net: fix incorrect credentials passing

[ Upstream commit 83f1b4ba917db5dc5a061a44b3403ddb6e783494 ]

Commit 257b5358b32f ("scm: Capture the full credentials of the scm
sender") changed the credentials passing code to pass in the effective
uid/gid instead of the real uid/gid.

Obviously this doesn't matter most of the time (since normally they are
the same), but it results in differences for suid binaries when the wrong
uid/gid ends up being used.

This just undoes that (presumably unintentional) part of the commit.

Reported-by: Andy Lutomirski <luto@amacapital.net>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Serge E. Hallyn <serge@hallyn.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/linux/socket.h b/include/linux/socket.h
index 635c2136ce3ec2be06d6ef7a1e9e03ce58ce0791..241795206b471af002c953bb98713cdd894253e1 100644 (file)
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -312,7 +312,8 @@ struct ucred {
 /* IPX options */
 #define IPX_TYPE       1
 
-extern void cred_to_ucred(struct pid *pid, const struct cred *cred, struct ucred *ucred);
+extern void cred_to_ucred(struct pid *pid, const struct cred *cred, struct ucred *ucred,
+                         bool use_effective);
 
 extern int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
 extern int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov,

diff --git a/include/net/scm.h b/include/net/scm.h
index 745460fa2f02cdd96e6b6befd79b8791d95965fd..820c1b365cba68b3cd109d44501cbd4c4a7bc15f 100644 (file)
--- a/include/net/scm.h
+++ b/include/net/scm.h
@@ -50,7 +50,7 @@ static __inline__ void scm_set_cred(struct scm_cookie *scm,
 {
        scm->pid  = get_pid(pid);
        scm->cred = get_cred(cred);
-       cred_to_ucred(pid, cred, &scm->creds);
+       cred_to_ucred(pid, cred, &scm->creds, false);
 }
 
 static __inline__ void scm_destroy_cred(struct scm_cookie *scm)

diff --git a/net/core/sock.c b/net/core/sock.c
index 3da11ba3b0a6807c17b607521f68afd041d6c013..b9d56107b051047686b5177dcd4d6609695e3ff7 100644 (file)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -752,15 +752,20 @@ EXPORT_SYMBOL(sock_setsockopt);
 
 
 void cred_to_ucred(struct pid *pid, const struct cred *cred,
-                  struct ucred *ucred)
+                  struct ucred *ucred, bool use_effective)
 {
        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);
+               if (use_effective) {
+                       ucred->uid = user_ns_map_uid(current_ns, cred, cred->euid);
+                       ucred->gid = user_ns_map_gid(current_ns, cred, cred->egid);
+               } else {
+                       ucred->uid = user_ns_map_uid(current_ns, cred, cred->uid);
+                       ucred->gid = user_ns_map_gid(current_ns, cred, cred->gid);
+               }
        }
 }
 EXPORT_SYMBOL_GPL(cred_to_ucred);
@@ -921,7 +926,8 @@ int sock_getsockopt(struct socket *sock, int level, int optname,
                struct ucred peercred;
                if (len > sizeof(peercred))
                        len = sizeof(peercred);
-               cred_to_ucred(sk->sk_peer_pid, sk->sk_peer_cred, &peercred);
+               cred_to_ucred(sk->sk_peer_pid, sk->sk_peer_cred,
+                             &peercred, true);
                if (copy_to_user(optval, &peercred, len))
                        return -EFAULT;
                goto lenout;