diff options
| -rw-r--r-- | fs/overlayfs/dir.c | 147 |
1 files changed, 79 insertions, 68 deletions
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index 8e8ede6a1217..0f01e005b915 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -581,47 +581,59 @@ out_cleanup_unlocked: goto out_dput; } -static const struct cred *ovl_setup_cred_for_create(struct dentry *dentry, - struct inode *inode, - umode_t mode, - const struct cred *old_cred) +static const struct cred *ovl_override_creator_creds(struct dentry *dentry, struct inode *inode, umode_t mode) { int err; - struct cred *override_cred; - override_cred = prepare_creds(); + if (WARN_ON_ONCE(current->cred != ovl_creds(dentry->d_sb))) + return ERR_PTR(-EINVAL); + + CLASS(prepare_creds, override_cred)(); if (!override_cred) return ERR_PTR(-ENOMEM); override_cred->fsuid = inode->i_uid; override_cred->fsgid = inode->i_gid; + err = security_dentry_create_files_as(dentry, mode, &dentry->d_name, - old_cred, override_cred); - if (err) { - put_cred(override_cred); + current->cred, override_cred); + if (err) return ERR_PTR(err); - } - /* - * Caller is going to match this with revert_creds() and drop - * referenec on the returned creds. - * We must be called with creator creds already, otherwise we risk - * leaking creds. - */ - old_cred = override_creds(override_cred); - WARN_ON_ONCE(old_cred != ovl_creds(dentry->d_sb)); + return override_creds(no_free_ptr(override_cred)); +} - return override_cred; +static void ovl_revert_creator_creds(const struct cred *old_cred) +{ + const struct cred *override_cred; + + override_cred = revert_creds(old_cred); + put_cred(override_cred); +} + +DEFINE_CLASS(ovl_override_creator_creds, + const struct cred *, + if (!IS_ERR_OR_NULL(_T)) ovl_revert_creator_creds(_T), + ovl_override_creator_creds(dentry, inode, mode), + struct dentry *dentry, struct inode *inode, umode_t mode) + +static int ovl_create_handle_whiteouts(struct dentry *dentry, + struct inode *inode, + struct ovl_cattr *attr) +{ + if (!ovl_dentry_is_whiteout(dentry)) + return ovl_create_upper(dentry, inode, attr); + + return ovl_create_over_whiteout(dentry, inode, attr); } static int ovl_create_or_link(struct dentry *dentry, struct inode *inode, struct ovl_cattr *attr, bool origin) { int err; - const struct cred *new_cred __free(put_cred) = NULL; struct dentry *parent = dentry->d_parent; - scoped_class(override_creds_ovl, old_cred, dentry->d_sb) { + with_ovl_creds(dentry->d_sb) { /* * When linking a file with copy up origin into a new parent, mark the * new parent dir "impure". @@ -632,29 +644,28 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode, return err; } - if (!attr->hardlink) { - /* - * In the creation cases(create, mkdir, mknod, symlink), - * ovl should transfer current's fs{u,g}id to underlying - * fs. Because underlying fs want to initialize its new - * inode owner using current's fs{u,g}id. And in this - * case, the @inode is a new inode that is initialized - * in inode_init_owner() to current's fs{u,g}id. So use - * the inode's i_{u,g}id to override the cred's fs{u,g}id. - * - * But in the other hardlink case, ovl_link() does not - * create a new inode, so just use the ovl mounter's - * fs{u,g}id. - */ - new_cred = ovl_setup_cred_for_create(dentry, inode, attr->mode, old_cred); - if (IS_ERR(new_cred)) - return PTR_ERR(new_cred); - } + /* + * In the creation cases(create, mkdir, mknod, symlink), + * ovl should transfer current's fs{u,g}id to underlying + * fs. Because underlying fs want to initialize its new + * inode owner using current's fs{u,g}id. And in this + * case, the @inode is a new inode that is initialized + * in inode_init_owner() to current's fs{u,g}id. So use + * the inode's i_{u,g}id to override the cred's fs{u,g}id. + * + * But in the other hardlink case, ovl_link() does not + * create a new inode, so just use the ovl mounter's + * fs{u,g}id. + */ - if (!ovl_dentry_is_whiteout(dentry)) - return ovl_create_upper(dentry, inode, attr); + if (attr->hardlink) + return ovl_create_handle_whiteouts(dentry, inode, attr); - return ovl_create_over_whiteout(dentry, inode, attr); + scoped_class(ovl_override_creator_creds, cred, dentry, inode, attr->mode) { + if (IS_ERR(cred)) + return PTR_ERR(cred); + return ovl_create_handle_whiteouts(dentry, inode, attr); + } } return err; } @@ -1345,7 +1356,6 @@ static int ovl_rename(struct mnt_idmap *idmap, struct inode *olddir, static int ovl_create_tmpfile(struct file *file, struct dentry *dentry, struct inode *inode, umode_t mode) { - const struct cred *new_cred __free(put_cred) = NULL; struct path realparentpath; struct file *realfile; struct ovl_file *of; @@ -1354,33 +1364,34 @@ static int ovl_create_tmpfile(struct file *file, struct dentry *dentry, int flags = file->f_flags | OVL_OPEN_FLAGS; int err; - scoped_class(override_creds_ovl, old_cred, dentry->d_sb) { - new_cred = ovl_setup_cred_for_create(dentry, inode, mode, old_cred); - if (IS_ERR(new_cred)) - return PTR_ERR(new_cred); - - ovl_path_upper(dentry->d_parent, &realparentpath); - realfile = backing_tmpfile_open(&file->f_path, flags, &realparentpath, - mode, current_cred()); - err = PTR_ERR_OR_ZERO(realfile); - pr_debug("tmpfile/open(%pd2, 0%o) = %i\n", realparentpath.dentry, mode, err); - if (err) - return err; + with_ovl_creds(dentry->d_sb) { + scoped_class(ovl_override_creator_creds, cred, dentry, inode, mode) { + if (IS_ERR(cred)) + return PTR_ERR(cred); + + ovl_path_upper(dentry->d_parent, &realparentpath); + realfile = backing_tmpfile_open(&file->f_path, flags, &realparentpath, + mode, current_cred()); + err = PTR_ERR_OR_ZERO(realfile); + pr_debug("tmpfile/open(%pd2, 0%o) = %i\n", realparentpath.dentry, mode, err); + if (err) + return err; - of = ovl_file_alloc(realfile); - if (!of) { - fput(realfile); - return -ENOMEM; - } + of = ovl_file_alloc(realfile); + if (!of) { + fput(realfile); + return -ENOMEM; + } - /* ovl_instantiate() consumes the newdentry reference on success */ - newdentry = dget(realfile->f_path.dentry); - err = ovl_instantiate(dentry, inode, newdentry, false, file); - if (!err) { - file->private_data = of; - } else { - dput(newdentry); - ovl_file_free(of); + /* ovl_instantiate() consumes the newdentry reference on success */ + newdentry = dget(realfile->f_path.dentry); + err = ovl_instantiate(dentry, inode, newdentry, false, file); + if (!err) { + file->private_data = of; + } else { + dput(newdentry); + ovl_file_free(of); + } } } return err; |