[2/2] VFS: add common error checks to lookup_one_qstr_excl()

Message ID	20250207034040.3402438-3-neilb@suse.de (mailing list archive)
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Headers	show Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8A89F185B5F; Fri, 7 Feb 2025 03:41:28 +0000 (UTC) From: NeilBrown <neilb@suse.de> To: Christian Brauner <brauner@kernel.org>, Alexander Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.cz> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, "Rafael J. Wysocki" <rafael@kernel.org>, Danilo Krummrich <dakr@kernel.org>, Kent Overstreet <kent.overstreet@linux.dev>, Trond Myklebust <trondmy@kernel.org>, Anna Schumaker <anna@kernel.org>, Namjae Jeon <linkinjeon@kernel.org>, Steve French <sfrench@samba.org>, Sergey Senozhatsky <senozhatsky@chromium.org>, Tom Talpey <tom@talpey.com>, Paul Moore <paul@paul-moore.com>, Eric Paris <eparis@redhat.com>, linux-kernel@vger.kernel.org, linux-bcachefs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, audit@vger.kernel.org Subject: [PATCH 2/2] VFS: add common error checks to lookup_one_qstr_excl() Date: Fri, 7 Feb 2025 14:36:48 +1100 Message-ID: <20250207034040.3402438-3-neilb@suse.de> In-Reply-To: <20250207034040.3402438-1-neilb@suse.de> References: <20250207034040.3402438-1-neilb@suse.de> Precedence: bulk MIME-Version: 1.0 Content-Transfer-Encoding: 8bit default: False [-2.80 / 50.00]; BAYES_HAM(-3.00)[100.00%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_MISSING_CHARSET(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; TO_DN_SOME(0.00)[]; ARC_NA(0.00)[]; RCPT_COUNT_TWELVE(0.00)[21]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; R_RATELIMIT(0.00)[to_ip_from(RLmkit3uosw3w8fnkezs66f8sm),from(RLewrxuus8mos16izbn)]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo]; RCVD_TLS_ALL(0.00)[]
Series	VFS: minor improvements to a couple of interfaces \| expand [0/2] VFS: minor improvements to a couple of interfaces [1/2] VFS: change kern_path_locked() and user_path_locked_at() to never return negative dentry [2/2] VFS: add common error checks to lookup_one_qstr_excl()

diff --git a/fs/namei.c b/fs/namei.c index e3047db7b2b4..e0527f4b0586 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1665,6 +1665,8 @@ static struct dentry *lookup_dcache(const struct qstr *name, * dentries - as the matter of fact, this only gets called * when directory is guaranteed to have no in-lookup children * at all. + * Will return -ENOENT if name isn't found and LOOKUP_CREATE wasn't passed. + * Will return -EEXIST if name is found and LOOKUP_EXCL was passed. */ struct dentry *lookup_one_qstr_excl(const struct qstr *name, struct dentry *base, @@ -1675,7 +1677,7 @@ struct dentry *lookup_one_qstr_excl(const struct qstr *name, struct inode *dir = base->d_inode; if (dentry) - return dentry; + goto found; /* Don't create child dentry for a dead directory. */ if (unlikely(IS_DEADDIR(dir))) @@ -1690,6 +1692,15 @@ struct dentry *lookup_one_qstr_excl(const struct qstr *name, dput(dentry); dentry = old; } +found: + if (d_is_negative(dentry) && !(flags & LOOKUP_CREATE)) { + dput(dentry); + return ERR_PTR(-ENOENT); + } + if (d_is_positive(dentry) && (flags & LOOKUP_EXCL)) { + dput(dentry); + return ERR_PTR(-EEXIST); + } return dentry; } EXPORT_SYMBOL(lookup_one_qstr_excl); @@ -2736,10 +2747,6 @@ static struct dentry *__kern_path_locked(int dfd, struct filename *name, struct } inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); d = lookup_one_qstr_excl(&last, path->dentry, 0); - if (!IS_ERR(d) && d_is_negative(d)) { - dput(d); - d = ERR_PTR(-ENOENT); - } if (IS_ERR(d)) { inode_unlock(path->dentry->d_inode); path_put(path); @@ -4077,27 +4084,13 @@ static struct dentry *filename_create(int dfd, struct filename *name, * '/', and a directory wasn't requested. */ if (last.name[last.len] && !want_dir) - create_flags = 0; + create_flags &= ~LOOKUP_CREATE; inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); dentry = lookup_one_qstr_excl(&last, path->dentry, reval_flag | create_flags); if (IS_ERR(dentry)) goto unlock; - error = -EEXIST; - if (d_is_positive(dentry)) - goto fail; - - /* - * Special case - lookup gave negative, but... we had foo/bar/ - * From the vfs_mknod() POV we just have a negative dentry - - * all is fine. Let's be bastards - you had / on the end, you've - * been asking for (non-existent) directory. -ENOENT for you. - */ - if (unlikely(!create_flags)) { - error = -ENOENT; - goto fail; - } if (unlikely(err2)) { error = err2; goto fail; @@ -4444,10 +4437,6 @@ int do_rmdir(int dfd, struct filename *name) error = PTR_ERR(dentry); if (IS_ERR(dentry)) goto exit3; - if (!dentry->d_inode) { - error = -ENOENT; - goto exit4; - } error = security_path_rmdir(&path, dentry); if (error) goto exit4; @@ -4578,7 +4567,7 @@ int do_unlinkat(int dfd, struct filename *name) if (!IS_ERR(dentry)) { /* Why not before? Because we want correct error value */ - if (last.name[last.len] || d_is_negative(dentry)) + if (last.name[last.len]) goto slashes; inode = dentry->d_inode; ihold(inode); @@ -4612,9 +4601,7 @@ int do_unlinkat(int dfd, struct filename *name) return error; slashes: - if (d_is_negative(dentry)) - error = -ENOENT; - else if (d_is_dir(dentry)) + if (d_is_dir(dentry)) error = -EISDIR; else error = -ENOTDIR; @@ -5114,7 +5101,8 @@ int do_renameat2(int olddfd, struct filename *from, int newdfd, struct qstr old_last, new_last; int old_type, new_type; struct inode *delegated_inode = NULL; - unsigned int lookup_flags = 0, target_flags = LOOKUP_RENAME_TARGET; + unsigned int lookup_flags = 0, target_flags = + LOOKUP_RENAME_TARGET | LOOKUP_CREATE; bool should_retry = false; int error = -EINVAL; @@ -5127,6 +5115,8 @@ int do_renameat2(int olddfd, struct filename *from, int newdfd, if (flags & RENAME_EXCHANGE) target_flags = 0; + if (flags & RENAME_NOREPLACE) + target_flags |= LOOKUP_EXCL; retry: error = filename_parentat(olddfd, from, lookup_flags, &old_path, @@ -5168,23 +5158,12 @@ int do_renameat2(int olddfd, struct filename *from, int newdfd, error = PTR_ERR(old_dentry); if (IS_ERR(old_dentry)) goto exit3; - /* source must exist */ - error = -ENOENT; - if (d_is_negative(old_dentry)) - goto exit4; new_dentry = lookup_one_qstr_excl(&new_last, new_path.dentry, lookup_flags | target_flags); error = PTR_ERR(new_dentry); if (IS_ERR(new_dentry)) goto exit4; - error = -EEXIST; - if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) - goto exit5; if (flags & RENAME_EXCHANGE) { - error = -ENOENT; - if (d_is_negative(new_dentry)) - goto exit5; - if (!d_is_dir(new_dentry)) { error = -ENOTDIR; if (new_last.name[new_last.len]) diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 2b04038b0e40..56cf16a72334 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -1532,7 +1532,8 @@ static int nfs_is_exclusive_create(struct inode *dir, unsigned int flags) { if (NFS_PROTO(dir)->version == 2) return 0; - return flags & LOOKUP_EXCL; + return (flags & (LOOKUP_CREATE | LOOKUP_EXCL)) == + (LOOKUP_CREATE | LOOKUP_EXCL); } /* diff --git a/fs/smb/server/vfs.c b/fs/smb/server/vfs.c index 6890016e1923..fe29acef5872 100644 --- a/fs/smb/server/vfs.c +++ b/fs/smb/server/vfs.c @@ -113,11 +113,6 @@ static int ksmbd_vfs_path_lookup_locked(struct ksmbd_share_config *share_conf, if (IS_ERR(d)) goto err_out; - if (d_is_negative(d)) { - dput(d); - goto err_out; - } - path->dentry = d; path->mnt = mntget(parent_path->mnt); @@ -693,6 +688,7 @@ int ksmbd_vfs_rename(struct ksmbd_work *work, const struct path *old_path, struct ksmbd_file *parent_fp; int new_type; int err, lookup_flags = LOOKUP_NO_SYMLINKS; + int target_lookup_flags = LOOKUP_RENAME_TARGET; if (ksmbd_override_fsids(work)) return -ENOMEM; @@ -703,6 +699,14 @@ int ksmbd_vfs_rename(struct ksmbd_work *work, const struct path *old_path, goto revert_fsids; } + /* + * explicitly handle file overwrite case, for compatibility with + * filesystems that may not support rename flags (e.g: fuse) + */ + if (flags & RENAME_NOREPLACE) + target_lookup_flags |= LOOKUP_EXCL; + flags &= ~(RENAME_NOREPLACE); + retry: err = vfs_path_parent_lookup(to, lookup_flags | LOOKUP_BENEATH, &new_path, &new_last, &new_type, @@ -743,7 +747,7 @@ int ksmbd_vfs_rename(struct ksmbd_work *work, const struct path *old_path, } new_dentry = lookup_one_qstr_excl(&new_last, new_path.dentry, - lookup_flags | LOOKUP_RENAME_TARGET); + lookup_flags | target_lookup_flags); if (IS_ERR(new_dentry)) { err = PTR_ERR(new_dentry); goto out3; @@ -754,16 +758,6 @@ int ksmbd_vfs_rename(struct ksmbd_work *work, const struct path *old_path, goto out4; } - /* - * explicitly handle file overwrite case, for compatibility with - * filesystems that may not support rename flags (e.g: fuse) - */ - if ((flags & RENAME_NOREPLACE) && d_is_positive(new_dentry)) { - err = -EEXIST; - goto out4; - } - flags &= ~(RENAME_NOREPLACE); - if (old_child == trap) { err = -EINVAL; goto out4;

[2/2] VFS: add common error checks to lookup_one_qstr_excl()

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