From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 62A89ECAAD3 for ; Fri, 9 Sep 2022 03:37:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229666AbiIIDhO (ORCPT ); Thu, 8 Sep 2022 23:37:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42924 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229576AbiIIDhM (ORCPT ); Thu, 8 Sep 2022 23:37:12 -0400 Received: from smtp-relay-canonical-1.canonical.com (smtp-relay-canonical-1.canonical.com [185.125.188.121]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 98E18F9FA9; Thu, 8 Sep 2022 20:37:09 -0700 (PDT) Received: from [192.168.192.83] (unknown [50.126.114.69]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-canonical-1.canonical.com (Postfix) with ESMTPSA id 573D93F3B3; Fri, 9 Sep 2022 03:37:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com; s=20210705; t=1662694628; bh=I9Pvh0sqIm2HlivSL7vW8JCwpG0/3MeBCV7NtQP/ma0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=vQVDOQDd1SV7LScurmRQZ6etJUrr0TWHngGyPpctl98uMpR8o71QwpbkeRIzIkezI D/imwHwua41DBDXVr103DdPEPQeECNvZbqbBVE2nxWg+ekGTCxsP3XPN1EuT+u5EHc twX7j9ESAAZlzn2rXnlf+YBxvd/gCjnSo2y7rEalPg0j6ri0RWdK99da2j8eUEArhh RhSNBD6My0i+jvw2JbODyk5RYnivazsSHI11JhCcXab7j47qFiFZHXuxiCwXwexuR5 76RwS+7iEvLnxnbSP24eKVf/YmCf1Ea0fuXedZmlsxPEIQEydi3pjPse0NNjzmqM+D b3SJ91ONzraXQ== Message-ID: <7518c623-c067-8a2e-5ae9-4bc8cb865d7b@canonical.com> Date: Thu, 8 Sep 2022 20:37:03 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH v6 1/5] security: create file_truncate hook from path_truncate hook Content-Language: en-US To: =?UTF-8?Q?G=c3=bcnther_Noack?= , linux-security-module@vger.kernel.org Cc: =?UTF-8?Q?Micka=c3=abl_Sala=c3=bcn?= , James Morris , Paul Moore , "Serge E . Hallyn" , linux-fsdevel@vger.kernel.org, Konstantin Meskhidze References: <20220908195805.128252-1-gnoack3000@gmail.com> <20220908195805.128252-2-gnoack3000@gmail.com> From: John Johansen Organization: Canonical In-Reply-To: <20220908195805.128252-2-gnoack3000@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: On 9/8/22 12:58, Günther Noack wrote: > Like path_truncate, the file_truncate hook also restricts file > truncation, but is called in the cases where truncation is attempted > on an already-opened file. > > This is required in a subsequent commit to handle ftruncate() > operations differently to truncate() operations. > > Signed-off-by: Günther Noack Acked-by: John Johansen > --- > fs/namei.c | 6 +++--- > fs/open.c | 4 ++-- > include/linux/lsm_hook_defs.h | 1 + > include/linux/security.h | 6 ++++++ > security/apparmor/lsm.c | 6 ++++++ > security/security.c | 5 +++++ > security/tomoyo/tomoyo.c | 13 +++++++++++++ > 7 files changed, 36 insertions(+), 5 deletions(-) > > diff --git a/fs/namei.c b/fs/namei.c > index 53b4bc094db2..52105873d1f8 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -53,8 +53,8 @@ > * The new code replaces the old recursive symlink resolution with > * an iterative one (in case of non-nested symlink chains). It does > * this with calls to _follow_link(). > - * As a side effect, dir_namei(), _namei() and follow_link() are now > - * replaced with a single function lookup_dentry() that can handle all > + * As a side effect, dir_namei(), _namei() and follow_link() are now > + * replaced with a single function lookup_dentry() that can handle all > * the special cases of the former code. > * > * With the new dcache, the pathname is stored at each inode, at least as > @@ -3211,7 +3211,7 @@ static int handle_truncate(struct user_namespace *mnt_userns, struct file *filp) > if (error) > return error; > > - error = security_path_truncate(path); > + error = security_file_truncate(filp); > if (!error) { > error = do_truncate(mnt_userns, path->dentry, 0, > ATTR_MTIME|ATTR_CTIME|ATTR_OPEN, > diff --git a/fs/open.c b/fs/open.c > index 8a813fa5ca56..0831433e493a 100644 > --- a/fs/open.c > +++ b/fs/open.c > @@ -188,7 +188,7 @@ long do_sys_ftruncate(unsigned int fd, loff_t length, int small) > if (IS_APPEND(file_inode(f.file))) > goto out_putf; > sb_start_write(inode->i_sb); > - error = security_path_truncate(&f.file->f_path); > + error = security_file_truncate(f.file); > if (!error) > error = do_truncate(file_mnt_user_ns(f.file), dentry, length, > ATTR_MTIME | ATTR_CTIME, f.file); > @@ -1271,7 +1271,7 @@ struct file *filp_open(const char *filename, int flags, umode_t mode) > { > struct filename *name = getname_kernel(filename); > struct file *file = ERR_CAST(name); > - > + > if (!IS_ERR(name)) { > file = file_open_name(name, flags, mode); > putname(name); > diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h > index 60fff133c0b1..dee35ab253ba 100644 > --- a/include/linux/lsm_hook_defs.h > +++ b/include/linux/lsm_hook_defs.h > @@ -177,6 +177,7 @@ LSM_HOOK(int, 0, file_send_sigiotask, struct task_struct *tsk, > struct fown_struct *fown, int sig) > LSM_HOOK(int, 0, file_receive, struct file *file) > LSM_HOOK(int, 0, file_open, struct file *file) > +LSM_HOOK(int, 0, file_truncate, struct file *file) > LSM_HOOK(int, 0, task_alloc, struct task_struct *task, > unsigned long clone_flags) > LSM_HOOK(void, LSM_RET_VOID, task_free, struct task_struct *task) > diff --git a/include/linux/security.h b/include/linux/security.h > index 7bd0c490703d..f80b23382dd9 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -394,6 +394,7 @@ int security_file_send_sigiotask(struct task_struct *tsk, > struct fown_struct *fown, int sig); > int security_file_receive(struct file *file); > int security_file_open(struct file *file); > +int security_file_truncate(struct file *file); > int security_task_alloc(struct task_struct *task, unsigned long clone_flags); > void security_task_free(struct task_struct *task); > int security_cred_alloc_blank(struct cred *cred, gfp_t gfp); > @@ -1011,6 +1012,11 @@ static inline int security_file_open(struct file *file) > return 0; > } > > +static inline int security_file_truncate(struct file *file) > +{ > + return 0; > +} > + > static inline int security_task_alloc(struct task_struct *task, > unsigned long clone_flags) > { > diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c > index e29cade7b662..98ecb7f221b8 100644 > --- a/security/apparmor/lsm.c > +++ b/security/apparmor/lsm.c > @@ -329,6 +329,11 @@ static int apparmor_path_truncate(const struct path *path) > return common_perm_cond(OP_TRUNC, path, MAY_WRITE | AA_MAY_SETATTR); > } > > +static int apparmor_file_truncate(struct file *file) > +{ > + return apparmor_path_truncate(&file->f_path); > +} > + > static int apparmor_path_symlink(const struct path *dir, struct dentry *dentry, > const char *old_name) > { > @@ -1232,6 +1237,7 @@ static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = { > LSM_HOOK_INIT(mmap_file, apparmor_mmap_file), > LSM_HOOK_INIT(file_mprotect, apparmor_file_mprotect), > LSM_HOOK_INIT(file_lock, apparmor_file_lock), > + LSM_HOOK_INIT(file_truncate, apparmor_file_truncate), > > LSM_HOOK_INIT(getprocattr, apparmor_getprocattr), > LSM_HOOK_INIT(setprocattr, apparmor_setprocattr), > diff --git a/security/security.c b/security/security.c > index 4b95de24bc8d..e491120c48ba 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -1210,6 +1210,11 @@ int security_path_truncate(const struct path *path) > return call_int_hook(path_truncate, 0, path); > } > > +int security_file_truncate(struct file *file) > +{ > + return call_int_hook(file_truncate, 0, file); > +} > + > int security_path_chmod(const struct path *path, umode_t mode) > { > if (unlikely(IS_PRIVATE(d_backing_inode(path->dentry)))) > diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c > index 71e82d855ebf..af04a7b7eb28 100644 > --- a/security/tomoyo/tomoyo.c > +++ b/security/tomoyo/tomoyo.c > @@ -134,6 +134,18 @@ static int tomoyo_path_truncate(const struct path *path) > return tomoyo_path_perm(TOMOYO_TYPE_TRUNCATE, path, NULL); > } > > +/** > + * tomoyo_file_truncate - Target for security_file_truncate(). > + * > + * @file: Pointer to "struct file". > + * > + * Returns 0 on success, negative value otherwise. > + */ > +static int tomoyo_file_truncate(struct file *file) > +{ > + return tomoyo_path_truncate(&file->f_path); > +} > + > /** > * tomoyo_path_unlink - Target for security_path_unlink(). > * > @@ -545,6 +557,7 @@ static struct security_hook_list tomoyo_hooks[] __lsm_ro_after_init = { > LSM_HOOK_INIT(bprm_check_security, tomoyo_bprm_check_security), > LSM_HOOK_INIT(file_fcntl, tomoyo_file_fcntl), > LSM_HOOK_INIT(file_open, tomoyo_file_open), > + LSM_HOOK_INIT(file_truncate, tomoyo_file_truncate), > LSM_HOOK_INIT(path_truncate, tomoyo_path_truncate), > LSM_HOOK_INIT(path_unlink, tomoyo_path_unlink), > LSM_HOOK_INIT(path_mkdir, tomoyo_path_mkdir),