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Date:	Fri, 7 Sep 2012 14:48:06 -0400
From:	Eric Paris <eparis@...isplace.org>
To:	Kees Cook <keescook@...omium.org>
Cc:	linux-kernel@...r.kernel.org,
	Rusty Russell <rusty@...tcorp.com.au>,
	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	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 2/2] security: introduce kernel_module_from_file hook

Acked-by: Eric Paris <eparis@...hat.com>

On Fri, Sep 7, 2012 at 2:38 PM, Kees Cook <keescook@...omium.org> wrote:
> Now that kernel module origins can be reasoned about, provide a hook to
> the LSMs to make policy decisions about the module file.
>
> Signed-off-by: Kees Cook <keescook@...omium.org>
> Acked-by: Serge E. Hallyn <serge.hallyn@...onical.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 c1e446e..0ad03c4 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 @@ 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)
> @@ -2468,6 +2473,10 @@ int copy_module_from_fd(int fd, struct load_info *info)
>         if (err)
>                 goto out;
>
> +       err = security_kernel_module_from_file(file);
> +       if (err)
> +               goto out;
> +
>         size = stat.size;
>         info->hdr = vmalloc(size);
>         if (!info->hdr) {
> 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)
>  {
> --
> 1.7.0.4
>
> --
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