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Subject[patch 08/22] vfs: immutable inode checking cleanup
From: Miklos Szeredi <mszeredi@suse.cz>

Move the immutable and append-only checks from chmod, chown and utimes
into notify_change(). Checks for immutable and append-only files are
always performed by the VFS and not by the filesystem (see
permission() and may_...() in namei.c), so these belong in
notify_change(), and not in inode_change_ok().

This causes the following semantic changes in sys_utimensat(), if both
times are either UTIME_NOW or UTIME_OMIT:

- if inode is immutable, then -EACCESS is returned instead of -EPERM
- if inode is append-only, then success is returned instead of -EPERM

This should be OK, becuase this makes the UTIME_NOW on both behave
exactly the same as times == NULL. If one of the times is UTIME_OMIT,
and the other is UTIME_NOW, it also makes no sense to return a
different error for immutable or append-only files.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: Ulrich Drepper <drepper@redhat.com>
---
fs/attr.c | 6 ++++++
fs/open.c | 24 ++----------------------
fs/utimes.c | 4 ----
3 files changed, 8 insertions(+), 26 deletions(-)
Index: linux-2.6/fs/open.c
===================================================================
--- linux-2.6.orig/fs/open.c 2008-05-16 17:50:35.000000000 +0200
+++ linux-2.6/fs/open.c 2008-05-16 17:50:45.000000000 +0200
@@ -582,9 +582,6 @@ asmlinkage long sys_fchmod(unsigned int
err = mnt_want_write(file->f_path.mnt);
if (err)
goto out_putf;
- err = -EPERM;
- if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
- goto out_drop_write;
mutex_lock(&inode->i_mutex);
if (mode == (mode_t) -1)
mode = inode->i_mode;
@@ -592,8 +589,6 @@ asmlinkage long sys_fchmod(unsigned int
newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
err = notify_change(dentry, &newattrs);
mutex_unlock(&inode->i_mutex);
-
-out_drop_write:
mnt_drop_write(file->f_path.mnt);
out_putf:
fput(file);
@@ -617,11 +612,6 @@ asmlinkage long sys_fchmodat(int dfd, co
error = mnt_want_write(nd.path.mnt);
if (error)
goto dput_and_out;
-
- error = -EPERM;
- if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
- goto out_drop_write;
-
mutex_lock(&inode->i_mutex);
if (mode == (mode_t) -1)
mode = inode->i_mode;
@@ -629,8 +619,6 @@ asmlinkage long sys_fchmodat(int dfd, co
newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
error = notify_change(nd.path.dentry, &newattrs);
mutex_unlock(&inode->i_mutex);
-
-out_drop_write:
mnt_drop_write(nd.path.mnt);
dput_and_out:
path_put(&nd.path);
@@ -645,18 +633,10 @@ asmlinkage long sys_chmod(const char __u

static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
{
- struct inode * inode;
+ struct inode *inode = dentry->d_inode;
int error;
struct iattr newattrs;

- error = -ENOENT;
- if (!(inode = dentry->d_inode)) {
- printk(KERN_ERR "chown_common: NULL inode\n");
- goto out;
- }
- error = -EPERM;
- if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
- goto out;
newattrs.ia_valid = ATTR_CTIME;
if (user != (uid_t) -1) {
newattrs.ia_valid |= ATTR_UID;
@@ -672,7 +652,7 @@ static int chown_common(struct dentry *
mutex_lock(&inode->i_mutex);
error = notify_change(dentry, &newattrs);
mutex_unlock(&inode->i_mutex);
-out:
+
return error;
}

Index: linux-2.6/fs/attr.c
===================================================================
--- linux-2.6.orig/fs/attr.c 2008-05-16 17:50:35.000000000 +0200
+++ linux-2.6/fs/attr.c 2008-05-16 17:50:45.000000000 +0200
@@ -108,6 +108,12 @@ int notify_change(struct dentry * dentry
struct timespec now;
unsigned int ia_valid = attr->ia_valid;

+ if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID |
+ ATTR_ATIME_SET | ATTR_MTIME_SET)) {
+ if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
+ return -EPERM;
+ }
+
now = current_fs_time(inode->i_sb);

attr->ia_ctime = now;
Index: linux-2.6/fs/utimes.c
===================================================================
--- linux-2.6.orig/fs/utimes.c 2008-05-16 17:50:35.000000000 +0200
+++ linux-2.6/fs/utimes.c 2008-05-16 17:50:45.000000000 +0200
@@ -105,10 +105,6 @@ long do_utimes(int dfd, char __user *fil
/* Don't worry, the checks are done in inode_change_ok() */
newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
if (times) {
- error = -EPERM;
- if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
- goto mnt_drop_write_and_out;
-
if (times[0].tv_nsec == UTIME_OMIT)
newattrs.ia_valid &= ~ATTR_ATIME;
else if (times[0].tv_nsec != UTIME_NOW) {
--


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