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ovl: improve mount helpers 

Move common checks into ovl_mount_dir() helper.

Create helper for looking up lower directories.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
This commit is contained in:
Miklos Szeredi 2014-12-13 00:59:49 +01:00
parent 3b7a9a249a
commit ab508822ca
1 changed files with 78 additions and 57 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

135
fs/overlayfs/super.c
View File

@ -669,24 +669,6 @@ static void ovl_unescape(char *s)
}
}
static int ovl_mount_dir(const char *name, struct path *path)
{
int err;
char *tmp = kstrdup(name, GFP_KERNEL);
if (!tmp)
return -ENOMEM;
ovl_unescape(tmp);
err = kern_path(tmp, LOOKUP_FOLLOW, path);
if (err) {
pr_err("overlayfs: failed to resolve '%s': %i\n", tmp, err);
err = -EINVAL;
}
kfree(tmp);
return err;
}
static bool ovl_is_allowed_fs_type(struct dentry *root)
{
const struct dentry_operations *dop = root->d_op;
@ -706,6 +688,71 @@ static bool ovl_is_allowed_fs_type(struct dentry *root)
return true;
}
static int ovl_mount_dir_noesc(const char *name, struct path *path)
{
int err;
err = kern_path(name, LOOKUP_FOLLOW, path);
if (err) {
pr_err("overlayfs: failed to resolve '%s': %i\n", name, err);
goto out;
}
err = -EINVAL;
if (!ovl_is_allowed_fs_type(path->dentry)) {
pr_err("overlayfs: filesystem on '%s' not supported\n", name);
goto out_put;
}
if (!S_ISDIR(path->dentry->d_inode->i_mode)) {
pr_err("overlayfs: '%s' not a directory\n", name);
goto out_put;
}
return 0;
out_put:
path_put(path);
out:
return err;
}
static int ovl_mount_dir(const char *name, struct path *path)
{
int err = -ENOMEM;
char *tmp = kstrdup(name, GFP_KERNEL);
if (tmp) {
ovl_unescape(tmp);
err = ovl_mount_dir_noesc(tmp, path);
kfree(tmp);
}
return err;
}
static int ovl_lower_dir(const char *name, struct path *path, long *namelen,
int *stack_depth)
{
int err;
struct kstatfs statfs;
err = ovl_mount_dir(name, path);
if (err)
goto out;
err = vfs_statfs(path, &statfs);
if (err) {
pr_err("overlayfs: statfs failed on '%s'\n", name);
goto out_put;
}
*namelen = max(*namelen, statfs.f_namelen);
*stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
return 0;
out_put:
path_put(path);
out:
return err;
}
/* Workdir should not be subdir of upperdir and vice versa */
static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
{
@ -726,7 +773,6 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
struct dentry *root_dentry;
struct ovl_entry *oe;
struct ovl_fs *ufs;
struct kstatfs statfs;
struct vfsmount *mnt;
unsigned int i;
int err;
@ -756,48 +802,23 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
if (err)
goto out_put_upperpath;
err = ovl_mount_dir(ufs->config.lowerdir, &lowerpath);
if (upperpath.mnt != workpath.mnt) {
pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
goto out_put_workpath;
}
if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) {
pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
goto out_put_workpath;
}
sb->s_stack_depth = upperpath.mnt->mnt_sb->s_stack_depth;
err = ovl_lower_dir(ufs->config.lowerdir, &lowerpath,
&ufs->lower_namelen, &sb->s_stack_depth);
if (err)
goto out_put_workpath;
err = -EINVAL;
if (!S_ISDIR(upperpath.dentry->d_inode->i_mode) ||
!S_ISDIR(lowerpath.dentry->d_inode->i_mode) ||
!S_ISDIR(workpath.dentry->d_inode->i_mode)) {
pr_err("overlayfs: upperdir or lowerdir or workdir not a directory\n");
goto out_put_lowerpath;
}
if (upperpath.mnt != workpath.mnt) {
pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
goto out_put_lowerpath;
}
if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) {
pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
goto out_put_lowerpath;
}
if (!ovl_is_allowed_fs_type(upperpath.dentry)) {
pr_err("overlayfs: filesystem of upperdir is not supported\n");
goto out_put_lowerpath;
}
if (!ovl_is_allowed_fs_type(lowerpath.dentry)) {
pr_err("overlayfs: filesystem of lowerdir is not supported\n");
goto out_put_lowerpath;
}
err = vfs_statfs(&lowerpath, &statfs);
if (err) {
pr_err("overlayfs: statfs failed on lowerpath\n");
goto out_put_lowerpath;
}
ufs->lower_namelen = statfs.f_namelen;
sb->s_stack_depth = max(upperpath.mnt->mnt_sb->s_stack_depth,
lowerpath.mnt->mnt_sb->s_stack_depth) + 1;
err = -EINVAL;
sb->s_stack_depth++;
if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
pr_err("overlayfs: maximum fs stacking depth exceeded\n");
goto out_put_lowerpath;