--- /dev/null
+/* 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/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->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: [%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_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(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);
+}
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