From 4d67431f80b1b822f0286afc9123ee453eac7334 Mon Sep 17 00:00:00 2001 From: David Howells Date: Mon, 13 Jun 2011 22:33:52 +0100 Subject: KEYS: Don't return EAGAIN to keyctl_assume_authority() Don't return EAGAIN to keyctl_assume_authority() to indicate that a key could not be found (ENOKEY is only returned if a negative key is found). Instead return ENOKEY in both cases. Signed-off-by: David Howells Signed-off-by: James Morris --- security/keys/request_key_auth.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'security/keys') diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c index 6cff37529b8..60d4e3f5e4b 100644 --- a/security/keys/request_key_auth.c +++ b/security/keys/request_key_auth.c @@ -251,6 +251,8 @@ struct key *key_get_instantiation_authkey(key_serial_t target_id) if (IS_ERR(authkey_ref)) { authkey = ERR_CAST(authkey_ref); + if (authkey == ERR_PTR(-EAGAIN)) + authkey = ERR_PTR(-ENOKEY); goto error; } -- cgit v1.2.3 From f91c2c5cfa2950a20265b45bcc13e49ed9e49aac Mon Sep 17 00:00:00 2001 From: Roberto Sassu Date: Mon, 27 Jun 2011 13:45:39 +0200 Subject: encrypted_keys: avoid dumping the master key if the request fails Do not dump the master key if an error is encountered during the request. Signed-off-by: Roberto Sassu Acked-by: Gianluca Ramunno Signed-off-by: Mimi Zohar --- security/keys/encrypted.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'security/keys') diff --git a/security/keys/encrypted.c b/security/keys/encrypted.c index b1cba5bf0a5..37cd913f18a 100644 --- a/security/keys/encrypted.c +++ b/security/keys/encrypted.c @@ -378,11 +378,13 @@ static struct key *request_master_key(struct encrypted_key_payload *epayload, } else goto out; - if (IS_ERR(mkey)) + if (IS_ERR(mkey)) { pr_info("encrypted_key: key %s not found", epayload->master_desc); - if (mkey) - dump_master_key(*master_key, *master_keylen); + goto out; + } + + dump_master_key(*master_key, *master_keylen); out: return mkey; } -- cgit v1.2.3 From 08fa2aa54e72ddde8076cc77126bace8d4780e0f Mon Sep 17 00:00:00 2001 From: Roberto Sassu Date: Mon, 27 Jun 2011 13:45:40 +0200 Subject: encrypted-keys: fixed valid_master_desc() function description Valid key type prefixes for the parameter 'key-type' are: 'trusted' and 'user'. Signed-off-by: Roberto Sassu Acked-by: Gianluca Ramunno Acked-by: David Howells Signed-off-by: Mimi Zohar --- security/keys/encrypted.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'security/keys') diff --git a/security/keys/encrypted.c b/security/keys/encrypted.c index 37cd913f18a..3ff2f72dad9 100644 --- a/security/keys/encrypted.c +++ b/security/keys/encrypted.c @@ -84,7 +84,7 @@ static int aes_get_sizes(void) /* * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key * - * key-type:= "trusted:" | "encrypted:" + * key-type:= "trusted:" | "user:" * desc:= master-key description * * Verify that 'key-type' is valid and that 'desc' exists. On key update, -- cgit v1.2.3 From 7103dff0e598cd634767f17a2958302c515700ca Mon Sep 17 00:00:00 2001 From: Roberto Sassu Date: Mon, 27 Jun 2011 13:45:41 +0200 Subject: encrypted-keys: added additional debug messages Some debug messages have been added in the function datablob_parse() in order to better identify errors returned when dealing with 'encrypted' keys. Changelog from version v4: - made the debug messages more understandable Signed-off-by: Roberto Sassu Acked-by: Gianluca Ramunno Signed-off-by: Mimi Zohar --- security/keys/encrypted.c | 45 ++++++++++++++++++++++++++++++++++----------- 1 file changed, 34 insertions(+), 11 deletions(-) (limited to 'security/keys') diff --git a/security/keys/encrypted.c b/security/keys/encrypted.c index 3ff2f72dad9..f36a105de79 100644 --- a/security/keys/encrypted.c +++ b/security/keys/encrypted.c @@ -133,46 +133,69 @@ static int datablob_parse(char *datablob, char **master_desc, substring_t args[MAX_OPT_ARGS]; int ret = -EINVAL; int key_cmd; - char *p; + char *keyword; - p = strsep(&datablob, " \t"); - if (!p) + keyword = strsep(&datablob, " \t"); + if (!keyword) { + pr_info("encrypted_key: insufficient parameters specified\n"); return ret; - key_cmd = match_token(p, key_tokens, args); + } + key_cmd = match_token(keyword, key_tokens, args); *master_desc = strsep(&datablob, " \t"); - if (!*master_desc) + if (!*master_desc) { + pr_info("encrypted_key: master key parameter is missing\n"); goto out; + } - if (valid_master_desc(*master_desc, NULL) < 0) + if (valid_master_desc(*master_desc, NULL) < 0) { + pr_info("encrypted_key: master key parameter \'%s\' " + "is invalid\n", *master_desc); goto out; + } if (decrypted_datalen) { *decrypted_datalen = strsep(&datablob, " \t"); - if (!*decrypted_datalen) + if (!*decrypted_datalen) { + pr_info("encrypted_key: keylen parameter is missing\n"); goto out; + } } switch (key_cmd) { case Opt_new: - if (!decrypted_datalen) + if (!decrypted_datalen) { + pr_info("encrypted_key: keyword \'%s\' not allowed " + "when called from .update method\n", keyword); break; + } ret = 0; break; case Opt_load: - if (!decrypted_datalen) + if (!decrypted_datalen) { + pr_info("encrypted_key: keyword \'%s\' not allowed " + "when called from .update method\n", keyword); break; + } *hex_encoded_iv = strsep(&datablob, " \t"); - if (!*hex_encoded_iv) + if (!*hex_encoded_iv) { + pr_info("encrypted_key: hex blob is missing\n"); break; + } ret = 0; break; case Opt_update: - if (decrypted_datalen) + if (decrypted_datalen) { + pr_info("encrypted_key: keyword \'%s\' not allowed " + "when called from .instantiate method\n", + keyword); break; + } ret = 0; break; case Opt_err: + pr_info("encrypted_key: keyword \'%s\' not recognized\n", + keyword); break; } out: -- cgit v1.2.3 From 4e561d388feff18e4b798cef6a1a84a2cc7f20c2 Mon Sep 17 00:00:00 2001 From: Roberto Sassu Date: Mon, 27 Jun 2011 13:45:42 +0200 Subject: encrypted-keys: add key format support This patch introduces a new parameter, called 'format', that defines the format of data stored by encrypted keys. The 'default' format identifies encrypted keys containing only the symmetric key, while other formats can be defined to support additional information. The 'format' parameter is written in the datablob produced by commands 'keyctl print' or 'keyctl pipe' and is integrity protected by the HMAC. Signed-off-by: Roberto Sassu Acked-by: Gianluca Ramunno Acked-by: David Howells Signed-off-by: Mimi Zohar --- Documentation/security/keys-trusted-encrypted.txt | 48 +++++--- include/keys/encrypted-type.h | 13 +- security/keys/encrypted.c | 141 ++++++++++++++++------ 3 files changed, 142 insertions(+), 60 deletions(-) (limited to 'security/keys') 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 + * Copyright (C) 2010 Politecnico di Torino, Italy + * TORSEC group -- http://security.polito.it + * + * Authors: + * Mimi Zohar + * Roberto Sassu * * 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 + * Roberto Sassu * * 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 - * load + * new [] + * load [] + * * update * * 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); -- cgit v1.2.3 From 79a73d188726b473ca3bf483244bc96096831905 Mon Sep 17 00:00:00 2001 From: Roberto Sassu Date: Mon, 27 Jun 2011 13:45:44 +0200 Subject: encrypted-keys: add ecryptfs format support The 'encrypted' key type defines its own payload format which contains a symmetric key randomly generated that cannot be used directly to mount an eCryptfs filesystem, because it expects an authentication token structure. This patch introduces the new format 'ecryptfs' that allows to store an authentication token structure inside the encrypted key payload containing a randomly generated symmetric key, as the same for the format 'default'. More details about the usage of encrypted keys with the eCryptfs filesystem can be found in the file 'Documentation/keys-ecryptfs.txt'. Signed-off-by: Roberto Sassu Acked-by: Gianluca Ramunno Acked-by: Tyler Hicks Signed-off-by: Mimi Zohar --- Documentation/keys-ecryptfs.txt | 68 +++++++++++++++++++ Documentation/security/keys-trusted-encrypted.txt | 6 +- security/keys/Makefile | 2 +- security/keys/ecryptfs_format.c | 81 +++++++++++++++++++++++ security/keys/ecryptfs_format.h | 30 +++++++++ security/keys/encrypted.c | 75 +++++++++++++++++++-- 6 files changed, 252 insertions(+), 10 deletions(-) create mode 100644 Documentation/keys-ecryptfs.txt create mode 100644 security/keys/ecryptfs_format.c create mode 100644 security/keys/ecryptfs_format.h (limited to 'security/keys') diff --git a/Documentation/keys-ecryptfs.txt b/Documentation/keys-ecryptfs.txt new file mode 100644 index 00000000000..c3bbeba6356 --- /dev/null +++ b/Documentation/keys-ecryptfs.txt @@ -0,0 +1,68 @@ + Encrypted keys for the eCryptfs filesystem + +ECryptfs is a stacked filesystem which transparently encrypts and decrypts each +file using a randomly generated File Encryption Key (FEK). + +Each FEK is in turn encrypted with a File Encryption Key Encryption Key (FEFEK) +either in kernel space or in user space with a daemon called 'ecryptfsd'. In +the former case the operation is performed directly by the kernel CryptoAPI +using a key, the FEFEK, derived from a user prompted passphrase; in the latter +the FEK is encrypted by 'ecryptfsd' with the help of external libraries in order +to support other mechanisms like public key cryptography, PKCS#11 and TPM based +operations. + +The data structure defined by eCryptfs to contain information required for the +FEK decryption is called authentication token and, currently, can be stored in a +kernel key of the 'user' type, inserted in the user's session specific keyring +by the userspace utility 'mount.ecryptfs' shipped with the package +'ecryptfs-utils'. + +The 'encrypted' key type has been extended with the introduction of the new +format 'ecryptfs' in order to be used in conjunction with the eCryptfs +filesystem. Encrypted keys of the newly introduced format store an +authentication token in its payload with a FEFEK randomly generated by the +kernel and protected by the parent master key. + +In order to avoid known-plaintext attacks, the datablob obtained through +commands 'keyctl print' or 'keyctl pipe' does not contain the overall +authentication token, which content is well known, but only the FEFEK in +encrypted form. + +The eCryptfs filesystem may really benefit from using encrypted keys in that the +required key can be securely generated by an Administrator and provided at boot +time after the unsealing of a 'trusted' key in order to perform the mount in a +controlled environment. Another advantage is that the key is not exposed to +threats of malicious software, because it is available in clear form only at +kernel level. + +Usage: + keyctl add encrypted name "new ecryptfs key-type:master-key-name keylen" ring + keyctl add encrypted name "load hex_blob" ring + keyctl update keyid "update key-type:master-key-name" + +name:= '<16 hexadecimal characters>' +key-type:= 'trusted' | 'user' +keylen:= 64 + + +Example of encrypted key usage with the eCryptfs filesystem: + +Create an encrypted key "1000100010001000" of length 64 bytes with format +'ecryptfs' and save it using a previously loaded user key "test": + + $ keyctl add encrypted 1000100010001000 "new ecryptfs user:test 64" @u + 19184530 + + $ keyctl print 19184530 + ecryptfs user:test 64 490045d4bfe48c99f0d465fbbbb79e7500da954178e2de0697 + dd85091f5450a0511219e9f7cd70dcd498038181466f78ac8d4c19504fcc72402bfc41c2 + f253a41b7507ccaa4b2b03fff19a69d1cc0b16e71746473f023a95488b6edfd86f7fdd40 + 9d292e4bacded1258880122dd553a661 + + $ keyctl pipe 19184530 > ecryptfs.blob + +Mount an eCryptfs filesystem using the created encrypted key "1000100010001000" +into the '/secret' directory: + + $ mount -i -t ecryptfs -oecryptfs_sig=1000100010001000,\ + ecryptfs_cipher=aes,ecryptfs_key_bytes=32 /secret /secret diff --git a/Documentation/security/keys-trusted-encrypted.txt b/Documentation/security/keys-trusted-encrypted.txt index 0afcb5023c7..5f50ccabfc8 100644 --- a/Documentation/security/keys-trusted-encrypted.txt +++ b/Documentation/security/keys-trusted-encrypted.txt @@ -63,7 +63,7 @@ Usage: keyctl add encrypted name "load hex_blob" ring keyctl update keyid "update key-type:master-key-name" -format:= 'default' +format:= 'default | ecryptfs' key-type:= 'trusted' | 'user' @@ -154,4 +154,6 @@ Load an encrypted key "evm" from saved blob: 24717c64 5972dcb82ab2dde83376d82b2e3c09ffc Other uses for trusted and encrypted keys, such as for disk and file encryption -are anticipated. +are anticipated. In particular the new format 'ecryptfs' has been defined in +in order to use encrypted keys to mount an eCryptfs filesystem. More details +about the usage can be found in the file 'Documentation/keys-ecryptfs.txt'. diff --git a/security/keys/Makefile b/security/keys/Makefile index 1bf090a885f..b34cc6ee690 100644 --- a/security/keys/Makefile +++ b/security/keys/Makefile @@ -14,7 +14,7 @@ obj-y := \ user_defined.o obj-$(CONFIG_TRUSTED_KEYS) += trusted.o -obj-$(CONFIG_ENCRYPTED_KEYS) += encrypted.o +obj-$(CONFIG_ENCRYPTED_KEYS) += ecryptfs_format.o encrypted.o obj-$(CONFIG_KEYS_COMPAT) += compat.o obj-$(CONFIG_PROC_FS) += proc.o obj-$(CONFIG_SYSCTL) += sysctl.o diff --git a/security/keys/ecryptfs_format.c b/security/keys/ecryptfs_format.c new file mode 100644 index 00000000000..6daa3b6ff9e --- /dev/null +++ b/security/keys/ecryptfs_format.c @@ -0,0 +1,81 @@ +/* + * ecryptfs_format.c: helper functions for the encrypted key type + * + * Copyright (C) 2006 International Business Machines Corp. + * Copyright (C) 2010 Politecnico di Torino, Italy + * TORSEC group -- http://security.polito.it + * + * Authors: + * Michael A. Halcrow + * Tyler Hicks + * Roberto Sassu + * + * 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 + * the Free Software Foundation, version 2 of the License. + */ + +#include +#include "ecryptfs_format.h" + +u8 *ecryptfs_get_auth_tok_key(struct ecryptfs_auth_tok *auth_tok) +{ + return auth_tok->token.password.session_key_encryption_key; +} +EXPORT_SYMBOL(ecryptfs_get_auth_tok_key); + +/* + * ecryptfs_get_versions() + * + * Source code taken from the software 'ecryptfs-utils' version 83. + * + */ +void ecryptfs_get_versions(int *major, int *minor, int *file_version) +{ + *major = ECRYPTFS_VERSION_MAJOR; + *minor = ECRYPTFS_VERSION_MINOR; + if (file_version) + *file_version = ECRYPTFS_SUPPORTED_FILE_VERSION; +} +EXPORT_SYMBOL(ecryptfs_get_versions); + +/* + * ecryptfs_fill_auth_tok - fill the ecryptfs_auth_tok structure + * + * Fill the ecryptfs_auth_tok structure with required ecryptfs data. + * The source code is inspired to the original function generate_payload() + * shipped with the software 'ecryptfs-utils' version 83. + * + */ +int ecryptfs_fill_auth_tok(struct ecryptfs_auth_tok *auth_tok, + const char *key_desc) +{ + int major, minor; + + ecryptfs_get_versions(&major, &minor, NULL); + auth_tok->version = (((uint16_t)(major << 8) & 0xFF00) + | ((uint16_t)minor & 0x00FF)); + auth_tok->token_type = ECRYPTFS_PASSWORD; + strncpy((char *)auth_tok->token.password.signature, key_desc, + ECRYPTFS_PASSWORD_SIG_SIZE); + auth_tok->token.password.session_key_encryption_key_bytes = + ECRYPTFS_MAX_KEY_BYTES; + /* + * Removed auth_tok->token.password.salt and + * auth_tok->token.password.session_key_encryption_key + * initialization from the original code + */ + /* TODO: Make the hash parameterizable via policy */ + auth_tok->token.password.flags |= + ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET; + /* The kernel code will encrypt the session key. */ + auth_tok->session_key.encrypted_key[0] = 0; + auth_tok->session_key.encrypted_key_size = 0; + /* Default; subject to change by kernel eCryptfs */ + auth_tok->token.password.hash_algo = PGP_DIGEST_ALGO_SHA512; + auth_tok->token.password.flags &= ~(ECRYPTFS_PERSISTENT_PASSWORD); + return 0; +} +EXPORT_SYMBOL(ecryptfs_fill_auth_tok); + +MODULE_LICENSE("GPL"); diff --git a/security/keys/ecryptfs_format.h b/security/keys/ecryptfs_format.h new file mode 100644 index 00000000000..40294de238b --- /dev/null +++ b/security/keys/ecryptfs_format.h @@ -0,0 +1,30 @@ +/* + * ecryptfs_format.h: helper functions for the encrypted key type + * + * Copyright (C) 2006 International Business Machines Corp. + * Copyright (C) 2010 Politecnico di Torino, Italy + * TORSEC group -- http://security.polito.it + * + * Authors: + * Michael A. Halcrow + * Tyler Hicks + * Roberto Sassu + * + * 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 + * the Free Software Foundation, version 2 of the License. + */ + +#ifndef __KEYS_ECRYPTFS_H +#define __KEYS_ECRYPTFS_H + +#include + +#define PGP_DIGEST_ALGO_SHA512 10 + +u8 *ecryptfs_get_auth_tok_key(struct ecryptfs_auth_tok *auth_tok); +void ecryptfs_get_versions(int *major, int *minor, int *file_version); +int ecryptfs_fill_auth_tok(struct ecryptfs_auth_tok *auth_tok, + const char *key_desc); + +#endif /* __KEYS_ECRYPTFS_H */ diff --git a/security/keys/encrypted.c b/security/keys/encrypted.c index 89981c987ba..e7eca9ec4c6 100644 --- a/security/keys/encrypted.c +++ b/security/keys/encrypted.c @@ -29,11 +29,13 @@ #include #include #include +#include #include #include #include #include "encrypted.h" +#include "ecryptfs_format.h" static const char KEY_TRUSTED_PREFIX[] = "trusted:"; static const char KEY_USER_PREFIX[] = "user:"; @@ -41,11 +43,13 @@ 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 const char key_format_ecryptfs[] = "ecryptfs"; static unsigned int ivsize; static int blksize; #define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1) #define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1) +#define KEY_ECRYPTFS_DESC_LEN 16 #define HASH_SIZE SHA256_DIGEST_SIZE #define MAX_DATA_SIZE 4096 #define MIN_DATA_SIZE 20 @@ -63,11 +67,12 @@ enum { }; enum { - Opt_error = -1, Opt_default + Opt_error = -1, Opt_default, Opt_ecryptfs }; static const match_table_t key_format_tokens = { {Opt_default, "default"}, + {Opt_ecryptfs, "ecryptfs"}, {Opt_error, NULL} }; @@ -94,6 +99,34 @@ static int aes_get_sizes(void) return 0; } +/* + * valid_ecryptfs_desc - verify the description of a new/loaded encrypted key + * + * The description of a encrypted key with format 'ecryptfs' must contain + * exactly 16 hexadecimal characters. + * + */ +static int valid_ecryptfs_desc(const char *ecryptfs_desc) +{ + int i; + + if (strlen(ecryptfs_desc) != KEY_ECRYPTFS_DESC_LEN) { + pr_err("encrypted_key: key description must be %d hexadecimal " + "characters long\n", KEY_ECRYPTFS_DESC_LEN); + return -EINVAL; + } + + for (i = 0; i < KEY_ECRYPTFS_DESC_LEN; i++) { + if (!isxdigit(ecryptfs_desc[i])) { + pr_err("encrypted_key: key description must contain " + "only hexadecimal characters\n"); + return -EINVAL; + } + } + + return 0; +} + /* * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key * @@ -158,7 +191,7 @@ static int datablob_parse(char *datablob, const char **format, } key_cmd = match_token(keyword, key_tokens, args); - /* Get optional format: default */ + /* Get optional format: default | ecryptfs */ p = strsep(&datablob, " \t"); if (!p) { pr_err("encrypted_key: insufficient parameters specified\n"); @@ -167,6 +200,7 @@ static int datablob_parse(char *datablob, const char **format, key_format = match_token(p, key_format_tokens, args); switch (key_format) { + case Opt_ecryptfs: case Opt_default: *format = p; *master_desc = strsep(&datablob, " \t"); @@ -601,6 +635,17 @@ static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, format_len = (!format) ? strlen(key_format_default) : strlen(format); decrypted_datalen = dlen; payload_datalen = decrypted_datalen; + if (format && !strcmp(format, key_format_ecryptfs)) { + if (dlen != ECRYPTFS_MAX_KEY_BYTES) { + pr_err("encrypted_key: keylen for the ecryptfs format " + "must be equal to %d bytes\n", + ECRYPTFS_MAX_KEY_BYTES); + return ERR_PTR(-EINVAL); + } + decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES; + payload_datalen = sizeof(struct ecryptfs_auth_tok); + } + encrypted_datalen = roundup(decrypted_datalen, blksize); datablob_len = format_len + 1 + strlen(master_desc) + 1 @@ -686,8 +731,14 @@ static void __ekey_init(struct encrypted_key_payload *epayload, if (!format) memcpy(epayload->format, key_format_default, format_len); - else + else { + if (!strcmp(format, key_format_ecryptfs)) + epayload->decrypted_data = + ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data); + memcpy(epayload->format, format, format_len); + } + memcpy(epayload->master_desc, master_desc, strlen(master_desc)); memcpy(epayload->datalen, datalen, strlen(datalen)); } @@ -699,11 +750,21 @@ 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 *format, const char *master_desc, - const char *datalen, const char *hex_encoded_iv) + const char *key_desc, const char *format, + const char *master_desc, const char *datalen, + const char *hex_encoded_iv) { int ret = 0; + if (format && !strcmp(format, key_format_ecryptfs)) { + ret = valid_ecryptfs_desc(key_desc); + if (ret < 0) + return ret; + + ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data, + key_desc); + } + __ekey_init(epayload, format, master_desc, datalen); if (!hex_encoded_iv) { get_random_bytes(epayload->iv, ivsize); @@ -753,8 +814,8 @@ static int encrypted_instantiate(struct key *key, const void *data, ret = PTR_ERR(epayload); goto out; } - ret = encrypted_init(epayload, format, master_desc, decrypted_datalen, - hex_encoded_iv); + ret = encrypted_init(epayload, key->description, format, master_desc, + decrypted_datalen, hex_encoded_iv); if (ret < 0) { kfree(epayload); goto out; -- cgit v1.2.3