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From: Kees Cook <keescook@chromium.org>
To: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: linux-security-module <linux-security-module@vger.kernel.org>,
	"Luis R. Rodriguez" <mcgrof@suse.com>,
	Kexec Mailing List <kexec@lists.infradead.org>,
	linux-modules@vger.kernel.org,
	David Howells <dhowells@redhat.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
	Eric Biederman <ebiederm@xmission.com>,
	Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [PATCH v3 18/22] kexec: replace call to copy_file_from_fd() with kernel version
Date: Thu, 4 Feb 2016 10:05:48 -0800
Message-ID: <CAGXu5jK45ejTH=XkCR=fyEqrShzQEp0GAho0H+iCHL1DXvMhpg@mail.gmail.com> (raw)
In-Reply-To: <1454526390-19792-19-git-send-email-zohar@linux.vnet.ibm.com>

On Wed, Feb 3, 2016 at 11:06 AM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
> Replace copy_file_from_fd() with kernel_read_file_from_fd().
>
> Two new identifiers named READING_KEXEC_IMAGE and READING_KEXEC_INITRAMFS
> are defined for measuring, appraising or auditing the kexec image and
> initramfs.
>
> Changelog v3:
> - return -EBADF, not -ENOEXEC
> - identifier change
> - moved copy_file_from_fd() to a separate patch
> - defer support for IMA
> v1:
> - re-order and squash the kexec patches
> v0: ima: measure and appraise kexec image and initramfs (squashed)
> - rename ima_read_hooks enumeration to ima_policy_id
> - use kstat file size type loff_t, not size_t
> - add union name "hooks" to fix sparse warning
> - Calculate the file hash from the in memory buffer
> (suggested by Dave Young)
> - Rename ima_read_and_process_file() to ima_hash_and_process_file()
> - replace individual case statements with range:
>         KEXEC_CHECK ... IMA_MAX_READ_CHECK - 1
> - Instead of ima_read_and_process_file() allocating memory, the caller
> allocates and frees the memory.
> - Moved the kexec measurement/appraisal call to copy_file_from_fd(). The
> same call now measures and appraises both the kexec image and initramfs.
>
> Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

Acked-by: Kees Cook <keescook@chromium.org>

-Kees

> ---
>  include/linux/fs.h  |  2 ++
>  kernel/kexec_file.c | 73 +++++++----------------------------------------------
>  2 files changed, 11 insertions(+), 64 deletions(-)
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 9e1f1e3..d4d556e 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2529,6 +2529,8 @@ extern int do_pipe_flags(int *, int);
>  enum kernel_read_file_id {
>         READING_FIRMWARE = 1,
>         READING_MODULE,
> +       READING_KEXEC_IMAGE,
> +       READING_KEXEC_INITRAMFS,
>         READING_MAX_ID
>  };
>
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index b70ada0..1443f93 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -18,6 +18,7 @@
>  #include <linux/kexec.h>
>  #include <linux/mutex.h>
>  #include <linux/list.h>
> +#include <linux/fs.h>
>  #include <crypto/hash.h>
>  #include <crypto/sha.h>
>  #include <linux/syscalls.h>
> @@ -33,65 +34,6 @@ size_t __weak kexec_purgatory_size = 0;
>
>  static int kexec_calculate_store_digests(struct kimage *image);
>
> -static int copy_file_from_fd(int fd, void **buf, unsigned long *buf_len)
> -{
> -       struct fd f = fdget(fd);
> -       int ret;
> -       struct kstat stat;
> -       loff_t pos;
> -       ssize_t bytes = 0;
> -
> -       if (!f.file)
> -               return -EBADF;
> -
> -       ret = vfs_getattr(&f.file->f_path, &stat);
> -       if (ret)
> -               goto out;
> -
> -       if (stat.size > INT_MAX) {
> -               ret = -EFBIG;
> -               goto out;
> -       }
> -
> -       /* Don't hand 0 to vmalloc, it whines. */
> -       if (stat.size == 0) {
> -               ret = -EINVAL;
> -               goto out;
> -       }
> -
> -       *buf = vmalloc(stat.size);
> -       if (!*buf) {
> -               ret = -ENOMEM;
> -               goto out;
> -       }
> -
> -       pos = 0;
> -       while (pos < stat.size) {
> -               bytes = kernel_read(f.file, pos, (char *)(*buf) + pos,
> -                                   stat.size - pos);
> -               if (bytes < 0) {
> -                       vfree(*buf);
> -                       ret = bytes;
> -                       goto out;
> -               }
> -
> -               if (bytes == 0)
> -                       break;
> -               pos += bytes;
> -       }
> -
> -       if (pos != stat.size) {
> -               ret = -EBADF;
> -               vfree(*buf);
> -               goto out;
> -       }
> -
> -       *buf_len = pos;
> -out:
> -       fdput(f);
> -       return ret;
> -}
> -
>  /* Architectures can provide this probe function */
>  int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
>                                          unsigned long buf_len)
> @@ -180,16 +122,17 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
>  {
>         int ret = 0;
>         void *ldata;
> +       loff_t size;
>
> -       ret = copy_file_from_fd(kernel_fd, &image->kernel_buf,
> -                               &image->kernel_buf_len);
> +       ret = kernel_read_file_from_fd(kernel_fd, &image->kernel_buf,
> +                                      &size, INT_MAX, READING_KEXEC_IMAGE);
>         if (ret)
>                 return ret;
> +       image->kernel_buf_len = size;
>
>         /* Call arch image probe handlers */
>         ret = arch_kexec_kernel_image_probe(image, image->kernel_buf,
>                                             image->kernel_buf_len);
> -
>         if (ret)
>                 goto out;
>
> @@ -204,10 +147,12 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
>  #endif
>         /* It is possible that there no initramfs is being loaded */
>         if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
> -               ret = copy_file_from_fd(initrd_fd, &image->initrd_buf,
> -                                       &image->initrd_buf_len);
> +               ret = kernel_read_file_from_fd(initrd_fd, &image->initrd_buf,
> +                                              &size, INT_MAX,
> +                                              READING_KEXEC_INITRAMFS);
>                 if (ret)
>                         goto out;
> +               image->initrd_buf_len = size;
>         }
>
>         if (cmdline_len) {
> --
> 2.1.0
>



-- 
Kees Cook
Chrome OS & Brillo Security

  reply index

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-03 19:06 [PATCH v3 00/22] vfs: support for a common kernel file loader Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 01/22] ima: separate 'security.ima' reading functionality from collect Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 02/22] ima: refactor ima_policy_show() to display "ima_hooks" rules Mimi Zohar
2016-02-07 19:45   ` Petko Manolov
2016-02-10 19:33   ` Dmitry Kasatkin
2016-02-03 19:06 ` [PATCH v3 03/22] ima: use "ima_hooks" enum as function argument Mimi Zohar
2016-02-07 19:46   ` Petko Manolov
2016-02-10 19:35   ` Dmitry Kasatkin
2016-02-03 19:06 ` [PATCH v3 04/22] firmware: simplify dev_*() print messages for generic helpers Mimi Zohar
2016-02-04 17:26   ` Kees Cook
2016-02-03 19:06 ` [PATCH v3 05/22] firmware: move completing fw into a helper Mimi Zohar
2016-02-04 17:27   ` Kees Cook
2016-02-03 19:06 ` [PATCH v3 06/22] firmware: fold successful fw read early Mimi Zohar
2016-02-04 17:36   ` Kees Cook
2016-02-04 20:26     ` Luis R. Rodriguez
2016-02-03 19:06 ` [PATCH v3 07/22] vfs: define a generic function to read a file from the kernel Mimi Zohar
2016-02-04 17:41   ` Kees Cook
2016-02-03 19:06 ` [PATCH v3 08/22] vfs: define kernel_read_file_id enumeration Mimi Zohar
2016-02-04 17:41   ` Kees Cook
2016-02-04 19:45   ` Luis R. Rodriguez
2016-02-03 19:06 ` [PATCH v3 09/22] ima: provide buffer hash calculation function Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 10/22] ima: calculate the hash of a buffer using aynchronous hash(ahash) Mimi Zohar
2016-02-10 19:58   ` Dmitry Kasatkin
2016-02-03 19:06 ` [PATCH v3 11/22] ima: define a new hook to measure and appraise a file already in memory Mimi Zohar
2016-02-10 20:27   ` Dmitry Kasatkin
2016-02-03 19:06 ` [PATCH v3 12/22] vfs: define kernel_read_file_from_path Mimi Zohar
2016-02-04 17:46   ` Kees Cook
2016-02-04 19:47   ` Luis R. Rodriguez
2016-02-03 19:06 ` [PATCH v3 13/22] firmware: replace call to fw_read_file_contents() with kernel version Mimi Zohar
2016-02-04 17:56   ` Kees Cook
2016-02-04 19:51   ` Luis R. Rodriguez
2016-02-03 19:06 ` [PATCH v3 14/22] security: define kernel_read_file hook Mimi Zohar
2016-02-04 17:57   ` Kees Cook
2016-02-04 19:54   ` Luis R. Rodriguez
2016-02-11 16:54   ` Casey Schaufler
2016-02-11 19:35     ` Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 15/22] vfs: define kernel_copy_file_from_fd() Mimi Zohar
2016-02-04 17:58   ` Kees Cook
2016-02-04 19:55   ` Luis R. Rodriguez
2016-02-03 19:06 ` [PATCH v3 16/22] module: replace copy_module_from_fd with kernel version Mimi Zohar
2016-02-04 18:04   ` Kees Cook
2016-02-04 19:56   ` Luis R. Rodriguez
2016-02-05  0:19     ` Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 17/22] ima: remove firmware and module specific cached status info Mimi Zohar
2016-02-07 19:56   ` Petko Manolov
2016-02-10 20:18   ` Dmitry Kasatkin
2016-02-10 23:14     ` Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 18/22] kexec: replace call to copy_file_from_fd() with kernel version Mimi Zohar
2016-02-04 18:05   ` Kees Cook [this message]
2016-02-04 19:57   ` Luis R. Rodriguez
2016-02-12 12:50   ` Dave Young
2016-02-03 19:06 ` [PATCH v3 19/22] ima: support for kexec image and initramfs Mimi Zohar
2016-02-07 20:10   ` Petko Manolov
2016-02-08 23:34     ` Mimi Zohar
2016-02-10 21:09   ` Dmitry Kasatkin
2016-02-10 23:21     ` Mimi Zohar
     [not found]       ` <CACE9dm8OJ1cgbKszUG-pCiEMVarUFLLWi_jewVV-JEMGAJsA-g@mail.gmail.com>
2016-02-11  2:08         ` Mimi Zohar
2016-02-11  8:47           ` Dmitry Kasatkin
2016-02-11 12:16             ` Mimi Zohar
2016-02-12 12:53   ` Dave Young
2016-02-12 13:09     ` Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 20/22] ima: load policy using path Mimi Zohar
2016-02-07 19:59   ` Petko Manolov
2016-02-08  9:58     ` Dmitry Kasatkin
2016-02-08 10:35       ` Petko Manolov
2016-02-08 10:45         ` Dmitry Kasatkin
2016-02-08 21:12           ` Mimi Zohar
2016-02-09  7:47             ` Petko Manolov
2016-02-03 19:06 ` [PATCH v3 21/22] ima: measure and appraise the IMA policy itself Mimi Zohar
2016-02-07 20:01   ` Petko Manolov
2016-02-10 20:22   ` Dmitry Kasatkin
2016-02-10 23:15     ` Mimi Zohar
2016-02-03 19:06 ` [PATCH v3 22/22] ima: require signed IMA policy Mimi Zohar
2016-02-07 20:02   ` Petko Manolov
2016-02-10 20:24   ` Dmitry Kasatkin
2016-02-04 18:15 ` [PATCH v3 00/22] vfs: support for a common kernel file loader Kees Cook
2016-02-04 23:54   ` Mimi Zohar

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