On Wed, Feb 3, 2016 at 11:06 AM, Mimi Zohar <zohar at 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 at linux.vnet.ibm.com>
Acked-by: Kees Cook <keescook at 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
