| /* 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_akid-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 */ |
| unsigned raw_akid_size; |
| const void *raw_akid; /* Raw authorityKeyId in ASN.1 */ |
| const void *akid_raw_issuer; /* Raw directoryName in authorityKeyId */ |
| unsigned akid_raw_issuer_size; |
| }; |
| |
| /* |
| * 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->akid_id); |
| kfree(cert->akid_skid); |
| 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 AuthorityKeyIdentifier */ |
| if (ctx->raw_akid) { |
| pr_devel("AKID: %u %*phN\n", |
| ctx->raw_akid_size, ctx->raw_akid_size, ctx->raw_akid); |
| ret = asn1_ber_decoder(&x509_akid_decoder, ctx, |
| ctx->raw_akid, ctx->raw_akid_size); |
| if (ret < 0) { |
| pr_warn("Couldn't decode AuthKeyIdentifier\n"); |
| 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; |
| |
| 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(v, vlen, "", 0); |
| 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 */ |
| ctx->raw_akid = v; |
| ctx->raw_akid_size = vlen; |
| return 0; |
| } |
| |
| return 0; |
| } |
| |
| /** |
| * x509_decode_time - Decode an X.509 time ASN.1 object |
| * @_t: The time to fill in |
| * @hdrlen: The length of the object header |
| * @tag: The object tag |
| * @value: The object value |
| * @vlen: The size of the object value |
| * |
| * Decode an ASN.1 universal time or generalised time field into a struct the |
| * kernel can handle and check it for validity. The time is decoded thus: |
| * |
| * [RFC5280 ยง4.1.2.5] |
| * CAs conforming to this profile MUST always encode certificate validity |
| * dates through the year 2049 as UTCTime; certificate validity dates in |
| * 2050 or later MUST be encoded as GeneralizedTime. Conforming |
| * applications MUST be able to process validity dates that are encoded in |
| * either UTCTime or GeneralizedTime. |
| */ |
| int x509_decode_time(time64_t *_t, size_t hdrlen, |
| unsigned char tag, |
| const unsigned char *value, size_t vlen) |
| { |
| static const unsigned char month_lengths[] = { 31, 29, 31, 30, 31, 30, |
| 31, 31, 30, 31, 30, 31 }; |
| const unsigned char *p = value; |
| unsigned year, mon, day, hour, min, sec, mon_len; |
| |
| #define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; }) |
| #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; |
| year = DD2bin(p); |
| if (year >= 50) |
| year += 1900; |
| else |
| year += 2000; |
| } else if (tag == ASN1_GENTIM) { |
| /* GenTime: YYYYMMDDHHMMSSZ */ |
| if (vlen != 15) |
| goto unsupported_time; |
| year = DD2bin(p) * 100 + DD2bin(p); |
| if (year >= 1950 && year <= 2049) |
| goto invalid_time; |
| } else { |
| goto unsupported_time; |
| } |
| |
| mon = DD2bin(p); |
| day = DD2bin(p); |
| hour = DD2bin(p); |
| min = DD2bin(p); |
| sec = DD2bin(p); |
| |
| if (*p != 'Z') |
| goto unsupported_time; |
| |
| mon_len = month_lengths[mon]; |
| if (mon == 2) { |
| if (year % 4 == 0) { |
| mon_len = 29; |
| if (year % 100 == 0) { |
| year /= 100; |
| if (year % 4 != 0) |
| mon_len = 28; |
| } |
| } |
| } |
| |
| if (year < 1970 || |
| mon < 1 || mon > 12 || |
| day < 1 || day > mon_len || |
| hour < 0 || hour > 23 || |
| min < 0 || min > 59 || |
| sec < 0 || sec > 59) |
| goto invalid_time; |
| |
| *_t = mktime64(year, mon, day, hour, min, sec); |
| return 0; |
| |
| unsupported_time: |
| pr_debug("Got unsupported time [tag %02x]: '%*phN'\n", |
| tag, (int)vlen, value); |
| return -EBADMSG; |
| invalid_time: |
| pr_debug("Got invalid time [tag %02x]: '%*phN'\n", |
| tag, (int)vlen, value); |
| return -EBADMSG; |
| } |
| EXPORT_SYMBOL_GPL(x509_decode_time); |
| |
| 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_decode_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_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen); |
| } |
| |
| /* |
| * Note a key identifier-based AuthorityKeyIdentifier |
| */ |
| int x509_akid_note_kid(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; |
| |
| pr_debug("AKID: keyid: %*phN\n", (int)vlen, value); |
| |
| if (ctx->cert->akid_skid) |
| return 0; |
| |
| kid = asymmetric_key_generate_id(value, vlen, "", 0); |
| if (IS_ERR(kid)) |
| return PTR_ERR(kid); |
| pr_debug("authkeyid %*phN\n", kid->len, kid->data); |
| ctx->cert->akid_skid = kid; |
| return 0; |
| } |
| |
| /* |
| * Note a directoryName in an AuthorityKeyIdentifier |
| */ |
| int x509_akid_note_name(void *context, size_t hdrlen, |
| unsigned char tag, |
| const void *value, size_t vlen) |
| { |
| struct x509_parse_context *ctx = context; |
| |
| pr_debug("AKID: name: %*phN\n", (int)vlen, value); |
| |
| ctx->akid_raw_issuer = value; |
| ctx->akid_raw_issuer_size = vlen; |
| return 0; |
| } |
| |
| /* |
| * Note a serial number in an AuthorityKeyIdentifier |
| */ |
| int x509_akid_note_serial(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; |
| |
| pr_debug("AKID: serial: %*phN\n", (int)vlen, value); |
| |
| if (!ctx->akid_raw_issuer || ctx->cert->akid_id) |
| return 0; |
| |
| kid = asymmetric_key_generate_id(value, |
| vlen, |
| ctx->akid_raw_issuer, |
| ctx->akid_raw_issuer_size); |
| if (IS_ERR(kid)) |
| return PTR_ERR(kid); |
| |
| pr_debug("authkeyid %*phN\n", kid->len, kid->data); |
| ctx->cert->akid_id = kid; |
| return 0; |
| } |