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https://github.com/torvalds/linux
synced 2024-09-06 09:51:23 +00:00
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:
parent
3b7a9a249a
commit
ab508822ca
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@ -669,24 +669,6 @@ static void ovl_unescape(char *s)
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}
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}
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static int ovl_mount_dir(const char *name, struct path *path)
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{
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int err;
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char *tmp = kstrdup(name, GFP_KERNEL);
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if (!tmp)
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return -ENOMEM;
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ovl_unescape(tmp);
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err = kern_path(tmp, LOOKUP_FOLLOW, path);
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if (err) {
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pr_err("overlayfs: failed to resolve '%s': %i\n", tmp, err);
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err = -EINVAL;
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}
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kfree(tmp);
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return err;
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}
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static bool ovl_is_allowed_fs_type(struct dentry *root)
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{
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const struct dentry_operations *dop = root->d_op;
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@ -706,6 +688,71 @@ static bool ovl_is_allowed_fs_type(struct dentry *root)
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return true;
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}
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static int ovl_mount_dir_noesc(const char *name, struct path *path)
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{
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int err;
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err = kern_path(name, LOOKUP_FOLLOW, path);
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if (err) {
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pr_err("overlayfs: failed to resolve '%s': %i\n", name, err);
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goto out;
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}
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err = -EINVAL;
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if (!ovl_is_allowed_fs_type(path->dentry)) {
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pr_err("overlayfs: filesystem on '%s' not supported\n", name);
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goto out_put;
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}
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if (!S_ISDIR(path->dentry->d_inode->i_mode)) {
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pr_err("overlayfs: '%s' not a directory\n", name);
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goto out_put;
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}
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return 0;
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out_put:
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path_put(path);
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out:
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return err;
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}
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static int ovl_mount_dir(const char *name, struct path *path)
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{
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int err = -ENOMEM;
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char *tmp = kstrdup(name, GFP_KERNEL);
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if (tmp) {
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ovl_unescape(tmp);
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err = ovl_mount_dir_noesc(tmp, path);
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kfree(tmp);
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}
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return err;
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}
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static int ovl_lower_dir(const char *name, struct path *path, long *namelen,
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int *stack_depth)
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{
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int err;
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struct kstatfs statfs;
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err = ovl_mount_dir(name, path);
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if (err)
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goto out;
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err = vfs_statfs(path, &statfs);
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if (err) {
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pr_err("overlayfs: statfs failed on '%s'\n", name);
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goto out_put;
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}
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*namelen = max(*namelen, statfs.f_namelen);
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*stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
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return 0;
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out_put:
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path_put(path);
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out:
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return err;
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}
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/* Workdir should not be subdir of upperdir and vice versa */
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static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
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{
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@ -726,7 +773,6 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
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struct dentry *root_dentry;
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struct ovl_entry *oe;
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struct ovl_fs *ufs;
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struct kstatfs statfs;
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struct vfsmount *mnt;
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unsigned int i;
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int err;
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@ -756,48 +802,23 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
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if (err)
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goto out_put_upperpath;
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err = ovl_mount_dir(ufs->config.lowerdir, &lowerpath);
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if (upperpath.mnt != workpath.mnt) {
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pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
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goto out_put_workpath;
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}
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if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) {
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pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
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goto out_put_workpath;
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}
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sb->s_stack_depth = upperpath.mnt->mnt_sb->s_stack_depth;
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err = ovl_lower_dir(ufs->config.lowerdir, &lowerpath,
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&ufs->lower_namelen, &sb->s_stack_depth);
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if (err)
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goto out_put_workpath;
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err = -EINVAL;
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if (!S_ISDIR(upperpath.dentry->d_inode->i_mode) ||
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!S_ISDIR(lowerpath.dentry->d_inode->i_mode) ||
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!S_ISDIR(workpath.dentry->d_inode->i_mode)) {
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pr_err("overlayfs: upperdir or lowerdir or workdir not a directory\n");
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goto out_put_lowerpath;
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}
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if (upperpath.mnt != workpath.mnt) {
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pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
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goto out_put_lowerpath;
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}
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if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) {
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pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
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goto out_put_lowerpath;
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}
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if (!ovl_is_allowed_fs_type(upperpath.dentry)) {
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pr_err("overlayfs: filesystem of upperdir is not supported\n");
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goto out_put_lowerpath;
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}
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if (!ovl_is_allowed_fs_type(lowerpath.dentry)) {
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pr_err("overlayfs: filesystem of lowerdir is not supported\n");
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goto out_put_lowerpath;
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}
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err = vfs_statfs(&lowerpath, &statfs);
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if (err) {
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pr_err("overlayfs: statfs failed on lowerpath\n");
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goto out_put_lowerpath;
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}
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ufs->lower_namelen = statfs.f_namelen;
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sb->s_stack_depth = max(upperpath.mnt->mnt_sb->s_stack_depth,
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lowerpath.mnt->mnt_sb->s_stack_depth) + 1;
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err = -EINVAL;
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sb->s_stack_depth++;
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if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
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pr_err("overlayfs: maximum fs stacking depth exceeded\n");
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goto out_put_lowerpath;
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