[elf] Reject ELFBoot images requiring virtual addressing

We do not set up any kind of virtual addressing before invoking an
ELFBoot image.  Reject if the image's program headers indicate that
virtual addresses are not equal to physical addresses.

This avoids problems when loading some RHEL5 kernels, which seem to
include ELFBoot headers using virtual addressing.  With this change,
these kernels are no longer detected as ELFBoot, and so may be
(correctly) detected as bzImage instead.

Reported-by: Torgeir.Wulfsberg@kongsberg.com
Signed-off-by: Michael Brown <mcb30@ipxe.org>

1 files changed, 32 insertions, 1 deletions

diff --git a/src/arch/i386/image/elfboot.c b/src/arch/i386/image/elfboot.c
index 3ff76203..dc356892 100644
--- a/src/arch/i386/image/elfboot.c
+++ b/src/arch/i386/image/elfboot.c
@@ -79,6 +79,27 @@ static int elfboot_exec ( struct image *image ) {
 }
 
 /**
+ * Check that ELF segment uses flat physical addressing
+ *
+ * @v image		ELF file
+ * @v phdr		ELF program header
+ * @v dest		Destination address
+ * @ret rc		Return status code
+ */
+static int elfboot_check_segment ( struct image *image, Elf_Phdr *phdr,
+				   physaddr_t dest ) {
+
+	/* Check that ELF segment uses flat physical addressing */
+	if ( phdr->p_vaddr != dest ) {
+		DBGC ( image, "ELF %p uses virtual addressing (phys %x, "
+		       "virt %x)\n", image, phdr->p_paddr, phdr->p_vaddr );
+		return -ENOEXEC;
+	}
+
+	return 0;
+}
+
+/**
  * Probe ELF image
  *
  * @v image		ELF file
@@ -95,14 +116,24 @@ static int elfboot_probe ( struct image *image ) {
 		[EI_DATA]	= ELFDATA2LSB,
 		[EI_VERSION]	= EV_CURRENT,
 	};
+	physaddr_t entry;
+	physaddr_t max;
+	int rc;
 
 	/* Read ELF header */
 	copy_from_user ( &ehdr, image->data, 0, sizeof ( ehdr ) );
 	if ( memcmp ( ehdr.e_ident, e_ident, sizeof ( e_ident ) ) != 0 ) {
-		DBG ( "Invalid ELF identifier\n" );
+		DBGC ( image, "Invalid ELF identifier\n" );
 		return -ENOEXEC;
 	}
 
+	/* Check that this image uses flat physical addressing */
+	if ( ( rc = elf_segments ( image, &ehdr, elfboot_check_segment,
+				   &entry, &max ) ) != 0 ) {
+		DBGC ( image, "Unloadable ELF image\n" );
+		return rc;
+	}
+
 	return 0;
 }