[138/272] af_unix: Avoid socket->sk NULL OOPS in stream connect security hooks.

Greg KH
2011-02-16T01:28:16Z

From: David S. Miller <davem@davemloft.net>

[ Upstream commit 3610cda53f247e176bcbb7a7cca64bc53b12acdb ]

unix_release() can asynchornously set socket->sk to NULL, and
it does so without holding the unix_state_lock() on "other"
during stream connects.

However, the reverse mapping, sk->sk_socket, is only transitioned
to NULL under the unix_state_lock().

Therefore make the security hooks follow the reverse mapping instead
of the forward mapping.

Reported-by: Jeremy Fitzhardinge <jeremy@goop.org>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
include/linux/security.h | 15 +++++++--------
net/unix/af_unix.c | 2 +-
security/capability.c | 2 +-
security/security.c | 3 +--
security/selinux/hooks.c | 10 +++++-----
security/smack/smack_lsm.c | 14 +++++++-------
6 files changed, 22 insertions(+), 24 deletions(-)

--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -796,8 +796,9 @@ static inline void security_free_mnt_opt
* @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.
+ * @sock contains the sock structure.
+ * @other contains the peer sock structure.
+ * @newsk contains the new sock structure.
* Return 0 if permission is granted.
* @unix_may_send:
* Check permissions before connecting or sending datagrams from @sock to
@@ -1568,8 +1569,7 @@ struct security_operations {
int (*inode_getsecctx)(struct inode *inode, void **ctx, u32 *ctxlen);

#ifdef CONFIG_SECURITY_NETWORK
- int (*unix_stream_connect) (struct socket *sock,
- struct socket *other, struct sock *newsk);
+ int (*unix_stream_connect) (struct sock *sock, struct sock *other, struct sock *newsk);
int (*unix_may_send) (struct socket *sock, struct socket *other);

int (*socket_create) (int family, int type, int protocol, int kern);
@@ -2525,8 +2525,7 @@ static inline int security_inode_getsecc

#ifdef CONFIG_SECURITY_NETWORK

-int security_unix_stream_connect(struct socket *sock, struct socket *other,
- struct sock *newsk);
+int security_unix_stream_connect(struct sock *sock, struct sock *other, struct sock *newsk);
int security_unix_may_send(struct socket *sock, struct socket *other);
int security_socket_create(int family, int type, int protocol, int kern);
int security_socket_post_create(struct socket *sock, int family,
@@ -2567,8 +2566,8 @@ void security_tun_dev_post_create(struct
int security_tun_dev_attach(struct sock *sk);

#else /* CONFIG_SECURITY_NETWORK */
-static inline int security_unix_stream_connect(struct socket *sock,
- struct socket *other,
+static inline int security_unix_stream_connect(struct sock *sock,
+ struct sock *other,
struct sock *newsk)
{
return 0;
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1156,7 +1156,7 @@ restart:
goto restart;
}

- err = security_unix_stream_connect(sock, other->sk_socket, newsk);
+ err = security_unix_stream_connect(sk, other, newsk);
if (err) {
unix_state_unlock(sk);
goto out_unlock;
--- a/security/capability.c
+++ b/security/capability.c
@@ -548,7 +548,7 @@ static int cap_sem_semop(struct sem_arra
}

#ifdef CONFIG_SECURITY_NETWORK
-static int cap_unix_stream_connect(struct socket *sock, struct socket *other,
+static int cap_unix_stream_connect(struct sock *sock, struct sock *other,
struct sock *newsk)
{
return 0;
--- a/security/security.c
+++ b/security/security.c
@@ -977,8 +977,7 @@ EXPORT_SYMBOL(security_inode_getsecctx);

#ifdef CONFIG_SECURITY_NETWORK

-int security_unix_stream_connect(struct socket *sock, struct socket *other,
- struct sock *newsk)
+int security_unix_stream_connect(struct sock *sock, struct sock *other, struct sock *newsk)
{
return security_ops->unix_stream_connect(sock, other, newsk);
}
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3921,18 +3921,18 @@ static int selinux_socket_shutdown(struc
return sock_has_perm(current, sock->sk, SOCKET__SHUTDOWN);
}

-static int selinux_socket_unix_stream_connect(struct socket *sock,
- struct socket *other,
+static int selinux_socket_unix_stream_connect(struct sock *sock,
+ struct sock *other,
struct sock *newsk)
{
- struct sk_security_struct *sksec_sock = sock->sk->sk_security;
- struct sk_security_struct *sksec_other = other->sk->sk_security;
+ struct sk_security_struct *sksec_sock = sock->sk_security;
+ struct sk_security_struct *sksec_other = other->sk_security;
struct sk_security_struct *sksec_new = newsk->sk_security;
struct common_audit_data ad;
int err;

COMMON_AUDIT_DATA_INIT(&ad, NET);
- ad.u.net.sk = other->sk;
+ ad.u.net.sk = other;

err = avc_has_perm(sksec_sock->sid, sksec_other->sid,
sksec_other->sclass,
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -2408,22 +2408,22 @@ static int smack_setprocattr(struct task

/**
* smack_unix_stream_connect - Smack access on UDS
- * @sock: one socket
- * @other: the other socket
+ * @sock: one sock
+ * @other: the other sock
* @newsk: unused
*
* Return 0 if a subject with the smack of sock could access
* an object with the smack of other, otherwise an error code
*/
-static int smack_unix_stream_connect(struct socket *sock,
- struct socket *other, struct sock *newsk)
+static int smack_unix_stream_connect(struct sock *sock,
+ struct sock *other, struct sock *newsk)
{
- struct inode *sp = SOCK_INODE(sock);
- struct inode *op = SOCK_INODE(other);
+ struct inode *sp = SOCK_INODE(sock->sk_socket);
+ struct inode *op = SOCK_INODE(other->sk_socket);
struct smk_audit_info ad;

smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_NET);
- smk_ad_setfield_u_net_sk(&ad, other->sk);
+ smk_ad_setfield_u_net_sk(&ad, other);
return smk_access(smk_of_inode(sp), smk_of_inode(op),
MAY_READWRITE, &ad);
}