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Subject[PATCH 1/3] ext2/3/4: enable "undeletable" file attribute.
Currently, although you can mark a file as undeletable with 'chattr'...

> touch /tmp/wibble
> ls -l /tmp/wibble
-rw-rw-r-- 1 james james 0 Nov 16 20:00 /tmp/wibble
> chattr +u /tmp/wibble # mark file as undeletable
> lsattr /tmp/wibble
-u----------- /tmp/wibble

... it's not honoured by the kernel:

> rm /tmp/wibble # yikes! this should fail!!

This patch makes ext3 aware of the undeletable attribute such that
attempting to delete a file marked as undeltable works as expected:

> chattr +u /tmp/wibble # mark file as undeletable
> lsattr /tmp/wibble
-u----------- /tmp/wibble
> rm /tmp/wibble
rm: cannot remove `/tmp/wibble': Operation not permitted
> chattr -u /tmp/wibble # remove undeletable attribute
> lsattr /tmp/wibble
------------- /tmp/wibble
> rm /tmp/wibble # works as expected this time

Tested with e2fsprogs-1.38-12 (FC5).

Signed-off-by: James Hunt <james@jameshunt.org.uk>
---
fs/ext3/inode.c | 4 +++-
fs/namei.c | 6 +++---
include/linux/fs.h | 3 +++
3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/fs/ext3/inode.c b/fs/ext3/inode.c
index 03ba5bc..dd1428e 100644
--- a/fs/ext3/inode.c
+++ b/fs/ext3/inode.c
@@ -2568,11 +2568,13 @@ void ext3_set_inode_flags(struct inode *
{
unsigned int flags = EXT3_I(inode)->i_flags;

- inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
+ inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|S_UNRM);
if (flags & EXT3_SYNC_FL)
inode->i_flags |= S_SYNC;
if (flags & EXT3_APPEND_FL)
inode->i_flags |= S_APPEND;
+ if (flags & EXT3_UNRM_FL)
+ inode->i_flags |= S_UNRM;
if (flags & EXT3_IMMUTABLE_FL)
inode->i_flags |= S_IMMUTABLE;
if (flags & EXT3_NOATIME_FL)
diff --git a/fs/namei.c b/fs/namei.c
index 28d49b3..d845d4d 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1376,8 +1376,8 @@ static inline int check_sticky(struct in
* a. be owner of dir, or
* b. be owner of victim, or
* c. have CAP_FOWNER capability
- * 6. If the victim is append-only or immutable we can't do antyhing with
- * links pointing to it.
+ * 6. If the victim is append-only or immutable or undeletable, we can't do
+ * anthying with links pointing to it.
* 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
* 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
* 9. We can't remove a root or mountpoint.
@@ -1400,7 +1400,7 @@ static int may_delete(struct inode *dir,
if (IS_APPEND(dir))
return -EPERM;
if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
- IS_IMMUTABLE(victim->d_inode))
+ IS_IMMUTABLE(victim->d_inode)||IS_UNRM(victim->d_inode))
return -EPERM;
if (isdir) {
if (!S_ISDIR(victim->d_inode->i_mode))
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 2fe6e3f..725d35d 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -146,6 +146,8 @@ #define S_DIRSYNC 64 /* Directory modifi
#define S_NOCMTIME 128 /* Do not update file c/mtime */
#define S_SWAPFILE 256 /* Do not truncate: swapon got its bmaps */
#define S_PRIVATE 512 /* Inode is fs-internal */
+#define S_UNRM 1024 /* Inode is undeletable */
+

/*
* Note that nosuid etc flags are inode-specific: setting some file-system
@@ -178,6 +180,7 @@ #define IS_DEADDIR(inode) ((inode)->i_fl
#define IS_NOCMTIME(inode) ((inode)->i_flags & S_NOCMTIME)
#define IS_SWAPFILE(inode) ((inode)->i_flags & S_SWAPFILE)
#define IS_PRIVATE(inode) ((inode)->i_flags & S_PRIVATE)
+#define IS_UNRM(inode) ((inode)->i_flags & S_UNRM)

/* the read-only stuff doesn't really belong here, but any other place is
probably as bad and I don't want to create yet another include file. */
--
1.4.1
--
JaMeS
-
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