Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757346Ab2JDUYL (ORCPT ); Thu, 4 Oct 2012 16:24:11 -0400 Received: from smtp.outflux.net ([198.145.64.163]:43518 "EHLO smtp.outflux.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757199Ab2JDUXH (ORCPT ); Thu, 4 Oct 2012 16:23:07 -0400 From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Andrew Morton , Rusty Russell , Mimi Zohar , Serge Hallyn , Arnd Bergmann , James Morris , Kees Cook , linux-security-module@vger.kernel.org Subject: [PATCH 2/4] security: introduce kernel_module_from_file hook Date: Thu, 4 Oct 2012 13:22:32 -0700 Message-Id: <1349382154-9804-3-git-send-email-keescook@chromium.org> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1349382154-9804-1-git-send-email-keescook@chromium.org> References: <1349382154-9804-1-git-send-email-keescook@chromium.org> X-HELO: www.outflux.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5417 Lines: 150 Now that kernel module origins can be reasoned about, provide a hook to the LSMs to make policy decisions about the module file. This will let Chrome OS enforce that loadable kernel modules can only come from its read-only hash-verified root filesystem. Other LSMs can, for example, read extended attributes for signatures, etc. Signed-off-by: Kees Cook Acked-by: Serge E. Hallyn Acked-by: Eric Paris Acked-by: Mimi Zohar --- include/linux/security.h | 13 +++++++++++++ kernel/module.c | 11 +++++++++++ security/capability.c | 6 ++++++ security/security.c | 5 +++++ 4 files changed, 35 insertions(+) diff --git a/include/linux/security.h b/include/linux/security.h index 3dea6a9..368e539 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -693,6 +693,12 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts) * userspace to load a kernel module with the given name. * @kmod_name name of the module requested by the kernel * Return 0 if successful. + * @kernel_module_from_file: + * Load a kernel module from userspace. + * @file contains the file structure pointing to the file containing + * the kernel module to load. If the module is being loaded from a blob, + * this argument will be NULL. + * Return 0 if permission is granted. * @task_fix_setuid: * Update the module's state after setting one or more of the user * identity attributes of the current process. The @flags parameter @@ -1507,6 +1513,7 @@ struct security_operations { int (*kernel_act_as)(struct cred *new, u32 secid); int (*kernel_create_files_as)(struct cred *new, struct inode *inode); int (*kernel_module_request)(char *kmod_name); + int (*kernel_module_from_file)(struct file *file); int (*task_fix_setuid) (struct cred *new, const struct cred *old, int flags); int (*task_setpgid) (struct task_struct *p, pid_t pgid); @@ -1764,6 +1771,7 @@ void security_transfer_creds(struct cred *new, const struct cred *old); int security_kernel_act_as(struct cred *new, u32 secid); int security_kernel_create_files_as(struct cred *new, struct inode *inode); int security_kernel_module_request(char *kmod_name); +int security_kernel_module_from_file(struct file *file); int security_task_fix_setuid(struct cred *new, const struct cred *old, int flags); int security_task_setpgid(struct task_struct *p, pid_t pgid); @@ -2277,6 +2285,11 @@ static inline int security_kernel_module_request(char *kmod_name) return 0; } +static inline int security_kernel_module_from_file(struct file *file) +{ + return 0; +} + static inline int security_task_fix_setuid(struct cred *new, const struct cred *old, int flags) diff --git a/kernel/module.c b/kernel/module.c index 321c6b9..261bf82 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -29,6 +29,7 @@ #include #include #include +#include #include #include #include @@ -2489,10 +2490,16 @@ static int elf_header_check(struct load_info *info) static int copy_module_from_user(const void __user *umod, unsigned long len, struct load_info *info) { + int err; + info->len = len; if (info->len < sizeof(*(info->hdr))) return -ENOEXEC; + err = security_kernel_module_from_file(NULL); + if (err) + return err; + /* Suck in entire file: we'll want most of it. */ info->hdr = vmalloc(info->len); if (!info->hdr) @@ -2519,6 +2526,10 @@ static int copy_module_from_fd(int fd, struct load_info *info) if (!file) return -ENOEXEC; + err = security_kernel_module_from_file(file); + if (err) + goto out; + err = vfs_getattr(file->f_vfsmnt, file->f_dentry, &stat); if (err) goto out; diff --git a/security/capability.c b/security/capability.c index 61095df..8acb304 100644 --- a/security/capability.c +++ b/security/capability.c @@ -395,6 +395,11 @@ static int cap_kernel_module_request(char *kmod_name) return 0; } +static int cap_kernel_module_from_file(struct file *file) +{ + return 0; +} + static int cap_task_setpgid(struct task_struct *p, pid_t pgid) { return 0; @@ -967,6 +972,7 @@ void __init security_fixup_ops(struct security_operations *ops) set_to_cap_if_null(ops, kernel_act_as); set_to_cap_if_null(ops, kernel_create_files_as); set_to_cap_if_null(ops, kernel_module_request); + set_to_cap_if_null(ops, kernel_module_from_file); set_to_cap_if_null(ops, task_fix_setuid); set_to_cap_if_null(ops, task_setpgid); set_to_cap_if_null(ops, task_getpgid); diff --git a/security/security.c b/security/security.c index 860aeb3..f7f8695 100644 --- a/security/security.c +++ b/security/security.c @@ -799,6 +799,11 @@ int security_kernel_module_request(char *kmod_name) return security_ops->kernel_module_request(kmod_name); } +int security_kernel_module_from_file(struct file *file) +{ + return security_ops->kernel_module_from_file(file); +} + int security_task_fix_setuid(struct cred *new, const struct cred *old, int flags) { -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/