From 77e69dac3cefacee939cb107ae9cd520a62338e0 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Fri, 1 Aug 2008 04:29:18 -0400 Subject: [PATCH] [PATCH] fix races and leaks in vfs_quota_on() users * new helper: vfs_quota_on_path(); equivalent of vfs_quota_on() sans the pathname resolution. * callers of vfs_quota_on() that do their own pathname resolution and checks based on it are switched to vfs_quota_on_path(); that way we avoid the races. * reiserfs leaked dentry/vfsmount references on several failure exits. Signed-off-by: Al Viro --- fs/dquot.c | 33 ++++++++++++++++++++------------- fs/ext3/super.c | 3 ++- fs/ext4/super.c | 3 ++- fs/reiserfs/super.c | 16 +++++++++------- include/linux/quotaops.h | 2 ++ 5 files changed, 35 insertions(+), 22 deletions(-) diff --git a/fs/dquot.c b/fs/dquot.c index 1346eebe74ce..8ec4d6cc7633 100644 --- a/fs/dquot.c +++ b/fs/dquot.c @@ -1793,6 +1793,21 @@ static int vfs_quota_on_remount(struct super_block *sb, int type) return ret; } +int vfs_quota_on_path(struct super_block *sb, int type, int format_id, + struct path *path) +{ + int error = security_quota_on(path->dentry); + if (error) + return error; + /* Quota file not on the same filesystem? */ + if (path->mnt->mnt_sb != sb) + error = -EXDEV; + else + error = vfs_quota_on_inode(path->dentry->d_inode, type, + format_id); + return error; +} + /* Actual function called from quotactl() */ int vfs_quota_on(struct super_block *sb, int type, int format_id, char *path, int remount) @@ -1804,19 +1819,10 @@ int vfs_quota_on(struct super_block *sb, int type, int format_id, char *path, return vfs_quota_on_remount(sb, type); error = path_lookup(path, LOOKUP_FOLLOW, &nd); - if (error < 0) - return error; - error = security_quota_on(nd.path.dentry); - if (error) - goto out_path; - /* Quota file not on the same filesystem? */ - if (nd.path.mnt->mnt_sb != sb) - error = -EXDEV; - else - error = vfs_quota_on_inode(nd.path.dentry->d_inode, type, - format_id); -out_path: - path_put(&nd.path); + if (!error) { + error = vfs_quota_on_path(sb, type, format_id, &nd.path); + path_put(&nd.path); + } return error; } @@ -2185,6 +2191,7 @@ EXPORT_SYMBOL(unregister_quota_format); EXPORT_SYMBOL(dqstats); EXPORT_SYMBOL(dq_data_lock); EXPORT_SYMBOL(vfs_quota_on); +EXPORT_SYMBOL(vfs_quota_on_path); EXPORT_SYMBOL(vfs_quota_on_mount); EXPORT_SYMBOL(vfs_quota_off); EXPORT_SYMBOL(vfs_quota_sync); diff --git a/fs/ext3/super.c b/fs/ext3/super.c index 8ddced384674..f38a5afc39a1 100644 --- a/fs/ext3/super.c +++ b/fs/ext3/super.c @@ -2810,8 +2810,9 @@ static int ext3_quota_on(struct super_block *sb, int type, int format_id, journal_unlock_updates(EXT3_SB(sb)->s_journal); } + err = vfs_quota_on_path(sb, type, format_id, &nd.path); path_put(&nd.path); - return vfs_quota_on(sb, type, format_id, path, remount); + return err; } /* Read data from quotafile - avoid pagecache and such because we cannot afford diff --git a/fs/ext4/super.c b/fs/ext4/super.c index b5479b1dff14..1e69f29a8c55 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -3352,8 +3352,9 @@ static int ext4_quota_on(struct super_block *sb, int type, int format_id, jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal); } + err = vfs_quota_on_path(sb, type, format_id, &nd.path); path_put(&nd.path); - return vfs_quota_on(sb, type, format_id, path, remount); + return err; } /* Read data from quotafile - avoid pagecache and such because we cannot afford diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c index 879e54d35c2d..282a13596c70 100644 --- a/fs/reiserfs/super.c +++ b/fs/reiserfs/super.c @@ -2076,8 +2076,8 @@ static int reiserfs_quota_on(struct super_block *sb, int type, int format_id, return err; /* Quotafile not on the same filesystem? */ if (nd.path.mnt->mnt_sb != sb) { - path_put(&nd.path); - return -EXDEV; + err = -EXDEV; + goto out; } inode = nd.path.dentry->d_inode; /* We must not pack tails for quota files on reiserfs for quota IO to work */ @@ -2087,8 +2087,8 @@ static int reiserfs_quota_on(struct super_block *sb, int type, int format_id, reiserfs_warning(sb, "reiserfs: Unpacking tail of quota file failed" " (%d). Cannot turn on quotas.", err); - path_put(&nd.path); - return -EINVAL; + err = -EINVAL; + goto out; } mark_inode_dirty(inode); } @@ -2109,13 +2109,15 @@ static int reiserfs_quota_on(struct super_block *sb, int type, int format_id, /* Just start temporary transaction and finish it */ err = journal_begin(&th, sb, 1); if (err) - return err; + goto out; err = journal_end_sync(&th, sb, 1); if (err) - return err; + goto out; } + err = vfs_quota_on_path(sb, type, format_id, &nd.path); +out: path_put(&nd.path); - return vfs_quota_on(sb, type, format_id, path, 0); + return err; } /* Read data from quotafile - avoid pagecache and such because we cannot afford diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h index 742187f7a05c..ca6b9b5c8d52 100644 --- a/include/linux/quotaops.h +++ b/include/linux/quotaops.h @@ -43,6 +43,8 @@ int dquot_mark_dquot_dirty(struct dquot *dquot); int vfs_quota_on(struct super_block *sb, int type, int format_id, char *path, int remount); +int vfs_quota_on_path(struct super_block *sb, int type, int format_id, + struct path *path); int vfs_quota_on_mount(struct super_block *sb, char *qf_name, int format_id, int type); int vfs_quota_off(struct super_block *sb, int type, int remount);