[PATCH] tools/hv: Check the source of netlink messages to be the kernel

[PATCH] tools/hv: Check the source of netlink messages to be the kernel

[Marcus Meissner]

Hi,

The hyper-v userspace helper daemon receives and handles netlink
messages. It assumes them to be from the kernel, but does not check
that.

This patch adds this checking (nl_pid == 0).

CVE-2012-2669

Ciao, Marcus

Signed-off-by: Marcus Meissner <meissner@suse.de>
Signed-off-by: Sebastian Krahmer <krahmer@suse.de>
Signed-off-by: Olaf Hering <ohering@suse.de>
---
 tools/hv/hv_kvp_daemon.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/tools/hv/hv_kvp_daemon.c b/tools/hv/hv_kvp_daemon.c
index 146fd61..f0566c8 100644
--- a/tools/hv/hv_kvp_daemon.c
+++ b/tools/hv/hv_kvp_daemon.c
@@ -701,14 +701,16 @@ int main(void)
 	pfd.fd = fd;
 
 	while (1) {
+		struct sockaddr *addr_p = (struct sockaddr *) &addr;
+		socklen_t addr_l = sizeof(addr);
 		pfd.events = POLLIN;
 		pfd.revents = 0;
 		poll(&pfd, 1, -1);
 
-		len = recv(fd, kvp_recv_buffer, sizeof(kvp_recv_buffer), 0);
+		len = recvfrom(fd, kvp_recv_buffer, sizeof(kvp_recv_buffer), 0, addr_p, &addr_l);
 
-		if (len < 0) {
-			syslog(LOG_ERR, "recv failed; error:%d", len);
+		if (len < 0 || addr.nl_pid) {
+			syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s", addr.nl_pid, errno, strerror(errno));
 			close(fd);
 			return -1;
 		}
-- 
1.7.9.2

RE: [PATCH] tools/hv: Check the source of netlink messages to be the kernel

[KY Srinivasan]

> -----Original Message-----
> From: Marcus Meissner [mailto:meissner@suse.de]
> Sent: Thursday, June 07, 2012 5:08 AM
> To: gregkh@linuxfoundation.org; KY Srinivasan; dan.carpenter@oracle.com;
> Haiyang Zhang; jkosina@suse.cz; linux-kernel@vger.kernel.org;
> stable@kernel.org
> Cc: Marcus Meissner; Sebastian Krahmer; Olaf Hering
> Subject: [PATCH] tools/hv: Check the source of netlink messages to be the kernel
> 
> Hi,
> 
> The hyper-v userspace helper daemon receives and handles netlink
> messages. It assumes them to be from the kernel, but does not check
> that.
> 
> This patch adds this checking (nl_pid == 0).
> 
> CVE-2012-2669
> 
> Ciao, Marcus
> 
> Signed-off-by: Marcus Meissner <meissner@suse.de>
> Signed-off-by: Sebastian Krahmer <krahmer@suse.de>
> Signed-off-by: Olaf Hering <ohering@suse.de>

Olaf already posted this patch and I signed off on it.

Regards,

K. Y
> ---
>  tools/hv/hv_kvp_daemon.c |    8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/hv/hv_kvp_daemon.c b/tools/hv/hv_kvp_daemon.c
> index 146fd61..f0566c8 100644
> --- a/tools/hv/hv_kvp_daemon.c
> +++ b/tools/hv/hv_kvp_daemon.c
> @@ -701,14 +701,16 @@ int main(void)
>  	pfd.fd = fd;
> 
>  	while (1) {
> +		struct sockaddr *addr_p = (struct sockaddr *) &addr;
> +		socklen_t addr_l = sizeof(addr);
>  		pfd.events = POLLIN;
>  		pfd.revents = 0;
>  		poll(&pfd, 1, -1);
> 
> -		len = recv(fd, kvp_recv_buffer, sizeof(kvp_recv_buffer), 0);
> +		len = recvfrom(fd, kvp_recv_buffer, sizeof(kvp_recv_buffer), 0,
> addr_p, &addr_l);
> 
> -		if (len < 0) {
> -			syslog(LOG_ERR, "recv failed; error:%d", len);
> +		if (len < 0 || addr.nl_pid) {
> +			syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s",
> addr.nl_pid, errno, strerror(errno));
>  			close(fd);
>  			return -1;
>  		}
> --
> 1.7.9.2
> 
> 
>