diff options
| -rw-r--r-- | Documentation/security/keys-trusted-encrypted.txt | 48 | ||||
| -rw-r--r-- | include/keys/encrypted-type.h | 13 | ||||
| -rw-r--r-- | security/keys/encrypted.c | 141 |
3 files changed, 142 insertions, 60 deletions
diff --git a/Documentation/security/keys-trusted-encrypted.txt b/Documentation/security/keys-trusted-encrypted.txt index 8fb79bc1ac4..0afcb5023c7 100644 --- a/Documentation/security/keys-trusted-encrypted.txt +++ b/Documentation/security/keys-trusted-encrypted.txt @@ -53,12 +53,19 @@ they are only as secure as the user key encrypting them. The master user key should therefore be loaded in as secure a way as possible, preferably early in boot. +The decrypted portion of encrypted keys can contain either a simple symmetric +key or a more complex structure. The format of the more complex structure is +application specific, which is identified by 'format'. + Usage: - keyctl add encrypted name "new key-type:master-key-name keylen" ring - keyctl add encrypted name "load hex_blob" ring - keyctl update keyid "update key-type:master-key-name" + keyctl add encrypted name "new [format] key-type:master-key-name keylen" + ring + keyctl add encrypted name "load hex_blob" ring + keyctl update keyid "update key-type:master-key-name" + +format:= 'default' +key-type:= 'trusted' | 'user' -where 'key-type' is either 'trusted' or 'user'. Examples of trusted and encrypted key usage: @@ -114,15 +121,25 @@ Reseal a trusted key under new pcr values: 7ef6a24defe4846104209bf0c3eced7fa1a672ed5b125fc9d8cd88b476a658a4434644ef df8ae9a178e9f83ba9f08d10fa47e4226b98b0702f06b3b8 -Create and save an encrypted key "evm" using the above trusted key "kmk": +The initial consumer of trusted keys is EVM, which at boot time needs a high +quality symmetric key for HMAC protection of file metadata. The use of a +trusted key provides strong guarantees that the EVM key has not been +compromised by a user level problem, and when sealed to specific boot PCR +values, protects against boot and offline attacks. Create and save an +encrypted key "evm" using the above trusted key "kmk": +option 1: omitting 'format' $ keyctl add encrypted evm "new trusted:kmk 32" @u 159771175 +option 2: explicitly defining 'format' as 'default' + $ keyctl add encrypted evm "new default trusted:kmk 32" @u + 159771175 + $ keyctl print 159771175 - trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b382dbbc55 - be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e024717c64 - 5972dcb82ab2dde83376d82b2e3c09ffc + default trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b3 + 82dbbc55be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e0 + 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc $ keyctl pipe 159771175 > evm.blob @@ -132,14 +149,9 @@ Load an encrypted key "evm" from saved blob: 831684262 $ keyctl print 831684262 - trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b382dbbc55 - be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e024717c64 - 5972dcb82ab2dde83376d82b2e3c09ffc - + default trusted:kmk 32 2375725ad57798846a9bbd240de8906f006e66c03af53b1b3 + 82dbbc55be2a44616e4959430436dc4f2a7a9659aa60bb4652aeb2120f149ed197c564e0 + 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc -The initial consumer of trusted keys is EVM, which at boot time needs a high -quality symmetric key for HMAC protection of file metadata. The use of a -trusted key provides strong guarantees that the EVM key has not been -compromised by a user level problem, and when sealed to specific boot PCR -values, protects against boot and offline attacks. Other uses for trusted and -encrypted keys, such as for disk and file encryption are anticipated. +Other uses for trusted and encrypted keys, such as for disk and file encryption +are anticipated. diff --git a/include/keys/encrypted-type.h b/include/keys/encrypted-type.h index 95855017a32..1d4541370a6 100644 --- a/include/keys/encrypted-type.h +++ b/include/keys/encrypted-type.h @@ -1,6 +1,11 @@ /* * Copyright (C) 2010 IBM Corporation - * Author: Mimi Zohar <zohar@us.ibm.com> + * Copyright (C) 2010 Politecnico di Torino, Italy + * TORSEC group -- http://security.polito.it + * + * Authors: + * Mimi Zohar <zohar@us.ibm.com> + * Roberto Sassu <roberto.sassu@polito.it> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -15,13 +20,17 @@ struct encrypted_key_payload { struct rcu_head rcu; + char *format; /* datablob: format */ char *master_desc; /* datablob: master key name */ char *datalen; /* datablob: decrypted key length */ u8 *iv; /* datablob: iv */ u8 *encrypted_data; /* datablob: encrypted data */ unsigned short datablob_len; /* length of datablob */ unsigned short decrypted_datalen; /* decrypted data length */ - u8 decrypted_data[0]; /* decrypted data + datablob + hmac */ + unsigned short payload_datalen; /* payload data length */ + unsigned short encrypted_key_format; /* encrypted key format */ + u8 *decrypted_data; /* decrypted data */ + u8 payload_data[0]; /* payload data + datablob + hmac */ }; extern struct key_type key_type_encrypted; diff --git a/security/keys/encrypted.c b/security/keys/encrypted.c index f36a105de79..89981c987ba 100644 --- a/security/keys/encrypted.c +++ b/security/keys/encrypted.c @@ -1,8 +1,11 @@ /* * Copyright (C) 2010 IBM Corporation + * Copyright (C) 2010 Politecnico di Torino, Italy + * TORSEC group -- http://security.polito.it * - * Author: + * Authors: * Mimi Zohar <zohar@us.ibm.com> + * Roberto Sassu <roberto.sassu@polito.it> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -37,6 +40,7 @@ static const char KEY_USER_PREFIX[] = "user:"; static const char hash_alg[] = "sha256"; static const char hmac_alg[] = "hmac(sha256)"; static const char blkcipher_alg[] = "cbc(aes)"; +static const char key_format_default[] = "default"; static unsigned int ivsize; static int blksize; @@ -58,6 +62,15 @@ enum { Opt_err = -1, Opt_new, Opt_load, Opt_update }; +enum { + Opt_error = -1, Opt_default +}; + +static const match_table_t key_format_tokens = { + {Opt_default, "default"}, + {Opt_error, NULL} +}; + static const match_table_t key_tokens = { {Opt_new, "new"}, {Opt_load, "load"}, @@ -118,8 +131,9 @@ out: * datablob_parse - parse the keyctl data * * datablob format: - * new <master-key name> <decrypted data length> - * load <master-key name> <decrypted data length> <encrypted iv + data> + * new [<format>] <master-key name> <decrypted data length> + * load [<format>] <master-key name> <decrypted data length> + * <encrypted iv + data> * update <new-master-key name> * * Tokenizes a copy of the keyctl data, returning a pointer to each token, @@ -127,13 +141,15 @@ out: * * On success returns 0, otherwise -EINVAL. */ -static int datablob_parse(char *datablob, char **master_desc, - char **decrypted_datalen, char **hex_encoded_iv) +static int datablob_parse(char *datablob, const char **format, + char **master_desc, char **decrypted_datalen, + char **hex_encoded_iv) { substring_t args[MAX_OPT_ARGS]; int ret = -EINVAL; int key_cmd; - char *keyword; + int key_format; + char *p, *keyword; keyword = strsep(&datablob, " \t"); if (!keyword) { @@ -142,7 +158,24 @@ static int datablob_parse(char *datablob, char **master_desc, } key_cmd = match_token(keyword, key_tokens, args); - *master_desc = strsep(&datablob, " \t"); + /* Get optional format: default */ + p = strsep(&datablob, " \t"); + if (!p) { + pr_err("encrypted_key: insufficient parameters specified\n"); + return ret; + } + + key_format = match_token(p, key_format_tokens, args); + switch (key_format) { + case Opt_default: + *format = p; + *master_desc = strsep(&datablob, " \t"); + break; + case Opt_error: + *master_desc = p; + break; + } + if (!*master_desc) { pr_info("encrypted_key: master key parameter is missing\n"); goto out; @@ -220,8 +253,8 @@ static char *datablob_format(struct encrypted_key_payload *epayload, ascii_buf[asciiblob_len] = '\0'; /* copy datablob master_desc and datalen strings */ - len = sprintf(ascii_buf, "%s %s ", epayload->master_desc, - epayload->datalen); + len = sprintf(ascii_buf, "%s %s %s ", epayload->format, + epayload->master_desc, epayload->datalen); /* convert the hex encoded iv, encrypted-data and HMAC to ascii */ bufp = &ascii_buf[len]; @@ -464,9 +497,9 @@ static int datablob_hmac_append(struct encrypted_key_payload *epayload, if (ret < 0) goto out; - digest = epayload->master_desc + epayload->datablob_len; + digest = epayload->format + epayload->datablob_len; ret = calc_hmac(digest, derived_key, sizeof derived_key, - epayload->master_desc, epayload->datablob_len); + epayload->format, epayload->datablob_len); if (!ret) dump_hmac(NULL, digest, HASH_SIZE); out: @@ -475,26 +508,35 @@ out: /* verify HMAC before decrypting encrypted key */ static int datablob_hmac_verify(struct encrypted_key_payload *epayload, - const u8 *master_key, size_t master_keylen) + const u8 *format, const u8 *master_key, + size_t master_keylen) { u8 derived_key[HASH_SIZE]; u8 digest[HASH_SIZE]; int ret; + char *p; + unsigned short len; ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); if (ret < 0) goto out; - ret = calc_hmac(digest, derived_key, sizeof derived_key, - epayload->master_desc, epayload->datablob_len); + len = epayload->datablob_len; + if (!format) { + p = epayload->master_desc; + len -= strlen(epayload->format) + 1; + } else + p = epayload->format; + + ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len); if (ret < 0) goto out; - ret = memcmp(digest, epayload->master_desc + epayload->datablob_len, + ret = memcmp(digest, epayload->format + epayload->datablob_len, sizeof digest); if (ret) { ret = -EINVAL; dump_hmac("datablob", - epayload->master_desc + epayload->datablob_len, + epayload->format + epayload->datablob_len, HASH_SIZE); dump_hmac("calc", digest, HASH_SIZE); } @@ -539,13 +581,16 @@ out: /* Allocate memory for decrypted key and datablob. */ static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, + const char *format, const char *master_desc, const char *datalen) { struct encrypted_key_payload *epayload = NULL; unsigned short datablob_len; unsigned short decrypted_datalen; + unsigned short payload_datalen; unsigned int encrypted_datalen; + unsigned int format_len; long dlen; int ret; @@ -553,29 +598,32 @@ static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE) return ERR_PTR(-EINVAL); + format_len = (!format) ? strlen(key_format_default) : strlen(format); decrypted_datalen = dlen; + payload_datalen = decrypted_datalen; encrypted_datalen = roundup(decrypted_datalen, blksize); - datablob_len = strlen(master_desc) + 1 + strlen(datalen) + 1 - + ivsize + 1 + encrypted_datalen; + datablob_len = format_len + 1 + strlen(master_desc) + 1 + + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen; - ret = key_payload_reserve(key, decrypted_datalen + datablob_len + ret = key_payload_reserve(key, payload_datalen + datablob_len + HASH_SIZE + 1); if (ret < 0) return ERR_PTR(ret); - epayload = kzalloc(sizeof(*epayload) + decrypted_datalen + + epayload = kzalloc(sizeof(*epayload) + payload_datalen + datablob_len + HASH_SIZE + 1, GFP_KERNEL); if (!epayload) return ERR_PTR(-ENOMEM); + epayload->payload_datalen = payload_datalen; epayload->decrypted_datalen = decrypted_datalen; epayload->datablob_len = datablob_len; return epayload; } static int encrypted_key_decrypt(struct encrypted_key_payload *epayload, - const char *hex_encoded_iv) + const char *format, const char *hex_encoded_iv) { struct key *mkey; u8 derived_key[HASH_SIZE]; @@ -596,14 +644,14 @@ static int encrypted_key_decrypt(struct encrypted_key_payload *epayload, hex2bin(epayload->iv, hex_encoded_iv, ivsize); hex2bin(epayload->encrypted_data, hex_encoded_data, encrypted_datalen); - hmac = epayload->master_desc + epayload->datablob_len; + hmac = epayload->format + epayload->datablob_len; hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), HASH_SIZE); mkey = request_master_key(epayload, &master_key, &master_keylen); if (IS_ERR(mkey)) return PTR_ERR(mkey); - ret = datablob_hmac_verify(epayload, master_key, master_keylen); + ret = datablob_hmac_verify(epayload, format, master_key, master_keylen); if (ret < 0) { pr_err("encrypted_key: bad hmac (%d)\n", ret); goto out; @@ -623,14 +671,23 @@ out: } static void __ekey_init(struct encrypted_key_payload *epayload, - const char *master_desc, const char *datalen) + const char *format, const char *master_desc, + const char *datalen) { - epayload->master_desc = epayload->decrypted_data - + epayload->decrypted_datalen; + unsigned int format_len; + + format_len = (!format) ? strlen(key_format_default) : strlen(format); + epayload->format = epayload->payload_data + epayload->payload_datalen; + epayload->master_desc = epayload->format + format_len + 1; epayload->datalen = epayload->master_desc + strlen(master_desc) + 1; epayload->iv = epayload->datalen + strlen(datalen) + 1; epayload->encrypted_data = epayload->iv + ivsize + 1; + epayload->decrypted_data = epayload->payload_data; + if (!format) + memcpy(epayload->format, key_format_default, format_len); + else + memcpy(epayload->format, format, format_len); memcpy(epayload->master_desc, master_desc, strlen(master_desc)); memcpy(epayload->datalen, datalen, strlen(datalen)); } @@ -642,19 +699,19 @@ static void __ekey_init(struct encrypted_key_payload *epayload, * itself. For an old key, decrypt the hex encoded data. */ static int encrypted_init(struct encrypted_key_payload *epayload, - const char *master_desc, const char *datalen, - const char *hex_encoded_iv) + const char *format, const char *master_desc, + const char *datalen, const char *hex_encoded_iv) { int ret = 0; - __ekey_init(epayload, master_desc, datalen); + __ekey_init(epayload, format, master_desc, datalen); if (!hex_encoded_iv) { get_random_bytes(epayload->iv, ivsize); get_random_bytes(epayload->decrypted_data, epayload->decrypted_datalen); } else - ret = encrypted_key_decrypt(epayload, hex_encoded_iv); + ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv); return ret; } @@ -671,6 +728,7 @@ static int encrypted_instantiate(struct key *key, const void *data, { struct encrypted_key_payload *epayload = NULL; char *datablob = NULL; + const char *format = NULL; char *master_desc = NULL; char *decrypted_datalen = NULL; char *hex_encoded_iv = NULL; @@ -684,17 +742,18 @@ static int encrypted_instantiate(struct key *key, const void *data, return -ENOMEM; datablob[datalen] = 0; memcpy(datablob, data, datalen); - ret = datablob_parse(datablob, &master_desc, &decrypted_datalen, - &hex_encoded_iv); + ret = datablob_parse(datablob, &format, &master_desc, + &decrypted_datalen, &hex_encoded_iv); if (ret < 0) goto out; - epayload = encrypted_key_alloc(key, master_desc, decrypted_datalen); + epayload = encrypted_key_alloc(key, format, master_desc, + decrypted_datalen); if (IS_ERR(epayload)) { ret = PTR_ERR(epayload); goto out; } - ret = encrypted_init(epayload, master_desc, decrypted_datalen, + ret = encrypted_init(epayload, format, master_desc, decrypted_datalen, hex_encoded_iv); if (ret < 0) { kfree(epayload); @@ -731,6 +790,7 @@ static int encrypted_update(struct key *key, const void *data, size_t datalen) struct encrypted_key_payload *new_epayload; char *buf; char *new_master_desc = NULL; + const char *format = NULL; int ret = 0; if (datalen <= 0 || datalen > 32767 || !data) @@ -742,7 +802,7 @@ static int encrypted_update(struct key *key, const void *data, size_t datalen) buf[datalen] = 0; memcpy(buf, data, datalen); - ret = datablob_parse(buf, &new_master_desc, NULL, NULL); + ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL); if (ret < 0) goto out; @@ -750,18 +810,19 @@ static int encrypted_update(struct key *key, const void *data, size_t datalen) if (ret < 0) goto out; - new_epayload = encrypted_key_alloc(key, new_master_desc, - epayload->datalen); + new_epayload = encrypted_key_alloc(key, epayload->format, + new_master_desc, epayload->datalen); if (IS_ERR(new_epayload)) { ret = PTR_ERR(new_epayload); goto out; } - __ekey_init(new_epayload, new_master_desc, epayload->datalen); + __ekey_init(new_epayload, epayload->format, new_master_desc, + epayload->datalen); memcpy(new_epayload->iv, epayload->iv, ivsize); - memcpy(new_epayload->decrypted_data, epayload->decrypted_data, - epayload->decrypted_datalen); + memcpy(new_epayload->payload_data, epayload->payload_data, + epayload->payload_datalen); rcu_assign_pointer(key->payload.data, new_epayload); call_rcu(&epayload->rcu, encrypted_rcu_free); |