sock: Introduce cred_to_ucred

To keep the coming code clear and to allow both the sock
code and the scm code to share the logic introduce a
fuction to translate from struct cred to struct ucred.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 19 insertions, 0 deletions

diff --git a/include/linux/socket.h b/include/linux/socket.h
index 032a19eb61b1..a2fada9becb6 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -24,6 +24,9 @@ struct __kernel_sockaddr_storage {
 #include <linux/types.h>                /* pid_t                        */
 #include <linux/compiler.h>             /* __user                       */
 
+struct pid;
+struct cred;
+
 #define __sockaddr_check_size(size)     \
         BUILD_BUG_ON(((size) > sizeof(struct __kernel_sockaddr_storage)))
 
@@ -309,6 +312,8 @@ struct ucred {
 #define IPX_TYPE        1
 
 #ifdef __KERNEL__
+extern void cred_to_ucred(struct pid *pid, const struct cred *cred, struct ucred *ucred);
+
 extern int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
 extern int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov,
                                int offset, int len);
diff --git a/net/core/sock.c b/net/core/sock.c
index f9ce0db41cd6..db8335ad7559 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -110,6 +110,7 @@
 #include <linux/tcp.h>
 #include <linux/init.h>
 #include <linux/highmem.h>
+#include <linux/user_namespace.h>
 
 #include <asm/uaccess.h>
 #include <asm/system.h>
@@ -749,6 +750,19 @@ set_rcvbuf:
 EXPORT_SYMBOL(sock_setsockopt);
 
 
+void cred_to_ucred(struct pid *pid, const struct cred *cred,
+                   struct ucred *ucred)
+{
+        ucred->pid = pid_vnr(pid);
+        ucred->uid = ucred->gid = -1;
+        if (cred) {
+                struct user_namespace *current_ns = current_user_ns();
+
+                ucred->uid = user_ns_map_uid(current_ns, cred, cred->euid);
+                ucred->gid = user_ns_map_gid(current_ns, cred, cred->egid);
+        }
+}
+
 int sock_getsockopt(struct socket *sock, int level, int optname,
                     char __user *optval, int __user *optlen)
 {