From patchwork Thu Nov 16 05:08:32 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Al Viro X-Patchwork-Id: 13457617 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b="pb3S3QYa" Received: from zeniv.linux.org.uk (zeniv.linux.org.uk [IPv6:2a03:a000:7:0:5054:ff:fe1c:15ff]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E88FA18D for ; Wed, 15 Nov 2023 21:08:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:Content-Type:MIME-Version: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To:References; bh=J8lKgVlZ5n3FsA+3Ej0KqD1BNz8AscLDLHOWD8f4JQs=; b=pb3S3QYaZPw5GIT29aMPHXNxiY WNuF8KEjG8xM1T1R1X35ambbpFIHVBGeYnPnDxybM2ND6BqNpY1TSMAYBfie5BczihfCDysnleP4i 3rHazwbXGeCdK8mUlSypWrbMRrHtNHExA+yLJrhwEcb1hCHXdrcBJNTNf8eF9IXcj2+zajJ0hSNHY k0AEPW1V7xBO/z1FTZ5XmqCqTt2yedhnFjYlCkcLejAWtlzLlPbiGjCoaQSpsX3thYDCL7W8bIVZZ iSuj2fswbTA/lueuJUZs6azF2lITAgIBCmXVpW76ZMRLdODqLG2OoiHpV1mDasdnGubArBWzDYLqH o6p9yavA==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.96 #2 (Red Hat Linux)) id 1r3UcD-00GObK-03; Thu, 16 Nov 2023 05:08:33 +0000 Date: Thu, 16 Nov 2023 05:08:32 +0000 From: Al Viro To: linux-fsdevel@vger.kernel.org Cc: Kent Overstreet Subject: [PATCH 1/2] new helper: user_path_locked_at() Message-ID: <20231116050832.GX1957730@ZenIV> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline Sender: Al Viro (in #work.namei; used for bcachefs locking fix) From 74d016ecc1a7974664e98d1afbf649cd4e0e0423 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 15 Nov 2023 22:41:27 -0500 Subject: [PATCH 1/2] new helper: user_path_locked_at() Equivalent of kern_path_locked() taking dfd/userland name. User introduced in the next commit. Signed-off-by: Al Viro --- fs/namei.c | 16 +++++++++++++--- include/linux/namei.h | 1 + 2 files changed, 14 insertions(+), 3 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 71c13b2990b4..3ffbe268d52c 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2573,13 +2573,13 @@ static int filename_parentat(int dfd, struct filename *name, } /* does lookup, returns the object with parent locked */ -static struct dentry *__kern_path_locked(struct filename *name, struct path *path) +static struct dentry *__kern_path_locked(int dfd, struct filename *name, struct path *path) { struct dentry *d; struct qstr last; int type, error; - error = filename_parentat(AT_FDCWD, name, 0, path, &last, &type); + error = filename_parentat(dfd, name, 0, path, &last, &type); if (error) return ERR_PTR(error); if (unlikely(type != LAST_NORM)) { @@ -2598,12 +2598,22 @@ static struct dentry *__kern_path_locked(struct filename *name, struct path *pat struct dentry *kern_path_locked(const char *name, struct path *path) { struct filename *filename = getname_kernel(name); - struct dentry *res = __kern_path_locked(filename, path); + struct dentry *res = __kern_path_locked(AT_FDCWD, filename, path); putname(filename); return res; } +struct dentry *user_path_locked_at(int dfd, const char __user *name, struct path *path) +{ + struct filename *filename = getname(name); + struct dentry *res = __kern_path_locked(dfd, filename, path); + + putname(filename); + return res; +} +EXPORT_SYMBOL(user_path_locked_at); + int kern_path(const char *name, unsigned int flags, struct path *path) { struct filename *filename = getname_kernel(name); diff --git a/include/linux/namei.h b/include/linux/namei.h index 3100371b5e32..74e0cc14ebf8 100644 --- a/include/linux/namei.h +++ b/include/linux/namei.h @@ -66,6 +66,7 @@ extern struct dentry *kern_path_create(int, const char *, struct path *, unsigne extern struct dentry *user_path_create(int, const char __user *, struct path *, unsigned int); extern void done_path_create(struct path *, struct dentry *); extern struct dentry *kern_path_locked(const char *, struct path *); +extern struct dentry *user_path_locked_at(int , const char __user *, struct path *); int vfs_path_parent_lookup(struct filename *filename, unsigned int flags, struct path *parent, struct qstr *last, int *type, const struct path *root); From patchwork Thu Nov 16 05:09:47 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Al Viro X-Patchwork-Id: 13457618 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linux.org.uk header.i=@linux.org.uk header.b="DtR5Rfdy" Received: from zeniv.linux.org.uk (zeniv.linux.org.uk [IPv6:2a03:a000:7:0:5054:ff:fe1c:15ff]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E4272181 for ; Wed, 15 Nov 2023 21:09:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=linux.org.uk; s=zeniv-20220401; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=pL9x/qlF0URqv9qHjS2gr076oNYkpmLKhf5sgiepgPU=; b=DtR5RfdyX6xEOywNgMrPIuIF4f 9HbxkZ7VLf/4UaK6aFV8N+sWRSTTN9v2KMw0eKiS++WoKhXfRtu15u1xqyW4BSZqaZhHC7EHSzW6x qEYzM2d4KqGCC2y4mIHKfQ6ZX82Vn3EMuujBrNS9dxaJj0xFQ7lt51pO0i5+Z1HDVrP3OYd+VmxaO BMbAguasIN61dGNil+95aGsxwwiy/J3ixCfLRQVv+F6pNrkhaHYoq5efR+EcbXIM3uqxHgQ9TcJbT uWo2iEPKo99N1hAE09PJv89Mg+9kSIF5rV9k8hZsi3v3Nc3C3RlVWBdeLWLRlBxpPzi2TNn1kwSav GcpoYL3g==; Received: from viro by zeniv.linux.org.uk with local (Exim 4.96 #2 (Red Hat Linux)) id 1r3UdP-00GOck-1W; Thu, 16 Nov 2023 05:09:47 +0000 Date: Thu, 16 Nov 2023 05:09:47 +0000 From: Al Viro To: linux-fsdevel@vger.kernel.org Cc: Kent Overstreet Subject: [PATCH 2/2] bch2_ioctl_subvolume_destroy(): fix locking Message-ID: <20231116050947.GA3907833@ZenIV> References: <20231116050832.GX1957730@ZenIV> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20231116050832.GX1957730@ZenIV> Sender: Al Viro (#for-bcachefs, on top of #work.namei) From bbe6a7c899e7f265c5a6d01a178336a405e98ed6 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Tue, 14 Nov 2023 18:52:42 -0500 Subject: [PATCH 2/2] bch2_ioctl_subvolume_destroy(): fix locking make it use user_path_locked_at() to get the normal directory protection for modifications, as well as stable ->d_parent and ->d_name in victim Signed-off-by: Al Viro --- fs/bcachefs/fs-ioctl.c | 31 +++++++++++++++++-------------- 1 file changed, 17 insertions(+), 14 deletions(-) diff --git a/fs/bcachefs/fs-ioctl.c b/fs/bcachefs/fs-ioctl.c index 5a39bcb597a3..c5ab5a2dc9be 100644 --- a/fs/bcachefs/fs-ioctl.c +++ b/fs/bcachefs/fs-ioctl.c @@ -453,33 +453,36 @@ static long bch2_ioctl_subvolume_create(struct bch_fs *c, struct file *filp, static long bch2_ioctl_subvolume_destroy(struct bch_fs *c, struct file *filp, struct bch_ioctl_subvolume arg) { + const char __user *name = (void __user *)(unsigned long)arg.dst_ptr; struct path path; struct inode *dir; + struct dentry *victim; int ret = 0; if (arg.flags) return -EINVAL; - ret = user_path_at(arg.dirfd, - (const char __user *)(unsigned long)arg.dst_ptr, - LOOKUP_FOLLOW, &path); - if (ret) - return ret; + victim = user_path_locked_at(arg.dirfd, name, &path); + if (IS_ERR(victim)) + return PTR_ERR(victim); - if (path.dentry->d_sb->s_fs_info != c) { + if (victim->d_sb->s_fs_info != c) { ret = -EXDEV; goto err; } - - dir = path.dentry->d_parent->d_inode; - - ret = __bch2_unlink(dir, path.dentry, true); - if (ret) + if (!d_is_positive(victim)) { + ret = -ENOENT; goto err; - - fsnotify_rmdir(dir, path.dentry); - d_delete(path.dentry); + } + dir = d_inode(path.dentry); + ret = __bch2_unlink(dir, victim, true); + if (!ret) { + fsnotify_rmdir(dir, victim); + d_delete(victim); + } + inode_unlock(dir); err: + dput(victim); path_put(&path); return ret; }