linux/net
Weiping Pan 06b6a1cf6e rds: set correct msg_namelen
Jay Fenlason (fenlason@redhat.com) found a bug,
that recvfrom() on an RDS socket can return the contents of random kernel
memory to userspace if it was called with a address length larger than
sizeof(struct sockaddr_in).
rds_recvmsg() also fails to set the addr_len paramater properly before
returning, but that's just a bug.
There are also a number of cases wher recvfrom() can return an entirely bogus
address. Anything in rds_recvmsg() that returns a non-negative value but does
not go through the "sin = (struct sockaddr_in *)msg->msg_name;" code path
at the end of the while(1) loop will return up to 128 bytes of kernel memory
to userspace.

And I write two test programs to reproduce this bug, you will see that in
rds_server, fromAddr will be overwritten and the following sock_fd will be
destroyed.
Yes, it is the programmer's fault to set msg_namelen incorrectly, but it is
better to make the kernel copy the real length of address to user space in
such case.

How to run the test programs ?
I test them on 32bit x86 system, 3.5.0-rc7.

1 compile
gcc -o rds_client rds_client.c
gcc -o rds_server rds_server.c

2 run ./rds_server on one console

3 run ./rds_client on another console

4 you will see something like:
server is waiting to receive data...
old socket fd=3
server received data from client:data from client
msg.msg_namelen=32
new socket fd=-1067277685
sendmsg()
: Bad file descriptor

/***************** rds_client.c ********************/

int main(void)
{
	int sock_fd;
	struct sockaddr_in serverAddr;
	struct sockaddr_in toAddr;
	char recvBuffer[128] = "data from client";
	struct msghdr msg;
	struct iovec iov;

	sock_fd = socket(AF_RDS, SOCK_SEQPACKET, 0);
	if (sock_fd < 0) {
		perror("create socket error\n");
		exit(1);
	}

	memset(&serverAddr, 0, sizeof(serverAddr));
	serverAddr.sin_family = AF_INET;
	serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
	serverAddr.sin_port = htons(4001);

	if (bind(sock_fd, (struct sockaddr*)&serverAddr, sizeof(serverAddr)) < 0) {
		perror("bind() error\n");
		close(sock_fd);
		exit(1);
	}

	memset(&toAddr, 0, sizeof(toAddr));
	toAddr.sin_family = AF_INET;
	toAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
	toAddr.sin_port = htons(4000);
	msg.msg_name = &toAddr;
	msg.msg_namelen = sizeof(toAddr);
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;
	msg.msg_iov->iov_base = recvBuffer;
	msg.msg_iov->iov_len = strlen(recvBuffer) + 1;
	msg.msg_control = 0;
	msg.msg_controllen = 0;
	msg.msg_flags = 0;

	if (sendmsg(sock_fd, &msg, 0) == -1) {
		perror("sendto() error\n");
		close(sock_fd);
		exit(1);
	}

	printf("client send data:%s\n", recvBuffer);

	memset(recvBuffer, '\0', 128);

	msg.msg_name = &toAddr;
	msg.msg_namelen = sizeof(toAddr);
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;
	msg.msg_iov->iov_base = recvBuffer;
	msg.msg_iov->iov_len = 128;
	msg.msg_control = 0;
	msg.msg_controllen = 0;
	msg.msg_flags = 0;
	if (recvmsg(sock_fd, &msg, 0) == -1) {
		perror("recvmsg() error\n");
		close(sock_fd);
		exit(1);
	}

	printf("receive data from server:%s\n", recvBuffer);

	close(sock_fd);

	return 0;
}

/***************** rds_server.c ********************/

int main(void)
{
	struct sockaddr_in fromAddr;
	int sock_fd;
	struct sockaddr_in serverAddr;
	unsigned int addrLen;
	char recvBuffer[128];
	struct msghdr msg;
	struct iovec iov;

	sock_fd = socket(AF_RDS, SOCK_SEQPACKET, 0);
	if(sock_fd < 0) {
		perror("create socket error\n");
		exit(0);
	}

	memset(&serverAddr, 0, sizeof(serverAddr));
	serverAddr.sin_family = AF_INET;
	serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
	serverAddr.sin_port = htons(4000);
	if (bind(sock_fd, (struct sockaddr*)&serverAddr, sizeof(serverAddr)) < 0) {
		perror("bind error\n");
		close(sock_fd);
		exit(1);
	}

	printf("server is waiting to receive data...\n");
	msg.msg_name = &fromAddr;

	/*
	 * I add 16 to sizeof(fromAddr), ie 32,
	 * and pay attention to the definition of fromAddr,
	 * recvmsg() will overwrite sock_fd,
	 * since kernel will copy 32 bytes to userspace.
	 *
	 * If you just use sizeof(fromAddr), it works fine.
	 * */
	msg.msg_namelen = sizeof(fromAddr) + 16;
	/* msg.msg_namelen = sizeof(fromAddr); */
	msg.msg_iov = &iov;
	msg.msg_iovlen = 1;
	msg.msg_iov->iov_base = recvBuffer;
	msg.msg_iov->iov_len = 128;
	msg.msg_control = 0;
	msg.msg_controllen = 0;
	msg.msg_flags = 0;

	while (1) {
		printf("old socket fd=%d\n", sock_fd);
		if (recvmsg(sock_fd, &msg, 0) == -1) {
			perror("recvmsg() error\n");
			close(sock_fd);
			exit(1);
		}
		printf("server received data from client:%s\n", recvBuffer);
		printf("msg.msg_namelen=%d\n", msg.msg_namelen);
		printf("new socket fd=%d\n", sock_fd);
		strcat(recvBuffer, "--data from server");
		if (sendmsg(sock_fd, &msg, 0) == -1) {
			perror("sendmsg()\n");
			close(sock_fd);
			exit(1);
		}
	}

	close(sock_fd);
	return 0;
}

Signed-off-by: Weiping Pan <wpan@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-07-23 01:01:44 -07:00
..
9p net: Fix (nearly-)kernel-doc comments for various functions 2012-07-10 23:13:45 -07:00
802 tokenring: delete all remaining driver support 2012-05-15 20:23:16 -04:00
8021q netpoll: move np->dev and np->dev_name init into __netpoll_setup() 2012-07-17 09:02:36 -07:00
appletalk net: Fix (nearly-)kernel-doc comments for various functions 2012-07-10 23:13:45 -07:00
atm net: Remove casts to same type 2012-06-04 11:45:11 -04:00
ax25 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2012-07-19 11:17:30 -07:00
batman-adv Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2012-07-10 23:56:33 -07:00
bluetooth Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next into for-davem 2012-07-20 12:30:48 -04:00
bridge net: fix race condition in several drivers when reading stats 2012-07-22 12:12:32 -07:00
caif Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2012-07-19 11:17:30 -07:00
can can: gw: Remove pointless casts 2012-07-10 22:36:17 +02:00
ceph net: Fix non-kernel-doc comments with kernel-doc start marker 2012-07-10 23:13:45 -07:00
core Merge branch 'kill_rtcache' 2012-07-22 17:04:15 -07:00
dcb net: Fix non-kernel-doc comments with kernel-doc start marker 2012-07-10 23:13:45 -07:00
dccp ipv4: Kill FLOWI_FLAG_RT_NOCACHE and associated code. 2012-07-20 13:36:54 -07:00
decnet net: Document dst->obsolete better. 2012-07-20 13:31:21 -07:00
dns_resolver Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2012-05-21 20:27:36 -07:00
dsa dsa: Convert compare_ether_addr to ether_addr_equal 2012-05-09 20:49:19 -04:00
ethernet ipx: move peII functions 2012-07-19 10:48:00 -07:00
ieee802154 6lowpan: Change byte order when storing/accessing to len field 2012-07-16 22:52:02 -07:00
ipv4 tcp: dont drop MTU reduction indications 2012-07-23 00:58:46 -07:00
ipv6 tcp: dont drop MTU reduction indications 2012-07-23 00:58:46 -07:00
ipx ipx: move peII functions 2012-07-19 10:48:00 -07:00
irda irda: Fix typo in irda 2012-07-16 23:23:52 -07:00
iucv net: remove skb_orphan_try() 2012-06-15 15:30:15 -07:00
key net: cleanup unsigned to unsigned int 2012-04-15 12:44:40 -04:00
l2tp net: l2tp_eth: provide tx_dropped counter 2012-06-29 00:52:32 -07:00
lapb lapb: Neaten debugging 2012-05-17 18:45:20 -04:00
llc net: Fix (nearly-)kernel-doc comments for various functions 2012-07-10 23:13:45 -07:00
mac80211 Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next into for-davem 2012-07-20 12:30:48 -04:00
mac802154 mac802154: sparse warnings: make symbols static 2012-07-12 07:54:45 -07:00
netfilter Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2012-07-19 11:17:30 -07:00
netlabel netlabel: use GFP flags from caller instead of GFP_ATOMIC 2012-03-22 19:29:57 -04:00
netlink net: Fix (nearly-)kernel-doc comments for various functions 2012-07-10 23:13:45 -07:00
netrom net: Convert all sysctl registrations to register_net_sysctl 2012-04-20 21:22:30 -04:00
nfc Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next into for-davem 2012-07-20 12:30:48 -04:00
openvswitch openvswitch: potential NULL deref in sample() 2012-07-23 00:59:54 -07:00
packet net: added support for 40GbE link. 2012-06-27 15:42:24 -07:00
phonet net: remove my future former mail address 2012-06-17 16:29:38 -07:00
rds rds: set correct msg_namelen 2012-07-23 01:01:44 -07:00
rfkill rfkill: Add the capability to switch all devices of all type in __rfkill_switch_all(). 2012-06-06 15:18:17 -04:00
rose net: Convert all sysctl registrations to register_net_sysctl 2012-04-20 21:22:30 -04:00
rxrpc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2012-07-10 23:56:33 -07:00
sched Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2012-07-19 11:17:30 -07:00
sctp Merge branch 'kill_rtcache' 2012-07-22 17:04:15 -07:00
sunrpc ipv6: add ipv6_addr_hash() helper 2012-07-18 11:28:46 -07:00
tipc tipc: remove print_buf and deprecated log buffer code 2012-07-13 19:34:43 -04:00
unix net: make sock diag per-namespace 2012-07-16 22:31:34 -07:00
wanrouter net/wanrouter: Deprecate and schedule for removal 2012-05-24 16:22:53 -04:00
wimax net: cleanup unsigned to unsigned int 2012-04-15 12:44:40 -04:00
wireless Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next into for-davem 2012-07-20 12:30:48 -04:00
x25 net: Fix (nearly-)kernel-doc comments for various functions 2012-07-10 23:13:45 -07:00
xfrm net: Document dst->obsolete better. 2012-07-20 13:31:21 -07:00
compat.c net: Fix references to out-of-scope variables in put_cmsg_compat() 2012-07-22 17:50:49 -07:00
Kconfig net: drop NET dependency from HAVE_BPF_JIT 2012-05-21 12:50:12 -07:00
Makefile econet: remove ancient bug ridden protocol 2012-05-18 01:35:08 -04:00
nonet.c
socket.c net: netprio_cgroup: rework update socket logic 2012-07-22 12:44:01 -07:00
sysctl_net.c net: delete all instances of special processing for token ring 2012-05-15 20:14:35 -04:00