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 "BPRM_CREDS_FOR_EXEC", 50 "MMAP", 51 "MPROTECT", 52 "KERNEL_READ", 53 "KERNEL_LOAD", 54 }; 55 56 static const char *const audit_prop_names[__IPE_PROP_MAX] = { 57 "boot_verified=FALSE", 58 "boot_verified=TRUE", 59 "dmverity_roothash=", 60 "dmverity_signature=FALSE", 61 "dmverity_signature=TRUE", 62 "fsverity_digest=", 63 "fsverity_signature=FALSE", 64 "fsverity_signature=TRUE", 65 }; 66 67 /** 68 * audit_dmv_roothash() - audit the roothash of a dmverity_roothash property. 69 * @ab: Supplies a pointer to the audit_buffer to append to. 70 * @rh: Supplies a pointer to the digest structure. 71 */ 72 static void audit_dmv_roothash(struct audit_buffer *ab, const void *rh) 73 { 74 audit_log_format(ab, "%s", audit_prop_names[IPE_PROP_DMV_ROOTHASH]); 75 ipe_digest_audit(ab, rh); 76 } 77 78 /** 79 * audit_fsv_digest() - audit the digest of a fsverity_digest property. 80 * @ab: Supplies a pointer to the audit_buffer to append to. 81 * @d: Supplies a pointer to the digest structure. 82 */ 83 static void audit_fsv_digest(struct audit_buffer *ab, const void *d) 84 { 85 audit_log_format(ab, "%s", audit_prop_names[IPE_PROP_FSV_DIGEST]); 86 ipe_digest_audit(ab, d); 87 } 88 89 /** 90 * audit_rule() - audit an IPE policy rule. 91 * @ab: Supplies a pointer to the audit_buffer to append to. 92 * @r: Supplies a pointer to the ipe_rule to approximate a string form for. 93 */ 94 static void audit_rule(struct audit_buffer *ab, const struct ipe_rule *r) 95 { 96 const struct ipe_prop *ptr; 97 98 audit_log_format(ab, " rule=\"op=%s ", audit_op_names[r->op]); 99 100 list_for_each_entry(ptr, &r->props, next) { 101 switch (ptr->type) { 102 case IPE_PROP_DMV_ROOTHASH: 103 audit_dmv_roothash(ab, ptr->value); 104 break; 105 case IPE_PROP_FSV_DIGEST: 106 audit_fsv_digest(ab, ptr->value); 107 break; 108 default: 109 audit_log_format(ab, "%s", audit_prop_names[ptr->type]); 110 break; 111 } 112 113 audit_log_format(ab, " "); 114 } 115 116 audit_log_format(ab, "action=%s\"", ACTSTR(r->action)); 117 } 118 119 /** 120 * ipe_audit_match() - Audit a rule match in a policy evaluation. 121 * @ctx: Supplies a pointer to the evaluation context that was used in the 122 * evaluation. 123 * @match_type: Supplies the scope of the match: rule, operation default, 124 * global default. 125 * @act: Supplies the IPE's evaluation decision, deny or allow. 126 * @r: Supplies a pointer to the rule that was matched, if possible. 127 */ 128 void ipe_audit_match(const struct ipe_eval_ctx *const ctx, 129 enum ipe_match match_type, 130 enum ipe_action_type act, const struct ipe_rule *const r) 131 { 132 const char *op = audit_op_names[ctx->op]; 133 char comm[sizeof(current->comm)]; 134 struct audit_buffer *ab; 135 struct inode *inode; 136 137 if (act != IPE_ACTION_DENY && !READ_ONCE(success_audit)) 138 return; 139 140 ab = audit_log_start(audit_context(), GFP_ATOMIC | __GFP_NOWARN, 141 AUDIT_IPE_ACCESS); 142 if (!ab) 143 return; 144 145 audit_log_format(ab, "ipe_op=%s ipe_hook=%s enforcing=%d pid=%d comm=", 146 op, audit_hook_names[ctx->hook], READ_ONCE(enforce), 147 task_tgid_nr(current)); 148 audit_log_untrustedstring(ab, get_task_comm(comm, current)); 149 150 if (ctx->file) { 151 audit_log_d_path(ab, " path=", &ctx->file->f_path); 152 inode = file_inode(ctx->file); 153 if (inode) { 154 audit_log_format(ab, " dev="); 155 audit_log_untrustedstring(ab, inode->i_sb->s_id); 156 audit_log_format(ab, " ino=%lu", inode->i_ino); 157 } else { 158 audit_log_format(ab, " dev=? ino=?"); 159 } 160 } else { 161 audit_log_format(ab, " path=? dev=? ino=?"); 162 } 163 164 if (match_type == IPE_MATCH_RULE) 165 audit_rule(ab, r); 166 else if (match_type == IPE_MATCH_TABLE) 167 audit_log_format(ab, " rule=\"DEFAULT op=%s action=%s\"", op, 168 ACTSTR(act)); 169 else 170 audit_log_format(ab, " rule=\"DEFAULT action=%s\"", 171 ACTSTR(act)); 172 173 audit_log_end(ab); 174 } 175 176 /** 177 * audit_policy() - Audit a policy's name, version and thumbprint to @ab. 178 * @ab: Supplies a pointer to the audit buffer to append to. 179 * @audit_format: Supplies a pointer to the audit format string 180 * @p: Supplies a pointer to the policy to audit. 181 */ 182 static void audit_policy(struct audit_buffer *ab, 183 const char *audit_format, 184 const struct ipe_policy *const p) 185 { 186 u8 digest[SHA256_DIGEST_SIZE]; 187 188 sha256(p->pkcs7, p->pkcs7len, digest); 189 190 audit_log_format(ab, audit_format, p->parsed->name, 191 p->parsed->version.major, p->parsed->version.minor, 192 p->parsed->version.rev); 193 audit_log_n_hex(ab, digest, sizeof(digest)); 194 } 195 196 /** 197 * ipe_audit_policy_activation() - Audit a policy being activated. 198 * @op: Supplies a pointer to the previously activated policy to audit. 199 * @np: Supplies a pointer to the newly activated policy to audit. 200 */ 201 void ipe_audit_policy_activation(const struct ipe_policy *const op, 202 const struct ipe_policy *const np) 203 { 204 struct audit_buffer *ab; 205 206 ab = audit_log_start(audit_context(), GFP_KERNEL, 207 AUDIT_IPE_CONFIG_CHANGE); 208 if (!ab) 209 return; 210 211 if (op) { 212 audit_policy(ab, AUDIT_OLD_ACTIVE_POLICY_FMT, op); 213 audit_log_format(ab, " "); 214 } else { 215 /* 216 * old active policy can be NULL if there is no kernel 217 * built-in policy 218 */ 219 audit_log_format(ab, AUDIT_OLD_ACTIVE_POLICY_NULL_FMT); 220 audit_log_format(ab, " "); 221 } 222 audit_policy(ab, AUDIT_NEW_ACTIVE_POLICY_FMT, np); 223 audit_log_format(ab, " auid=%u ses=%u lsm=ipe res=1", 224 from_kuid(&init_user_ns, audit_get_loginuid(current)), 225 audit_get_sessionid(current)); 226 227 audit_log_end(ab); 228 } 229 230 /** 231 * ipe_audit_policy_load() - Audit a policy loading event. 232 * @p: Supplies a pointer to the policy to audit or an error pointer. 233 */ 234 void ipe_audit_policy_load(const struct ipe_policy *const p) 235 { 236 struct audit_buffer *ab; 237 int err = 0; 238 239 ab = audit_log_start(audit_context(), GFP_KERNEL, 240 AUDIT_IPE_POLICY_LOAD); 241 if (!ab) 242 return; 243 244 if (!IS_ERR(p)) { 245 audit_policy(ab, AUDIT_POLICY_LOAD_FMT, p); 246 } else { 247 audit_log_format(ab, AUDIT_POLICY_LOAD_NULL_FMT); 248 err = PTR_ERR(p); 249 } 250 251 audit_log_format(ab, " auid=%u ses=%u lsm=ipe res=%d errno=%d", 252 from_kuid(&init_user_ns, audit_get_loginuid(current)), 253 audit_get_sessionid(current), !err, err); 254 255 audit_log_end(ab); 256 } 257 258 /** 259 * ipe_audit_enforce() - Audit a change in IPE's enforcement state. 260 * @new_enforce: The new value enforce to be set. 261 * @old_enforce: The old value currently in enforce. 262 */ 263 void ipe_audit_enforce(bool new_enforce, bool old_enforce) 264 { 265 struct audit_buffer *ab; 266 267 ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_MAC_STATUS); 268 if (!ab) 269 return; 270 271 audit_log(audit_context(), GFP_KERNEL, AUDIT_MAC_STATUS, 272 "enforcing=%d old_enforcing=%d auid=%u ses=%u" 273 " enabled=1 old-enabled=1 lsm=ipe res=1", 274 new_enforce, old_enforce, 275 from_kuid(&init_user_ns, audit_get_loginuid(current)), 276 audit_get_sessionid(current)); 277 278 audit_log_end(ab); 279 } 280