>-			sk = udp_hash[result & (UDP_HTABLE_SIZE - 1)];
>-			if (!sk) {
>-				if (result > sysctl_local_port_range[1])
>-					result = sysctl_local_port_range[0] +
>-						((result - sysctl_local_port_range[0]) &
>-						 (UDP_HTABLE_SIZE - 1));
>+			sk = udp_hash[rover & (UDP_HTABLE_SIZE - 1)];
>+			if (!sk)
> 				goto gotit;
>-			}
>-			size = 0;
> 			do {
> 				if (++size >= best_size_so_far)
> 					goto next;
> 			} while ((sk = sk->next) != NULL);
> 			best_size_so_far = size;
>-			best = result;
>-		next:;
>-		}
>-		result = best;
>-		for(i = 0; i < (1 << 16) / UDP_HTABLE_SIZE; i++, result += UDP_HTABLE_SIZE) {
>-			if (result > sysctl_local_port_range[1])
>-				result = sysctl_local_port_range[0]
>-					+ ((result - sysctl_local_port_range[0]) &
>-					   (UDP_HTABLE_SIZE - 1));
>-			if (!udp_lport_inuse(result))
>-				break;
>+			best = rover;
>+		next:
>+			/* fold back if end of range */
>+			if (++rover > high)
>+				rover = low + ((rover - low)
>+				            & (UDP_HTABLE_SIZE - 1));
>+		}
>+		/* 2nd pass: find hole in shortest hash chain */
>+		rover = best;
>+		for (i = 0; i < (1 << 16) / UDP_HTABLE_SIZE; i++) {
>+			if (!udp_lport_inuse(rover))
>+				goto gotit;
>+			rover += UDP_HTABLE_SIZE;
>+			if (rover > high)
>+				rover = low + ((rover - low)
>+				            & (UDP_HTABLE_SIZE - 1));
> 		}
>-		if (i >= (1 << 16) / UDP_HTABLE_SIZE)
>-			goto fail;
>+		/* All ports in use! */
>+		goto fail;
> gotit:
>-		udp_port_rover = snum = result;
>+		snum = rover;
> 	} else {
> 		struct sock *sk2;
> 		int addr_type = ipv6_addr_type(&sk->net_pinfo.af_inet6.rcv_saddr);
>diff -Naur linux.default/net/netsyms.c linux/net/netsyms.c
>--- linux.default/net/netsyms.c	2008-07-09 23:24:42.000000000 +0800
>+++ linux/net/netsyms.c	2008-07-10 08:22:22.000000000 +0800
>@@ -66,7 +66,6 @@
> 
> extern int sysctl_local_port_range[2];
> extern int tcp_port_rover;
>-extern int udp_port_rover;
> #endif
> 
> #endif
>@@ -376,7 +375,6 @@
> EXPORT_SYMBOL(tcp_reset_keepalive_timer);
> EXPORT_SYMBOL(sysctl_local_port_range);
> EXPORT_SYMBOL(tcp_port_rover);
>-EXPORT_SYMBOL(udp_port_rover);
> EXPORT_SYMBOL(tcp_sync_mss);
> EXPORT_SYMBOL(net_statistics); 
> EXPORT_SYMBOL(__tcp_mem_reclaim);

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Attachments on bug 454566: 311378 | 311379 | 311434 | 311435