[PATCH] move executable checking into ->permission()

For execute permission on a regular files we need to check if file has
any execute bits at all, regardless of capabilites.

This check is normally performed by generic_permission() but was also
added to the case when the filesystem defines its own ->permission()
method.  In the latter case the filesystem should be responsible for
performing this check.

Move the check from inode_permission() inside filesystems which are
not calling generic_permission().

Create a helper function execute_ok() that returns true if the inode
is a directory or if any execute bits are present in i_mode.

Also fix up the following code:

 - coda control file is never executable
 - sysctl files are never executable
 - hfs_permission seems broken on MAY_EXEC, remove
 - hfsplus_permission is eqivalent to generic_permission(), remove

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

9 files changed, 30 insertions, 44 deletions

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 89c64a8dcb9..84cc011a16e 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -275,9 +275,12 @@ static int cifs_permission(struct inode *inode, int mask)
 
 	cifs_sb = CIFS_SB(inode->i_sb);
 
-	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_PERM)
-		return 0;
-	else /* file mode might have been restricted at mount time
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_PERM) {
+		if ((mask & MAY_EXEC) && !execute_ok(inode))
+			return -EACCES;
+		else
+			return 0;
+	} else /* file mode might have been restricted at mount time
 		on the client (above and beyond ACL on servers) for
 		servers which do not support setting and viewing mode bits,
 		so allowing client to check permissions is useful */
diff --git a/fs/coda/dir.c b/fs/coda/dir.c
index c5916228243..75b1fa90b2c 100644
--- a/fs/coda/dir.c
+++ b/fs/coda/dir.c
@@ -146,6 +146,9 @@ int coda_permission(struct inode *inode, int mask)
 	if (!mask)
 		return 0; 
 
+	if ((mask & MAY_EXEC) && !execute_ok(inode))
+		return -EACCES;
+
 	lock_kernel();
 
 	if (coda_cache_check(inode, mask))
diff --git a/fs/coda/pioctl.c b/fs/coda/pioctl.c
index c51365422aa..773f2ce9aa0 100644
--- a/fs/coda/pioctl.c
+++ b/fs/coda/pioctl.c
@@ -43,7 +43,7 @@ const struct file_operations coda_ioctl_operations = {
 /* the coda pioctl inode ops */
 static int coda_ioctl_permission(struct inode *inode, int mask)
 {
-        return 0;
+	return (mask & MAY_EXEC) ? -EACCES : 0;
 }
 
 static int coda_pioctl(struct inode * inode, struct file * filp, 
diff --git a/fs/hfs/inode.c b/fs/hfs/inode.c
index 7e19835efa2..c69b7ac75bf 100644
--- a/fs/hfs/inode.c
+++ b/fs/hfs/inode.c
@@ -511,13 +511,6 @@ void hfs_clear_inode(struct inode *inode)
 	}
 }
 
-static int hfs_permission(struct inode *inode, int mask)
-{
-	if (S_ISREG(inode->i_mode) && mask & MAY_EXEC)
-		return 0;
-	return generic_permission(inode, mask, NULL);
-}
-
 static int hfs_file_open(struct inode *inode, struct file *file)
 {
 	if (HFS_IS_RSRC(inode))
@@ -616,7 +609,6 @@ static const struct inode_operations hfs_file_inode_operations = {
 	.lookup		= hfs_file_lookup,
 	.truncate	= hfs_file_truncate,
 	.setattr	= hfs_inode_setattr,
-	.permission	= hfs_permission,
 	.setxattr	= hfs_setxattr,
 	.getxattr	= hfs_getxattr,
 	.listxattr	= hfs_listxattr,
diff --git a/fs/hfsplus/inode.c b/fs/hfsplus/inode.c
index 963be644297..b207f0e6fc2 100644
--- a/fs/hfsplus/inode.c
+++ b/fs/hfsplus/inode.c
@@ -238,18 +238,6 @@ static void hfsplus_set_perms(struct inode *inode, struct hfsplus_perm *perms)
 	perms->dev = cpu_to_be32(HFSPLUS_I(inode).dev);
 }
 
-static int hfsplus_permission(struct inode *inode, int mask)
-{
-	/* MAY_EXEC is also used for lookup, if no x bit is set allow lookup,
-	 * open_exec has the same test, so it's still not executable, if a x bit
-	 * is set fall back to standard permission check.
-	 */
-	if (S_ISREG(inode->i_mode) && mask & MAY_EXEC && !(inode->i_mode & 0111))
-		return 0;
-	return generic_permission(inode, mask, NULL);
-}
-
-
 static int hfsplus_file_open(struct inode *inode, struct file *file)
 {
 	if (HFSPLUS_IS_RSRC(inode))
@@ -281,7 +269,6 @@ static int hfsplus_file_release(struct inode *inode, struct file *file)
 static const struct inode_operations hfsplus_file_inode_operations = {
 	.lookup		= hfsplus_file_lookup,
 	.truncate	= hfsplus_file_truncate,
-	.permission	= hfsplus_permission,
 	.setxattr	= hfsplus_setxattr,
 	.getxattr	= hfsplus_getxattr,
 	.listxattr	= hfsplus_listxattr,
diff --git a/fs/namei.c b/fs/namei.c
index 9e2a534383d..09ce58e49e7 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -212,8 +212,7 @@ int generic_permission(struct inode *inode, int mask,
 	 * Read/write DACs are always overridable.
 	 * Executable DACs are overridable if at least one exec bit is set.
 	 */
-	if (!(mask & MAY_EXEC) ||
-	    (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode))
+	if (!(mask & MAY_EXEC) || execute_ok(inode))
 		if (capable(CAP_DAC_OVERRIDE))
 			return 0;
 
@@ -249,23 +248,11 @@ int inode_permission(struct inode *inode, int mask)
 	}
 
 	/* Ordinary permission routines do not understand MAY_APPEND. */
-	if (inode->i_op && inode->i_op->permission) {
+	if (inode->i_op && inode->i_op->permission)
 		retval = inode->i_op->permission(inode, mask);
-		if (!retval) {
-			/*
-			 * Exec permission on a regular file is denied if none
-			 * of the execute bits are set.
-			 *
-			 * This check should be done by the ->permission()
-			 * method.
-			 */
-			if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode) &&
-			    !(inode->i_mode & S_IXUGO))
-				return -EACCES;
-		}
-	} else {
+	else
 		retval = generic_permission(inode, mask, NULL);
-	}
+
 	if (retval)
 		return retval;
 
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index c216c8786c5..3e64b98f3a9 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1957,6 +1957,9 @@ force_lookup:
 	} else
 		res = PTR_ERR(cred);
 out:
+	if (!res && (mask & MAY_EXEC) && !execute_ok(inode))
+		res = -EACCES;
+
 	dfprintk(VFS, "NFS: permission(%s/%ld), mask=0x%x, res=%d\n",
 		inode->i_sb->s_id, inode->i_ino, mask, res);
 	return res;
diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 5fe210c0917..7b997754a25 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -298,13 +298,19 @@ static int proc_sys_permission(struct inode *inode, int mask)
 	 * sysctl entries that are not writeable,
 	 * are _NOT_ writeable, capabilities or not.
 	 */
-	struct ctl_table_header *head = grab_header(inode);
-	struct ctl_table *table = PROC_I(inode)->sysctl_entry;
+	struct ctl_table_header *head;
+	struct ctl_table *table;
 	int error;
 
+	/* Executable files are not allowed under /proc/sys/ */
+	if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode))
+		return -EACCES;
+
+	head = grab_header(inode);
 	if (IS_ERR(head))
 		return PTR_ERR(head);
 
+	table = PROC_I(inode)->sysctl_entry;
 	if (!table) /* global root - r-xr-xr-x */
 		error = mask & MAY_WRITE ? -EACCES : 0;
 	else /* Use the permissions on the sysctl table entry */
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 5f70aa62cf0..025a4a251b6 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1851,6 +1851,11 @@ extern int inode_permission(struct inode *, int);
 extern int generic_permission(struct inode *, int,
 		int (*check_acl)(struct inode *, int));
 
+static inline bool execute_ok(struct inode *inode)
+{
+	return (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode);
+}
+
 extern int get_write_access(struct inode *);
 extern int deny_write_access(struct file *);
 static inline void put_write_access(struct inode * inode)