From patchwork Wed Nov 2 17:10:23 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tetsuo Handa X-Patchwork-Id: 13028660 X-Patchwork-Delegate: paul@paul-moore.com 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 5F20BC43217 for ; Wed, 2 Nov 2022 17:12:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229880AbiKBRMT (ORCPT ); Wed, 2 Nov 2022 13:12:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37054 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231624AbiKBRLi (ORCPT ); Wed, 2 Nov 2022 13:11:38 -0400 Received: from www262.sakura.ne.jp (www262.sakura.ne.jp [202.181.97.72]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D683C186FE for ; Wed, 2 Nov 2022 10:11:35 -0700 (PDT) Received: from fsav311.sakura.ne.jp (fsav311.sakura.ne.jp [153.120.85.142]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 2A2HAvah021893; Thu, 3 Nov 2022 02:10:57 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav311.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav311.sakura.ne.jp); Thu, 03 Nov 2022 02:10:57 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav311.sakura.ne.jp) Received: from localhost.localdomain (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 2A2HAnkJ021849 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Thu, 3 Nov 2022 02:10:56 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) From: Tetsuo Handa To: linux-security-module@vger.kernel.org, Casey Schaufler , Paul Moore , John Johansen , Kees Cook Cc: Tetsuo Handa Subject: [PATCH 08/10] CaitSith: Add pathname calculation functions. Date: Thu, 3 Nov 2022 02:10:23 +0900 Message-Id: <20221102171025.126961-8-penguin-kernel@I-love.SAKURA.ne.jp> X-Mailer: git-send-email 2.18.4 In-Reply-To: <20221102171025.126961-1-penguin-kernel@I-love.SAKURA.ne.jp> References: <20221102171025.126961-1-penguin-kernel@I-love.SAKURA.ne.jp> Precedence: bulk List-ID: This file implements similar functions provided by security/tomoyo/realpath.c file. Signed-off-by: Tetsuo Handa --- security/caitsith/realpath.c | 415 +++++++++++++++++++++++++++++++++++ 1 file changed, 415 insertions(+) create mode 100644 security/caitsith/realpath.c diff --git a/security/caitsith/realpath.c b/security/caitsith/realpath.c new file mode 100644 index 000000000000..ed6b1407a54d --- /dev/null +++ b/security/caitsith/realpath.c @@ -0,0 +1,415 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * realpath.c + * + * Copyright (C) 2005-2012 NTT DATA CORPORATION + * + * Version: 0.2.10 2021/06/06 + */ + +#include "caitsith.h" + +#include + +/***** SECTION1: Constants definition *****/ + +/***** SECTION2: Structure definition *****/ + +/***** SECTION3: Prototype definition section *****/ + +static char *cs_get_absolute_path(const struct path *path, char * const buffer, + const int buflen); +static char *cs_get_dentry_path(struct dentry *dentry, char * const buffer, + const int buflen); +static char *cs_get_local_path(struct dentry *dentry, char * const buffer, + const int buflen); +static int cs_const_part_length(const char *filename); + +/***** SECTION4: Standalone functions section *****/ + +/** + * cs_realpath_lock - Take locks for __d_path(). + * + * Returns nothing. + */ +static inline void cs_realpath_lock(void) +{ + /* dcache_lock is locked by __d_path(). */ + /* vfsmount_lock is locked by __d_path(). */ +} + +/** + * cs_realpath_unlock - Release locks for __d_path(). + * + * Returns nothing. + */ +static inline void cs_realpath_unlock(void) +{ + /* vfsmount_lock is unlocked by __d_path(). */ + /* dcache_lock is unlocked by __d_path(). */ +} + +/***** SECTION5: Variables definition section *****/ + +/***** SECTION6: Dependent functions section *****/ + +/** + * cs_get_absolute_path - Get the path of a dentry but ignores chroot'ed root. + * + * @path: Pointer to "struct path". + * @buffer: Pointer to buffer to return value in. + * @buflen: Sizeof @buffer. + * + * Returns the buffer on success, an error code otherwise. + * + * Caller holds the dcache_lock and vfsmount_lock. + * Based on __d_path() in fs/dcache.c + */ +static char *cs_get_absolute_path(const struct path *path, char * const buffer, + const int buflen) +{ + if (buflen < 256) + return ERR_PTR(-ENOMEM); + return d_absolute_path(path, buffer, buflen - 1); +} + +/** + * cs_get_dentry_path - Get the path of a dentry. + * + * @dentry: Pointer to "struct dentry". + * @buffer: Pointer to buffer to return value in. + * @buflen: Sizeof @buffer. + * + * Returns the buffer on success, an error code otherwise. + * + * Based on dentry_path() in fs/dcache.c + */ +static char *cs_get_dentry_path(struct dentry *dentry, char * const buffer, + const int buflen) +{ + if (buflen < 256) + return ERR_PTR(-ENOMEM); + /* rename_lock is locked/unlocked by dentry_path_raw(). */ + return dentry_path_raw(dentry, buffer, buflen - 1); +} + +/** + * cs_get_local_path - Get the path of a dentry. + * + * @dentry: Pointer to "struct dentry". + * @buffer: Pointer to buffer to return value in. + * @buflen: Sizeof @buffer. + * + * Returns the buffer on success, an error code otherwise. + */ +static char *cs_get_local_path(struct dentry *dentry, char * const buffer, + const int buflen) +{ + struct super_block *sb = dentry->d_sb; + char *pos = cs_get_dentry_path(dentry, buffer, buflen); + + if (IS_ERR(pos)) + return pos; + /* Convert from $PID to self if $PID is current thread. */ + if (sb->s_magic == PROC_SUPER_MAGIC && *pos == '/') { + char *ep; + const pid_t pid = (pid_t) simple_strtoul(pos + 1, &ep, 10); + + if (*ep == '/' && pid && pid == + task_tgid_nr_ns(current, proc_pid_ns(sb))) { + pos = ep - 5; + if (pos < buffer) + goto out; + memmove(pos, "/self", 5); + } + goto prepend_filesystem_name; + } + /* Use filesystem name for unnamed devices. */ + if (!MAJOR(sb->s_dev)) + goto prepend_filesystem_name; + { + struct inode *inode = d_backing_inode(sb->s_root); + + /* + * Use filesystem name if filesystems does not support rename() + * operation. + */ + if (!inode->i_op->rename) + goto prepend_filesystem_name; + } + /* Prepend device name. */ + { + char name[64]; + int name_len; + const dev_t dev = sb->s_dev; + + name[sizeof(name) - 1] = '\0'; + snprintf(name, sizeof(name) - 1, "dev(%u,%u):", MAJOR(dev), + MINOR(dev)); + name_len = strlen(name); + pos -= name_len; + if (pos < buffer) + goto out; + memmove(pos, name, name_len); + return pos; + } + /* Prepend filesystem name. */ +prepend_filesystem_name: + { + const char *name = sb->s_type->name; + const int name_len = strlen(name); + + pos -= name_len + 1; + if (pos < buffer) + goto out; + memmove(pos, name, name_len); + pos[name_len] = ':'; + } + return pos; +out: + return ERR_PTR(-ENOMEM); +} + +/** + * cs_realpath - Returns realpath(3) of the given pathname but ignores chroot'ed root. + * + * @path: Pointer to "struct path". + * + * Returns the realpath of the given @path on success, NULL otherwise. + * + * This function uses kzalloc(), so caller must kfree() if this function + * didn't return NULL. + */ +char *cs_realpath(const struct path *path) +{ + char *buf = NULL; + char *name = NULL; + unsigned int buf_len = PAGE_SIZE / 2; + struct dentry *dentry = path->dentry; + struct super_block *sb; + + if (!dentry) + return NULL; + sb = dentry->d_sb; + while (1) { + char *pos; + struct inode *inode; + + buf_len <<= 1; + kfree(buf); + buf = kmalloc(buf_len, GFP_NOFS); + if (!buf) + break; + /* To make sure that pos is '\0' terminated. */ + buf[buf_len - 1] = '\0'; + /* For "pipe:[\$]" and "socket:[\$]". */ + if (dentry->d_op && dentry->d_op->d_dname) { + pos = dentry->d_op->d_dname(dentry, buf, buf_len - 1); + goto encode; + } + inode = d_backing_inode(sb->s_root); + /* + * Use local name for "filesystems without rename() operation + * and device file" or "path without vfsmount" or "absolute + * name is unavailable" cases. + */ + if (!path->mnt || + (!inode->i_op->rename && + !(sb->s_type->fs_flags & FS_REQUIRES_DEV))) + pos = ERR_PTR(-EINVAL); + else + pos = cs_get_absolute_path(path, buf, buf_len - 1); + if (pos == ERR_PTR(-EINVAL)) + pos = cs_get_local_path(path->dentry, buf, + buf_len - 1); +encode: + if (IS_ERR(pos)) + continue; + name = cs_encode(pos); + break; + } + kfree(buf); + if (!name) + cs_warn_oom(__func__); + return name; +} + +/** + * cs_encode2 - Encode binary string to ascii string. + * + * @str: String in binary format. Maybe NULL. + * @str_len: Size of @str in byte. + * + * Returns pointer to @str in ascii format on success, NULL otherwise. + * + * This function uses kzalloc(), so caller must kfree() if this function + * didn't return NULL. + */ +char *cs_encode2(const char *str, int str_len) +{ + int i; + int len; + const char *p = str; + char *cp; + char *cp0; + + if (!p) + return NULL; + len = str_len; + for (i = 0; i < str_len; i++) { + const unsigned char c = p[i]; + + if (!(c > ' ' && c < 127 && c != '\\')) + len += 3; + } + len++; + cp = kzalloc(len, GFP_NOFS); + if (!cp) + return NULL; + cp0 = cp; + p = str; + for (i = 0; i < str_len; i++) { + const unsigned char c = p[i]; + + if (c > ' ' && c < 127 && c != '\\') { + *cp++ = c; + } else { + *cp++ = '\\'; + *cp++ = (c >> 6) + '0'; + *cp++ = ((c >> 3) & 7) + '0'; + *cp++ = (c & 7) + '0'; + } + } + return cp0; +} + +/** + * cs_encode - Encode binary string to ascii string. + * + * @str: String in binary format. Maybe NULL. + * + * Returns pointer to @str in ascii format on success, NULL otherwise. + * + * This function uses kzalloc(), so caller must kfree() if this function + * didn't return NULL. + */ +char *cs_encode(const char *str) +{ + return str ? cs_encode2(str, strlen(str)) : NULL; +} + +/** + * cs_const_part_length - Evaluate the initial length without a pattern in a token. + * + * @filename: The string to evaluate. Maybe NULL. + * + * Returns the initial length without a pattern in @filename. + */ +static int cs_const_part_length(const char *filename) +{ + char c; + int len = 0; + + if (!filename) + return 0; + while (1) { + c = *filename++; + if (!c) + break; + if (c != '\\') { + len++; + continue; + } + c = *filename++; + switch (c) { + case '0': /* "\ooo" */ + case '1': + case '2': + case '3': + c = *filename++; + if (c < '0' || c > '7') + break; + c = *filename++; + if (c < '0' || c > '7') + break; + len += 4; + continue; + } + break; + } + return len; +} + +/** + * cs_fill_path_info - Fill in "struct cs_path_info" members. + * + * @ptr: Pointer to "struct cs_path_info" to fill in. + * + * Returns nothing. + * + * The caller sets "struct cs_path_info"->name. + */ +void cs_fill_path_info(struct cs_path_info *ptr) +{ + const char *name = ptr->name; + const int len = strlen(name); + + ptr->total_len = len; + ptr->const_len = cs_const_part_length(name); + ptr->hash = full_name_hash(NULL, name, len); +} + +/** + * cs_get_exe - Get cs_realpath() of current process. + * + * Returns the cs_realpath() of current process on success, NULL otherwise. + * + * This function uses kzalloc(), so the caller must kfree() + * if this function didn't return NULL. + */ +char *cs_get_exe(void) +{ + struct mm_struct *mm; + struct file *exe_file; + + if (current->flags & PF_KTHREAD) + return kstrdup("", GFP_NOFS); + mm = current->mm; + if (!mm) + goto task_has_no_mm; + /* Not using get_mm_exe_file() as it is not exported. */ + rcu_read_lock(); + exe_file = rcu_dereference(mm->exe_file); + if (exe_file && !get_file_rcu(exe_file)) + exe_file = NULL; + rcu_read_unlock(); + if (exe_file) { + char *cp = cs_realpath(&exe_file->f_path); + + fput(exe_file); + return cp; + } +task_has_no_mm: + /* I'don't know. */ + return kstrdup("", GFP_NOFS); +} + +/** + * cs_get_exename - Get cs_realpath() of current process. + * + * @buf: Pointer to "struct cs_path_info". + * + * Returns true on success, false otherwise. + * + * This function uses kzalloc(), so the caller must kfree() + * if this function returned true. + */ +bool cs_get_exename(struct cs_path_info *buf) +{ + buf->name = cs_get_exe(); + if (buf->name) { + cs_fill_path_info(buf); + return true; + } + return false; +}