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SubjectRe: NULL pointer dereference in selinux_ip_postroute_compat
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Date
On Wed, 2012-08-08 at 22:09 +0200, Eric Dumazet wrote:
> On Wed, 2012-08-08 at 15:59 -0400, Eric Paris wrote:
>
> > Seems wrong. We shouldn't ever need ifdef CONFIG_SECURITY in core
> > code.
>
> Sure but it seems include file misses an accessor for this.
>
> We could add it on a future cleanup patch, as Paul mentioned.

I cooked following patch.
But smack/smack_lsm.c makes a reference to
smk_of_current()... so it seems we are in a hole...

It makes little sense to me to have any kind of security on this
internal sockets.

Maybe selinux should not crash if sk->sk_security is NULL ?



include/linux/security.h | 6 +++---
net/core/sock.c | 2 +-
net/ipv4/ip_output.c | 4 +++-
security/security.c | 4 ++--
security/selinux/hooks.c | 5 ++++-
security/smack/smack_lsm.c | 5 ++++-
6 files changed, 17 insertions(+), 9 deletions(-)
diff --git a/include/linux/security.h b/include/linux/security.h
index 4e5a73c..aa648b2 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1601,7 +1601,7 @@ struct security_operations {
int (*socket_sock_rcv_skb) (struct sock *sk, struct sk_buff *skb);
int (*socket_getpeersec_stream) (struct socket *sock, char __user *optval, int __user *optlen, unsigned len);
int (*socket_getpeersec_dgram) (struct socket *sock, struct sk_buff *skb, u32 *secid);
- int (*sk_alloc_security) (struct sock *sk, int family, gfp_t priority);
+ int (*sk_alloc_security) (struct sock *sk, int family, gfp_t priority, bool check);
void (*sk_free_security) (struct sock *sk);
void (*sk_clone_security) (const struct sock *sk, struct sock *newsk);
void (*sk_getsecid) (struct sock *sk, u32 *secid);
@@ -2539,7 +2539,7 @@ int security_sock_rcv_skb(struct sock *sk, struct sk_buff *skb);
int security_socket_getpeersec_stream(struct socket *sock, char __user *optval,
int __user *optlen, unsigned len);
int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, u32 *secid);
-int security_sk_alloc(struct sock *sk, int family, gfp_t priority);
+int security_sk_alloc(struct sock *sk, int family, gfp_t priority, bool check);
void security_sk_free(struct sock *sk);
void security_sk_clone(const struct sock *sk, struct sock *newsk);
void security_sk_classify_flow(struct sock *sk, struct flowi *fl);
@@ -2667,7 +2667,7 @@ static inline int security_socket_getpeersec_dgram(struct socket *sock, struct s
return -ENOPROTOOPT;
}

-static inline int security_sk_alloc(struct sock *sk, int family, gfp_t priority)
+static inline int security_sk_alloc(struct sock *sk, int family, gfp_t priority, bool check)
{
return 0;
}
diff --git a/net/core/sock.c b/net/core/sock.c
index 8f67ced..e00cadf 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1186,7 +1186,7 @@ static struct sock *sk_prot_alloc(struct proto *prot, gfp_t priority,
if (sk != NULL) {
kmemcheck_annotate_bitfield(sk, flags);

- if (security_sk_alloc(sk, family, priority))
+ if (security_sk_alloc(sk, family, priority, false))
goto out_free;

if (!try_module_get(prot->owner))
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 76dde25..b233d6e 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1524,6 +1524,8 @@ void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr,
sk->sk_priority = skb->priority;
sk->sk_protocol = ip_hdr(skb)->protocol;
sk->sk_bound_dev_if = arg->bound_dev_if;
+ if (security_sk_alloc(sk, PF_INET, GFP_ATOMIC, true))
+ goto out;
sock_net_set(sk, net);
__skb_queue_head_init(&sk->sk_write_queue);
sk->sk_sndbuf = sysctl_wmem_default;
@@ -1539,7 +1541,7 @@ void ip_send_unicast_reply(struct net *net, struct sk_buff *skb, __be32 daddr,
skb_set_queue_mapping(nskb, skb_get_queue_mapping(skb));
ip_push_pending_frames(sk, &fl4);
}
-
+out:
put_cpu_var(unicast_sock);

ip_rt_put(rt);
diff --git a/security/security.c b/security/security.c
index 860aeb3..af7404e 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1146,9 +1146,9 @@ int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb, u
}
EXPORT_SYMBOL(security_socket_getpeersec_dgram);

-int security_sk_alloc(struct sock *sk, int family, gfp_t priority)
+int security_sk_alloc(struct sock *sk, int family, gfp_t priority, bool check)
{
- return security_ops->sk_alloc_security(sk, family, priority);
+ return security_ops->sk_alloc_security(sk, family, priority, check);
}

void security_sk_free(struct sock *sk)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 6c77f63..459eca6 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4289,10 +4289,13 @@ out:
return 0;
}

-static int selinux_sk_alloc_security(struct sock *sk, int family, gfp_t priority)
+static int selinux_sk_alloc_security(struct sock *sk, int family, gfp_t priority, bool check)
{
struct sk_security_struct *sksec;

+ if (check && sk->sk_security)
+ return 0;
+
sksec = kzalloc(sizeof(*sksec), priority);
if (!sksec)
return -ENOMEM;
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 8221514..8965cf1 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -1754,11 +1754,14 @@ static void smack_task_to_inode(struct task_struct *p, struct inode *inode)
*
* Returns 0 on success, -ENOMEM is there's no memory
*/
-static int smack_sk_alloc_security(struct sock *sk, int family, gfp_t gfp_flags)
+static int smack_sk_alloc_security(struct sock *sk, int family, gfp_t gfp_flags, bool check)
{
char *csp = smk_of_current();
struct socket_smack *ssp;

+ if (check && sk->sk_security)
+ return 0;
+
ssp = kzalloc(sizeof(struct socket_smack), gfp_flags);
if (ssp == NULL)
return -ENOMEM;




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