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| author | Seunghun Lee <waydi1@gmail.com> | 2015-01-03 02:26:49 +0900 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@suse.cz> | 2015-01-08 14:47:21 +0100 |
| commit | 3cdf6fe91041b3afd6761f76254f7b6cbe8020fc (patch) | |
| tree | 5ec7e50d2280727e59da23dd6af59c12d3c009d2 /fs/overlayfs | |
| parent | a425c037f3dd8a56469158ab5f37beb46402d958 (diff) | |
| download | lwn-3cdf6fe91041b3afd6761f76254f7b6cbe8020fc.tar.gz lwn-3cdf6fe91041b3afd6761f76254f7b6cbe8020fc.zip | |
ovl: Prevent rw remount when it should be ro mount
Overlayfs should be mounted read-only when upper-fs is read-only or nonexistent.
But now it can be remounted read-write and this can cause kernel panic.
So we should prevent read-write remount when the above situation happens.
Signed-off-by: Seunghun Lee <waydi1@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Diffstat (limited to 'fs/overlayfs')
| -rw-r--r-- | fs/overlayfs/super.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 9e94f4acef1a..b90952f528b1 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -525,10 +525,22 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry) return 0; } +static int ovl_remount(struct super_block *sb, int *flags, char *data) +{ + struct ovl_fs *ufs = sb->s_fs_info; + + if (!(*flags & MS_RDONLY) && + (!ufs->upper_mnt || (ufs->upper_mnt->mnt_sb->s_flags & MS_RDONLY))) + return -EROFS; + + return 0; +} + static const struct super_operations ovl_super_operations = { .put_super = ovl_put_super, .statfs = ovl_statfs, .show_options = ovl_show_options, + .remount_fs = ovl_remount, }; enum { |