1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2020-2024 Microsoft Corporation. All rights reserved.
4 */
5
6 #include <linux/slab.h>
7 #include <linux/audit.h>
8 #include <linux/types.h>
9 #include <crypto/sha2.h>
10
11 #include "ipe.h"
12 #include "eval.h"
13 #include "hooks.h"
14 #include "policy.h"
15 #include "audit.h"
16 #include "digest.h"
17
18 #define ACTSTR(x) ((x) == IPE_ACTION_ALLOW ? "ALLOW" : "DENY")
19
20 #define IPE_AUDIT_HASH_ALG "sha256" /* keep in sync with audit_policy() */
21
22 #define AUDIT_POLICY_LOAD_FMT "policy_name=\"%s\" policy_version=%hu.%hu.%hu "\
23 "policy_digest=" IPE_AUDIT_HASH_ALG ":"
24 #define AUDIT_POLICY_LOAD_NULL_FMT "policy_name=? policy_version=? "\
25 "policy_digest=?"
26 #define AUDIT_OLD_ACTIVE_POLICY_FMT "old_active_pol_name=\"%s\" "\
27 "old_active_pol_version=%hu.%hu.%hu "\
28 "old_policy_digest=" IPE_AUDIT_HASH_ALG ":"
29 #define AUDIT_OLD_ACTIVE_POLICY_NULL_FMT "old_active_pol_name=? "\
30 "old_active_pol_version=? "\
31 "old_policy_digest=?"
32 #define AUDIT_NEW_ACTIVE_POLICY_FMT "new_active_pol_name=\"%s\" "\
33 "new_active_pol_version=%hu.%hu.%hu "\
34 "new_policy_digest=" IPE_AUDIT_HASH_ALG ":"
35
36 static const char *const audit_op_names[__IPE_OP_MAX + 1] = {
37 "EXECUTE",
38 "FIRMWARE",
39 "KMODULE",
40 "KEXEC_IMAGE",
41 "KEXEC_INITRAMFS",
42 "POLICY",
43 "X509_CERT",
44 "UNKNOWN",
45 };
46
47 static const char *const audit_hook_names[__IPE_HOOK_MAX] = {
48 "BPRM_CHECK",
49 "MMAP",
50 "MPROTECT",
51 "KERNEL_READ",
52 "KERNEL_LOAD",
53 };
54
55 static const char *const audit_prop_names[__IPE_PROP_MAX] = {
56 "boot_verified=FALSE",
57 "boot_verified=TRUE",
58 "dmverity_roothash=",
59 "dmverity_signature=FALSE",
60 "dmverity_signature=TRUE",
61 "fsverity_digest=",
62 "fsverity_signature=FALSE",
63 "fsverity_signature=TRUE",
64 };
65
66 /**
67 * audit_dmv_roothash() - audit the roothash of a dmverity_roothash property.
68 * @ab: Supplies a pointer to the audit_buffer to append to.
69 * @rh: Supplies a pointer to the digest structure.
70 */
audit_dmv_roothash(struct audit_buffer * ab,const void * rh)71 static void audit_dmv_roothash(struct audit_buffer *ab, const void *rh)
72 {
73 audit_log_format(ab, "%s", audit_prop_names[IPE_PROP_DMV_ROOTHASH]);
74 ipe_digest_audit(ab, rh);
75 }
76
77 /**
78 * audit_fsv_digest() - audit the digest of a fsverity_digest property.
79 * @ab: Supplies a pointer to the audit_buffer to append to.
80 * @d: Supplies a pointer to the digest structure.
81 */
audit_fsv_digest(struct audit_buffer * ab,const void * d)82 static void audit_fsv_digest(struct audit_buffer *ab, const void *d)
83 {
84 audit_log_format(ab, "%s", audit_prop_names[IPE_PROP_FSV_DIGEST]);
85 ipe_digest_audit(ab, d);
86 }
87
88 /**
89 * audit_rule() - audit an IPE policy rule.
90 * @ab: Supplies a pointer to the audit_buffer to append to.
91 * @r: Supplies a pointer to the ipe_rule to approximate a string form for.
92 */
audit_rule(struct audit_buffer * ab,const struct ipe_rule * r)93 static void audit_rule(struct audit_buffer *ab, const struct ipe_rule *r)
94 {
95 const struct ipe_prop *ptr;
96
97 audit_log_format(ab, " rule=\"op=%s ", audit_op_names[r->op]);
98
99 list_for_each_entry(ptr, &r->props, next) {
100 switch (ptr->type) {
101 case IPE_PROP_DMV_ROOTHASH:
102 audit_dmv_roothash(ab, ptr->value);
103 break;
104 case IPE_PROP_FSV_DIGEST:
105 audit_fsv_digest(ab, ptr->value);
106 break;
107 default:
108 audit_log_format(ab, "%s", audit_prop_names[ptr->type]);
109 break;
110 }
111
112 audit_log_format(ab, " ");
113 }
114
115 audit_log_format(ab, "action=%s\"", ACTSTR(r->action));
116 }
117
118 /**
119 * ipe_audit_match() - Audit a rule match in a policy evaluation.
120 * @ctx: Supplies a pointer to the evaluation context that was used in the
121 * evaluation.
122 * @match_type: Supplies the scope of the match: rule, operation default,
123 * global default.
124 * @act: Supplies the IPE's evaluation decision, deny or allow.
125 * @r: Supplies a pointer to the rule that was matched, if possible.
126 */
ipe_audit_match(const struct ipe_eval_ctx * const ctx,enum ipe_match match_type,enum ipe_action_type act,const struct ipe_rule * const r)127 void ipe_audit_match(const struct ipe_eval_ctx *const ctx,
128 enum ipe_match match_type,
129 enum ipe_action_type act, const struct ipe_rule *const r)
130 {
131 const char *op = audit_op_names[ctx->op];
132 char comm[sizeof(current->comm)];
133 struct audit_buffer *ab;
134 struct inode *inode;
135
136 if (act != IPE_ACTION_DENY && !READ_ONCE(success_audit))
137 return;
138
139 ab = audit_log_start(audit_context(), GFP_ATOMIC | __GFP_NOWARN,
140 AUDIT_IPE_ACCESS);
141 if (!ab)
142 return;
143
144 audit_log_format(ab, "ipe_op=%s ipe_hook=%s enforcing=%d pid=%d comm=",
145 op, audit_hook_names[ctx->hook], READ_ONCE(enforce),
146 task_tgid_nr(current));
147 audit_log_untrustedstring(ab, get_task_comm(comm, current));
148
149 if (ctx->file) {
150 audit_log_d_path(ab, " path=", &ctx->file->f_path);
151 inode = file_inode(ctx->file);
152 if (inode) {
153 audit_log_format(ab, " dev=");
154 audit_log_untrustedstring(ab, inode->i_sb->s_id);
155 audit_log_format(ab, " ino=%lu", inode->i_ino);
156 } else {
157 audit_log_format(ab, " dev=? ino=?");
158 }
159 } else {
160 audit_log_format(ab, " path=? dev=? ino=?");
161 }
162
163 if (match_type == IPE_MATCH_RULE)
164 audit_rule(ab, r);
165 else if (match_type == IPE_MATCH_TABLE)
166 audit_log_format(ab, " rule=\"DEFAULT op=%s action=%s\"", op,
167 ACTSTR(act));
168 else
169 audit_log_format(ab, " rule=\"DEFAULT action=%s\"",
170 ACTSTR(act));
171
172 audit_log_end(ab);
173 }
174
175 /**
176 * audit_policy() - Audit a policy's name, version and thumbprint to @ab.
177 * @ab: Supplies a pointer to the audit buffer to append to.
178 * @audit_format: Supplies a pointer to the audit format string
179 * @p: Supplies a pointer to the policy to audit.
180 */
audit_policy(struct audit_buffer * ab,const char * audit_format,const struct ipe_policy * const p)181 static void audit_policy(struct audit_buffer *ab,
182 const char *audit_format,
183 const struct ipe_policy *const p)
184 {
185 u8 digest[SHA256_DIGEST_SIZE];
186
187 sha256(p->pkcs7, p->pkcs7len, digest);
188
189 audit_log_format(ab, audit_format, p->parsed->name,
190 p->parsed->version.major, p->parsed->version.minor,
191 p->parsed->version.rev);
192 audit_log_n_hex(ab, digest, sizeof(digest));
193 }
194
195 /**
196 * ipe_audit_policy_activation() - Audit a policy being activated.
197 * @op: Supplies a pointer to the previously activated policy to audit.
198 * @np: Supplies a pointer to the newly activated policy to audit.
199 */
ipe_audit_policy_activation(const struct ipe_policy * const op,const struct ipe_policy * const np)200 void ipe_audit_policy_activation(const struct ipe_policy *const op,
201 const struct ipe_policy *const np)
202 {
203 struct audit_buffer *ab;
204
205 ab = audit_log_start(audit_context(), GFP_KERNEL,
206 AUDIT_IPE_CONFIG_CHANGE);
207 if (!ab)
208 return;
209
210 if (op) {
211 audit_policy(ab, AUDIT_OLD_ACTIVE_POLICY_FMT, op);
212 audit_log_format(ab, " ");
213 } else {
214 /*
215 * old active policy can be NULL if there is no kernel
216 * built-in policy
217 */
218 audit_log_format(ab, AUDIT_OLD_ACTIVE_POLICY_NULL_FMT);
219 audit_log_format(ab, " ");
220 }
221 audit_policy(ab, AUDIT_NEW_ACTIVE_POLICY_FMT, np);
222 audit_log_format(ab, " auid=%u ses=%u lsm=ipe res=1",
223 from_kuid(&init_user_ns, audit_get_loginuid(current)),
224 audit_get_sessionid(current));
225
226 audit_log_end(ab);
227 }
228
229 /**
230 * ipe_audit_policy_load() - Audit a policy loading event.
231 * @p: Supplies a pointer to the policy to audit or an error pointer.
232 */
ipe_audit_policy_load(const struct ipe_policy * const p)233 void ipe_audit_policy_load(const struct ipe_policy *const p)
234 {
235 struct audit_buffer *ab;
236 int err = 0;
237
238 ab = audit_log_start(audit_context(), GFP_KERNEL,
239 AUDIT_IPE_POLICY_LOAD);
240 if (!ab)
241 return;
242
243 if (!IS_ERR(p)) {
244 audit_policy(ab, AUDIT_POLICY_LOAD_FMT, p);
245 } else {
246 audit_log_format(ab, AUDIT_POLICY_LOAD_NULL_FMT);
247 err = PTR_ERR(p);
248 }
249
250 audit_log_format(ab, " auid=%u ses=%u lsm=ipe res=%d errno=%d",
251 from_kuid(&init_user_ns, audit_get_loginuid(current)),
252 audit_get_sessionid(current), !err, err);
253
254 audit_log_end(ab);
255 }
256
257 /**
258 * ipe_audit_enforce() - Audit a change in IPE's enforcement state.
259 * @new_enforce: The new value enforce to be set.
260 * @old_enforce: The old value currently in enforce.
261 */
ipe_audit_enforce(bool new_enforce,bool old_enforce)262 void ipe_audit_enforce(bool new_enforce, bool old_enforce)
263 {
264 struct audit_buffer *ab;
265
266 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_MAC_STATUS);
267 if (!ab)
268 return;
269
270 audit_log(audit_context(), GFP_KERNEL, AUDIT_MAC_STATUS,
271 "enforcing=%d old_enforcing=%d auid=%u ses=%u"
272 " enabled=1 old-enabled=1 lsm=ipe res=1",
273 new_enforce, old_enforce,
274 from_kuid(&init_user_ns, audit_get_loginuid(current)),
275 audit_get_sessionid(current));
276
277 audit_log_end(ab);
278 }
279