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Message-ID: <1348231376.2278.40.camel@falcor.watson.ibm.com>
Date: Fri, 21 Sep 2012 08:42:56 -0400
From: Mimi Zohar <zohar@...ux.vnet.ibm.com>
To: Kees Cook <keescook@...omium.org>
Cc: linux-kernel@...r.kernel.org,
Andrew Morton <akpm@...ux-foundation.org>,
Rusty Russell <rusty@...tcorp.com.au>,
Serge Hallyn <serge.hallyn@...onical.com>,
Arnd Bergmann <arnd@...db.de>,
James Morris <james.l.morris@...cle.com>,
Al Viro <viro@...iv.linux.org.uk>,
Eric Paris <eparis@...hat.com>, Jiri Kosina <jkosina@...e.cz>,
linux-security-module@...r.kernel.org
Subject: Re: [PATCH 2/4] security: introduce kernel_module_from_file hook
On Thu, 2012-09-20 at 15:14 -0700, Kees Cook wrote:
> 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 <keescook@...omium.org>
> Acked-by: Serge E. Hallyn <serge.hallyn@...onical.com>
> Acked-by: Eric Paris <eparis@...hat.com>
Thanks, please include my
Acked-by: Mimi Zohar <zohar@...ibm.com>
> ---
> include/linux/security.h | 13 +++++++++++++
> kernel/module.c | 9 +++++++++
> security/capability.c | 6 ++++++
> security/security.c | 5 +++++
> 4 files changed, 33 insertions(+), 0 deletions(-)
>
> 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 afe2f69..511b8e9 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -29,6 +29,7 @@
> #include <linux/vmalloc.h>
> #include <linux/elf.h>
> #include <linux/proc_fs.h>
> +#include <linux/security.h>
> #include <linux/seq_file.h>
> #include <linux/syscalls.h>
> #include <linux/fcntl.h>
> @@ -2430,6 +2431,10 @@ static int copy_module_from_user(const void __user *umod, unsigned long 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)
> @@ -2464,6 +2469,10 @@ 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)
> {
--
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