Return-path: Received: from e31.co.us.ibm.com ([32.97.110.149]:48299 "EHLO e31.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965868AbaGRRLt (ORCPT ); Fri, 18 Jul 2014 13:11:49 -0400 Received: from /spool/local by e31.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 18 Jul 2014 11:11:48 -0600 Message-ID: <1405703500.11182.5.camel@dhcp-9-2-203-236.watson.ibm.com> (sfid-20140718_191232_958054_19E35295) Subject: Re: [PATCH 3/7] security: introduce kernel_fw_from_file hook From: Mimi Zohar To: Kees Cook Cc: linux-kernel@vger.kernel.org, Ming Lei , "Luis R. Rodriguez" , Greg Kroah-Hartman , James Morris , David Howells , linux-doc@vger.kernel.org, linux-security-module@vger.kernel.org, linux-firmware@kernel.org, linux-wireless Date: Fri, 18 Jul 2014 13:11:40 -0400 In-Reply-To: <1405373897-31671-4-git-send-email-keescook@chromium.org> References: <1405373897-31671-1-git-send-email-keescook@chromium.org> <1405373897-31671-4-git-send-email-keescook@chromium.org> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Mon, 2014-07-14 at 14:38 -0700, Kees Cook wrote: > In order to validate the contents of firmware being loaded, there must be > a hook to evaluate any loaded firmware that wasn't built into the kernel > itself. Without this, there is a risk that a root user could load malicious > firmware designed to mount an attack against kernel memory (e.g. via DMA). > > Signed-off-by: Kees Cook > --- > include/linux/security.h | 16 ++++++++++++++++ > security/capability.c | 6 ++++++ > security/security.c | 6 ++++++ > 3 files changed, 28 insertions(+) > > diff --git a/include/linux/security.h b/include/linux/security.h > index 9c6b9722ff48..dbb80b3e99d7 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -702,6 +702,14 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts) > * @inode points to the inode to use as a reference. > * The current task must be the one that nominated @inode. > * Return 0 if successful. > + * @kernel_fw_from_file: > + * Load firmware from userspace. > + * @file contains the file structure pointing to the file containing > + * the firmware to load. If the module is being loaded from a blob, > + * this argument will be NULL. > + * @buf pointer to buffer containing firmware contents. > + * @size length of the firmware contents. > + * Return 0 if permission is granted. > * @kernel_module_request: > * Ability to trigger the kernel to automatically upcall to userspace for > * userspace to load a kernel module with the given name. > @@ -1565,6 +1573,7 @@ struct security_operations { > void (*cred_transfer)(struct cred *new, const struct cred *old); > int (*kernel_act_as)(struct cred *new, u32 secid); > int (*kernel_create_files_as)(struct cred *new, struct inode *inode); > + int (*kernel_fw_from_file)(struct file *file, char *buf, size_t size); > 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, > @@ -1837,6 +1846,7 @@ int security_prepare_creds(struct cred *new, const struct cred *old, gfp_t gfp); > 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_fw_from_file(struct file *file, char *buf, size_t size); > 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, > @@ -2363,6 +2373,12 @@ static inline int security_kernel_create_files_as(struct cred *cred, > return 0; > } > > +static inline int security_kernel_fw_from_file(struct file *file, > + char *buf, size_t size) > +{ > + return 0; > +} > + > static inline int security_kernel_module_request(char *kmod_name) > { > return 0; > diff --git a/security/capability.c b/security/capability.c > index e76373de3129..a74fde6a7468 100644 > --- a/security/capability.c > +++ b/security/capability.c > @@ -401,6 +401,11 @@ static int cap_kernel_create_files_as(struct cred *new, struct inode *inode) > return 0; > } > > +static int cap_kernel_fw_from_file(struct file *file, char *buf, size_t size) > +{ > + return 0; > +} > + > static int cap_kernel_module_request(char *kmod_name) > { > return 0; > @@ -1015,6 +1020,7 @@ void __init security_fixup_ops(struct security_operations *ops) > set_to_cap_if_null(ops, cred_transfer); > 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_fw_from_file); > 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); > diff --git a/security/security.c b/security/security.c > index 31614e9e96e5..35d37d0f0d49 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -845,6 +845,12 @@ int security_kernel_create_files_as(struct cred *new, struct inode *inode) > return security_ops->kernel_create_files_as(new, inode); > } > > +int security_kernel_fw_from_file(struct file *file, char *buf, size_t size) > +{ > + return security_ops->kernel_fw_from_file(file, buf, size); > +} > +EXPORT_SYMBOL_GPL(security_kernel_fw_from_file); > + Nice set of patches! I'll need to send you a patch to call IMA. Mimi > int security_kernel_module_request(char *kmod_name) > { > return security_ops->kernel_module_request(kmod_name);