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[multiboot] Remove userptr_t from Multiboot and ELF image parsing

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Simplify Multiboot and ELF image parsing by assuming that the
Multiboot and ELF headers are directly accessible via pointer
dereferences, and add some missing header validations.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2025-04-28 11:20:16 +01:00
parent c8c5cd685f
commit ba2135d0fd
4 changed files with 105 additions and 88 deletions
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39
src/image/elf.c
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@@ -35,7 +35,6 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <errno.h>
#include <elf.h>
#include <ipxe/uaccess.h>
#include <ipxe/segment.h>
#include <ipxe/image.h>
#include <ipxe/elf.h>
@@ -48,9 +47,9 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
* @v dest Destination address
* @ret rc Return status code
*/
static int elf_load_segment ( struct image *image, Elf_Phdr *phdr,
static int elf_load_segment ( struct image *image, const Elf_Phdr *phdr,
physaddr_t dest ) {
userptr_t buffer = phys_to_virt ( dest );
void *buffer = phys_to_virt ( dest );
int rc;
DBGC ( image, "ELF %s loading segment [%x,%x) to [%lx,%lx,%lx)\n",
@@ -82,9 +81,11 @@ static int elf_load_segment ( struct image *image, Elf_Phdr *phdr,
* @ret max Maximum used address
* @ret rc Return status code
*/
static int elf_segment ( struct image *image, Elf_Ehdr *ehdr, Elf_Phdr *phdr,
static int elf_segment ( struct image *image, const Elf_Ehdr *ehdr,
const Elf_Phdr *phdr,
int ( * process ) ( struct image *image,
Elf_Phdr *phdr, physaddr_t dest ),
const Elf_Phdr *phdr,
physaddr_t dest ),
physaddr_t *entry, physaddr_t *max ) {
physaddr_t dest;
physaddr_t end;
@@ -151,11 +152,12 @@ static int elf_segment ( struct image *image, Elf_Ehdr *ehdr, Elf_Phdr *phdr,
* @ret max Maximum used address
* @ret rc Return status code
*/
int elf_segments ( struct image *image, Elf_Ehdr *ehdr,
int ( * process ) ( struct image *image, Elf_Phdr *phdr,
int elf_segments ( struct image *image, const Elf_Ehdr *ehdr,
int ( * process ) ( struct image *image,
const Elf_Phdr *phdr,
physaddr_t dest ),
physaddr_t *entry, physaddr_t *max ) {
Elf_Phdr phdr;
const Elf_Phdr *phdr;
Elf_Off phoff;
unsigned int phnum;
int rc;
@@ -169,13 +171,14 @@ int elf_segments ( struct image *image, Elf_Ehdr *ehdr,
/* Read and process ELF program headers */
for ( phoff = ehdr->e_phoff , phnum = ehdr->e_phnum ; phnum ;
phoff += ehdr->e_phentsize, phnum-- ) {
if ( phoff > image->len ) {
if ( ( image->len < phoff ) ||
( ( image->len - phoff ) < sizeof ( *phdr ) ) ) {
DBGC ( image, "ELF %s program header %d outside "
"image\n", image->name, phnum );
return -ENOEXEC;
}
copy_from_user ( &phdr, image->data, phoff, sizeof ( phdr ) );
if ( ( rc = elf_segment ( image, ehdr, &phdr, process,
phdr = ( image->data + phoff );
if ( ( rc = elf_segment ( image, ehdr, phdr, process,
entry, max ) ) != 0 )
return rc;
}
@@ -206,19 +209,23 @@ int elf_load ( struct image *image, physaddr_t *entry, physaddr_t *max ) {
[EI_MAG3] = ELFMAG3,
[EI_CLASS] = ELFCLASS,
};
Elf_Ehdr ehdr;
const Elf_Ehdr *ehdr;
int rc;
/* Read ELF header */
copy_from_user ( &ehdr, image->data, 0, sizeof ( ehdr ) );
if ( memcmp ( &ehdr.e_ident[EI_MAG0], e_ident,
sizeof ( e_ident ) ) != 0 ) {
if ( image->len < sizeof ( *ehdr ) ) {
DBGC ( image, "ELF %s too short for ELF header\n",
image->name );
return -ENOEXEC;
}
ehdr = image->data;
if ( memcmp ( ehdr->e_ident, e_ident, sizeof ( e_ident ) ) != 0 ) {
DBGC ( image, "ELF %s has invalid signature\n", image->name );
return -ENOEXEC;
}
/* Load ELF segments into memory */
if ( ( rc = elf_segments ( image, &ehdr, elf_load_segment,
if ( ( rc = elf_segments ( image, ehdr, elf_load_segment,
entry, max ) ) != 0 )
return rc;