1b4d0d230SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-or-later
2734114f8SDavid Howells /* System hash blacklist.
3734114f8SDavid Howells *
4734114f8SDavid Howells * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
5734114f8SDavid Howells * Written by David Howells (dhowells@redhat.com)
6734114f8SDavid Howells */
7734114f8SDavid Howells
8734114f8SDavid Howells #define pr_fmt(fmt) "blacklist: "fmt
9734114f8SDavid Howells #include <linux/module.h>
10734114f8SDavid Howells #include <linux/slab.h>
11734114f8SDavid Howells #include <linux/key.h>
12734114f8SDavid Howells #include <linux/key-type.h>
13734114f8SDavid Howells #include <linux/sched.h>
14734114f8SDavid Howells #include <linux/ctype.h>
15734114f8SDavid Howells #include <linux/err.h>
16734114f8SDavid Howells #include <linux/seq_file.h>
17a6cb0ab7SMickaël Salaün #include <linux/uidgid.h>
1860050ffeSDavid Howells #include <keys/asymmetric-type.h>
19734114f8SDavid Howells #include <keys/system_keyring.h>
20734114f8SDavid Howells #include "blacklist.h"
21734114f8SDavid Howells
22bf21dc59SMickaël Salaün /*
23bf21dc59SMickaël Salaün * According to crypto/asymmetric_keys/x509_cert_parser.c:x509_note_pkey_algo(),
24bf21dc59SMickaël Salaün * the size of the currently longest supported hash algorithm is 512 bits,
25bf21dc59SMickaël Salaün * which translates into 128 hex characters.
26bf21dc59SMickaël Salaün */
27bf21dc59SMickaël Salaün #define MAX_HASH_LEN 128
28bf21dc59SMickaël Salaün
296364d106SMickaël Salaün #define BLACKLIST_KEY_PERM (KEY_POS_SEARCH | KEY_POS_VIEW | \
306364d106SMickaël Salaün KEY_USR_SEARCH | KEY_USR_VIEW)
316364d106SMickaël Salaün
32bf21dc59SMickaël Salaün static const char tbs_prefix[] = "tbs";
33bf21dc59SMickaël Salaün static const char bin_prefix[] = "bin";
34bf21dc59SMickaël Salaün
35734114f8SDavid Howells static struct key *blacklist_keyring;
36734114f8SDavid Howells
37d1f04410SEric Snowberg #ifdef CONFIG_SYSTEM_REVOCATION_LIST
38d1f04410SEric Snowberg extern __initconst const u8 revocation_certificate_list[];
39d1f04410SEric Snowberg extern __initconst const unsigned long revocation_certificate_list_size;
40d1f04410SEric Snowberg #endif
41d1f04410SEric Snowberg
42734114f8SDavid Howells /*
43734114f8SDavid Howells * The description must be a type prefix, a colon and then an even number of
44734114f8SDavid Howells * hex digits. The hash is kept in the description.
45734114f8SDavid Howells */
blacklist_vet_description(const char * desc)46734114f8SDavid Howells static int blacklist_vet_description(const char *desc)
47734114f8SDavid Howells {
48bf21dc59SMickaël Salaün int i, prefix_len, tbs_step = 0, bin_step = 0;
49734114f8SDavid Howells
50bf21dc59SMickaël Salaün /* The following algorithm only works if prefix lengths match. */
51bf21dc59SMickaël Salaün BUILD_BUG_ON(sizeof(tbs_prefix) != sizeof(bin_prefix));
52bf21dc59SMickaël Salaün prefix_len = sizeof(tbs_prefix) - 1;
53bf21dc59SMickaël Salaün for (i = 0; *desc; desc++, i++) {
54bf21dc59SMickaël Salaün if (*desc == ':') {
55bf21dc59SMickaël Salaün if (tbs_step == prefix_len)
56734114f8SDavid Howells goto found_colon;
57bf21dc59SMickaël Salaün if (bin_step == prefix_len)
58bf21dc59SMickaël Salaün goto found_colon;
59bf21dc59SMickaël Salaün return -EINVAL;
60bf21dc59SMickaël Salaün }
61bf21dc59SMickaël Salaün if (i >= prefix_len)
62bf21dc59SMickaël Salaün return -EINVAL;
63bf21dc59SMickaël Salaün if (*desc == tbs_prefix[i])
64bf21dc59SMickaël Salaün tbs_step++;
65bf21dc59SMickaël Salaün if (*desc == bin_prefix[i])
66bf21dc59SMickaël Salaün bin_step++;
67bf21dc59SMickaël Salaün }
68734114f8SDavid Howells return -EINVAL;
69734114f8SDavid Howells
70734114f8SDavid Howells found_colon:
71734114f8SDavid Howells desc++;
72bf21dc59SMickaël Salaün for (i = 0; *desc && i < MAX_HASH_LEN; desc++, i++) {
7384ffbefdSMickaël Salaün if (!isxdigit(*desc) || isupper(*desc))
74734114f8SDavid Howells return -EINVAL;
75734114f8SDavid Howells }
76bf21dc59SMickaël Salaün if (*desc)
77bf21dc59SMickaël Salaün /* The hash is greater than MAX_HASH_LEN. */
78bf21dc59SMickaël Salaün return -ENOPKG;
79734114f8SDavid Howells
80bf21dc59SMickaël Salaün /* Checks for an even number of hexadecimal characters. */
81bf21dc59SMickaël Salaün if (i == 0 || i & 1)
82734114f8SDavid Howells return -EINVAL;
83734114f8SDavid Howells return 0;
84734114f8SDavid Howells }
85734114f8SDavid Howells
blacklist_key_instantiate(struct key * key,struct key_preparsed_payload * prep)866364d106SMickaël Salaün static int blacklist_key_instantiate(struct key *key,
876364d106SMickaël Salaün struct key_preparsed_payload *prep)
88734114f8SDavid Howells {
896364d106SMickaël Salaün #ifdef CONFIG_SYSTEM_BLACKLIST_AUTH_UPDATE
906364d106SMickaël Salaün int err;
916364d106SMickaël Salaün #endif
926364d106SMickaël Salaün
936364d106SMickaël Salaün /* Sets safe default permissions for keys loaded by user space. */
946364d106SMickaël Salaün key->perm = BLACKLIST_KEY_PERM;
956364d106SMickaël Salaün
966364d106SMickaël Salaün /*
976364d106SMickaël Salaün * Skips the authentication step for builtin hashes, they are not
986364d106SMickaël Salaün * signed but still trusted.
996364d106SMickaël Salaün */
1006364d106SMickaël Salaün if (key->flags & (1 << KEY_FLAG_BUILTIN))
1016364d106SMickaël Salaün goto out;
1026364d106SMickaël Salaün
1036364d106SMickaël Salaün #ifdef CONFIG_SYSTEM_BLACKLIST_AUTH_UPDATE
1046364d106SMickaël Salaün /*
1056364d106SMickaël Salaün * Verifies the description's PKCS#7 signature against the builtin
1066364d106SMickaël Salaün * trusted keyring.
1076364d106SMickaël Salaün */
1086364d106SMickaël Salaün err = verify_pkcs7_signature(key->description,
1096364d106SMickaël Salaün strlen(key->description), prep->data, prep->datalen,
1106364d106SMickaël Salaün NULL, VERIFYING_UNSPECIFIED_SIGNATURE, NULL, NULL);
1116364d106SMickaël Salaün if (err)
1126364d106SMickaël Salaün return err;
1136364d106SMickaël Salaün #else
1146364d106SMickaël Salaün /*
1156364d106SMickaël Salaün * It should not be possible to come here because the keyring doesn't
1166364d106SMickaël Salaün * have KEY_USR_WRITE and the only other way to call this function is
1176364d106SMickaël Salaün * for builtin hashes.
1186364d106SMickaël Salaün */
1196364d106SMickaël Salaün WARN_ON_ONCE(1);
1206364d106SMickaël Salaün return -EPERM;
1216364d106SMickaël Salaün #endif
1226364d106SMickaël Salaün
1236364d106SMickaël Salaün out:
1246364d106SMickaël Salaün return generic_key_instantiate(key, prep);
125734114f8SDavid Howells }
126734114f8SDavid Howells
blacklist_key_update(struct key * key,struct key_preparsed_payload * prep)1276364d106SMickaël Salaün static int blacklist_key_update(struct key *key,
1286364d106SMickaël Salaün struct key_preparsed_payload *prep)
129734114f8SDavid Howells {
1306364d106SMickaël Salaün return -EPERM;
131734114f8SDavid Howells }
132734114f8SDavid Howells
blacklist_describe(const struct key * key,struct seq_file * m)133734114f8SDavid Howells static void blacklist_describe(const struct key *key, struct seq_file *m)
134734114f8SDavid Howells {
135734114f8SDavid Howells seq_puts(m, key->description);
136734114f8SDavid Howells }
137734114f8SDavid Howells
138734114f8SDavid Howells static struct key_type key_type_blacklist = {
139734114f8SDavid Howells .name = "blacklist",
140734114f8SDavid Howells .vet_description = blacklist_vet_description,
1416364d106SMickaël Salaün .instantiate = blacklist_key_instantiate,
1426364d106SMickaël Salaün .update = blacklist_key_update,
143734114f8SDavid Howells .describe = blacklist_describe,
144734114f8SDavid Howells };
145734114f8SDavid Howells
get_raw_hash(const u8 * hash,size_t hash_len,enum blacklist_hash_type hash_type)146141e5239SMickaël Salaün static char *get_raw_hash(const u8 *hash, size_t hash_len,
147141e5239SMickaël Salaün enum blacklist_hash_type hash_type)
148141e5239SMickaël Salaün {
149141e5239SMickaël Salaün size_t type_len;
150141e5239SMickaël Salaün const char *type_prefix;
151141e5239SMickaël Salaün char *buffer, *p;
152141e5239SMickaël Salaün
153141e5239SMickaël Salaün switch (hash_type) {
154141e5239SMickaël Salaün case BLACKLIST_HASH_X509_TBS:
155141e5239SMickaël Salaün type_len = sizeof(tbs_prefix) - 1;
156141e5239SMickaël Salaün type_prefix = tbs_prefix;
157141e5239SMickaël Salaün break;
158141e5239SMickaël Salaün case BLACKLIST_HASH_BINARY:
159141e5239SMickaël Salaün type_len = sizeof(bin_prefix) - 1;
160141e5239SMickaël Salaün type_prefix = bin_prefix;
161141e5239SMickaël Salaün break;
162141e5239SMickaël Salaün default:
163141e5239SMickaël Salaün WARN_ON_ONCE(1);
164141e5239SMickaël Salaün return ERR_PTR(-EINVAL);
165141e5239SMickaël Salaün }
166141e5239SMickaël Salaün buffer = kmalloc(type_len + 1 + hash_len * 2 + 1, GFP_KERNEL);
167141e5239SMickaël Salaün if (!buffer)
168141e5239SMickaël Salaün return ERR_PTR(-ENOMEM);
169141e5239SMickaël Salaün p = memcpy(buffer, type_prefix, type_len);
170141e5239SMickaël Salaün p += type_len;
171141e5239SMickaël Salaün *p++ = ':';
172141e5239SMickaël Salaün bin2hex(p, hash, hash_len);
173141e5239SMickaël Salaün p += hash_len * 2;
174141e5239SMickaël Salaün *p = '\0';
175141e5239SMickaël Salaün return buffer;
176141e5239SMickaël Salaün }
177141e5239SMickaël Salaün
178734114f8SDavid Howells /**
179141e5239SMickaël Salaün * mark_raw_hash_blacklisted - Add a hash to the system blacklist
1800b2d443bSAlex Shi * @hash: The hash as a hex string with a type prefix (eg. "tbs:23aa429783")
181734114f8SDavid Howells */
mark_raw_hash_blacklisted(const char * hash)182141e5239SMickaël Salaün static int mark_raw_hash_blacklisted(const char *hash)
183734114f8SDavid Howells {
184734114f8SDavid Howells key_ref_t key;
185734114f8SDavid Howells
186*c95e8f6fSThomas Weißschuh key = key_create(make_key_ref(blacklist_keyring, true),
187734114f8SDavid Howells "blacklist",
188734114f8SDavid Howells hash,
189734114f8SDavid Howells NULL,
190734114f8SDavid Howells 0,
1916364d106SMickaël Salaün BLACKLIST_KEY_PERM,
192734114f8SDavid Howells KEY_ALLOC_NOT_IN_QUOTA |
193734114f8SDavid Howells KEY_ALLOC_BUILT_IN);
194734114f8SDavid Howells if (IS_ERR(key)) {
195*c95e8f6fSThomas Weißschuh if (PTR_ERR(key) == -EEXIST)
196*c95e8f6fSThomas Weißschuh pr_warn("Duplicate blacklisted hash %s\n", hash);
197*c95e8f6fSThomas Weißschuh else
19806b53b02SThomas Weißschuh pr_err("Problem blacklisting hash %s: %pe\n", hash, key);
199734114f8SDavid Howells return PTR_ERR(key);
200734114f8SDavid Howells }
201734114f8SDavid Howells return 0;
202734114f8SDavid Howells }
203734114f8SDavid Howells
mark_hash_blacklisted(const u8 * hash,size_t hash_len,enum blacklist_hash_type hash_type)204141e5239SMickaël Salaün int mark_hash_blacklisted(const u8 *hash, size_t hash_len,
205141e5239SMickaël Salaün enum blacklist_hash_type hash_type)
206141e5239SMickaël Salaün {
207141e5239SMickaël Salaün const char *buffer;
208141e5239SMickaël Salaün int err;
209141e5239SMickaël Salaün
210141e5239SMickaël Salaün buffer = get_raw_hash(hash, hash_len, hash_type);
211141e5239SMickaël Salaün if (IS_ERR(buffer))
212141e5239SMickaël Salaün return PTR_ERR(buffer);
213141e5239SMickaël Salaün err = mark_raw_hash_blacklisted(buffer);
214141e5239SMickaël Salaün kfree(buffer);
215141e5239SMickaël Salaün return err;
216141e5239SMickaël Salaün }
217141e5239SMickaël Salaün
218734114f8SDavid Howells /**
219734114f8SDavid Howells * is_hash_blacklisted - Determine if a hash is blacklisted
220734114f8SDavid Howells * @hash: The hash to be checked as a binary blob
221734114f8SDavid Howells * @hash_len: The length of the binary hash
222141e5239SMickaël Salaün * @hash_type: Type of hash
223734114f8SDavid Howells */
is_hash_blacklisted(const u8 * hash,size_t hash_len,enum blacklist_hash_type hash_type)224141e5239SMickaël Salaün int is_hash_blacklisted(const u8 *hash, size_t hash_len,
225141e5239SMickaël Salaün enum blacklist_hash_type hash_type)
226734114f8SDavid Howells {
227734114f8SDavid Howells key_ref_t kref;
228141e5239SMickaël Salaün const char *buffer;
229734114f8SDavid Howells int ret = 0;
230734114f8SDavid Howells
231141e5239SMickaël Salaün buffer = get_raw_hash(hash, hash_len, hash_type);
232141e5239SMickaël Salaün if (IS_ERR(buffer))
233141e5239SMickaël Salaün return PTR_ERR(buffer);
234734114f8SDavid Howells kref = keyring_search(make_key_ref(blacklist_keyring, true),
235dcf49dbcSDavid Howells &key_type_blacklist, buffer, false);
236734114f8SDavid Howells if (!IS_ERR(kref)) {
237734114f8SDavid Howells key_ref_put(kref);
238734114f8SDavid Howells ret = -EKEYREJECTED;
239734114f8SDavid Howells }
240734114f8SDavid Howells
241734114f8SDavid Howells kfree(buffer);
242734114f8SDavid Howells return ret;
243734114f8SDavid Howells }
244734114f8SDavid Howells EXPORT_SYMBOL_GPL(is_hash_blacklisted);
245734114f8SDavid Howells
is_binary_blacklisted(const u8 * hash,size_t hash_len)2462434f7d2SNayna Jain int is_binary_blacklisted(const u8 *hash, size_t hash_len)
2472434f7d2SNayna Jain {
248141e5239SMickaël Salaün if (is_hash_blacklisted(hash, hash_len, BLACKLIST_HASH_BINARY) ==
249141e5239SMickaël Salaün -EKEYREJECTED)
2502434f7d2SNayna Jain return -EPERM;
2512434f7d2SNayna Jain
2522434f7d2SNayna Jain return 0;
2532434f7d2SNayna Jain }
2542434f7d2SNayna Jain EXPORT_SYMBOL_GPL(is_binary_blacklisted);
2552434f7d2SNayna Jain
25656c58126SEric Snowberg #ifdef CONFIG_SYSTEM_REVOCATION_LIST
25756c58126SEric Snowberg /**
25856c58126SEric Snowberg * add_key_to_revocation_list - Add a revocation certificate to the blacklist
25956c58126SEric Snowberg * @data: The data blob containing the certificate
26056c58126SEric Snowberg * @size: The size of data blob
26156c58126SEric Snowberg */
add_key_to_revocation_list(const char * data,size_t size)26256c58126SEric Snowberg int add_key_to_revocation_list(const char *data, size_t size)
26356c58126SEric Snowberg {
26456c58126SEric Snowberg key_ref_t key;
26556c58126SEric Snowberg
26656c58126SEric Snowberg key = key_create_or_update(make_key_ref(blacklist_keyring, true),
26756c58126SEric Snowberg "asymmetric",
26856c58126SEric Snowberg NULL,
26956c58126SEric Snowberg data,
27056c58126SEric Snowberg size,
2716364d106SMickaël Salaün KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH
2726364d106SMickaël Salaün | KEY_USR_VIEW,
2736364d106SMickaël Salaün KEY_ALLOC_NOT_IN_QUOTA | KEY_ALLOC_BUILT_IN
2746364d106SMickaël Salaün | KEY_ALLOC_BYPASS_RESTRICTION);
27556c58126SEric Snowberg
27656c58126SEric Snowberg if (IS_ERR(key)) {
27756c58126SEric Snowberg pr_err("Problem with revocation key (%ld)\n", PTR_ERR(key));
27856c58126SEric Snowberg return PTR_ERR(key);
27956c58126SEric Snowberg }
28056c58126SEric Snowberg
28156c58126SEric Snowberg return 0;
28256c58126SEric Snowberg }
28356c58126SEric Snowberg
28456c58126SEric Snowberg /**
28556c58126SEric Snowberg * is_key_on_revocation_list - Determine if the key for a PKCS#7 message is revoked
28656c58126SEric Snowberg * @pkcs7: The PKCS#7 message to check
28756c58126SEric Snowberg */
is_key_on_revocation_list(struct pkcs7_message * pkcs7)28856c58126SEric Snowberg int is_key_on_revocation_list(struct pkcs7_message *pkcs7)
28956c58126SEric Snowberg {
29056c58126SEric Snowberg int ret;
29156c58126SEric Snowberg
29256c58126SEric Snowberg ret = pkcs7_validate_trust(pkcs7, blacklist_keyring);
29356c58126SEric Snowberg
29456c58126SEric Snowberg if (ret == 0)
29556c58126SEric Snowberg return -EKEYREJECTED;
29656c58126SEric Snowberg
29756c58126SEric Snowberg return -ENOKEY;
29856c58126SEric Snowberg }
29956c58126SEric Snowberg #endif
30056c58126SEric Snowberg
restrict_link_for_blacklist(struct key * dest_keyring,const struct key_type * type,const union key_payload * payload,struct key * restrict_key)3016364d106SMickaël Salaün static int restrict_link_for_blacklist(struct key *dest_keyring,
3026364d106SMickaël Salaün const struct key_type *type, const union key_payload *payload,
3036364d106SMickaël Salaün struct key *restrict_key)
3046364d106SMickaël Salaün {
3056364d106SMickaël Salaün if (type == &key_type_blacklist)
3066364d106SMickaël Salaün return 0;
3076364d106SMickaël Salaün return -EOPNOTSUPP;
3086364d106SMickaël Salaün }
3096364d106SMickaël Salaün
310734114f8SDavid Howells /*
3116e7c2b4dSMasahiro Yamada * Initialise the blacklist
3124d997501SMickaël Salaün *
3134d997501SMickaël Salaün * The blacklist_init() function is registered as an initcall via
3144d997501SMickaël Salaün * device_initcall(). As a result if the blacklist_init() function fails for
3154d997501SMickaël Salaün * any reason the kernel continues to execute. While cleanly returning -ENODEV
3164d997501SMickaël Salaün * could be acceptable for some non-critical kernel parts, if the blacklist
3174d997501SMickaël Salaün * keyring fails to load it defeats the certificate/key based deny list for
3184d997501SMickaël Salaün * signed modules. If a critical piece of security functionality that users
3194d997501SMickaël Salaün * expect to be present fails to initialize, panic()ing is likely the right
3204d997501SMickaël Salaün * thing to do.
321734114f8SDavid Howells */
blacklist_init(void)322734114f8SDavid Howells static int __init blacklist_init(void)
323734114f8SDavid Howells {
324734114f8SDavid Howells const char *const *bl;
3256364d106SMickaël Salaün struct key_restriction *restriction;
326734114f8SDavid Howells
327734114f8SDavid Howells if (register_key_type(&key_type_blacklist) < 0)
328734114f8SDavid Howells panic("Can't allocate system blacklist key type\n");
329734114f8SDavid Howells
3306364d106SMickaël Salaün restriction = kzalloc(sizeof(*restriction), GFP_KERNEL);
3316364d106SMickaël Salaün if (!restriction)
3326364d106SMickaël Salaün panic("Can't allocate blacklist keyring restriction\n");
3336364d106SMickaël Salaün restriction->check = restrict_link_for_blacklist;
3346364d106SMickaël Salaün
335734114f8SDavid Howells blacklist_keyring =
336734114f8SDavid Howells keyring_alloc(".blacklist",
337a6cb0ab7SMickaël Salaün GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, current_cred(),
3386364d106SMickaël Salaün KEY_POS_VIEW | KEY_POS_READ | KEY_POS_SEARCH |
3396364d106SMickaël Salaün KEY_POS_WRITE |
3406364d106SMickaël Salaün KEY_USR_VIEW | KEY_USR_READ | KEY_USR_SEARCH
3416364d106SMickaël Salaün #ifdef CONFIG_SYSTEM_BLACKLIST_AUTH_UPDATE
3426364d106SMickaël Salaün | KEY_USR_WRITE
3436364d106SMickaël Salaün #endif
3446364d106SMickaël Salaün , KEY_ALLOC_NOT_IN_QUOTA |
3454993e1f9SDavid Howells KEY_ALLOC_SET_KEEP,
3466364d106SMickaël Salaün restriction, NULL);
347734114f8SDavid Howells if (IS_ERR(blacklist_keyring))
348734114f8SDavid Howells panic("Can't allocate system blacklist keyring\n");
349734114f8SDavid Howells
350734114f8SDavid Howells for (bl = blacklist_hashes; *bl; bl++)
351141e5239SMickaël Salaün if (mark_raw_hash_blacklisted(*bl) < 0)
352734114f8SDavid Howells pr_err("- blacklisting failed\n");
353734114f8SDavid Howells return 0;
354734114f8SDavid Howells }
355734114f8SDavid Howells
356734114f8SDavid Howells /*
357734114f8SDavid Howells * Must be initialised before we try and load the keys into the keyring.
358734114f8SDavid Howells */
359734114f8SDavid Howells device_initcall(blacklist_init);
360d1f04410SEric Snowberg
361d1f04410SEric Snowberg #ifdef CONFIG_SYSTEM_REVOCATION_LIST
362d1f04410SEric Snowberg /*
363d1f04410SEric Snowberg * Load the compiled-in list of revocation X.509 certificates.
364d1f04410SEric Snowberg */
load_revocation_certificate_list(void)365d1f04410SEric Snowberg static __init int load_revocation_certificate_list(void)
366d1f04410SEric Snowberg {
367d1f04410SEric Snowberg if (revocation_certificate_list_size)
368d1f04410SEric Snowberg pr_notice("Loading compiled-in revocation X.509 certificates\n");
369d1f04410SEric Snowberg
37060050ffeSDavid Howells return x509_load_certificate_list(revocation_certificate_list,
37160050ffeSDavid Howells revocation_certificate_list_size,
372d1f04410SEric Snowberg blacklist_keyring);
373d1f04410SEric Snowberg }
374d1f04410SEric Snowberg late_initcall(load_revocation_certificate_list);
375d1f04410SEric Snowberg #endif
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