- 根目录:
- crypto
- asymmetric_keys
- x509_cert_parser.c
/* X.509 certificate 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) "X.509: "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 "x509_parser.h"
#include "x509-asn1.h"
#include "x509_rsakey-asn1.h"
struct x509_parse_context {
struct x509_certificate *cert; /* Certificate being constructed */
unsigned long data; /* Start of data */
const void *cert_start; /* Start of cert content */
const void *key; /* Key data */
size_t key_size; /* Size of key data */
enum OID last_oid; /* Last OID encountered */
enum OID algo_oid; /* Algorithm OID */
unsigned char nr_mpi; /* Number of MPIs stored */
u8 o_size; /* Size of organizationName (O) */
u8 cn_size; /* Size of commonName (CN) */
u8 email_size; /* Size of emailAddress */
u16 o_offset; /* Offset of organizationName (O) */
u16 cn_offset; /* Offset of commonName (CN) */
u16 email_offset; /* Offset of emailAddress */
};
/*
* Free an X.509 certificate
*/
void x509_free_certificate(struct x509_certificate *cert)
{
if (cert) {
public_key_destroy(cert->pub);
kfree(cert->issuer);
kfree(cert->subject);
kfree(cert->id);
kfree(cert->skid);
kfree(cert->authority);
kfree(cert->sig.digest);
mpi_free(cert->sig.rsa.s);
kfree(cert);
}
}
EXPORT_SYMBOL_GPL(x509_free_certificate);
/*
* Parse an X.509 certificate
*/
struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
{
struct x509_certificate *cert;
struct x509_parse_context *ctx;
struct asymmetric_key_id *kid;
long ret;
ret = -ENOMEM;
cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
if (!cert)
goto error_no_cert;
cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
if (!cert->pub)
goto error_no_ctx;
ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
if (!ctx)
goto error_no_ctx;
ctx->cert = cert;
ctx->data = (unsigned long)data;
/* Attempt to decode the certificate */
ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
if (ret < 0)
goto error_decode;
/* Decode the public key */
ret = asn1_ber_decoder(&x509_rsakey_decoder, ctx,
ctx->key, ctx->key_size);
if (ret < 0)
goto error_decode;
/* Generate cert issuer + serial number key ID */
kid = asymmetric_key_generate_id(cert->raw_serial,
cert->raw_serial_size,
cert->raw_issuer,
cert->raw_issuer_size);
if (IS_ERR(kid)) {
ret = PTR_ERR(kid);
goto error_decode;
}
cert->id = kid;
kfree(ctx);
return cert;
error_decode:
kfree(ctx);
error_no_ctx:
x509_free_certificate(cert);
error_no_cert:
return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(x509_cert_parse);
/*
* Note an OID when we find one for later processing when we know how
* to interpret it.
*/
int x509_note_OID(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct x509_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));
pr_debug("Unknown OID: [%lu] %s\n",
(unsigned long)value - ctx->data, buffer);
}
return 0;
}
/*
* Save the position of the TBS data so that we can check the signature over it
* later.
*/
int x509_note_tbs_certificate(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct x509_parse_context *ctx = context;
pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
hdrlen, tag, (unsigned long)value - ctx->data, vlen);
ctx->cert->tbs = value - hdrlen;
ctx->cert->tbs_size = vlen + hdrlen;
return 0;
}
/*
* Record the public key algorithm
*/
int x509_note_pkey_algo(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct x509_parse_context *ctx = context;
pr_debug("PubKey Algo: %u\n", ctx->last_oid);
switch (ctx->last_oid) {
case OID_md2WithRSAEncryption:
case OID_md3WithRSAEncryption:
default:
return -ENOPKG; /* Unsupported combination */
case OID_md4WithRSAEncryption:
ctx->cert->sig.pkey_hash_algo = HASH_ALGO_MD5;
ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
break;
case OID_sha1WithRSAEncryption:
ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA1;
ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
break;
case OID_sha256WithRSAEncryption:
ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA256;
ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
break;
case OID_sha384WithRSAEncryption:
ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA384;
ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
break;
case OID_sha512WithRSAEncryption:
ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA512;
ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
break;
case OID_sha224WithRSAEncryption:
ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA224;
ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
break;
}
ctx->algo_oid = ctx->last_oid;
return 0;
}
/*
* Note the whereabouts and type of the signature.
*/
int x509_note_signature(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct x509_parse_context *ctx = context;
pr_debug("Signature type: %u size %zu\n", ctx->last_oid, vlen);
if (ctx->last_oid != ctx->algo_oid) {
pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n",
ctx->algo_oid, ctx->last_oid);
return -EINVAL;
}
ctx->cert->raw_sig = value;
ctx->cert->raw_sig_size = vlen;
return 0;
}
/*
* Note the certificate serial number
*/
int x509_note_serial(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct x509_parse_context *ctx = context;
ctx->cert->raw_serial = value;
ctx->cert->raw_serial_size = vlen;
return 0;
}
/*
* Note some of the name segments from which we'll fabricate a name.
*/
int x509_extract_name_segment(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct x509_parse_context *ctx = context;
switch (ctx->last_oid) {
case OID_commonName:
ctx->cn_size = vlen;
ctx->cn_offset = (unsigned long)value - ctx->data;
break;
case OID_organizationName:
ctx->o_size = vlen;
ctx->o_offset = (unsigned long)value - ctx->data;
break;
case OID_email_address:
ctx->email_size = vlen;
ctx->email_offset = (unsigned long)value - ctx->data;
break;
default:
break;
}
return 0;
}
/*
* Fabricate and save the issuer and subject names
*/
static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
unsigned char tag,
char **_name, size_t vlen)
{
const void *name, *data = (const void *)ctx->data;
size_t namesize;
char *buffer;
if (*_name)
return -EINVAL;
/* Empty name string if no material */
if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
buffer = kmalloc(1, GFP_KERNEL);
if (!buffer)
return -ENOMEM;
buffer[0] = 0;
goto done;
}
if (ctx->cn_size && ctx->o_size) {
/* Consider combining O and CN, but use only the CN if it is
* prefixed by the O, or a significant portion thereof.
*/
namesize = ctx->cn_size;
name = data + ctx->cn_offset;
if (ctx->cn_size >= ctx->o_size &&
memcmp(data + ctx->cn_offset, data + ctx->o_offset,
ctx->o_size) == 0)
goto single_component;
if (ctx->cn_size >= 7 &&
ctx->o_size >= 7 &&
memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
goto single_component;
buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
GFP_KERNEL);
if (!buffer)
return -ENOMEM;
memcpy(buffer,
data + ctx->o_offset, ctx->o_size);
buffer[ctx->o_size + 0] = ':';
buffer[ctx->o_size + 1] = ' ';
memcpy(buffer + ctx->o_size + 2,
data + ctx->cn_offset, ctx->cn_size);
buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
goto done;
} else if (ctx->cn_size) {
namesize = ctx->cn_size;
name = data + ctx->cn_offset;
} else if (ctx->o_size) {
namesize = ctx->o_size;
name = data + ctx->o_offset;
} else {
namesize = ctx->email_size;
name = data + ctx->email_offset;
}
single_component:
buffer = kmalloc(namesize + 1, GFP_KERNEL);
if (!buffer)
return -ENOMEM;
memcpy(buffer, name, namesize);
buffer[namesize] = 0;
done:
*_name = buffer;
ctx->cn_size = 0;
ctx->o_size = 0;
ctx->email_size = 0;
return 0;
}
int x509_note_issuer(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct x509_parse_context *ctx = context;
ctx->cert->raw_issuer = value;
ctx->cert->raw_issuer_size = vlen;
return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
}
int x509_note_subject(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct x509_parse_context *ctx = context;
ctx->cert->raw_subject = value;
ctx->cert->raw_subject_size = vlen;
return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
}
/*
* Extract the data for the public key algorithm
*/
int x509_extract_key_data(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct x509_parse_context *ctx = context;
if (ctx->last_oid != OID_rsaEncryption)
return -ENOPKG;
ctx->cert->pub->pkey_algo = PKEY_ALGO_RSA;
/* Discard the BIT STRING metadata */
ctx->key = value + 1;
ctx->key_size = vlen - 1;
return 0;
}
/*
* Extract a RSA public key value
*/
int rsa_extract_mpi(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct x509_parse_context *ctx = context;
MPI mpi;
if (ctx->nr_mpi >= ARRAY_SIZE(ctx->cert->pub->mpi)) {
pr_err("Too many public key MPIs in certificate\n");
return -EBADMSG;
}
mpi = mpi_read_raw_data(value, vlen);
if (!mpi)
return -ENOMEM;
ctx->cert->pub->mpi[ctx->nr_mpi++] = mpi;
return 0;
}
/* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
#define SEQ_TAG_KEYID (ASN1_CONT << 6)
/*
* Process certificate extensions that are used to qualify the certificate.
*/
int x509_process_extension(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct x509_parse_context *ctx = context;
struct asymmetric_key_id *kid;
const unsigned char *v = value;
int i;
pr_debug("Extension: %u\n", ctx->last_oid);
if (ctx->last_oid == OID_subjectKeyIdentifier) {
/* Get hold of the key fingerprint */
if (ctx->cert->skid || vlen < 3)
return -EBADMSG;
if (v[0] != ASN1_OTS || v[1] != vlen - 2)
return -EBADMSG;
v += 2;
vlen -= 2;
ctx->cert->raw_skid_size = vlen;
ctx->cert->raw_skid = v;
kid = asymmetric_key_generate_id(ctx->cert->raw_subject,
ctx->cert->raw_subject_size,
v, vlen);
if (IS_ERR(kid))
return PTR_ERR(kid);
ctx->cert->skid = kid;
pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
return 0;
}
if (ctx->last_oid == OID_authorityKeyIdentifier) {
/* Get hold of the CA key fingerprint */
if (ctx->cert->authority || vlen < 5)
return -EBADMSG;
/* Authority Key Identifier must be a Constructed SEQUENCE */
if (v[0] != (ASN1_SEQ | (ASN1_CONS << 5)))
return -EBADMSG;
/* Authority Key Identifier is not indefinite length */
if (unlikely(vlen == ASN1_INDEFINITE_LENGTH))
return -EBADMSG;
if (vlen < ASN1_INDEFINITE_LENGTH) {
/* Short Form length */
if (v[1] != vlen - 2 ||
v[2] != SEQ_TAG_KEYID ||
v[3] > vlen - 4)
return -EBADMSG;
vlen = v[3];
v += 4;
} else {
/* Long Form length */
size_t seq_len = 0;
size_t sub = v[1] - ASN1_INDEFINITE_LENGTH;
if (sub > 2)
return -EBADMSG;
/* calculate the length from subsequent octets */
v += 2;
for (i = 0; i < sub; i++) {
seq_len <<= 8;
seq_len |= v[i];
}
if (seq_len != vlen - 2 - sub ||
v[sub] != SEQ_TAG_KEYID ||
v[sub + 1] > vlen - 4 - sub)
return -EBADMSG;
vlen = v[sub + 1];
v += (sub + 2);
}
kid = asymmetric_key_generate_id(ctx->cert->raw_issuer,
ctx->cert->raw_issuer_size,
v, vlen);
if (IS_ERR(kid))
return PTR_ERR(kid);
pr_debug("authkeyid %*phN\n", kid->len, kid->data);
ctx->cert->authority = kid;
return 0;
}
return 0;
}
/*
* Record a certificate time.
*/
static int x509_note_time(struct tm *tm, size_t hdrlen,
unsigned char tag,
const unsigned char *value, size_t vlen)
{
const unsigned char *p = value;
#define dec2bin(X) ((X) - '0')
#define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
if (tag == ASN1_UNITIM) {
/* UTCTime: YYMMDDHHMMSSZ */
if (vlen != 13)
goto unsupported_time;
tm->tm_year = DD2bin(p);
if (tm->tm_year >= 50)
tm->tm_year += 1900;
else
tm->tm_year += 2000;
} else if (tag == ASN1_GENTIM) {
/* GenTime: YYYYMMDDHHMMSSZ */
if (vlen != 15)
goto unsupported_time;
tm->tm_year = DD2bin(p) * 100 + DD2bin(p);
} else {
goto unsupported_time;
}
tm->tm_year -= 1900;
tm->tm_mon = DD2bin(p) - 1;
tm->tm_mday = DD2bin(p);
tm->tm_hour = DD2bin(p);
tm->tm_min = DD2bin(p);
tm->tm_sec = DD2bin(p);
if (*p != 'Z')
goto unsupported_time;
return 0;
unsupported_time:
pr_debug("Got unsupported time [tag %02x]: '%*.*s'\n",
tag, (int)vlen, (int)vlen, value);
return -EBADMSG;
}
int x509_note_not_before(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct x509_parse_context *ctx = context;
return x509_note_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
}
int x509_note_not_after(void *context, size_t hdrlen,
unsigned char tag,
const void *value, size_t vlen)
{
struct x509_parse_context *ctx = context;
return x509_note_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
}