[ 68/72] tools: hv: Netlink source address validation allows DoS

Greg Kroah-Hartman
2013-03-26T22:57:54Z

From: Tomas Hozza <thozza@redhat.com>

commit 95a69adab9acfc3981c504737a2b6578e4d846ef upstream.

The source code without this patch caused hypervkvpd to exit when it processed
a spoofed Netlink packet which has been sent from an untrusted local user.
Now Netlink messages with a non-zero nl_pid source address are ignored
and a warning is printed into the syslog.

Signed-off-by: Tomas Hozza <thozza@redhat.com>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
tools/hv/hv_kvp_daemon.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

--- a/tools/hv/hv_kvp_daemon.c
+++ b/tools/hv/hv_kvp_daemon.c
@@ -727,13 +727,19 @@ int main(void)
len = recvfrom(fd, kvp_recv_buffer, sizeof(kvp_recv_buffer), 0,
addr_p, &addr_l);

- if (len < 0 || addr.nl_pid) {
+ if (len < 0) {
syslog(LOG_ERR, "recvfrom failed; pid:%u error:%d %s",
addr.nl_pid, errno, strerror(errno));
close(fd);
return -1;
}

+ if (addr.nl_pid) {
+ syslog(LOG_WARNING, "Received packet from untrusted pid:%u",
+ addr.nl_pid);
+ continue;
+ }
+
incoming_msg = (struct nlmsghdr *)kvp_recv_buffer;
incoming_cn_msg = (struct cn_msg *)NLMSG_DATA(incoming_msg);
hv_msg = (struct hv_kvp_msg *)incoming_cn_msg->data;