From patchwork Wed Jul 7 12:27:38 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dmitry Kadashev X-Patchwork-Id: 12362511 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8BE9C11F66 for ; Wed, 7 Jul 2021 12:28:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BE19C61C82 for ; Wed, 7 Jul 2021 12:28:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231582AbhGGMap (ORCPT ); Wed, 7 Jul 2021 08:30:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41394 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231553AbhGGMan (ORCPT ); Wed, 7 Jul 2021 08:30:43 -0400 Received: from mail-ej1-x62f.google.com (mail-ej1-x62f.google.com [IPv6:2a00:1450:4864:20::62f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 010F5C061574; Wed, 7 Jul 2021 05:28:03 -0700 (PDT) Received: by mail-ej1-x62f.google.com with SMTP id c17so2929860ejk.13; Wed, 07 Jul 2021 05:28:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=xqr2s+A/IvkPLe4a4IGu4i1RJV8tZqdSAJM7YR4tQUc=; b=E1ztIUDfdyRTFastwhcHNO7JBecdsAi6djWLhBjjyaO5czIFfIaAf4YT02lNrCkzUR CeVyoj7sabIeAh7mtcbZZ4bbGimo0jqW7JOdrsLKASahrD1gHG4VR6gXLqy6BNm6CuV6 NGDoXpb8ghleIWGC3QLRNiHO7qfWacpk12DnCgzReyq5gVH1oRzmxJe1Bjk+5kXzvqIa JFAPnmSL56B3etz57MD+DMwH1mBIMcLefVl/3HKoKn2WQcP/4bjVSXSA5FZR+dLDdxPq EmLwin6T9+4zAF59HX3SX5bfLDeQPY/IkgrFmjlth5uczzsu6Nkn4lJUyywCapO/BMnM VCGw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=xqr2s+A/IvkPLe4a4IGu4i1RJV8tZqdSAJM7YR4tQUc=; b=C33DIKFmmC2TCJl6peYTn1Yle/WQBC8bgY1BgCeaadnNI0wGR8YaYxhuK/FxHesUaE LSwHHgK6hKdAd+kETB8w0P0n4uam93YXKgkB7hutTObR+QTmNwTEpJbQXMnX7B9X9BOP HKT8Pn/fqzBQPNAJAGJ1c4MJz1CWnt3cd2a/h20J7+U/GQ2cON0hek4+frOhgJOeQwZZ Pn3bmNaLTFoDrEpXN7WJL4wWsSO2r/CAK431E52WuvOrbWShwHXXOGQE79+RJ82nP+Zi IASDu8XQX8lYRpebm4wXCV6z3rodM54UjRM/Z9Fi9HclfHIZb/MKGWA19RFZX6wDpf8x JPMQ== X-Gm-Message-State: AOAM530TQ3/kf7D01YVCPHcvwqPshN1PL4wF6Mey3snOqoMWRcDdFU80 Fo8c60K552O0HN5/LBU1RVM= X-Google-Smtp-Source: ABdhPJytkHAOdBIA1aY1O6F8g6jYJzmhlw3F5jB6QivL4Dml4/vR1+M8LTHquaQRcGi4iVibacFB4w== X-Received: by 2002:a17:906:c208:: with SMTP id d8mr23850339ejz.67.1625660881618; Wed, 07 Jul 2021 05:28:01 -0700 (PDT) Received: from carbon.v ([108.61.166.58]) by smtp.googlemail.com with ESMTPSA id ze15sm7019821ejb.79.2021.07.07.05.28.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Jul 2021 05:28:01 -0700 (PDT) From: Dmitry Kadashev To: Jens Axboe , Alexander Viro , Christian Brauner , Linus Torvalds Cc: Pavel Begunkov , linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org, Dmitry Kadashev Subject: [PATCH v8 02/11] namei: change filename_parentat() calling conventions Date: Wed, 7 Jul 2021 19:27:38 +0700 Message-Id: <20210707122747.3292388-3-dkadashev@gmail.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210707122747.3292388-1-dkadashev@gmail.com> References: <20210707122747.3292388-1-dkadashev@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Since commit 5c31b6cedb675 ("namei: saner calling conventions for filename_parentat()") filename_parentat() had the following behavior WRT the passed in struct filename *: * On error the name is consumed (putname() is called on it); * On success the name is returned back as the return value; Now there is a need for filename_create() and filename_lookup() variants that do not consume the passed filename, and following the same "consume the name only on error" semantics is proven to be hard to reason about and result in confusing code. Hence this preparation change splits filename_parentat() into two: one that always consumes the name and another that never consumes the name. This will allow to implement two filename_create() variants in the same way, and is a consistent and hopefully easier to reason about approach. Link: https://lore.kernel.org/io-uring/CAOKbgA7MiqZAq3t-HDCpSGUFfco4hMA9ArAE-74fTpU+EkvKPw@mail.gmail.com/ Cc: Linus Torvalds Cc: Al Viro Cc: Christian Brauner Signed-off-by: Dmitry Kadashev --- fs/namei.c | 108 ++++++++++++++++++++++++++--------------------------- 1 file changed, 53 insertions(+), 55 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 70caf4ef1134..2995b3695724 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2485,7 +2485,7 @@ static int path_parentat(struct nameidata *nd, unsigned flags, return err; } -static struct filename *filename_parentat(int dfd, struct filename *name, +static int __filename_parentat(int dfd, struct filename *name, unsigned int flags, struct path *parent, struct qstr *last, int *type) { @@ -2493,7 +2493,7 @@ static struct filename *filename_parentat(int dfd, struct filename *name, struct nameidata nd; if (IS_ERR(name)) - return name; + return PTR_ERR(name); set_nameidata(&nd, dfd, name); retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); if (unlikely(retval == -ECHILD)) @@ -2504,29 +2504,34 @@ static struct filename *filename_parentat(int dfd, struct filename *name, *last = nd.last; *type = nd.last_type; audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); - } else { - putname(name); - name = ERR_PTR(retval); } restore_nameidata(); - return name; + return retval; +} + +static int filename_parentat(int dfd, struct filename *name, + unsigned int flags, struct path *parent, + struct qstr *last, int *type) +{ + int retval = __filename_parentat(dfd, name, flags, parent, last, type); + + putname(name); + return retval; } /* does lookup, returns the object with parent locked */ struct dentry *kern_path_locked(const char *name, struct path *path) { - struct filename *filename; struct dentry *d; struct qstr last; - int type; + int type, error; - filename = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, + error = filename_parentat(AT_FDCWD, getname_kernel(name), 0, path, &last, &type); - if (IS_ERR(filename)) - return ERR_CAST(filename); + if (error) + return ERR_PTR(error); if (unlikely(type != LAST_NORM)) { path_put(path); - putname(filename); return ERR_PTR(-EINVAL); } inode_lock_nested(path->dentry->d_inode, I_MUTEX_PARENT); @@ -2535,7 +2540,6 @@ struct dentry *kern_path_locked(const char *name, struct path *path) inode_unlock(path->dentry->d_inode); path_put(path); } - putname(filename); return d; } @@ -3575,9 +3579,9 @@ static struct dentry *filename_create(int dfd, struct filename *name, */ lookup_flags &= LOOKUP_REVAL; - name = filename_parentat(dfd, name, lookup_flags, path, &last, &type); - if (IS_ERR(name)) - return ERR_CAST(name); + error = filename_parentat(dfd, name, lookup_flags, path, &last, &type); + if (error) + return ERR_PTR(error); /* * Yucky last component or no last component at all? @@ -3615,7 +3619,6 @@ static struct dentry *filename_create(int dfd, struct filename *name, error = err2; goto fail; } - putname(name); return dentry; fail: dput(dentry); @@ -3626,7 +3629,6 @@ static struct dentry *filename_create(int dfd, struct filename *name, mnt_drop_write(path->mnt); out: path_put(path); - putname(name); return dentry; } @@ -3917,59 +3919,59 @@ EXPORT_SYMBOL(vfs_rmdir); long do_rmdir(int dfd, struct filename *name) { struct user_namespace *mnt_userns; - int error = 0; + int error; struct dentry *dentry; struct path path; struct qstr last; int type; unsigned int lookup_flags = 0; retry: - name = filename_parentat(dfd, name, lookup_flags, - &path, &last, &type); - if (IS_ERR(name)) - return PTR_ERR(name); + error = __filename_parentat(dfd, name, lookup_flags, &path, &last, &type); + if (error) + goto exit1; switch (type) { case LAST_DOTDOT: error = -ENOTEMPTY; - goto exit1; + goto exit2; case LAST_DOT: error = -EINVAL; - goto exit1; + goto exit2; case LAST_ROOT: error = -EBUSY; - goto exit1; + goto exit2; } error = mnt_want_write(path.mnt); if (error) - goto exit1; + goto exit2; inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); dentry = __lookup_hash(&last, path.dentry, lookup_flags); error = PTR_ERR(dentry); if (IS_ERR(dentry)) - goto exit2; + goto exit3; if (!dentry->d_inode) { error = -ENOENT; - goto exit3; + goto exit4; } error = security_path_rmdir(&path, dentry); if (error) - goto exit3; + goto exit4; mnt_userns = mnt_user_ns(path.mnt); error = vfs_rmdir(mnt_userns, path.dentry->d_inode, dentry); -exit3: +exit4: dput(dentry); -exit2: +exit3: inode_unlock(path.dentry->d_inode); mnt_drop_write(path.mnt); -exit1: +exit2: path_put(&path); if (retry_estale(error, lookup_flags)) { lookup_flags |= LOOKUP_REVAL; goto retry; } +exit1: putname(name); return error; } @@ -4063,17 +4065,17 @@ long do_unlinkat(int dfd, struct filename *name) struct inode *delegated_inode = NULL; unsigned int lookup_flags = 0; retry: - name = filename_parentat(dfd, name, lookup_flags, &path, &last, &type); - if (IS_ERR(name)) - return PTR_ERR(name); + error = __filename_parentat(dfd, name, lookup_flags, &path, &last, &type); + if (error) + goto exit1; error = -EISDIR; if (type != LAST_NORM) - goto exit1; + goto exit2; error = mnt_want_write(path.mnt); if (error) - goto exit1; + goto exit2; retry_deleg: inode_lock_nested(path.dentry->d_inode, I_MUTEX_PARENT); dentry = __lookup_hash(&last, path.dentry, lookup_flags); @@ -4090,11 +4092,11 @@ long do_unlinkat(int dfd, struct filename *name) ihold(inode); error = security_path_unlink(&path, dentry); if (error) - goto exit2; + goto exit3; mnt_userns = mnt_user_ns(path.mnt); error = vfs_unlink(mnt_userns, path.dentry->d_inode, dentry, &delegated_inode); -exit2: +exit3: dput(dentry); } inode_unlock(path.dentry->d_inode); @@ -4107,13 +4109,14 @@ long do_unlinkat(int dfd, struct filename *name) goto retry_deleg; } mnt_drop_write(path.mnt); -exit1: +exit2: path_put(&path); if (retry_estale(error, lookup_flags)) { lookup_flags |= LOOKUP_REVAL; inode = NULL; goto retry; } +exit1: putname(name); return error; @@ -4124,7 +4127,7 @@ long do_unlinkat(int dfd, struct filename *name) error = -EISDIR; else error = -ENOTDIR; - goto exit2; + goto exit3; } SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag) @@ -4595,29 +4598,25 @@ int do_renameat2(int olddfd, struct filename *from, int newdfd, int error = -EINVAL; if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) - goto put_both; + goto put_names; if ((flags & (RENAME_NOREPLACE | RENAME_WHITEOUT)) && (flags & RENAME_EXCHANGE)) - goto put_both; + goto put_names; if (flags & RENAME_EXCHANGE) target_flags = 0; retry: - from = filename_parentat(olddfd, from, lookup_flags, &old_path, + error = __filename_parentat(olddfd, from, lookup_flags, &old_path, &old_last, &old_type); - if (IS_ERR(from)) { - error = PTR_ERR(from); - goto put_new; - } + if (error) + goto put_names; - to = filename_parentat(newdfd, to, lookup_flags, &new_path, &new_last, + error = __filename_parentat(newdfd, to, lookup_flags, &new_path, &new_last, &new_type); - if (IS_ERR(to)) { - error = PTR_ERR(to); + if (error) goto exit1; - } error = -EXDEV; if (old_path.mnt != new_path.mnt) @@ -4720,9 +4719,8 @@ int do_renameat2(int olddfd, struct filename *from, int newdfd, lookup_flags |= LOOKUP_REVAL; goto retry; } -put_both: +put_names: putname(from); -put_new: putname(to); return error; }