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[crypto] Remove userptr_t from ASN.1 parsers

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Simplify the ASN.1 code by assuming that all objects are fully
accessible via pointer dereferences.  This allows the concept of
"additional data beyond the end of the cursor" to be removed, and
simplifies parsing of all ASN.1 image formats.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2025-04-21 22:40:59 +01:00
parent 04d0b2fdf9
commit 3f8937d2f3
10 changed files with 70 additions and 109 deletions
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64
src/crypto/asn1.c
View File

@@ -88,7 +88,6 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
*
* @v cursor ASN.1 object cursor
* @v type Expected type, or ASN1_ANY
* @v extra Additional length not present within partial cursor
* @ret len Length of object body, or negative error
*
* The object cursor will be updated to point to the start of the
@@ -100,8 +99,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
* modified. If any other error occurs, the object cursor will be
* invalidated.
*/
static int asn1_start ( struct asn1_cursor *cursor, unsigned int type,
size_t extra ) {
static int asn1_start ( struct asn1_cursor *cursor, unsigned int type ) {
unsigned int len_len;
unsigned int len;
@@ -145,9 +143,9 @@ static int asn1_start ( struct asn1_cursor *cursor, unsigned int type,
cursor->data++;
cursor->len--;
}
if ( ( cursor->len + extra ) < len ) {
if ( cursor->len < len ) {
DBGC ( cursor, "ASN1 %p bad length %d (max %zd)\n",
cursor, len, ( cursor->len + extra ) );
cursor, len, cursor->len );
asn1_invalidate_cursor ( cursor );
return -EINVAL_ASN1_LEN;
}
@@ -155,41 +153,6 @@ static int asn1_start ( struct asn1_cursor *cursor, unsigned int type,
return len;
}
/**
* Enter ASN.1 partial object
*
* @v cursor ASN.1 object cursor
* @v type Expected type, or ASN1_ANY
* @v extra Additional length beyond partial object
* @ret rc Return status code
*
* The object cursor and additional length will be updated to point to
* the body of the current ASN.1 object.
*
* If any error occurs, the object cursor will be invalidated.
*/
int asn1_enter_partial ( struct asn1_cursor *cursor, unsigned int type,
size_t *extra ) {
int len;
/* Parse current object */
len = asn1_start ( cursor, type, *extra );
if ( len < 0 ) {
asn1_invalidate_cursor ( cursor );
return len;
}
/* Update cursor and additional length */
if ( ( ( size_t ) len ) <= cursor->len )
cursor->len = len;
assert ( ( len - cursor->len ) <= *extra );
*extra = ( len - cursor->len );
DBGC ( cursor, "ASN1 %p entered object type %02x (len %x)\n",
cursor, type, len );
return 0;
}
/**
* Enter ASN.1 object
*
@@ -203,9 +166,22 @@ int asn1_enter_partial ( struct asn1_cursor *cursor, unsigned int type,
* If any error occurs, the object cursor will be invalidated.
*/
int asn1_enter ( struct asn1_cursor *cursor, unsigned int type ) {
static size_t no_extra = 0;
int len;
return asn1_enter_partial ( cursor, type, &no_extra );
/* Parse current object */
len = asn1_start ( cursor, type );
if ( len < 0 ) {
asn1_invalidate_cursor ( cursor );
return len;
}
/* Update cursor */
if ( ( ( size_t ) len ) <= cursor->len )
cursor->len = len;
DBGC ( cursor, "ASN1 %p entered object type %02x (len %x)\n",
cursor, type, len );
return 0;
}
/**
@@ -226,7 +202,7 @@ int asn1_skip_if_exists ( struct asn1_cursor *cursor, unsigned int type ) {
int len;
/* Parse current object */
len = asn1_start ( cursor, type, 0 );
len = asn1_start ( cursor, type );
if ( len < 0 )
return len;
@@ -281,7 +257,7 @@ int asn1_shrink ( struct asn1_cursor *cursor, unsigned int type ) {
/* Find end of object */
memcpy ( &temp, cursor, sizeof ( temp ) );
len = asn1_start ( &temp, type, 0 );
len = asn1_start ( &temp, type );
if ( len < 0 ) {
asn1_invalidate_cursor ( cursor );
return len;

2
src/drivers/net/iphone.c
View File

@@ -1476,7 +1476,7 @@ static int ipair_rx_pubkey ( struct ipair *ipair, char *msg ) {
}
/* Decode inner layer of Base64 */
next = pem_asn1 ( virt_to_user ( decoded ), len, 0, &key );
next = pem_asn1 ( decoded, len, 0, &key );
if ( next < 0 ) {
rc = next;
DBGC ( ipair, "IPAIR %p invalid inner public key:\n%s\n",

24
src/image/der.c
View File

@@ -28,7 +28,6 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <assert.h>
#include <ipxe/asn1.h>
#include <ipxe/der.h>
#include <ipxe/uaccess.h>
#include <ipxe/image.h>
/** @file
@@ -49,7 +48,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
* The caller is responsible for eventually calling free() on the
* allocated ASN.1 cursor.
*/
int der_asn1 ( userptr_t data, size_t len, size_t offset,
int der_asn1 ( const void *data, size_t len, size_t offset,
struct asn1_cursor **cursor ) {
size_t remaining;
void *raw;
@@ -67,7 +66,7 @@ int der_asn1 ( userptr_t data, size_t len, size_t offset,
/* Populate cursor and data buffer */
(*cursor)->data = raw;
(*cursor)->len = remaining;
copy_from_user ( raw, data, offset, remaining );
memcpy ( raw, ( data + offset ), remaining );
/* Shrink cursor */
asn1_shrink_any ( *cursor );
@@ -83,30 +82,21 @@ int der_asn1 ( userptr_t data, size_t len, size_t offset,
*/
static int der_image_probe ( struct image *image ) {
struct asn1_cursor cursor;
uint8_t buf[8];
size_t extra;
int rc;
/* Sanity check: no realistic DER image can be smaller than this */
if ( image->len < sizeof ( buf ) )
return -ENOEXEC;
/* Prepare partial cursor */
cursor.data = buf;
cursor.len = sizeof ( buf );
copy_from_user ( buf, image->data, 0, sizeof ( buf ) );
extra = ( image->len - sizeof ( buf ) );
/* Prepare cursor */
cursor.data = image->data;
cursor.len = image->len;
/* Check that image begins with an ASN.1 sequence object */
if ( ( rc = asn1_enter_partial ( &cursor, ASN1_SEQUENCE,
&extra ) ) != 0 ) {
if ( ( rc = asn1_skip ( &cursor, ASN1_SEQUENCE ) ) != 0 ) {
DBGC ( image, "DER %s is not valid ASN.1: %s\n",
image->name, strerror ( rc ) );
return rc;
}
/* Check that image comprises a single well-formed ASN.1 object */
if ( extra != ( image->len - sizeof ( buf ) ) ) {
if ( cursor.len ) {
DBGC ( image, "DER %s is not single ASN.1\n", image->name );
return -ENOEXEC;
}

51
src/image/efi_siglist.c
View File

@@ -49,8 +49,9 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
* @v dhdr Signature data header to fill in
* @ret rc Return status code
*/
static int efisig_find ( userptr_t data, size_t len, size_t *start,
EFI_SIGNATURE_LIST *lhdr, EFI_SIGNATURE_DATA *dhdr ) {
static int efisig_find ( const void *data, size_t len, size_t *start,
const EFI_SIGNATURE_LIST **lhdr,
const EFI_SIGNATURE_DATA **dhdr ) {
size_t offset;
size_t remaining;
size_t skip;
@@ -63,38 +64,38 @@ static int efisig_find ( userptr_t data, size_t len, size_t *start,
/* Read list header */
assert ( offset <= len );
remaining = ( len - offset );
if ( remaining < sizeof ( *lhdr ) ) {
if ( remaining < sizeof ( **lhdr ) ) {
DBGC ( data, "EFISIG [%#zx,%#zx) truncated header "
"at +%#zx\n", *start, len, offset );
return -EINVAL;
}
copy_from_user ( lhdr, data, offset, sizeof ( *lhdr ) );
*lhdr = ( data + offset );
/* Get length of this signature list */
if ( remaining < lhdr->SignatureListSize ) {
if ( remaining < (*lhdr)->SignatureListSize ) {
DBGC ( data, "EFISIG [%#zx,%#zx) truncated list at "
"+%#zx\n", *start, len, offset );
return -EINVAL;
}
remaining = lhdr->SignatureListSize;
remaining = (*lhdr)->SignatureListSize;
/* Get length of each signature in list */
dlen = lhdr->SignatureSize;
if ( dlen < sizeof ( *dhdr ) ) {
dlen = (*lhdr)->SignatureSize;
if ( dlen < sizeof ( **dhdr ) ) {
DBGC ( data, "EFISIG [%#zx,%#zx) underlength "
"signatures at +%#zx\n", *start, len, offset );
return -EINVAL;
}
/* Strip list header (including variable portion) */
if ( ( remaining < sizeof ( *lhdr ) ) ||
( ( remaining - sizeof ( *lhdr ) ) <
lhdr->SignatureHeaderSize ) ) {
if ( ( remaining < sizeof ( **lhdr ) ) ||
( ( remaining - sizeof ( **lhdr ) ) <
(*lhdr)->SignatureHeaderSize ) ) {
DBGC ( data, "EFISIG [%#zx,%#zx) malformed header at "
"+%#zx\n", *start, len, offset );
return -EINVAL;
}
skip = ( sizeof ( *lhdr ) + lhdr->SignatureHeaderSize );
skip = ( sizeof ( **lhdr ) + (*lhdr)->SignatureHeaderSize );
offset += skip;
remaining -= skip;
@@ -113,12 +114,12 @@ static int efisig_find ( userptr_t data, size_t len, size_t *start,
continue;
/* Read data header */
copy_from_user ( dhdr, data, offset, sizeof ( *dhdr ));
*dhdr = ( data + offset );
DBGC2 ( data, "EFISIG [%#zx,%#zx) %s ",
offset, ( offset + dlen ),
efi_guid_ntoa ( &lhdr->SignatureType ) );
efi_guid_ntoa ( &(*lhdr)->SignatureType ) );
DBGC2 ( data, "owner %s\n",
efi_guid_ntoa ( &dhdr->SignatureOwner ) );
efi_guid_ntoa ( &(*dhdr)->SignatureOwner ) );
*start = offset;
return 0;
}
@@ -137,23 +138,23 @@ static int efisig_find ( userptr_t data, size_t len, size_t *start,
* The caller is responsible for eventually calling free() on the
* allocated ASN.1 cursor.
*/
int efisig_asn1 ( userptr_t data, size_t len, size_t offset,
int efisig_asn1 ( const void *data, size_t len, size_t offset,
struct asn1_cursor **cursor ) {
EFI_SIGNATURE_LIST lhdr;
EFI_SIGNATURE_DATA dhdr;
int ( * asn1 ) ( userptr_t data, size_t len, size_t offset,
const EFI_SIGNATURE_LIST *lhdr;
const EFI_SIGNATURE_DATA *dhdr;
int ( * asn1 ) ( const void *data, size_t len, size_t offset,
struct asn1_cursor **cursor );
size_t skip = offsetof ( typeof ( dhdr ), SignatureData );
size_t skip = offsetof ( typeof ( *dhdr ), SignatureData );
int next;
int rc;
/* Locate signature list entry */
if ( ( rc = efisig_find ( data, len, &offset, &lhdr, &dhdr ) ) != 0 )
goto err_entry;
len = ( offset + lhdr.SignatureSize );
len = ( offset + lhdr->SignatureSize );
/* Parse as PEM or DER based on first character */
asn1 = ( ( dhdr.SignatureData[0] == ASN1_SEQUENCE ) ?
asn1 = ( ( dhdr->SignatureData[0] == ASN1_SEQUENCE ) ?
der_asn1 : pem_asn1 );
DBGC2 ( data, "EFISIG [%#zx,%#zx) extracting %s\n", offset, len,
( ( asn1 == der_asn1 ) ? "DER" : "PEM" ) );
@@ -189,8 +190,8 @@ int efisig_asn1 ( userptr_t data, size_t len, size_t offset,
* @ret rc Return status code
*/
static int efisig_image_probe ( struct image *image ) {
EFI_SIGNATURE_LIST lhdr;
EFI_SIGNATURE_DATA dhdr;
const EFI_SIGNATURE_LIST *lhdr;
const EFI_SIGNATURE_DATA *dhdr;
size_t offset = 0;
unsigned int count = 0;
int rc;
@@ -205,7 +206,7 @@ static int efisig_image_probe ( struct image *image ) {
}
/* Skip this entry */
offset += lhdr.SignatureSize;
offset += lhdr->SignatureSize;
count++;
/* Check if we have reached end of the image */

24
src/image/pem.c
View File

@@ -28,7 +28,6 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <assert.h>
#include <ipxe/asn1.h>
#include <ipxe/base64.h>
#include <ipxe/uaccess.h>
#include <ipxe/image.h>
#include <ipxe/pem.h>
@@ -46,14 +45,14 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
* @v offset Starting offset
* @ret next Offset to next line
*/
static size_t pem_next ( userptr_t data, size_t len, size_t offset ) {
off_t eol;
static size_t pem_next ( const void *data, size_t len, size_t offset ) {
const void *sep;
/* Find and skip next newline character, if any */
eol = memchr_user ( data, offset, '\n', ( len - offset ) );
if ( eol < 0 )
sep = memchr ( ( data + offset ), '\n', ( len - offset ) );
if ( ! sep )
return len;
return ( eol + 1 );
return ( ( sep - data ) + 1 );
}
/**
@@ -65,9 +64,9 @@ static size_t pem_next ( userptr_t data, size_t len, size_t offset ) {
* @v marker Boundary marker
* @ret offset Offset to boundary marker line, or negative error
*/
static int pem_marker ( userptr_t data, size_t len, size_t offset,
static int pem_marker ( const void *data, size_t len, size_t offset,
const char *marker ) {
char buf[ strlen ( marker ) ];
size_t marker_len = strlen ( marker );
/* Sanity check */
assert ( offset <= len );
@@ -76,10 +75,9 @@ static int pem_marker ( userptr_t data, size_t len, size_t offset,
while ( offset < len ) {
/* Check for marker */
if ( ( len - offset ) < sizeof ( buf ) )
if ( ( len - offset ) < marker_len )
break;
copy_from_user ( buf, data, offset, sizeof ( buf ) );
if ( memcmp ( buf, marker, sizeof ( buf ) ) == 0 )
if ( memcmp ( ( data + offset ), marker, marker_len ) == 0 )
return offset;
/* Move to next line */
@@ -102,7 +100,7 @@ static int pem_marker ( userptr_t data, size_t len, size_t offset,
* The caller is responsible for eventually calling free() on the
* allocated ASN.1 cursor.
*/
int pem_asn1 ( userptr_t data, size_t len, size_t offset,
int pem_asn1 ( const void *data, size_t len, size_t offset,
struct asn1_cursor **cursor ) {
size_t encoded_len;
size_t decoded_max_len;
@@ -140,7 +138,7 @@ int pem_asn1 ( userptr_t data, size_t len, size_t offset,
rc = -ENOMEM;
goto err_alloc_encoded;
}
copy_from_user ( encoded, data, begin, encoded_len );
memcpy ( encoded, ( data + begin ), encoded_len );
encoded[encoded_len] = '\0';
/* Allocate cursor and data buffer */

2
src/include/ipxe/asn1.h
View File

@@ -481,8 +481,6 @@ asn1_built ( struct asn1_builder *builder ) {
return &u->cursor;
}
extern int asn1_enter_partial ( struct asn1_cursor *cursor, unsigned int type,
size_t *extra );
extern int asn1_enter ( struct asn1_cursor *cursor, unsigned int type );
extern int asn1_skip_if_exists ( struct asn1_cursor *cursor,
unsigned int type );

2
src/include/ipxe/der.h
View File

@@ -13,7 +13,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <ipxe/asn1.h>
#include <ipxe/image.h>
extern int der_asn1 ( userptr_t data, size_t len, size_t offset,
extern int der_asn1 ( const void *data, size_t len, size_t offset,
struct asn1_cursor **cursor );
extern struct image_type der_image_type __image_type ( PROBE_NORMAL );

3
src/include/ipxe/efi/efi_siglist.h
View File

@@ -10,11 +10,10 @@
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <stdint.h>
#include <ipxe/uaccess.h>
#include <ipxe/asn1.h>
#include <ipxe/image.h>
extern int efisig_asn1 ( userptr_t data, size_t len, size_t offset,
extern int efisig_asn1 ( const void *data, size_t len, size_t offset,
struct asn1_cursor **cursor );
extern struct image_type efisig_image_type __image_type ( PROBE_NORMAL );

3
src/include/ipxe/pem.h
View File

@@ -10,7 +10,6 @@
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <stdint.h>
#include <ipxe/uaccess.h>
#include <ipxe/asn1.h>
#include <ipxe/image.h>
@@ -20,7 +19,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
/** Post-encapsulation boundary marker */
#define PEM_END "-----END"
extern int pem_asn1 ( userptr_t data, size_t len, size_t offset,
extern int pem_asn1 ( const void *data, size_t len, size_t offset,
struct asn1_cursor **cursor );
extern struct image_type pem_image_type __image_type ( PROBE_NORMAL );

4
src/interface/efi/efi_cacert.c
View File

@@ -54,14 +54,14 @@ static struct x509_chain efi_cacerts = {
* @v offset Offset within data
* @v next Next offset, or negative error
*/
static int efi_cacert ( void *data, size_t len, size_t offset ) {
static int efi_cacert ( const void *data, size_t len, size_t offset ) {
struct asn1_cursor *cursor;
struct x509_certificate *cert;
int next;
int rc;
/* Extract ASN.1 object */
next = efisig_asn1 ( virt_to_user ( data ), len, offset, &cursor );
next = efisig_asn1 ( data, len, offset, &cursor );
if ( next < 0 ) {
rc = next;
DBGC ( &efi_cacerts, "EFICA could not parse at +%#zx: %s\n",