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[PATCH] LSM networking: af_unix hooks for 2.5.59 (7/8)

To: "David S. Miller" <davem@xxxxxxxxxx>, <kuznet@xxxxxxxxxxxxx>
Subject: [PATCH] LSM networking: af_unix hooks for 2.5.59 (7/8)
From: James Morris <jmorris@xxxxxxxxxxxxxxxx>
Date: Fri, 31 Jan 2003 10:17:01 +1100 (EST)
Cc: netdev@xxxxxxxxxxx, <linux-security-module@xxxxxxxxx>
In-reply-to: <Pine.LNX.4.44.0301311006230.31382-100000@xxxxxxxxxxxxxxxxxxxxxxxxxx>
Sender: netdev-bounce@xxxxxxxxxxx
 include/linux/security.h |   54 +++++++++++++++++++++++++++++++++++++++++++++++
 net/unix/af_unix.c       |   16 +++++++++++++
 security/dummy.c         |   15 +++++++++++++
 3 files changed, 85 insertions(+)

diff -urN -X dontdiff linux-2.5.59.w0/include/linux/security.h 
linux-2.5.59.w1/include/linux/security.h
--- linux-2.5.59.w0/include/linux/security.h    Thu Jan 30 21:41:57 2003
+++ linux-2.5.59.w1/include/linux/security.h    Thu Jan 30 21:41:38 2003
@@ -1018,6 +1018,29 @@
  *     @skb contains the sk_buff structure for the netlink message.
  *     Return 0 if permission is granted.
  *
+ * @unix_stream_connect:
+ *     Check permissions before establishing a Unix domain stream connection
+ *     between @sock and @other.
+ *     @sock contains the socket structure.
+ *     @other contains the peer socket structure.
+ *     Return 0 if permission is granted.
+ * @unix_may_send:
+ *     Check permissions before connecting or sending datagrams from @sock to
+ *     @other.
+ *     @sock contains the socket structure.
+ *     @sock contains the peer socket structure.
+ *     Return 0 if permission is granted.
+ *
+ * The @unix_stream_connect and @unix_may_send hooks were necessary because
+ * Linux provides an alternative to the conventional file name space for Unix
+ * domain sockets.  Whereas binding and connecting to sockets in the file name
+ * space is mediated by the typical file permissions (and caught by the mknod
+ * and permission hooks in inode_security_ops), binding and connecting to
+ * sockets in the abstract name space is completely unmediated.  Sufficient
+ * control of Unix domain sockets in the abstract name space isn't possible
+ * using only the socket layer hooks, since we need to know the actual target
+ * socket, which is not looked up until we are inside the af_unix code.
+ *
  * @register_security:
  *     allow module stacking.
  *     @name contains the name of the security module being stacked.
@@ -1201,6 +1224,10 @@
                                    struct security_operations *ops);
 
 #ifdef CONFIG_SECURITY_NETWORK
+       int (*unix_stream_connect) (struct socket * sock,
+                                   struct socket * other, struct sock * newsk);
+       int (*unix_may_send) (struct socket * sock, struct socket * other);
+
        int (*socket_create) (int family, int type, int protocol);
        void (*socket_post_create) (struct socket * sock, int family,
                                    int type, int protocol);
@@ -2433,6 +2460,20 @@
 
 #ifdef CONFIG_SECURITY_NETWORK
 
+static inline int security_unix_stream_connect(struct socket * sock,
+                                              struct socket * other, 
+                                              struct sock * newsk)
+{
+       return security_ops->unix_stream_connect(sock, other, newsk);
+}
+
+
+static inline int security_unix_may_send(struct socket * sock, 
+                                        struct socket * other)
+{
+       return security_ops->unix_may_send(sock, other);
+}
+
 static inline int security_socket_create (int family, int type, int protocol)
 {
        return security_ops->socket_create(family, type, protocol);
@@ -2596,6 +2637,19 @@
 
 #else  /* CONFIG_SECURITY_NETWORK */
 
+static inline int security_unix_stream_connect(struct socket * sock,
+                                              struct socket * other, 
+                                              struct sock * newsk)
+{
+       return 0;
+}
+
+static inline int security_unix_may_send(struct socket * sock, 
+                                        struct socket * other)
+{
+       return 0;
+}
+
 static inline int security_socket_create (int family, int type, int protocol)
 {
        return 0;
diff -urN -X dontdiff linux-2.5.59.w0/net/unix/af_unix.c 
linux-2.5.59.w1/net/unix/af_unix.c
--- linux-2.5.59.w0/net/unix/af_unix.c  Sat Jan 11 10:47:20 2003
+++ linux-2.5.59.w1/net/unix/af_unix.c  Thu Jan 30 21:41:38 2003
@@ -115,6 +115,7 @@
 #include <linux/rtnetlink.h>
 #include <linux/mount.h>
 #include <net/checksum.h>
+#include <linux/security.h>
 
 int sysctl_unix_max_dgram_qlen = 10;
 
@@ -816,6 +817,11 @@
                err = -EPERM;
                if (!unix_may_send(sk, other))
                        goto out_unlock;
+
+               err = security_unix_may_send(sk->socket, other->socket);
+               if (err)
+                       goto out_unlock;
+
        } else {
                /*
                 *      1003.1g breaking connected state with AF_UNSPEC
@@ -981,6 +987,12 @@
                goto restart;
        }
 
+       err = security_unix_stream_connect(sock, other->socket, newsk);
+       if (err) {
+               unix_state_wunlock(sk);
+               goto out_unlock;
+       }
+
        /* The way is open! Fastly set all the necessary fields... */
 
        sock_hold(sk);
@@ -1280,6 +1292,10 @@
        if (other->shutdown&RCV_SHUTDOWN)
                goto out_unlock;
 
+       err = security_unix_may_send(sk->socket, other->socket);
+       if (err)
+               goto out_unlock;
+
        if (unix_peer(other) != sk &&
            skb_queue_len(&other->receive_queue) > other->max_ack_backlog) {
                if (!timeo) {
diff -urN -X dontdiff linux-2.5.59.w0/security/dummy.c 
linux-2.5.59.w1/security/dummy.c
--- linux-2.5.59.w0/security/dummy.c    Thu Jan 30 21:41:57 2003
+++ linux-2.5.59.w1/security/dummy.c    Thu Jan 30 21:41:38 2003
@@ -625,6 +625,19 @@
 
 #ifdef CONFIG_SECURITY_NETWORK
 
+static int dummy_unix_stream_connect (struct socket *sock,
+                                     struct socket *other,
+                                     struct sock *newsk)
+{
+       return 0;
+}
+
+static int dummy_unix_may_send (struct socket *sock,
+                               struct socket *other)
+{
+       return 0;
+}
+
 static int dummy_socket_create (int family, int type, int protocol)
 {
        return 0;
@@ -910,6 +923,8 @@
        set_to_dummy_if_null(ops, netlink_recv);        
        set_to_dummy_if_null(ops, ip_decode_options);
 #ifdef CONFIG_SECURITY_NETWORK
+       set_to_dummy_if_null(ops, unix_stream_connect);
+       set_to_dummy_if_null(ops, unix_may_send);
        set_to_dummy_if_null(ops, socket_create);
        set_to_dummy_if_null(ops, socket_post_create);
        set_to_dummy_if_null(ops, socket_bind);




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