elfloader: factor out check_hash()

Signed-off-by: Axel Heider <axel.heider@hensoldt.net>

Author: Axel Heider

elfloader-tool/src/common.c

@@ -17,10 +17,12 @@
 #include <elfloader.h>
 #include <fdt.h>
 
-#ifdef CONFIG_HASH_SHA
+#if defined(CONFIG_HASH_SHA)
 #include "crypt_sha256.h"
-#elif CONFIG_HASH_MD5
+#elif defined(CONFIG_HASH_MD5)
 #include "crypt_md5.h"
+#elif !defined(CONFIG_HASH_NONE)
+#error "invalid configuration"
 #endif
 
 #include "hash.h"
@@ -90,6 +92,77 @@ static int ensure_phys_range_valid(
     return 0;
 }
 
+#ifndef CONFIG_HASH_NONE
+/*
+ * check hash of ELF
+ */
+static int check_hash(
+    void const *cpio,
+    size_t cpio_len,
+    void const *elf_blob,
+    size_t elf_blob_size,
+    char const *elf_hash_filename)
+{
+    /* Get the binary file that contains the Hash */
+    unsigned long cpio_file_size = 0;
+    void const *file_hash = cpio_get_file(cpio,
+                                          cpio_len,
+                                          elf_hash_filename,
+                                          &cpio_file_size);
+
+    /* If the file hash doesn't have a pointer, the file doesn't exist, so we
+     * cannot confirm the file is what we expect.
+     */
+    if (file_hash == NULL) {
+        printf("ERROR: hash file '%s' doesn't exist\n", elf_hash_filename);
+        return -1;
+    }
+
+    /* Ensure we can safely cast the CPIO API type to our preferred type. */
+    _Static_assert(sizeof(cpio_file_size) <= sizeof(size_t),
+                   "integer model mismatch");
+    size_t file_hash_len = (size_t)cpio_file_size;
+
+#if defined(CONFIG_HASH_SHA)
+    uint8_t calculated_hash[32];
+    hashes_t hashes = { .hash_type = SHA_256 };
+#elif defined(CONFIG_HASH_MD5)
+    uint8_t calculated_hash[16];
+    hashes_t hashes = { .hash_type = MD5 };
+#else
+#error "unsupported hash algorithm"
+#endif
+
+    if (file_hash_len < sizeof(calculated_hash)) {
+        printf("ERROR: hash file '%s' size %u invalid, expected at least %u\n",
+               elf_hash_filename, file_hash_len, sizeof(calculated_hash));
+    }
+
+    /* Print the Hash for the user to see */
+    printf("Hash from ELF File: ");
+    print_hash(file_hash, sizeof(calculated_hash));
+
+    /* This does not return anything */
+    get_hash(hashes, elf_blob, elf_blob_size, calculated_hash);
+
+    /* Print the hash so the user can see they're the same or different */
+    printf("Hash for ELF Input: ");
+    print_hash(calculated_hash, sizeof(calculated_hash));
+
+    /* Check the hashes are the same. There is no memcmp() in the striped down
+     * runtime lib of ELF Loader, so we compare here byte per byte.
+     */
+    for (unsigned int i = 0; i < sizeof(calculated_hash); i++) {
+        if (((char const *)file_hash)[i] != ((char const *)calculated_hash)[i]) {
+            printf("ERROR: Hashes are different\n");
+            return -1;
+        }
+    }
+
+    return 0;
+}
+#endif /* not CONFIG_HASH_NONE */
+
 /*
  * Unpack an ELF file to the given physical address.
  */
@@ -217,67 +290,17 @@ static int load_elf(
     }
 
 #ifdef CONFIG_HASH_NONE
-
     UNUSED_VARIABLE(cpio);
     UNUSED_VARIABLE(cpio_len);
     UNUSED_VARIABLE(elf_blob_size);
     UNUSED_VARIABLE(elf_hash_filename);
-
 #else
-
-    /* Get the binary file that contains the Hash */
-    unsigned long cpio_file_size = 0;
-    void const *file_hash = cpio_get_file(cpio,
-                                          cpio_len,
-                                          elf_hash_filename,
-                                          &cpio_file_size);
-
-    /* If the file hash doesn't have a pointer, the file doesn't exist, so we
-     * cannot confirm the file is what we expect.
-     */
-    if (file_hash == NULL) {
-        printf("ERROR: hash file '%s' doesn't exist\n", elf_hash_filename);
+    ret = check_hash(cpio, cpio_len, elf_blob, elf_blob_size, elf_hash_filename);
+    if (0 != ret) {
+        printf("ERROR: hash check failed for %s (%d)\n", name, ret);
         return -1;
     }
-
-    /* Ensure we can safely cast the CPIO API type to our preferred type. */
-    _Static_assert(sizeof(cpio_file_size) <= sizeof(size_t),
-                   "integer model mismatch");
-    size_t file_hash_len = (size_t)cpio_file_size;
-
-#ifdef CONFIG_HASH_SHA
-    uint8_t calculated_hash[32];
-    hashes_t hashes = { .hash_type = SHA_256 };
-#else
-    uint8_t calculated_hash[16];
-    hashes_t hashes = { .hash_type = MD5 };
-#endif
-
-    if (file_hash_len < sizeof(calculated_hash)) {
-        printf("ERROR: hash file '%s' size %u invalid, expected at least %u\n",
-               elf_hash_filename, file_hash_len, sizeof(calculated_hash));
-    }
-
-    /* Print the Hash for the user to see */
-    printf("Hash from ELF File: ");
-    print_hash(file_hash, sizeof(calculated_hash));
-
-    get_hash(hashes, elf_blob, elf_blob_size, calculated_hash);
-
-    /* Print the hash so the user can see they're the same or different */
-    printf("Hash for ELF Input: ");
-    print_hash(calculated_hash, sizeof(calculated_hash));
-
-    /* Check the hashes are the same. There is no memcmp() in the striped down
-     * runtime lib of ELF Loader, so we compare here byte per byte. */
-    for (unsigned int i = 0; i < sizeof(calculated_hash); i++) {
-        if (((char const *)file_hash)[i] != ((char const *)calculated_hash)[i]) {
-            printf("ERROR: Hashes are different\n");
-            return -1;
-        }
-    }
-
-#endif  /* CONFIG_HASH_NONE */
+#endif /* [not] CONFIG_HASH_NONE */
 
     /* Print diagnostics. */
     printf("  paddr=[%p..%p]\n", dest_paddr, dest_paddr + image_size - 1);