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Subject[PATCH BUGFIX -rc6] Smackfs: remove redundant lock, fix open(,O_RDWR)
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Hi all,

Older smackfs was parsing MAC rules by characters, thus a need of
locking write sessions on open() was needed. This lock is no longer
useful now since each rule is handled by a single write() call.

This is also a bugfix since seq_open() was not called if an open()
O_RDWR flag was given, leading to a seq_read() without an initialized
seq_file, thus an Oops.

Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com>
Reported-by: Jonathan Corbet <corbet@lwn.net>
--

security/smack/smackfs.c | 35 ++---------------------------------
1 file changed, 2 insertions(+), 33 deletions(-)

diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index afe7c9b..cfae8af 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -74,11 +74,6 @@ struct smk_list_entry *smack_list;
#define SEQ_READ_FINISHED 1

/*
- * Disable concurrent writing open() operations
- */
-static struct semaphore smack_write_sem;
-
-/*
* Values for parsing cipso rules
* SMK_DIGITLEN: Length of a digit field in a rule.
* SMK_CIPSOMIN: Minimum possible cipso rule length.
@@ -168,32 +163,7 @@ static struct seq_operations load_seq_ops = {
*/
static int smk_open_load(struct inode *inode, struct file *file)
{
- if ((file->f_flags & O_ACCMODE) == O_RDONLY)
- return seq_open(file, &load_seq_ops);
-
- if (down_interruptible(&smack_write_sem))
- return -ERESTARTSYS;
-
- return 0;
-}
-
-/**
- * smk_release_load - release() for /smack/load
- * @inode: inode structure representing file
- * @file: "load" file pointer
- *
- * For a reading session, use the seq_file release
- * implementation.
- * Otherwise, we are at the end of a writing session so
- * clean everything up.
- */
-static int smk_release_load(struct inode *inode, struct file *file)
-{
- if ((file->f_flags & O_ACCMODE) == O_RDONLY)
- return seq_release(inode, file);
-
- up(&smack_write_sem);
- return 0;
+ return seq_open(file, &load_seq_ops);
}

/**
@@ -341,7 +311,7 @@ static const struct file_operations smk_load_ops = {
.read = seq_read,
.llseek = seq_lseek,
.write = smk_write_load,
- .release = smk_release_load,
+ .release = seq_release,
};

/**
@@ -1011,7 +981,6 @@ static int __init init_smk_fs(void)
}
}

- sema_init(&smack_write_sem, 1);
smk_cipso_doi();
smk_unlbl_ambient(NULL);

Regards,
--

"Better to light a candle, than curse the darkness"

Ahmed S. Darwish
Homepage: http://darwish.07.googlepages.com
Blog: http://darwish-07.blogspot.com



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