From c26fd69fa00916a31a47f5f096fd7be924106df8 Mon Sep 17 00:00:00 2001 From: David Howells Date: Mon, 24 Sep 2012 17:11:48 +0100 Subject: X.509: Add a crypto key parser for binary (DER) X.509 certificates Add a crypto key parser for binary (DER) encoded X.509 certificates. The certificate is parsed and, if possible, the signature is verified. An X.509 key can be added like this: # keyctl padd crypto bar @s Signed-off-by: Rusty Russell --- crypto/asymmetric_keys/x509_cert_parser.c | 497 ++++++++++++++++++++++++++++++ 1 file changed, 497 insertions(+) create mode 100644 crypto/asymmetric_keys/x509_cert_parser.c (limited to 'crypto/asymmetric_keys/x509_cert_parser.c') diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c new file mode 100644 index 000000000000..8fcac9493b7a --- /dev/null +++ b/crypto/asymmetric_keys/x509_cert_parser.c @@ -0,0 +1,497 @@ +/* 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 +#include +#include +#include +#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->fingerprint); + kfree(cert->authority); + kfree(cert); + } +} + +/* + * 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; + 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; + + kfree(ctx); + return cert; + +error_decode: + kfree(ctx); +error_no_ctx: + x509_free_certificate(cert); +error_no_cert: + return ERR_PTR(ret); +} + +/* + * 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: [%zu] %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_hash_algo = PKEY_HASH_MD5; + ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA; + break; + + case OID_sha1WithRSAEncryption: + ctx->cert->sig_hash_algo = PKEY_HASH_SHA1; + ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA; + break; + + case OID_sha256WithRSAEncryption: + ctx->cert->sig_hash_algo = PKEY_HASH_SHA256; + ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA; + break; + + case OID_sha384WithRSAEncryption: + ctx->cert->sig_hash_algo = PKEY_HASH_SHA384; + ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA; + break; + + case OID_sha512WithRSAEncryption: + ctx->cert->sig_hash_algo = PKEY_HASH_SHA512; + ctx->cert->sig_pkey_algo = PKEY_ALGO_RSA; + break; + + case OID_sha224WithRSAEncryption: + ctx->cert->sig_hash_algo = PKEY_HASH_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->sig = value; + ctx->cert->sig_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; + 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; + 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; + + /* There seems to be an extraneous 0 byte on the front of the data */ + ctx->cert->pkey_algo = PKEY_ALGO_RSA; + 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; +} + +/* + * 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; + const unsigned char *v = value; + char *f; + int i; + + pr_debug("Extension: %u\n", ctx->last_oid); + + if (ctx->last_oid == OID_subjectKeyIdentifier) { + /* Get hold of the key fingerprint */ + if (vlen < 3) + return -EBADMSG; + if (v[0] != ASN1_OTS || v[1] != vlen - 2) + return -EBADMSG; + v += 2; + vlen -= 2; + + f = kmalloc(vlen * 2 + 1, GFP_KERNEL); + if (!f) + return -ENOMEM; + for (i = 0; i < vlen; i++) + sprintf(f + i * 2, "%02x", v[i]); + pr_debug("fingerprint %s\n", f); + ctx->cert->fingerprint = f; + return 0; + } + + if (ctx->last_oid == OID_authorityKeyIdentifier) { + /* Get hold of the CA key fingerprint */ + if (vlen < 5) + return -EBADMSG; + if (v[0] != (ASN1_SEQ | (ASN1_CONS << 5)) || + v[1] != vlen - 2 || + v[2] != (ASN1_CONT << 6) || + v[3] != vlen - 4) + return -EBADMSG; + v += 4; + vlen -= 4; + + f = kmalloc(vlen * 2 + 1, GFP_KERNEL); + if (!f) + return -ENOMEM; + for (i = 0; i < vlen; i++) + sprintf(f + i * 2, "%02x", v[i]); + pr_debug("authority %s\n", f); + ctx->cert->authority = f; + return 0; + } + + return 0; +} + +/* + * Record a certificate time. + */ +static int x509_note_time(time_t *_time, size_t hdrlen, + unsigned char tag, + const unsigned char *value, size_t vlen) +{ + unsigned YY, MM, DD, hh, mm, ss; + 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; + YY = DD2bin(p); + if (YY > 50) + YY += 1900; + else + YY += 2000; + } else if (tag == ASN1_GENTIM) { + /* GenTime: YYYYMMDDHHMMSSZ */ + if (vlen != 15) + goto unsupported_time; + YY = DD2bin(p) * 100 + DD2bin(p); + } else { + goto unsupported_time; + } + + MM = DD2bin(p); + DD = DD2bin(p); + hh = DD2bin(p); + mm = DD2bin(p); + ss = DD2bin(p); + + if (*p != 'Z') + goto unsupported_time; + + *_time = mktime(YY, MM, DD, hh, mm, ss); + 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); +} -- cgit v1.2.3