linux/crypto/asymmetric_keys/pkcs7_parser.c
David Howells 46963b774d KEYS: Overhaul key identification when searching for asymmetric keys
Make use of the new match string preparsing to overhaul key identification
when searching for asymmetric keys.  The following changes are made:

 (1) Use the previously created asymmetric_key_id struct to hold the following
     key IDs derived from the X.509 certificate or PKCS#7 message:

	id: serial number + issuer
	skid: subjKeyId + subject
	authority: authKeyId + issuer

 (2) Replace the hex fingerprint attached to key->type_data[1] with an
     asymmetric_key_ids struct containing the id and the skid (if present).

 (3) Make the asymmetric_type match data preparse select one of two searches:

     (a) An iterative search for the key ID given if prefixed with "id:".  The
     	 prefix is expected to be followed by a hex string giving the ID to
     	 search for.  The criterion key ID is checked against all key IDs
     	 recorded on the key.

     (b) A direct search if the key ID is not prefixed with "id:".  This will
     	 look for an exact match on the key description.

 (4) Make x509_request_asymmetric_key() take a key ID.  This is then converted
     into "id:<hex>" and passed into keyring_search() where match preparsing
     will turn it back into a binary ID.

 (5) X.509 certificate verification then takes the authority key ID and looks
     up a key that matches it to find the public key for the certificate
     signature.

 (6) PKCS#7 certificate verification then takes the id key ID and looks up a
     key that matches it to find the public key for the signed information
     block signature.

Additional changes:

 (1) Multiple subjKeyId and authKeyId values on an X.509 certificate cause the
     cert to be rejected with -EBADMSG.

 (2) The 'fingerprint' ID is gone.  This was primarily intended to convey PGP
     public key fingerprints.  If PGP is supported in future, this should
     generate a key ID that carries the fingerprint.

 (3) Th ca_keyid= kernel command line option is now converted to a key ID and
     used to match the authority key ID.  Possibly this should only match the
     actual authKeyId part and not the issuer as well.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-16 17:36:13 +01:00

418 lines
10 KiB
C

/* PKCS#7 parser
*
* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#define pr_fmt(fmt) "PKCS7: "fmt
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/oid_registry.h>
#include "public_key.h"
#include "pkcs7_parser.h"
#include "pkcs7-asn1.h"
struct pkcs7_parse_context {
struct pkcs7_message *msg; /* Message being constructed */
struct pkcs7_signed_info *sinfo; /* SignedInfo being constructed */
struct pkcs7_signed_info **ppsinfo;
struct x509_certificate *certs; /* Certificate cache */
struct x509_certificate **ppcerts;
unsigned long data; /* Start of data */
enum OID last_oid; /* Last OID encountered */
unsigned x509_index;
unsigned sinfo_index;
const void *raw_serial;
unsigned raw_serial_size;
unsigned raw_issuer_size;
const void *raw_issuer;
};
/*
* Free a signed information block.
*/
static void pkcs7_free_signed_info(struct pkcs7_signed_info *sinfo)
{
if (sinfo) {
mpi_free(sinfo->sig.mpi[0]);
kfree(sinfo->sig.digest);
kfree(sinfo->signing_cert_id);
kfree(sinfo);
}
}
/**
* pkcs7_free_message - Free a PKCS#7 message
* @pkcs7: The PKCS#7 message to free
*/
void pkcs7_free_message(struct pkcs7_message *pkcs7)
{
struct x509_certificate *cert;
struct pkcs7_signed_info *sinfo;
if (pkcs7) {
while (pkcs7->certs) {
cert = pkcs7->certs;
pkcs7->certs = cert->next;
x509_free_certificate(cert);
}
while (pkcs7->crl) {
cert = pkcs7->crl;
pkcs7->crl = cert->next;
x509_free_certificate(cert);
}
while (pkcs7->signed_infos) {
sinfo = pkcs7->signed_infos;
pkcs7->signed_infos = sinfo->next;
pkcs7_free_signed_info(sinfo);
}
kfree(pkcs7);
}
}
EXPORT_SYMBOL_GPL(pkcs7_free_message);
/**
* pkcs7_parse_message - Parse a PKCS#7 message
* @data: The raw binary ASN.1 encoded message to be parsed
* @datalen: The size of the encoded message
*/
struct pkcs7_message *pkcs7_parse_message(const void *data, size_t datalen)
{
struct pkcs7_parse_context *ctx;
struct pkcs7_message *msg = ERR_PTR(-ENOMEM);
int ret;
ctx = kzalloc(sizeof(struct pkcs7_parse_context), GFP_KERNEL);
if (!ctx)
goto out_no_ctx;
ctx->msg = kzalloc(sizeof(struct pkcs7_message), GFP_KERNEL);
if (!ctx->msg)
goto out_no_msg;
ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
if (!ctx->sinfo)
goto out_no_sinfo;
ctx->data = (unsigned long)data;
ctx->ppcerts = &ctx->certs;
ctx->ppsinfo = &ctx->msg->signed_infos;
/* Attempt to decode the signature */
ret = asn1_ber_decoder(&pkcs7_decoder, ctx, data, datalen);
if (ret < 0) {
msg = ERR_PTR(ret);
goto out;
}
msg = ctx->msg;
ctx->msg = NULL;
out:
while (ctx->certs) {
struct x509_certificate *cert = ctx->certs;
ctx->certs = cert->next;
x509_free_certificate(cert);
}
pkcs7_free_signed_info(ctx->sinfo);
out_no_sinfo:
pkcs7_free_message(ctx->msg);
out_no_msg:
kfree(ctx);
out_no_ctx:
return msg;
}
EXPORT_SYMBOL_GPL(pkcs7_parse_message);
/**
* pkcs7_get_content_data - Get access to the PKCS#7 content
* @pkcs7: The preparsed PKCS#7 message to access
* @_data: Place to return a pointer to the data
* @_data_len: Place to return the data length
* @want_wrapper: True if the ASN.1 object header should be included in the data
*
* Get access to the data content of the PKCS#7 message, including, optionally,
* the header of the ASN.1 object that contains it. Returns -ENODATA if the
* data object was missing from the message.
*/
int pkcs7_get_content_data(const struct pkcs7_message *pkcs7,
const void **_data, size_t *_data_len,
bool want_wrapper)
{
size_t wrapper;
if (!pkcs7->data)
return -ENODATA;
wrapper = want_wrapper ? pkcs7->data_hdrlen : 0;
*_data = pkcs7->data - wrapper;
*_data_len = pkcs7->data_len + wrapper;
return 0;
}
EXPORT_SYMBOL_GPL(pkcs7_get_content_data);
/*
* Note an OID when we find one for later processing when we know how
* to interpret it.
*/
int pkcs7_note_OID(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct pkcs7_parse_context *ctx = context;
ctx->last_oid = look_up_OID(value, vlen);
if (ctx->last_oid == OID__NR) {
char buffer[50];
sprint_oid(value, vlen, buffer, sizeof(buffer));
printk("PKCS7: Unknown OID: [%lu] %s\n",
(unsigned long)value - ctx->data, buffer);
}
return 0;
}
/*
* Note the digest algorithm for the signature.
*/
int pkcs7_sig_note_digest_algo(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct pkcs7_parse_context *ctx = context;
switch (ctx->last_oid) {
case OID_md4:
ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_MD4;
break;
case OID_md5:
ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_MD5;
break;
case OID_sha1:
ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_SHA1;
break;
case OID_sha256:
ctx->sinfo->sig.pkey_hash_algo = HASH_ALGO_SHA256;
break;
default:
printk("Unsupported digest algo: %u\n", ctx->last_oid);
return -ENOPKG;
}
return 0;
}
/*
* Note the public key algorithm for the signature.
*/
int pkcs7_sig_note_pkey_algo(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct pkcs7_parse_context *ctx = context;
switch (ctx->last_oid) {
case OID_rsaEncryption:
ctx->sinfo->sig.pkey_algo = PKEY_ALGO_RSA;
break;
default:
printk("Unsupported pkey algo: %u\n", ctx->last_oid);
return -ENOPKG;
}
return 0;
}
/*
* Extract a certificate and store it in the context.
*/
int pkcs7_extract_cert(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct pkcs7_parse_context *ctx = context;
struct x509_certificate *x509;
if (tag != ((ASN1_UNIV << 6) | ASN1_CONS_BIT | ASN1_SEQ)) {
pr_debug("Cert began with tag %02x at %lu\n",
tag, (unsigned long)ctx - ctx->data);
return -EBADMSG;
}
/* We have to correct for the header so that the X.509 parser can start
* from the beginning. Note that since X.509 stipulates DER, there
* probably shouldn't be an EOC trailer - but it is in PKCS#7 (which
* stipulates BER).
*/
value -= hdrlen;
vlen += hdrlen;
if (((u8*)value)[1] == 0x80)
vlen += 2; /* Indefinite length - there should be an EOC */
x509 = x509_cert_parse(value, vlen);
if (IS_ERR(x509))
return PTR_ERR(x509);
x509->index = ++ctx->x509_index;
pr_debug("Got cert %u for %s\n", x509->index, x509->subject);
pr_debug("- fingerprint %*phN\n", x509->id->len, x509->id->data);
*ctx->ppcerts = x509;
ctx->ppcerts = &x509->next;
return 0;
}
/*
* Save the certificate list
*/
int pkcs7_note_certificate_list(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct pkcs7_parse_context *ctx = context;
pr_devel("Got cert list (%02x)\n", tag);
*ctx->ppcerts = ctx->msg->certs;
ctx->msg->certs = ctx->certs;
ctx->certs = NULL;
ctx->ppcerts = &ctx->certs;
return 0;
}
/*
* Extract the data from the message and store that and its content type OID in
* the context.
*/
int pkcs7_note_data(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct pkcs7_parse_context *ctx = context;
pr_debug("Got data\n");
ctx->msg->data = value;
ctx->msg->data_len = vlen;
ctx->msg->data_hdrlen = hdrlen;
ctx->msg->data_type = ctx->last_oid;
return 0;
}
/*
* Parse authenticated attributes
*/
int pkcs7_sig_note_authenticated_attr(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct pkcs7_parse_context *ctx = context;
pr_devel("AuthAttr: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);
switch (ctx->last_oid) {
case OID_messageDigest:
if (tag != ASN1_OTS)
return -EBADMSG;
ctx->sinfo->msgdigest = value;
ctx->sinfo->msgdigest_len = vlen;
return 0;
default:
return 0;
}
}
/*
* Note the set of auth attributes for digestion purposes [RFC2315 9.3]
*/
int pkcs7_sig_note_set_of_authattrs(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct pkcs7_parse_context *ctx = context;
/* We need to switch the 'CONT 0' to a 'SET OF' when we digest */
ctx->sinfo->authattrs = value - (hdrlen - 1);
ctx->sinfo->authattrs_len = vlen + (hdrlen - 1);
return 0;
}
/*
* Note the issuing certificate serial number
*/
int pkcs7_sig_note_serial(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct pkcs7_parse_context *ctx = context;
ctx->raw_serial = value;
ctx->raw_serial_size = vlen;
return 0;
}
/*
* Note the issuer's name
*/
int pkcs7_sig_note_issuer(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct pkcs7_parse_context *ctx = context;
ctx->raw_issuer = value;
ctx->raw_issuer_size = vlen;
return 0;
}
/*
* Note the signature data
*/
int pkcs7_sig_note_signature(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct pkcs7_parse_context *ctx = context;
MPI mpi;
BUG_ON(ctx->sinfo->sig.pkey_algo != PKEY_ALGO_RSA);
mpi = mpi_read_raw_data(value, vlen);
if (!mpi)
return -ENOMEM;
ctx->sinfo->sig.mpi[0] = mpi;
ctx->sinfo->sig.nr_mpi = 1;
return 0;
}
/*
* Note a signature information block
*/
int pkcs7_note_signed_info(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct pkcs7_parse_context *ctx = context;
struct pkcs7_signed_info *sinfo = ctx->sinfo;
struct asymmetric_key_id *kid;
/* Generate cert issuer + serial number key ID */
kid = asymmetric_key_generate_id(ctx->raw_serial,
ctx->raw_serial_size,
ctx->raw_issuer,
ctx->raw_issuer_size);
if (IS_ERR(kid))
return PTR_ERR(kid);
sinfo->signing_cert_id = kid;
sinfo->index = ++ctx->sinfo_index;
*ctx->ppsinfo = sinfo;
ctx->ppsinfo = &sinfo->next;
ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
if (!ctx->sinfo)
return -ENOMEM;
return 0;
}