kexec: replace call to copy_file_from_fd() with kernel version

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
- split patch, moving copy_file_from_fd() to a separate patch
- split patch, moving IMA changes to a separate patch
v0:
- use kstat file size type loff_t, not size_t
- Calculate the file hash from the in memory buffer - Dave Young

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Luis R. Rodriguez <mcgrof@kernel.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Acked-by: Dave Young <dyoung@redhat.com>

1 files changed, 9 insertions, 64 deletions

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 007b791f676d..b696c3f3708f 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)
@@ -182,16 +124,17 @@ 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;
 
@@ -206,10 +149,12 @@ 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) {