From patchwork Sat Jun 27 07:27:04 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11629267 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A664D90 for ; Sat, 27 Jun 2020 07:28:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 87D20214D8 for ; Sat, 27 Jun 2020 07:28:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="TlPnTimq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726430AbgF0H1w (ORCPT ); Sat, 27 Jun 2020 03:27:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58582 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726412AbgF0H1t (ORCPT ); Sat, 27 Jun 2020 03:27:49 -0400 Received: from casper.infradead.org (unknown [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 01F01C03E97A; Sat, 27 Jun 2020 00:27:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=mURemflipje9eYopYQ4h3uusWn3YXYVAu+uuVrAN7pQ=; b=TlPnTimqsO2m30LvldYZKWVizZ hpNyMesz2KmBGpNgKstCa9x+hZjeq/G/LSRMkegjvZ22YoGmrkgnX+pZNWw5KGTu0v468zw9T4sZI Xu/MpJ2eSYmAE+ipVFlRyXHmj7yINmDtCVRDeT4inn/UpLST2JkhmV8QUh9BXIQDcWZI6goY8hoTK 4LzatZU6wTyWdTn1fSGkRe6TQ02ZarzjB0rP81o5Zm/pl6DVfHmLMMgslXwjVzsTycl+tfWpI1waO hEgw54/dYKj+ZkSuM7HhgjVT0BbFo583J9Wu65cTYBtF8e6ZyiugH7Oj2JWPx8rHz3ol1injsjGRn /VsHUW/A==; Received: from [2001:4bb8:184:76e3:595:ba65:ae56:65a6] (helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jp5FI-0006XS-Jx; Sat, 27 Jun 2020 07:27:30 +0000 From: Christoph Hellwig To: Al Viro Cc: Arnd Bergmann , Brian Gerst , Luis Chamberlain , linux-arm-kernel@lists.infradead.org, x86@kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 5/5] exec: add a kernel_execveat helper Date: Sat, 27 Jun 2020 09:27:04 +0200 Message-Id: <20200627072704.2447163-6-hch@lst.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200627072704.2447163-1-hch@lst.de> References: <20200627072704.2447163-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org Add a kernel_execveat helper to execute a binary with kernel space argv and envp pointers. Switch executing init and user mode helpers to this new helper instead of relying on the implicit set_fs(KERNEL_DS) for early init code and kernel threads, and move the getname call into the do_execve helper. Signed-off-by: Christoph Hellwig --- fs/exec.c | 109 ++++++++++++++++++++++++++++++++-------- include/linux/binfmts.h | 6 +-- init/main.c | 6 +-- kernel/umh.c | 8 ++- 4 files changed, 95 insertions(+), 34 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index 34781db6bf6889..7923b8334ae600 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -435,6 +435,21 @@ static int count_strings(const char __user *const __user *argv) return i; } +static int count_kernel_strings(const char *const *argv) +{ + int i; + + if (!argv) + return 0; + + for (i = 0; argv[i]; i++) { + if (i >= MAX_ARG_STRINGS) + return -E2BIG; + } + + return i; +} + static int check_arg_limit(struct linux_binprm *bprm) { unsigned long limit, ptr_size; @@ -611,6 +626,19 @@ int copy_string_kernel(const char *arg, struct linux_binprm *bprm) } EXPORT_SYMBOL(copy_string_kernel); +static int copy_strings_kernel(int argc, const char *const *argv, + struct linux_binprm *bprm) +{ + int ret; + + while (argc-- > 0) { + ret = copy_string_kernel(argv[argc], bprm); + if (ret) + break; + } + return ret; +} + #ifdef CONFIG_MMU /* @@ -1793,9 +1821,11 @@ static int exec_binprm(struct linux_binprm *bprm) return 0; } -int do_execveat(int fd, struct filename *filename, +static int __do_execveat(int fd, struct filename *filename, const char __user *const __user *argv, const char __user *const __user *envp, + const char *const *kernel_argv, + const char *const *kernel_envp, int flags, struct file *file) { char *pathbuf = NULL; @@ -1876,16 +1906,30 @@ int do_execveat(int fd, struct filename *filename, if (retval) goto out_unmark; - bprm->argc = count_strings(argv); - if (bprm->argc < 0) { - retval = bprm->argc; - goto out; - } + if (unlikely(kernel_argv)) { + bprm->argc = count_kernel_strings(kernel_argv); + if (bprm->argc < 0) { + retval = bprm->argc; + goto out; + } - bprm->envc = count_strings(envp); - if (bprm->envc < 0) { - retval = bprm->envc; - goto out; + bprm->envc = count_kernel_strings(kernel_envp); + if (bprm->envc < 0) { + retval = bprm->envc; + goto out; + } + } else { + bprm->argc = count_strings(argv); + if (bprm->argc < 0) { + retval = bprm->argc; + goto out; + } + + bprm->envc = count_strings(envp); + if (bprm->envc < 0) { + retval = bprm->envc; + goto out; + } } retval = check_arg_limit(bprm); @@ -1902,13 +1946,22 @@ int do_execveat(int fd, struct filename *filename, goto out; bprm->exec = bprm->p; - retval = copy_strings(bprm->envc, envp, bprm); - if (retval < 0) - goto out; - retval = copy_strings(bprm->argc, argv, bprm); - if (retval < 0) - goto out; + if (unlikely(kernel_argv)) { + retval = copy_strings_kernel(bprm->envc, kernel_envp, bprm); + if (retval < 0) + goto out; + retval = copy_strings_kernel(bprm->argc, kernel_argv, bprm); + if (retval < 0) + goto out; + } else { + retval = copy_strings(bprm->envc, envp, bprm); + if (retval < 0) + goto out; + retval = copy_strings(bprm->argc, argv, bprm); + if (retval < 0) + goto out; + } retval = exec_binprm(bprm); if (retval < 0) @@ -1959,6 +2012,23 @@ int do_execveat(int fd, struct filename *filename, return retval; } +static int do_execveat(int fd, const char *filename, + const char __user *const __user *argv, + const char __user *const __user *envp, int flags) +{ + int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0; + struct filename *name = getname_flags(filename, lookup_flags, NULL); + + return __do_execveat(fd, name, argv, envp, NULL, NULL, flags, NULL); +} + +int kernel_execveat(int fd, const char *filename, const char *const *argv, + const char *const *envp, int flags, struct file *file) +{ + return __do_execveat(fd, getname_kernel(filename), NULL, NULL, argv, + envp, flags, file); +} + void set_binfmt(struct linux_binfmt *new) { struct mm_struct *mm = current->mm; @@ -1988,7 +2058,7 @@ SYSCALL_DEFINE3(execve, const char __user *const __user *, argv, const char __user *const __user *, envp) { - return do_execveat(AT_FDCWD, getname(filename), argv, envp, 0, NULL); + return do_execveat(AT_FDCWD, filename, argv, envp, 0); } SYSCALL_DEFINE5(execveat, @@ -1997,8 +2067,5 @@ SYSCALL_DEFINE5(execveat, const char __user *const __user *, envp, int, flags) { - int lookup_flags = (flags & AT_EMPTY_PATH) ? LOOKUP_EMPTY : 0; - struct filename *name = getname_flags(filename, lookup_flags, NULL); - - return do_execveat(fd, name, argv, envp, flags, NULL); + return do_execveat(fd, filename, argv, envp, flags); } diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h index bed702e4b1fbd9..1e61c980c16354 100644 --- a/include/linux/binfmts.h +++ b/include/linux/binfmts.h @@ -134,9 +134,7 @@ int copy_string_kernel(const char *arg, struct linux_binprm *bprm); extern void set_binfmt(struct linux_binfmt *new); extern ssize_t read_code(struct file *, unsigned long, loff_t, size_t); -int do_execveat(int fd, struct filename *filename, - const char __user *const __user *__argv, - const char __user *const __user *__envp, - int flags, struct file *file); +int kernel_execveat(int fd, const char *filename, const char *const *argv, + const char *const *envp, int flags, struct file *file); #endif /* _LINUX_BINFMTS_H */ diff --git a/init/main.c b/init/main.c index 838950ea7bca22..33de235dc2aa00 100644 --- a/init/main.c +++ b/init/main.c @@ -1329,10 +1329,8 @@ static int run_init_process(const char *init_filename) pr_debug(" with environment:\n"); for (p = envp_init; *p; p++) pr_debug(" %s\n", *p); - return do_execveat(AT_FDCWD, getname_kernel(init_filename), - (const char __user *const __user *)argv_init, - (const char __user *const __user *)envp_init, - 0, NULL); + return kernel_execveat(AT_FDCWD, init_filename, argv_init, envp_init, 0, + NULL); } static int try_to_run_init_process(const char *init_filename) diff --git a/kernel/umh.c b/kernel/umh.c index 7aa9a5817582ca..1284823dbad338 100644 --- a/kernel/umh.c +++ b/kernel/umh.c @@ -103,11 +103,9 @@ static int call_usermodehelper_exec_async(void *data) commit_creds(new); sub_info->pid = task_pid_nr(current); - retval = do_execveat(AT_FDCWD, - sub_info->path ? getname_kernel(sub_info->path) : NULL, - (const char __user *const __user *)sub_info->argv, - (const char __user *const __user *)sub_info->envp, - 0, sub_info->file); + retval = kernel_execveat(AT_FDCWD, sub_info->path, + (const char *const *)sub_info->argv, + (const char *const *)sub_info->envp, 0, sub_info->file); if (sub_info->file && !retval) current->flags |= PF_UMH; out: