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Subject[PATCH v1 20/22] Move common usercopy into security_getpeersec_stream
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[PATCH 20/22] Move common usercopy into security_getpeersec_stream

The modules implementing hook for getpeersec_stream
don't need to be duplicating the copy-to-user checks.
Moving the user copy part into the infrastructure makes
the security module code simpler and reduces the places
where user copy code may go awry.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
include/linux/lsm_hooks.h | 10 ++++------
include/linux/security.h | 6 ++++--
security/apparmor/lsm.c | 28 ++++++++++------------------
security/security.c | 17 +++++++++++++++--
security/selinux/hooks.c | 22 +++++++---------------
security/smack/smack_lsm.c | 19 ++++++++-----------
6 files changed, 48 insertions(+), 54 deletions(-)

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 7c321d11d994..8d247e7ce2fb 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -846,9 +846,8 @@
* SO_GETPEERSEC. For tcp sockets this can be meaningful if the
* socket is associated with an ipsec SA.
* @sock is the local socket.
- * @optval userspace memory where the security state is to be copied.
- * @optlen userspace int where the module should copy the actual length
- * of the security state.
+ * @optval the security state.
+ * @optlen the actual length of the security state.
* @len as input is the maximum length to copy to userspace provided
* by the caller.
* Return 0 if all is well, otherwise, typical getsockopt return
@@ -1680,9 +1679,8 @@ union security_list_options {
int (*socket_setsockopt)(struct socket *sock, int level, int optname);
int (*socket_shutdown)(struct socket *sock, int how);
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 int len);
+ int (*socket_getpeersec_stream)(struct socket *sock, char **optval,
+ int *optlen, unsigned int len);
int (*socket_getpeersec_dgram)(struct socket *sock,
struct sk_buff *skb,
struct secids *secid);
diff --git a/include/linux/security.h b/include/linux/security.h
index 9095f63c65a9..7d3300d34f25 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1377,8 +1377,10 @@ static inline int security_sock_rcv_skb(struct sock *sk,
return 0;
}

-static inline int security_socket_getpeersec_stream(struct socket *sock, char __user *optval,
- int __user *optlen, unsigned len)
+static inline int security_socket_getpeersec_stream(struct socket *sock,
+ char __user *optval,
+ int __user *optlen,
+ unsigned int len)
{
return -ENOPROTOOPT;
}
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index b0200481c811..7a2a8d0efa09 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -1026,10 +1026,8 @@ static struct aa_label *sk_peer_label(struct sock *sk)
*
* Note: for tcp only valid if using ipsec or cipso on lan
*/
-static int apparmor_socket_getpeersec_stream(struct socket *sock,
- char __user *optval,
- int __user *optlen,
- unsigned int len)
+static int apparmor_socket_getpeersec_stream(struct socket *sock, char **optval,
+ int *optlen, unsigned int len)
{
char *name;
int slen, error = 0;
@@ -1046,22 +1044,16 @@ static int apparmor_socket_getpeersec_stream(struct socket *sock,
FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
FLAG_HIDDEN_UNCONFINED, GFP_KERNEL);
/* don't include terminating \0 in slen, it breaks some apps */
- if (slen < 0) {
+ if (slen < 0)
error = -ENOMEM;
- } else {
- if (slen > len) {
- error = -ERANGE;
- } else if (copy_to_user(optval, name, slen)) {
- error = -EFAULT;
- goto out;
- }
- if (put_user(slen, optlen))
- error = -EFAULT;
-out:
- kfree(name);
-
+ else if (slen > len)
+ error = -ERANGE;
+ else {
+ *optlen = slen;
+ *optval = name;
}
-
+ if (error)
+ kfree(name);
done:
end_current_label_crit_section(label);

diff --git a/security/security.c b/security/security.c
index 90e741db0a42..521afa12293e 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1930,8 +1930,21 @@ EXPORT_SYMBOL(security_sock_rcv_skb);
int security_socket_getpeersec_stream(struct socket *sock, char __user *optval,
int __user *optlen, unsigned len)
{
- return call_int_hook(socket_getpeersec_stream, -ENOPROTOOPT, sock,
- optval, optlen, len);
+ char *tval = NULL;
+ u32 tlen;
+ int rc;
+
+ rc = call_int_hook(socket_getpeersec_stream, -ENOPROTOOPT, sock,
+ &tval, &tlen, len);
+ if (rc == 0) {
+ tlen = strlen(tval) + 1;
+ if (put_user(tlen, optlen))
+ rc = -EFAULT;
+ else if (copy_to_user(optval, tval, tlen))
+ rc = -EFAULT;
+ kfree(tval);
+ }
+ return rc;
}

int security_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *skb,
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index c12c36f72258..6614d46feac4 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -4986,10 +4986,8 @@ static int selinux_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
return err;
}

-static int selinux_socket_getpeersec_stream(struct socket *sock,
- __user char *optval,
- __user int *optlen,
- unsigned int len)
+static int selinux_socket_getpeersec_stream(struct socket *sock, char **optval,
+ int *optlen, unsigned int len)
{
int err = 0;
char *scontext;
@@ -5010,18 +5008,12 @@ static int selinux_socket_getpeersec_stream(struct socket *sock,
return err;

if (scontext_len > len) {
- err = -ERANGE;
- goto out_len;
+ kfree(scontext);
+ return -ERANGE;
}
-
- if (copy_to_user(optval, scontext, scontext_len))
- err = -EFAULT;
-
-out_len:
- if (put_user(scontext_len, optlen))
- err = -EFAULT;
- kfree(scontext);
- return err;
+ *optval = scontext;
+ *optlen = scontext_len;
+ return 0;
}

static int selinux_socket_getpeersec_dgram(struct socket *sock,
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 157c6a731305..d4552b2286bc 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -3895,14 +3895,12 @@ static int smack_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
*
* returns zero on success, an error code otherwise
*/
-static int smack_socket_getpeersec_stream(struct socket *sock,
- char __user *optval,
- int __user *optlen, unsigned len)
+static int smack_socket_getpeersec_stream(struct socket *sock, char **optval,
+ int *optlen, unsigned int len)
{
struct socket_smack *ssp;
char *rcp = "";
int slen = 1;
- int rc = 0;

ssp = smack_sock(sock->sk);
if (ssp->smk_packet != NULL) {
@@ -3911,14 +3909,13 @@ static int smack_socket_getpeersec_stream(struct socket *sock,
}

if (slen > len)
- rc = -ERANGE;
- else if (copy_to_user(optval, rcp, slen) != 0)
- rc = -EFAULT;
-
- if (put_user(slen, optlen) != 0)
- rc = -EFAULT;
+ return -ERANGE;

- return rc;
+ *optval = kstrdup(rcp, GFP_ATOMIC);
+ if (*optval == NULL)
+ return -ENOMEM;
+ *optlen = slen;
+ return 0;
}


--
2.17.1

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