1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Copyright (C) 2019 Microsoft Corporation.
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Author: Jaskaran Singh Khurana <jaskarankhurana@linux.microsoft.com>
6*4882a593Smuzhiyun *
7*4882a593Smuzhiyun */
8*4882a593Smuzhiyun #include <linux/device-mapper.h>
9*4882a593Smuzhiyun #include <linux/verification.h>
10*4882a593Smuzhiyun #include <keys/user-type.h>
11*4882a593Smuzhiyun #include <linux/module.h>
12*4882a593Smuzhiyun #include "dm-verity.h"
13*4882a593Smuzhiyun #include "dm-verity-verify-sig.h"
14*4882a593Smuzhiyun
15*4882a593Smuzhiyun #define DM_VERITY_VERIFY_ERR(s) DM_VERITY_ROOT_HASH_VERIFICATION " " s
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun static bool require_signatures;
18*4882a593Smuzhiyun module_param(require_signatures, bool, 0444);
19*4882a593Smuzhiyun MODULE_PARM_DESC(require_signatures,
20*4882a593Smuzhiyun "Verify the roothash of dm-verity hash tree");
21*4882a593Smuzhiyun
22*4882a593Smuzhiyun #define DM_VERITY_IS_SIG_FORCE_ENABLED() \
23*4882a593Smuzhiyun (require_signatures != false)
24*4882a593Smuzhiyun
verity_verify_is_sig_opt_arg(const char * arg_name)25*4882a593Smuzhiyun bool verity_verify_is_sig_opt_arg(const char *arg_name)
26*4882a593Smuzhiyun {
27*4882a593Smuzhiyun return (!strcasecmp(arg_name,
28*4882a593Smuzhiyun DM_VERITY_ROOT_HASH_VERIFICATION_OPT_SIG_KEY));
29*4882a593Smuzhiyun }
30*4882a593Smuzhiyun
verity_verify_get_sig_from_key(const char * key_desc,struct dm_verity_sig_opts * sig_opts)31*4882a593Smuzhiyun static int verity_verify_get_sig_from_key(const char *key_desc,
32*4882a593Smuzhiyun struct dm_verity_sig_opts *sig_opts)
33*4882a593Smuzhiyun {
34*4882a593Smuzhiyun struct key *key;
35*4882a593Smuzhiyun const struct user_key_payload *ukp;
36*4882a593Smuzhiyun int ret = 0;
37*4882a593Smuzhiyun
38*4882a593Smuzhiyun key = request_key(&key_type_user,
39*4882a593Smuzhiyun key_desc, NULL);
40*4882a593Smuzhiyun if (IS_ERR(key))
41*4882a593Smuzhiyun return PTR_ERR(key);
42*4882a593Smuzhiyun
43*4882a593Smuzhiyun down_read(&key->sem);
44*4882a593Smuzhiyun
45*4882a593Smuzhiyun ukp = user_key_payload_locked(key);
46*4882a593Smuzhiyun if (!ukp) {
47*4882a593Smuzhiyun ret = -EKEYREVOKED;
48*4882a593Smuzhiyun goto end;
49*4882a593Smuzhiyun }
50*4882a593Smuzhiyun
51*4882a593Smuzhiyun sig_opts->sig = kmalloc(ukp->datalen, GFP_KERNEL);
52*4882a593Smuzhiyun if (!sig_opts->sig) {
53*4882a593Smuzhiyun ret = -ENOMEM;
54*4882a593Smuzhiyun goto end;
55*4882a593Smuzhiyun }
56*4882a593Smuzhiyun sig_opts->sig_size = ukp->datalen;
57*4882a593Smuzhiyun
58*4882a593Smuzhiyun memcpy(sig_opts->sig, ukp->data, sig_opts->sig_size);
59*4882a593Smuzhiyun
60*4882a593Smuzhiyun end:
61*4882a593Smuzhiyun up_read(&key->sem);
62*4882a593Smuzhiyun key_put(key);
63*4882a593Smuzhiyun
64*4882a593Smuzhiyun return ret;
65*4882a593Smuzhiyun }
66*4882a593Smuzhiyun
verity_verify_sig_parse_opt_args(struct dm_arg_set * as,struct dm_verity * v,struct dm_verity_sig_opts * sig_opts,unsigned int * argc,const char * arg_name)67*4882a593Smuzhiyun int verity_verify_sig_parse_opt_args(struct dm_arg_set *as,
68*4882a593Smuzhiyun struct dm_verity *v,
69*4882a593Smuzhiyun struct dm_verity_sig_opts *sig_opts,
70*4882a593Smuzhiyun unsigned int *argc,
71*4882a593Smuzhiyun const char *arg_name)
72*4882a593Smuzhiyun {
73*4882a593Smuzhiyun struct dm_target *ti = v->ti;
74*4882a593Smuzhiyun int ret = 0;
75*4882a593Smuzhiyun const char *sig_key = NULL;
76*4882a593Smuzhiyun
77*4882a593Smuzhiyun if (!*argc) {
78*4882a593Smuzhiyun ti->error = DM_VERITY_VERIFY_ERR("Signature key not specified");
79*4882a593Smuzhiyun return -EINVAL;
80*4882a593Smuzhiyun }
81*4882a593Smuzhiyun
82*4882a593Smuzhiyun sig_key = dm_shift_arg(as);
83*4882a593Smuzhiyun (*argc)--;
84*4882a593Smuzhiyun
85*4882a593Smuzhiyun ret = verity_verify_get_sig_from_key(sig_key, sig_opts);
86*4882a593Smuzhiyun if (ret < 0)
87*4882a593Smuzhiyun ti->error = DM_VERITY_VERIFY_ERR("Invalid key specified");
88*4882a593Smuzhiyun
89*4882a593Smuzhiyun v->signature_key_desc = kstrdup(sig_key, GFP_KERNEL);
90*4882a593Smuzhiyun if (!v->signature_key_desc)
91*4882a593Smuzhiyun return -ENOMEM;
92*4882a593Smuzhiyun
93*4882a593Smuzhiyun return ret;
94*4882a593Smuzhiyun }
95*4882a593Smuzhiyun
96*4882a593Smuzhiyun /*
97*4882a593Smuzhiyun * verify_verify_roothash - Verify the root hash of the verity hash device
98*4882a593Smuzhiyun * using builtin trusted keys.
99*4882a593Smuzhiyun *
100*4882a593Smuzhiyun * @root_hash: For verity, the roothash/data to be verified.
101*4882a593Smuzhiyun * @root_hash_len: Size of the roothash/data to be verified.
102*4882a593Smuzhiyun * @sig_data: The trusted signature that verifies the roothash/data.
103*4882a593Smuzhiyun * @sig_len: Size of the signature.
104*4882a593Smuzhiyun *
105*4882a593Smuzhiyun */
verity_verify_root_hash(const void * root_hash,size_t root_hash_len,const void * sig_data,size_t sig_len)106*4882a593Smuzhiyun int verity_verify_root_hash(const void *root_hash, size_t root_hash_len,
107*4882a593Smuzhiyun const void *sig_data, size_t sig_len)
108*4882a593Smuzhiyun {
109*4882a593Smuzhiyun int ret;
110*4882a593Smuzhiyun
111*4882a593Smuzhiyun if (!root_hash || root_hash_len == 0)
112*4882a593Smuzhiyun return -EINVAL;
113*4882a593Smuzhiyun
114*4882a593Smuzhiyun if (!sig_data || sig_len == 0) {
115*4882a593Smuzhiyun if (DM_VERITY_IS_SIG_FORCE_ENABLED())
116*4882a593Smuzhiyun return -ENOKEY;
117*4882a593Smuzhiyun else
118*4882a593Smuzhiyun return 0;
119*4882a593Smuzhiyun }
120*4882a593Smuzhiyun
121*4882a593Smuzhiyun ret = verify_pkcs7_signature(root_hash, root_hash_len, sig_data,
122*4882a593Smuzhiyun sig_len, NULL, VERIFYING_UNSPECIFIED_SIGNATURE,
123*4882a593Smuzhiyun NULL, NULL);
124*4882a593Smuzhiyun
125*4882a593Smuzhiyun return ret;
126*4882a593Smuzhiyun }
127*4882a593Smuzhiyun
verity_verify_sig_opts_cleanup(struct dm_verity_sig_opts * sig_opts)128*4882a593Smuzhiyun void verity_verify_sig_opts_cleanup(struct dm_verity_sig_opts *sig_opts)
129*4882a593Smuzhiyun {
130*4882a593Smuzhiyun kfree(sig_opts->sig);
131*4882a593Smuzhiyun sig_opts->sig = NULL;
132*4882a593Smuzhiyun sig_opts->sig_size = 0;
133*4882a593Smuzhiyun }
134