[RFC 03/21] vfs: Add IS_ACL() and IS_RICHACL() tests

[Andreas Gruenbacher]

The vfs does not apply the umask for file systems that support acls. The test
used for this used to be called IS_POSIXACL(). Switch to a new IS_ACL() test to
check for either posix acls or richacls instead. Add a new MS_RICHACL flag and
IS_RICHACL() test for richacls alone. The IS_POSIXACL() test is still needed
by file systems that specifically support POSIX ACLs, like nfsd.

Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
---
 fs/Kconfig              |  3 +++
 fs/namei.c              |  8 ++++----
 include/linux/fs.h      | 12 ++++++++++++
 include/uapi/linux/fs.h |  3 ++-
 4 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/fs/Kconfig b/fs/Kconfig
index ec35851..8b84f99 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -58,6 +58,9 @@ endif # BLOCK
 config FS_POSIX_ACL
 	def_bool n
 
+config FS_RICHACL
+	def_bool n
+
 config EXPORTFS
 	tristate
 
diff --git a/fs/namei.c b/fs/namei.c
index c83145a..0ba4bbc 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2696,7 +2696,7 @@ static int atomic_open(struct nameidata *nd, struct dentry *dentry,
 	}
 
 	mode = op->mode;
-	if ((open_flag & O_CREAT) && !IS_POSIXACL(dir))
+	if ((open_flag & O_CREAT) && !IS_ACL(dir))
 		mode &= ~current_umask();
 
 	excl = (open_flag & (O_EXCL | O_CREAT)) == (O_EXCL | O_CREAT);
@@ -2880,7 +2880,7 @@ static int lookup_open(struct nameidata *nd, struct path *path,
 	/* Negative dentry, just create the file */
 	if (!dentry->d_inode && (op->open_flag & O_CREAT)) {
 		umode_t mode = op->mode;
-		if (!IS_POSIXACL(dir->d_inode))
+		if (!IS_ACL(dir->d_inode))
 			mode &= ~current_umask();
 		/*
 		 * This write is needed to ensure that a
@@ -3481,7 +3481,7 @@ retry:
 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);
 
-	if (!IS_POSIXACL(path.dentry->d_inode))
+	if (!IS_ACL(path.dentry->d_inode))
 		mode &= ~current_umask();
 	error = security_path_mknod(&path, dentry, mode, dev);
 	if (error)
@@ -3550,7 +3550,7 @@ retry:
 	if (IS_ERR(dentry))
 		return PTR_ERR(dentry);
 
-	if (!IS_POSIXACL(path.dentry->d_inode))
+	if (!IS_ACL(path.dentry->d_inode))
 		mode &= ~current_umask();
 	error = security_path_mkdir(&path, dentry, mode);
 	if (!error)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b4d71b5..f64eb45 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1708,6 +1708,12 @@ struct super_operations {
 #define IS_IMMUTABLE(inode)	((inode)->i_flags & S_IMMUTABLE)
 #define IS_POSIXACL(inode)	__IS_FLG(inode, MS_POSIXACL)
 
+#ifdef CONFIG_FS_RICHACL
+#define IS_RICHACL(inode)	__IS_FLG(inode, MS_RICHACL)
+#else
+#define IS_RICHACL(inode)	0
+#endif
+
 #define IS_DEADDIR(inode)	((inode)->i_flags & S_DEAD)
 #define IS_NOCMTIME(inode)	((inode)->i_flags & S_NOCMTIME)
 #define IS_SWAPFILE(inode)	((inode)->i_flags & S_SWAPFILE)
@@ -1721,6 +1727,12 @@ struct super_operations {
 				 (inode)->i_rdev == WHITEOUT_DEV)
 
 /*
+ * IS_ACL() tells the VFS to not apply the umask
+ * and use check_acl for acl permission checks when defined.
+ */
+#define IS_ACL(inode)		__IS_FLG(inode, MS_POSIXACL | MS_RICHACL)
+
+/*
  * Inode state bits.  Protected by inode->i_lock
  *
  * Three bits determine the dirty state of the inode, I_DIRTY_SYNC,
diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
index 9b964a5..6ac6bc9 100644
--- a/include/uapi/linux/fs.h
+++ b/include/uapi/linux/fs.h
@@ -81,7 +81,7 @@ struct inodes_stat_t {
 #define MS_VERBOSE	32768	/* War is peace. Verbosity is silence.
 				   MS_VERBOSE is deprecated. */
 #define MS_SILENT	32768
-#define MS_POSIXACL	(1<<16)	/* VFS does not apply the umask */
+#define MS_POSIXACL	(1<<16)	/* Supports POSIX ACLs */
 #define MS_UNBINDABLE	(1<<17)	/* change to unbindable */
 #define MS_PRIVATE	(1<<18)	/* change to private */
 #define MS_SLAVE	(1<<19)	/* change to slave */
@@ -91,6 +91,7 @@ struct inodes_stat_t {
 #define MS_I_VERSION	(1<<23) /* Update inode I_version field */
 #define MS_STRICTATIME	(1<<24) /* Always perform atime updates */
 #define MS_LAZYTIME	(1<<25) /* Update the on-disk [acm]times lazily */
+#define MS_RICHACL	(1<<26) /* Supports richacls */
 
 /* These sb flags are internal to the kernel */
 #define MS_NOSEC	(1<<28)
-- 
2.1.0