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 */ 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 */ 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 */ 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 */ 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 */ 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 */ 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 */ 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 */ 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