diff mbox

net: heap overflow in __audit_sockaddr()

Message ID 20131002185811.GA23438@elgon.mountain
State Superseded, archived
Delegated to: David Miller
Headers show

Commit Message

Dan Carpenter Oct. 2, 2013, 6:58 p.m. UTC 
We need to cap ->msg_namelen or it leads to a buffer overflow when we
to the memcpy() in __audit_sockaddr().  It requires CAP_AUDIT_CONTROL to
exploit this bug.

The call tree is:
___sys_recvmsg()
  move_addr_to_user()
    audit_sockaddr()
      __audit_sockaddr()

Reported-by: Jüri Aedla <juri.aedla@gmail.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>

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Comments

Ben Hutchings Oct. 2, 2013, 9:11 p.m. UTC | #1 
On Wed, 2013-10-02 at 21:58 +0300, Dan Carpenter wrote:
> We need to cap ->msg_namelen or it leads to a buffer overflow when we
> to the memcpy() in __audit_sockaddr().  It requires CAP_AUDIT_CONTROL to
> exploit this bug.
> 
> The call tree is:
> ___sys_recvmsg()
>   move_addr_to_user()
>     audit_sockaddr()
>       __audit_sockaddr()
> 
> Reported-by: Jüri Aedla <juri.aedla@gmail.com>
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
>
> diff --git a/net/socket.c b/net/socket.c
> index ebed4b6..c226ace 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -1964,6 +1964,16 @@ struct used_address {
>  	unsigned int name_len;
>  };
>  
> +static int copy_msghdr_from_user(struct msghdr *kmsg,
> +				 struct msghdr __user *umsg)
> +{
> +	if (copy_from_user(kmsg, umsg, sizeof(struct msghdr)))
> +		return -EFAULT;
> +	if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
> +		return -EINVAL;
> +	return 0;
> +}
> +
>  static int ___sys_sendmsg(struct socket *sock, struct msghdr __user *msg,
>  			 struct msghdr *msg_sys, unsigned int flags,
>  			 struct used_address *used_address)
> @@ -1982,8 +1992,11 @@ static int ___sys_sendmsg(struct socket *sock, struct msghdr __user *msg,
>  	if (MSG_CMSG_COMPAT & flags) {
>  		if (get_compat_msghdr(msg_sys, msg_compat))
>  			return -EFAULT;
> -	} else if (copy_from_user(msg_sys, msg, sizeof(struct msghdr)))
> -		return -EFAULT;
> +	} else {
> +		err = copy_msghdr_from_user(msg_sys, msg);
> +		if (err)
> +			return err;
> +	}
[...]

This doesn't cover compat tasks, since get_compat_msghdr() has no such
check.

Ben.
Dan Carpenter Oct. 2, 2013, 9:26 p.m. UTC | #2 
On Wed, Oct 02, 2013 at 10:11:46PM +0100, Ben Hutchings wrote:
> On Wed, 2013-10-02 at 21:58 +0300, Dan Carpenter wrote:
> > We need to cap ->msg_namelen or it leads to a buffer overflow when we
> > to the memcpy() in __audit_sockaddr().  It requires CAP_AUDIT_CONTROL to
> > exploit this bug.
> > 
> > The call tree is:
> > ___sys_recvmsg()
> >   move_addr_to_user()
> >     audit_sockaddr()
> >       __audit_sockaddr()
> > 
> > Reported-by: Jüri Aedla <juri.aedla@gmail.com>
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> >
> > diff --git a/net/socket.c b/net/socket.c
> > index ebed4b6..c226ace 100644
> > --- a/net/socket.c
> > +++ b/net/socket.c
> > @@ -1964,6 +1964,16 @@ struct used_address {
> >  	unsigned int name_len;
> >  };
> >  
> > +static int copy_msghdr_from_user(struct msghdr *kmsg,
> > +				 struct msghdr __user *umsg)
> > +{
> > +	if (copy_from_user(kmsg, umsg, sizeof(struct msghdr)))
> > +		return -EFAULT;
> > +	if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
> > +		return -EINVAL;
> > +	return 0;
> > +}
> > +
> >  static int ___sys_sendmsg(struct socket *sock, struct msghdr __user *msg,
> >  			 struct msghdr *msg_sys, unsigned int flags,
> >  			 struct used_address *used_address)
> > @@ -1982,8 +1992,11 @@ static int ___sys_sendmsg(struct socket *sock, struct msghdr __user *msg,
> >  	if (MSG_CMSG_COMPAT & flags) {
> >  		if (get_compat_msghdr(msg_sys, msg_compat))
> >  			return -EFAULT;
> > -	} else if (copy_from_user(msg_sys, msg, sizeof(struct msghdr)))
> > -		return -EFAULT;
> > +	} else {
> > +		err = copy_msghdr_from_user(msg_sys, msg);
> > +		if (err)
> > +			return err;
> > +	}
> [...]
> 
> This doesn't cover compat tasks, since get_compat_msghdr() has no such
> check.
> 

Oops.  Gar...  Thanks for catching that.  I forgot to add that chunk to
the commit.

regards,
dan carpenter

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diff mbox

Patch

diff --git a/net/socket.c b/net/socket.c
index ebed4b6..c226ace 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1964,6 +1964,16 @@  struct used_address {
 	unsigned int name_len;
 };
 
+static int copy_msghdr_from_user(struct msghdr *kmsg,
+				 struct msghdr __user *umsg)
+{
+	if (copy_from_user(kmsg, umsg, sizeof(struct msghdr)))
+		return -EFAULT;
+	if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
+		return -EINVAL;
+	return 0;
+}
+
 static int ___sys_sendmsg(struct socket *sock, struct msghdr __user *msg,
 			 struct msghdr *msg_sys, unsigned int flags,
 			 struct used_address *used_address)
@@ -1982,8 +1992,11 @@  static int ___sys_sendmsg(struct socket *sock, struct msghdr __user *msg,
 	if (MSG_CMSG_COMPAT & flags) {
 		if (get_compat_msghdr(msg_sys, msg_compat))
 			return -EFAULT;
-	} else if (copy_from_user(msg_sys, msg, sizeof(struct msghdr)))
-		return -EFAULT;
+	} else {
+		err = copy_msghdr_from_user(msg_sys, msg);
+		if (err)
+			return err;
+	}
 
 	if (msg_sys->msg_iovlen > UIO_FASTIOV) {
 		err = -EMSGSIZE;
@@ -2191,8 +2204,11 @@  static int ___sys_recvmsg(struct socket *sock, struct msghdr __user *msg,
 	if (MSG_CMSG_COMPAT & flags) {
 		if (get_compat_msghdr(msg_sys, msg_compat))
 			return -EFAULT;
-	} else if (copy_from_user(msg_sys, msg, sizeof(struct msghdr)))
-		return -EFAULT;
+	} else {
+		err = copy_msghdr_from_user(msg_sys, msg);
+		if (err)
+			return err;
+	}
 
 	if (msg_sys->msg_iovlen > UIO_FASTIOV) {
 		err = -EMSGSIZE;