Karmic CVE-2010-3880, inet_diag: Make sure we actually run the same bytecode we audited

[Stefan Bader]

On 02/02/2011 08:02 PM, Tim Gardner wrote:
> The following changes since commit 67180c643503bba1187f18c1fda2fd0725d5a957:
>   Kulikov Vasiliy (1):
>         net: tipc: fix information leak to userland, CVE-2010-3877
> 
> are available in the git repository at:
> 
>   git://kernel.ubuntu.com/rtg/ubuntu-karmic.git CVE-2010-3880
> 
> Nelson Elhage (1):
>       inet_diag: Make sure we actually run the same bytecode we audited, CVE-2010-3880
> 
>  include/net/netlink.h |    2 +-
>  net/ipv4/inet_diag.c  |   27 ++++++++++++++++-----------
>  2 files changed, 17 insertions(+), 12 deletions(-)
> 
> From 1a485553d24cd8021b0d0d86a97b9a5f036228a3 Mon Sep 17 00:00:00 2001
> From: Nelson Elhage <nelhage at ksplice.com>
> Date: Wed, 3 Nov 2010 16:35:41 +0000
> Subject: [PATCH] inet_diag: Make sure we actually run the same bytecode we audited, CVE-2010-3880
> 
> BugLink: http://bugs.launchpad.net/bugs/711865
> 
> CVE-2010-3880
> 
> We were using nlmsg_find_attr() to look up the bytecode by attribute when
> auditing, but then just using the first attribute when actually running
> bytecode. So, if we received a message with two attribute elements, where only
> the second had type INET_DIAG_REQ_BYTECODE, we would validate and run different
> bytecode strings.
> 
> Fix this by consistently using nlmsg_find_attr everywhere.
> 
> Signed-off-by: Nelson Elhage <nelhage at ksplice.com>
> Signed-off-by: Thomas Graf <tgraf at infradead.org>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> (back ported from commit 22e76c849d505d87c5ecf3d3e6742a65f0ff4860)
> 
> Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
Acked-by: Stefan Bader <stefan.bader at canonical.com>
> ---
>  include/net/netlink.h |    2 +-
>  net/ipv4/inet_diag.c  |   27 ++++++++++++++++-----------
>  2 files changed, 17 insertions(+), 12 deletions(-)
> 
> diff --git a/include/net/netlink.h b/include/net/netlink.h
> index 007bdb0..9cbc3fb 100644
> --- a/include/net/netlink.h
> +++ b/include/net/netlink.h
> @@ -384,7 +384,7 @@ static inline int nlmsg_parse(struct nlmsghdr *nlh, int hdrlen,
>   *
>   * Returns the first attribute which matches the specified type.
>   */
> -static inline struct nlattr *nlmsg_find_attr(struct nlmsghdr *nlh,
> +static inline struct nlattr *nlmsg_find_attr(const struct nlmsghdr *nlh,
>  					     int hdrlen, int attrtype)
>  {
>  	return nla_find(nlmsg_attrdata(nlh, hdrlen),
> diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
> index a706a47..6fe360f 100644
> --- a/net/ipv4/inet_diag.c
> +++ b/net/ipv4/inet_diag.c
> @@ -489,9 +489,11 @@ static int inet_csk_diag_dump(struct sock *sk,
>  {
>  	struct inet_diag_req *r = NLMSG_DATA(cb->nlh);
>  
> -	if (cb->nlh->nlmsg_len > 4 + NLMSG_SPACE(sizeof(*r))) {
> +	if (nlmsg_attrlen(cb->nlh, sizeof(*r))) {
>  		struct inet_diag_entry entry;
> -		struct rtattr *bc = (struct rtattr *)(r + 1);
> +		const struct nlattr *bc = nlmsg_find_attr(cb->nlh,
> +							  sizeof(*r),
> +							  INET_DIAG_REQ_BYTECODE);
>  		struct inet_sock *inet = inet_sk(sk);
>  
>  		entry.family = sk->sk_family;
> @@ -511,7 +513,7 @@ static int inet_csk_diag_dump(struct sock *sk,
>  		entry.dport = ntohs(inet->dport);
>  		entry.userlocks = sk->sk_userlocks;
>  
> -		if (!inet_diag_bc_run(RTA_DATA(bc), RTA_PAYLOAD(bc), &entry))
> +		if (!inet_diag_bc_run(nla_data(bc), nla_len(bc), &entry))
>  			return 0;
>  	}
>  
> @@ -526,9 +528,11 @@ static int inet_twsk_diag_dump(struct inet_timewait_sock *tw,
>  {
>  	struct inet_diag_req *r = NLMSG_DATA(cb->nlh);
>  
> -	if (cb->nlh->nlmsg_len > 4 + NLMSG_SPACE(sizeof(*r))) {
> +	if (nlmsg_attrlen(cb->nlh, sizeof(*r))) {
>  		struct inet_diag_entry entry;
> -		struct rtattr *bc = (struct rtattr *)(r + 1);
> +		const struct nlattr *bc = nlmsg_find_attr(cb->nlh,
> +							  sizeof(*r),
> +							  INET_DIAG_REQ_BYTECODE);
>  
>  		entry.family = tw->tw_family;
>  #if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
> @@ -547,7 +551,7 @@ static int inet_twsk_diag_dump(struct inet_timewait_sock *tw,
>  		entry.dport = ntohs(tw->tw_dport);
>  		entry.userlocks = 0;
>  
> -		if (!inet_diag_bc_run(RTA_DATA(bc), RTA_PAYLOAD(bc), &entry))
> +		if (!inet_diag_bc_run(nla_data(bc), nla_len(bc), &entry))
>  			return 0;
>  	}
>  
> @@ -617,7 +621,7 @@ static int inet_diag_dump_reqs(struct sk_buff *skb, struct sock *sk,
>  	struct inet_diag_req *r = NLMSG_DATA(cb->nlh);
>  	struct inet_connection_sock *icsk = inet_csk(sk);
>  	struct listen_sock *lopt;
> -	struct rtattr *bc = NULL;
> +	const struct nlattr *bc = NULL;
>  	struct inet_sock *inet = inet_sk(sk);
>  	int j, s_j;
>  	int reqnum, s_reqnum;
> @@ -637,8 +641,9 @@ static int inet_diag_dump_reqs(struct sk_buff *skb, struct sock *sk,
>  	if (!lopt || !lopt->qlen)
>  		goto out;
>  
> -	if (cb->nlh->nlmsg_len > 4 + NLMSG_SPACE(sizeof(*r))) {
> -		bc = (struct rtattr *)(r + 1);
> +	if (nlmsg_attrlen(cb->nlh, sizeof(*r))) {
> +		bc = nlmsg_find_attr(cb->nlh, sizeof(*r),
> +				     INET_DIAG_REQ_BYTECODE);
>  		entry.sport = inet->num;
>  		entry.userlocks = sk->sk_userlocks;
>  	}
> @@ -671,8 +676,8 @@ static int inet_diag_dump_reqs(struct sk_buff *skb, struct sock *sk,
>  					&ireq->rmt_addr;
>  				entry.dport = ntohs(ireq->rmt_port);
>  
> -				if (!inet_diag_bc_run(RTA_DATA(bc),
> -						    RTA_PAYLOAD(bc), &entry))
> +				if (!inet_diag_bc_run(nla_data(bc),
> +						      nla_len(bc), &entry))
>  					continue;
>  			}
>