Merge commit '5bc66170dc486556a1e36fd384463536573f4b82' into x86/urgent

From Borislav Petkov <bp@amd64.org>:

Below is a RAS fix which reverts the addition of a sysfs attribute
which we agreed is not needed, post-factum. And this should go in now
because that sysfs attribute is going to end up in 3.7 otherwise and
thus exposed to userspace; removing it then would be a lot harder.

This is done as a merge rather than a simple patch/cherry-pick since
the baseline for this patch was not in the previous x86/urgent.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 33 insertions, 14 deletions

diff --git a/net/core/scm.c b/net/core/scm.c
index 040cebeed45..ab570841a53 100644
--- a/net/core/scm.c
+++ b/net/core/scm.c
@@ -45,12 +45,17 @@
 static __inline__ int scm_check_creds(struct ucred *creds)
 {
 	const struct cred *cred = current_cred();
+	kuid_t uid = make_kuid(cred->user_ns, creds->uid);
+	kgid_t gid = make_kgid(cred->user_ns, creds->gid);
+
+	if (!uid_valid(uid) || !gid_valid(gid))
+		return -EINVAL;
 
 	if ((creds->pid == task_tgid_vnr(current) || capable(CAP_SYS_ADMIN)) &&
-	    ((creds->uid == cred->uid   || creds->uid == cred->euid ||
-	      creds->uid == cred->suid) || capable(CAP_SETUID)) &&
-	    ((creds->gid == cred->gid   || creds->gid == cred->egid ||
-	      creds->gid == cred->sgid) || capable(CAP_SETGID))) {
+	    ((uid_eq(uid, cred->uid)   || uid_eq(uid, cred->euid) ||
+	      uid_eq(uid, cred->suid)) || capable(CAP_SETUID)) &&
+	    ((gid_eq(gid, cred->gid)   || gid_eq(gid, cred->egid) ||
+	      gid_eq(gid, cred->sgid)) || capable(CAP_SETGID))) {
 	       return 0;
 	}
 	return -EPERM;
@@ -149,39 +154,54 @@ int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
 				goto error;
 			break;
 		case SCM_CREDENTIALS:
+		{
+			struct ucred creds;
+			kuid_t uid;
+			kgid_t gid;
 			if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct ucred)))
 				goto error;
-			memcpy(&p->creds, CMSG_DATA(cmsg), sizeof(struct ucred));
-			err = scm_check_creds(&p->creds);
+			memcpy(&creds, CMSG_DATA(cmsg), sizeof(struct ucred));
+			err = scm_check_creds(&creds);
 			if (err)
 				goto error;
 
-			if (!p->pid || pid_vnr(p->pid) != p->creds.pid) {
+			p->creds.pid = creds.pid;
+			if (!p->pid || pid_vnr(p->pid) != creds.pid) {
 				struct pid *pid;
 				err = -ESRCH;
-				pid = find_get_pid(p->creds.pid);
+				pid = find_get_pid(creds.pid);
 				if (!pid)
 					goto error;
 				put_pid(p->pid);
 				p->pid = pid;
 			}
 
+			err = -EINVAL;
+			uid = make_kuid(current_user_ns(), creds.uid);
+			gid = make_kgid(current_user_ns(), creds.gid);
+			if (!uid_valid(uid) || !gid_valid(gid))
+				goto error;
+
+			p->creds.uid = uid;
+			p->creds.gid = gid;
+
 			if (!p->cred ||
-			    (p->cred->euid != p->creds.uid) ||
-			    (p->cred->egid != p->creds.gid)) {
+			    !uid_eq(p->cred->euid, uid) ||
+			    !gid_eq(p->cred->egid, gid)) {
 				struct cred *cred;
 				err = -ENOMEM;
 				cred = prepare_creds();
 				if (!cred)
 					goto error;
 
-				cred->uid = cred->euid = p->creds.uid;
-				cred->gid = cred->egid = p->creds.gid;
+				cred->uid = cred->euid = uid;
+				cred->gid = cred->egid = gid;
 				if (p->cred)
 					put_cred(p->cred);
 				p->cred = cred;
 			}
 			break;
+		}
 		default:
 			goto error;
 		}
@@ -281,11 +301,10 @@ void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm)
 			break;
 		}
 		/* Bump the usage count and install the file. */
-		get_file(fp[i]);
 		sock = sock_from_file(fp[i], &err);
 		if (sock)
 			sock_update_netprioidx(sock->sk, current);
-		fd_install(new_fd, fp[i]);
+		fd_install(new_fd, get_file(fp[i]));
 	}
 
 	if (i > 0)