efi_loader: carve out efi_check_pe()

Carve out a function to check that a buffer contains a PE-COFF image.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

diff --git a/include/efi_loader.h b/include/efi_loader.h
index 4719fa9..df29d45 100644 (file)
--- a/include/efi_loader.h
+++ b/include/efi_loader.h
@@ -460,6 +460,8 @@ efi_status_t efi_set_watchdog(unsigned long timeout);
 
 /* Called from places to check whether a timer expired */
 void efi_timer_check(void);
+/* Check if a buffer contains a PE-COFF image */
+efi_status_t efi_check_pe(void *buffer, size_t size, void **nt_header);
 /* PE loader implementation */
 efi_status_t efi_load_pe(struct efi_loaded_image_obj *handle,
                         void *efi, size_t efi_size,

diff --git a/lib/efi_loader/efi_image_loader.c b/lib/efi_loader/efi_image_loader.c
index 94f76ef..d4dd9e9 100644 (file)
--- a/lib/efi_loader/efi_image_loader.c
+++ b/lib/efi_loader/efi_image_loader.c
@@ -675,6 +675,46 @@ static bool efi_image_authenticate(void *efi, size_t efi_size)
 }
 #endif /* CONFIG_EFI_SECURE_BOOT */
 
+
+/**
+ * efi_check_pe() - check if a memory buffer contains a PE-COFF image
+ *
+ * @buffer:    buffer to check
+ * @size:      size of buffer
+ * @nt_header: on return pointer to NT header of PE-COFF image
+ * Return:     EFI_SUCCESS if the buffer contains a PE-COFF image
+ */
+efi_status_t efi_check_pe(void *buffer, size_t size, void **nt_header)
+{
+       IMAGE_DOS_HEADER *dos = buffer;
+       IMAGE_NT_HEADERS32 *nt;
+
+       if (size < sizeof(*dos))
+               return EFI_INVALID_PARAMETER;
+
+       /* Check for DOS magix */
+       if (dos->e_magic != IMAGE_DOS_SIGNATURE)
+               return EFI_INVALID_PARAMETER;
+
+       /*
+        * Check if the image section header fits into the file. Knowing that at
+        * least one section header follows we only need to check for the length
+        * of the 64bit header which is longer than the 32bit header.
+        */
+       if (size < dos->e_lfanew + sizeof(IMAGE_NT_HEADERS32))
+               return EFI_INVALID_PARAMETER;
+       nt = (IMAGE_NT_HEADERS32 *)((u8 *)buffer + dos->e_lfanew);
+
+       /* Check for PE-COFF magic */
+       if (nt->Signature != IMAGE_NT_SIGNATURE)
+               return EFI_INVALID_PARAMETER;
+
+       if (nt_header)
+               *nt_header = nt;
+
+       return EFI_SUCCESS;
+}
+
 /**
  * efi_load_pe() - relocate EFI binary
  *
@@ -705,36 +745,10 @@ efi_status_t efi_load_pe(struct efi_loaded_image_obj *handle,
        int supported = 0;
        efi_status_t ret;
 
-       /* Sanity check for a file header */
-       if (efi_size < sizeof(*dos)) {
-               log_err("Truncated DOS Header\n");
-               ret = EFI_LOAD_ERROR;
-               goto err;
-       }
-
-       dos = efi;
-       if (dos->e_magic != IMAGE_DOS_SIGNATURE) {
-               log_err("Invalid DOS Signature\n");
-               ret = EFI_LOAD_ERROR;
-               goto err;
-       }
-
-       /*
-        * Check if the image section header fits into the file. Knowing that at
-        * least one section header follows we only need to check for the length
-        * of the 64bit header which is longer than the 32bit header.
-        */
-       if (efi_size < dos->e_lfanew + sizeof(IMAGE_NT_HEADERS64)) {
-               log_err("Invalid offset for Extended Header\n");
-               ret = EFI_LOAD_ERROR;
-               goto err;
-       }
-
-       nt = (void *) ((char *)efi + dos->e_lfanew);
-       if (nt->Signature != IMAGE_NT_SIGNATURE) {
-               log_err("Invalid NT Signature\n");
-               ret = EFI_LOAD_ERROR;
-               goto err;
+       ret = efi_check_pe(efi, efi_size, (void **)&nt);
+       if (ret != EFI_SUCCESS) {
+               log_err("Not a PE-COFF file\n");
+               return EFI_LOAD_ERROR;
        }
 
        for (i = 0; machines[i]; i++)
@@ -746,8 +760,7 @@ efi_status_t efi_load_pe(struct efi_loaded_image_obj *handle,
        if (!supported) {
                log_err("Machine type 0x%04x is not supported\n",
                        nt->FileHeader.Machine);
-               ret = EFI_LOAD_ERROR;
-               goto err;
+               return EFI_LOAD_ERROR;
        }
 
        num_sections = nt->FileHeader.NumberOfSections;
@@ -757,8 +770,7 @@ efi_status_t efi_load_pe(struct efi_loaded_image_obj *handle,
        if (efi_size < ((void *)sections + sizeof(sections[0]) * num_sections
                        - efi)) {
                log_err("Invalid number of sections: %d\n", num_sections);
-               ret = EFI_LOAD_ERROR;
-               goto err;
+               return EFI_LOAD_ERROR;
        }
 
        /* Authenticate an image */