// SPDX-License-Identifier: GPL-2.0-only /* * Copyright (C) 2008 IBM Corporation * Author: Mimi Zohar * * ima_policy.c * - initialize default measure policy rules */ #include #include #include #include #include #include #include #include #include #include #include #include #include "ima.h" /* flags definitions */ #define IMA_FUNC 0x0001 #define IMA_MASK 0x0002 #define IMA_FSMAGIC 0x0004 #define IMA_UID 0x0008 #define IMA_FOWNER 0x0010 #define IMA_FSUUID 0x0020 #define IMA_INMASK 0x0040 #define IMA_EUID 0x0080 #define IMA_PCR 0x0100 #define IMA_FSNAME 0x0200 #define IMA_KEYRINGS 0x0400 #define IMA_LABEL 0x0800 #define IMA_VALIDATE_ALGOS 0x1000 #define UNKNOWN 0 #define MEASURE 0x0001 /* same as IMA_MEASURE */ #define DONT_MEASURE 0x0002 #define APPRAISE 0x0004 /* same as IMA_APPRAISE */ #define DONT_APPRAISE 0x0008 #define AUDIT 0x0040 #define HASH 0x0100 #define DONT_HASH 0x0200 #define INVALID_PCR(a) (((a) < 0) || \ (a) >= (sizeof_field(struct integrity_iint_cache, measured_pcrs) * 8)) int ima_policy_flag; static int temp_ima_appraise; static int build_ima_appraise __ro_after_init; atomic_t ima_setxattr_allowed_hash_algorithms; #define MAX_LSM_RULES 6 enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE, LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE }; enum policy_types { ORIGINAL_TCB = 1, DEFAULT_TCB }; enum policy_rule_list { IMA_DEFAULT_POLICY = 1, IMA_CUSTOM_POLICY }; struct ima_rule_opt_list { size_t count; char *items[]; }; struct ima_rule_entry { struct list_head list; int action; unsigned int flags; enum ima_hooks func; int mask; unsigned long fsmagic; uuid_t fsuuid; kuid_t uid; kuid_t fowner; bool (*uid_op)(kuid_t, kuid_t); /* Handlers for operators */ bool (*fowner_op)(kuid_t, kuid_t); /* uid_eq(), uid_gt(), uid_lt() */ int pcr; unsigned int allowed_algos; /* bitfield of allowed hash algorithms */ struct { void *rule; /* LSM file metadata specific */ char *args_p; /* audit value */ int type; /* audit type */ } lsm[MAX_LSM_RULES]; char *fsname; struct ima_rule_opt_list *keyrings; /* Measure keys added to these keyrings */ struct ima_rule_opt_list *label; /* Measure data grouped under this label */ struct ima_template_desc *template; }; /* * sanity check in case the kernels gains more hash algorithms that can * fit in an unsigned int */ static_assert( 8 * sizeof(unsigned int) >= HASH_ALGO__LAST, "The bitfield allowed_algos in ima_rule_entry is too small to contain all the supported hash algorithms, consider using a bigger type"); /* * Without LSM specific knowledge, the default policy can only be * written in terms of .action, .func, .mask, .fsmagic, .uid, and .fowner */ /* * The minimum rule set to allow for full TCB coverage. Measures all files * opened or mmap for exec and everything read by root. Dangerous because * normal users can easily run the machine out of memory simply building * and running executables. */ static struct ima_rule_entry dont_measure_rules[] __ro_after_init = { {.action = DONT_MEASURE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_MEASURE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_MEASURE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_MEASURE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_MEASURE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_MEASURE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_MEASURE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_MEASURE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_MEASURE, .fsmagic = SMACK_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_MEASURE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_MEASURE, .fsmagic = CGROUP2_SUPER_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_MEASURE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC} }; static struct ima_rule_entry original_measurement_rules[] __ro_after_init = { {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC, .flags = IMA_FUNC | IMA_MASK}, {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC, .flags = IMA_FUNC | IMA_MASK}, {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ, .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq, .flags = IMA_FUNC | IMA_MASK | IMA_UID}, {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC}, {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC}, }; static struct ima_rule_entry default_measurement_rules[] __ro_after_init = { {.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC, .flags = IMA_FUNC | IMA_MASK}, {.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC, .flags = IMA_FUNC | IMA_MASK}, {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ, .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq, .flags = IMA_FUNC | IMA_INMASK | IMA_EUID}, {.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ, .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq, .flags = IMA_FUNC | IMA_INMASK | IMA_UID}, {.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC}, {.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC}, {.action = MEASURE, .func = POLICY_CHECK, .flags = IMA_FUNC}, }; static struct ima_rule_entry default_appraise_rules[] __ro_after_init = { {.action = DONT_APPRAISE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = TMPFS_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = RAMFS_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = DEVPTS_SUPER_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = BINFMTFS_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = SECURITYFS_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = SMACK_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = CGROUP2_SUPER_MAGIC, .flags = IMA_FSMAGIC}, #ifdef CONFIG_IMA_WRITE_POLICY {.action = APPRAISE, .func = POLICY_CHECK, .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, #endif #ifndef CONFIG_IMA_APPRAISE_SIGNED_INIT {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &uid_eq, .flags = IMA_FOWNER}, #else /* force signature */ {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &uid_eq, .flags = IMA_FOWNER | IMA_DIGSIG_REQUIRED}, #endif }; static struct ima_rule_entry build_appraise_rules[] __ro_after_init = { #ifdef CONFIG_IMA_APPRAISE_REQUIRE_MODULE_SIGS {.action = APPRAISE, .func = MODULE_CHECK, .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, #endif #ifdef CONFIG_IMA_APPRAISE_REQUIRE_FIRMWARE_SIGS {.action = APPRAISE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, #endif #ifdef CONFIG_IMA_APPRAISE_REQUIRE_KEXEC_SIGS {.action = APPRAISE, .func = KEXEC_KERNEL_CHECK, .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, #endif #ifdef CONFIG_IMA_APPRAISE_REQUIRE_POLICY_SIGS {.action = APPRAISE, .func = POLICY_CHECK, .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, #endif }; static struct ima_rule_entry secure_boot_rules[] __ro_after_init = { {.action = APPRAISE, .func = MODULE_CHECK, .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, {.action = APPRAISE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, {.action = APPRAISE, .func = KEXEC_KERNEL_CHECK, .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, {.action = APPRAISE, .func = POLICY_CHECK, .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, }; static struct ima_rule_entry critical_data_rules[] __ro_after_init = { {.action = MEASURE, .func = CRITICAL_DATA, .flags = IMA_FUNC}, }; /* An array of architecture specific rules */ static struct ima_rule_entry *arch_policy_entry __ro_after_init; static LIST_HEAD(ima_default_rules); static LIST_HEAD(ima_policy_rules); static LIST_HEAD(ima_temp_rules); static struct list_head __rcu *ima_rules = (struct list_head __rcu *)(&ima_default_rules); static int ima_policy __initdata; static int __init default_measure_policy_setup(char *str) { if (ima_policy) return 1; ima_policy = ORIGINAL_TCB; return 1; } __setup("ima_tcb", default_measure_policy_setup); static bool ima_use_appraise_tcb __initdata; static bool ima_use_secure_boot __initdata; static bool ima_use_critical_data __initdata; static bool ima_fail_unverifiable_sigs __ro_after_init; static int __init policy_setup(char *str) { char *p; while ((p = strsep(&str, " |\n")) != NULL) { if (*p == ' ') continue; if ((strcmp(p, "tcb") == 0) && !ima_policy) ima_policy = DEFAULT_TCB; else if (strcmp(p, "appraise_tcb") == 0) ima_use_appraise_tcb = true; else if (strcmp(p, "secure_boot") == 0) ima_use_secure_boot = true; else if (strcmp(p, "critical_data") == 0) ima_use_critical_data = true; else if (strcmp(p, "fail_securely") == 0) ima_fail_unverifiable_sigs = true; else pr_err("policy \"%s\" not found", p); } return 1; } __setup("ima_policy=", policy_setup); static int __init default_appraise_policy_setup(char *str) { ima_use_appraise_tcb = true; return 1; } __setup("ima_appraise_tcb", default_appraise_policy_setup); static struct ima_rule_opt_list *ima_alloc_rule_opt_list(const substring_t *src) { struct ima_rule_opt_list *opt_list; size_t count = 0; char *src_copy; char *cur, *next; size_t i; src_copy = match_strdup(src); if (!src_copy) return ERR_PTR(-ENOMEM); next = src_copy; while ((cur = strsep(&next, "|"))) { /* Don't accept an empty list item */ if (!(*cur)) { kfree(src_copy); return ERR_PTR(-EINVAL); } count++; } /* Don't accept an empty list */ if (!count) { kfree(src_copy); return ERR_PTR(-EINVAL); } opt_list = kzalloc(struct_size(opt_list, items, count), GFP_KERNEL); if (!opt_list) { kfree(src_copy); return ERR_PTR(-ENOMEM); } /* * strsep() has already replaced all instances of '|' with '\0', * leaving a byte sequence of NUL-terminated strings. Reference each * string with the array of items. * * IMPORTANT: Ownership of the allocated buffer is transferred from * src_copy to the first element in the items array. To free the * buffer, kfree() must only be called on the first element of the * array. */ for (i = 0, cur = src_copy; i < count; i++) { opt_list->items[i] = cur; cur = strchr(cur, '\0') + 1; } opt_list->count = count; return opt_list; } static void ima_free_rule_opt_list(struct ima_rule_opt_list *opt_list) { if (!opt_list) return; if (opt_list->count) { kfree(opt_list->items[0]); opt_list->count = 0; } kfree(opt_list); } static void ima_lsm_free_rule(struct ima_rule_entry *entry) { int i; for (i = 0; i < MAX_LSM_RULES; i++) { ima_filter_rule_free(entry->lsm[i].rule); kfree(entry->lsm[i].args_p); } } static void ima_free_rule(struct ima_rule_entry *entry) { if (!entry) return; /* * entry->template->fields may be allocated in ima_parse_rule() but that * reference is owned by the corresponding ima_template_desc element in * the defined_templates list and cannot be freed here */ kfree(entry->fsname); ima_free_rule_opt_list(entry->keyrings); ima_lsm_free_rule(entry); kfree(entry); } static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry) { struct ima_rule_entry *nentry; int i; /* * Immutable elements are copied over as pointers and data; only * lsm rules can change */ nentry = kmemdup(entry, sizeof(*nentry), GFP_KERNEL); if (!nentry) return NULL; memset(nentry->lsm, 0, sizeof_field(struct ima_rule_entry, lsm)); for (i = 0; i < MAX_LSM_RULES; i++) { if (!entry->lsm[i].args_p) continue; nentry->lsm[i].type = entry->lsm[i].type; nentry->lsm[i].args_p = entry->lsm[i].args_p; ima_filter_rule_init(nentry->lsm[i].type, Audit_equal, nentry->lsm[i].args_p, &nentry->lsm[i].rule); if (!nentry->lsm[i].rule) pr_warn("rule for LSM \'%s\' is undefined\n", nentry->lsm[i].args_p); } return nentry; } static int ima_lsm_update_rule(struct ima_rule_entry *entry) { int i; struct ima_rule_entry *nentry; nentry = ima_lsm_copy_rule(entry); if (!nentry) return -ENOMEM; list_replace_rcu(&entry->list, &nentry->list); synchronize_rcu(); /* * ima_lsm_copy_rule() shallow copied all references, except for the * LSM references, from entry to nentry so we only want to free the LSM * references and the entry itself. All other memory refrences will now * be owned by nentry. */ for (i = 0; i < MAX_LSM_RULES; i++) ima_filter_rule_free(entry->lsm[i].rule); kfree(entry); return 0; } static bool ima_rule_contains_lsm_cond(struct ima_rule_entry *entry) { int i; for (i = 0; i < MAX_LSM_RULES; i++) if (entry->lsm[i].args_p) return true; return false; } /* * The LSM policy can be reloaded, leaving the IMA LSM based rules referring * to the old, stale LSM policy. Update the IMA LSM based rules to reflect * the reloaded LSM policy. */ static void ima_lsm_update_rules(void) { struct ima_rule_entry *entry, *e; int result; list_for_each_entry_safe(entry, e, &ima_policy_rules, list) { if (!ima_rule_contains_lsm_cond(entry)) continue; result = ima_lsm_update_rule(entry); if (result) { pr_err("lsm rule update error %d\n", result); return; } } } int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event, void *lsm_data) { if (event != LSM_POLICY_CHANGE) return NOTIFY_DONE; ima_lsm_update_rules(); return NOTIFY_OK; } /** * ima_match_rule_data - determine whether func_data matches the policy rule * @rule: a pointer to a rule * @func_data: data to match against the measure rule data * @cred: a pointer to a credentials structure for user validation * * Returns true if func_data matches one in the rule, false otherwise. */ static bool ima_match_rule_data(struct ima_rule_entry *rule, const char *func_data, const struct cred *cred) { const struct ima_rule_opt_list *opt_list = NULL; bool matched = false; size_t i; if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid)) return false; switch (rule->func) { case KEY_CHECK: if (!rule->keyrings) return true; opt_list = rule->keyrings; break; case CRITICAL_DATA: if (!rule->label) return true; opt_list = rule->label; break; default: return false; } if (!func_data) return false; for (i = 0; i < opt_list->count; i++) { if (!strcmp(opt_list->items[i], func_data)) { matched = true; break; } } return matched; } /** * ima_match_rules - determine whether an inode matches the policy rule. * @rule: a pointer to a rule * @mnt_userns: user namespace of the mount the inode was found from * @inode: a pointer to an inode * @cred: a pointer to a credentials structure for user validation * @secid: the secid of the task to be validated * @func: LIM hook identifier * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC) * @func_data: func specific data, may be NULL * * Returns true on rule match, false on failure. */ static bool ima_match_rules(struct ima_rule_entry *rule, struct user_namespace *mnt_userns, struct inode *inode, const struct cred *cred, u32 secid, enum ima_hooks func, int mask, const char *func_data) { int i; bool result = false; struct ima_rule_entry *lsm_rule = rule; bool rule_reinitialized = false; if ((rule->flags & IMA_FUNC) && (rule->func != func && func != POST_SETATTR)) return false; switch (func) { case KEY_CHECK: case CRITICAL_DATA: return ((rule->func == func) && ima_match_rule_data(rule, func_data, cred)); default: break; } if ((rule->flags & IMA_MASK) && (rule->mask != mask && func != POST_SETATTR)) return false; if ((rule->flags & IMA_INMASK) && (!(rule->mask & mask) && func != POST_SETATTR)) return false; if ((rule->flags & IMA_FSMAGIC) && rule->fsmagic != inode->i_sb->s_magic) return false; if ((rule->flags & IMA_FSNAME) && strcmp(rule->fsname, inode->i_sb->s_type->name)) return false; if ((rule->flags & IMA_FSUUID) && !uuid_equal(&rule->fsuuid, &inode->i_sb->s_uuid)) return false; if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid)) return false; if (rule->flags & IMA_EUID) { if (has_capability_noaudit(current, CAP_SETUID)) { if (!rule->uid_op(cred->euid, rule->uid) && !rule->uid_op(cred->suid, rule->uid) && !rule->uid_op(cred->uid, rule->uid)) return false; } else if (!rule->uid_op(cred->euid, rule->uid)) return false; } if ((rule->flags & IMA_FOWNER) && !rule->fowner_op(i_uid_into_mnt(mnt_userns, inode), rule->fowner)) return false; for (i = 0; i < MAX_LSM_RULES; i++) { int rc = 0; u32 osid; if (!lsm_rule->lsm[i].rule) { if (!lsm_rule->lsm[i].args_p) continue; else return false; } retry: switch (i) { case LSM_OBJ_USER: case LSM_OBJ_ROLE: case LSM_OBJ_TYPE: security_inode_getsecid(inode, &osid); rc = ima_filter_rule_match(osid, lsm_rule->lsm[i].type, Audit_equal, lsm_rule->lsm[i].rule); break; case LSM_SUBJ_USER: case LSM_SUBJ_ROLE: case LSM_SUBJ_TYPE: rc = ima_filter_rule_match(secid, lsm_rule->lsm[i].type, Audit_equal, lsm_rule->lsm[i].rule); break; default: break; } if (rc == -ESTALE && !rule_reinitialized) { lsm_rule = ima_lsm_copy_rule(rule); if (lsm_rule) { rule_reinitialized = true; goto retry; } } if (!rc) { result = false; goto out; } } result = true; out: if (rule_reinitialized) { for (i = 0; i < MAX_LSM_RULES; i++) ima_filter_rule_free(lsm_rule->lsm[i].rule); kfree(lsm_rule); } return result; } /* * In addition to knowing that we need to appraise the file in general, * we need to differentiate between calling hooks, for hook specific rules. */ static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func) { if (!(rule->flags & IMA_FUNC)) return IMA_FILE_APPRAISE; switch (func) { case MMAP_CHECK: return IMA_MMAP_APPRAISE; case BPRM_CHECK: return IMA_BPRM_APPRAISE; case CREDS_CHECK: return IMA_CREDS_APPRAISE; case FILE_CHECK: case POST_SETATTR: return IMA_FILE_APPRAISE; case MODULE_CHECK ... MAX_CHECK - 1: default: return IMA_READ_APPRAISE; } } /** * ima_match_policy - decision based on LSM and other conditions * @mnt_userns: user namespace of the mount the inode was found from * @inode: pointer to an inode for which the policy decision is being made * @cred: pointer to a credentials structure for which the policy decision is * being made * @secid: LSM secid of the task to be validated * @func: IMA hook identifier * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC) * @pcr: set the pcr to extend * @template_desc: the template that should be used for this rule * @func_data: func specific data, may be NULL * @allowed_algos: allowlist of hash algorithms for the IMA xattr * * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type) * conditions. * * Since the IMA policy may be updated multiple times we need to lock the * list when walking it. Reads are many orders of magnitude more numerous * than writes so ima_match_policy() is classical RCU candidate. */ int ima_match_policy(struct user_namespace *mnt_userns, struct inode *inode, const struct cred *cred, u32 secid, enum ima_hooks func, int mask, int flags, int *pcr, struct ima_template_desc **template_desc, const char *func_data, unsigned int *allowed_algos) { struct ima_rule_entry *entry; int action = 0, actmask = flags | (flags << 1); struct list_head *ima_rules_tmp; if (template_desc && !*template_desc) *template_desc = ima_template_desc_current(); rcu_read_lock(); ima_rules_tmp = rcu_dereference(ima_rules); list_for_each_entry_rcu(entry, ima_rules_tmp, list) { if (!(entry->action & actmask)) continue; if (!ima_match_rules(entry, mnt_userns, inode, cred, secid, func, mask, func_data)) continue; action |= entry->flags & IMA_ACTION_FLAGS; action |= entry->action & IMA_DO_MASK; if (entry->action & IMA_APPRAISE) { action |= get_subaction(entry, func); action &= ~IMA_HASH; if (ima_fail_unverifiable_sigs) action |= IMA_FAIL_UNVERIFIABLE_SIGS; if (allowed_algos && entry->flags & IMA_VALIDATE_ALGOS) *allowed_algos = entry->allowed_algos; } if (entry->action & IMA_DO_MASK) actmask &= ~(entry->action | entry->action << 1); else actmask &= ~(entry->action | entry->action >> 1); if ((pcr) && (entry->flags & IMA_PCR)) *pcr = entry->pcr; if (template_desc && entry->template) *template_desc = entry->template; if (!actmask) break; } rcu_read_unlock(); return action; } /** * ima_update_policy_flags() - Update global IMA variables * * Update ima_policy_flag and ima_setxattr_allowed_hash_algorithms * based on the currently loaded policy. * * With ima_policy_flag, the decision to short circuit out of a function * or not call the function in the first place can be made earlier. * * With ima_setxattr_allowed_hash_algorithms, the policy can restrict the * set of hash algorithms accepted when updating the security.ima xattr of * a file. * * Context: called after a policy update and at system initialization. */ void ima_update_policy_flags(void) { struct ima_rule_entry *entry; int new_policy_flag = 0; struct list_head *ima_rules_tmp; rcu_read_lock(); ima_rules_tmp = rcu_dereference(ima_rules); list_for_each_entry_rcu(entry, ima_rules_tmp, list) { /* * SETXATTR_CHECK rules do not implement a full policy check * because rule checking would probably have an important * performance impact on setxattr(). As a consequence, only one * SETXATTR_CHECK can be active at a given time. * Because we want to preserve that property, we set out to use * atomic_cmpxchg. Either: * - the atomic was non-zero: a setxattr hash policy is * already enforced, we do nothing * - the atomic was zero: no setxattr policy was set, enable * the setxattr hash policy */ if (entry->func == SETXATTR_CHECK) { atomic_cmpxchg(&ima_setxattr_allowed_hash_algorithms, 0, entry->allowed_algos); /* SETXATTR_CHECK doesn't impact ima_policy_flag */ continue; } if (entry->action & IMA_DO_MASK) new_policy_flag |= entry->action; } rcu_read_unlock(); ima_appraise |= (build_ima_appraise | temp_ima_appraise); if (!ima_appraise) new_policy_flag &= ~IMA_APPRAISE; ima_policy_flag = new_policy_flag; } static int ima_appraise_flag(enum ima_hooks func) { if (func == MODULE_CHECK) return IMA_APPRAISE_MODULES; else if (func == FIRMWARE_CHECK) return IMA_APPRAISE_FIRMWARE; else if (func == POLICY_CHECK) return IMA_APPRAISE_POLICY; else if (func == KEXEC_KERNEL_CHECK) return IMA_APPRAISE_KEXEC; return 0; } static void add_rules(struct ima_rule_entry *entries, int count, enum policy_rule_list policy_rule) { int i = 0; for (i = 0; i < count; i++) { struct ima_rule_entry *entry; if (policy_rule & IMA_DEFAULT_POLICY) list_add_tail(&entries[i].list, &ima_default_rules); if (policy_rule & IMA_CUSTOM_POLICY) { entry = kmemdup(&entries[i], sizeof(*entry), GFP_KERNEL); if (!entry) continue; list_add_tail(&entry->list, &ima_policy_rules); } if (entries[i].action == APPRAISE) { if (entries != build_appraise_rules) temp_ima_appraise |= ima_appraise_flag(entries[i].func); else build_ima_appraise |= ima_appraise_flag(entries[i].func); } } } static int ima_parse_rule(char *rule, struct ima_rule_entry *entry); static int __init ima_init_arch_policy(void) { const char * const *arch_rules; const char * const *rules; int arch_entries = 0; int i = 0; arch_rules = arch_get_ima_policy(); if (!arch_rules) return arch_entries; /* Get number of rules */ for (rules = arch_rules; *rules != NULL; rules++) arch_entries++; arch_policy_entry = kcalloc(arch_entries + 1, sizeof(*arch_policy_entry), GFP_KERNEL); if (!arch_policy_entry) return 0; /* Convert each policy string rules to struct ima_rule_entry format */ for (rules = arch_rules, i = 0; *rules != NULL; rules++) { char rule[255]; int result; result = strlcpy(rule, *rules, sizeof(rule)); INIT_LIST_HEAD(&arch_policy_entry[i].list); result = ima_parse_rule(rule, &arch_policy_entry[i]); if (result) { pr_warn("Skipping unknown architecture policy rule: %s\n", rule); memset(&arch_policy_entry[i], 0, sizeof(*arch_policy_entry)); continue; } i++; } return i; } /** * ima_init_policy - initialize the default measure rules. * * ima_rules points to either the ima_default_rules or the * the new ima_policy_rules. */ void __init ima_init_policy(void) { int build_appraise_entries, arch_entries; /* if !ima_policy, we load NO default rules */ if (ima_policy) add_rules(dont_measure_rules, ARRAY_SIZE(dont_measure_rules), IMA_DEFAULT_POLICY); switch (ima_policy) { case ORIGINAL_TCB: add_rules(original_measurement_rules, ARRAY_SIZE(original_measurement_rules), IMA_DEFAULT_POLICY); break; case DEFAULT_TCB: add_rules(default_measurement_rules, ARRAY_SIZE(default_measurement_rules), IMA_DEFAULT_POLICY); break; default: break; } /* * Based on runtime secure boot flags, insert arch specific measurement * and appraise rules requiring file signatures for both the initial * and custom policies, prior to other appraise rules. * (Highest priority) */ arch_entries = ima_init_arch_policy(); if (!arch_entries) pr_info("No architecture policies found\n"); else add_rules(arch_policy_entry, arch_entries, IMA_DEFAULT_POLICY | IMA_CUSTOM_POLICY); /* * Insert the builtin "secure_boot" policy rules requiring file * signatures, prior to other appraise rules. */ if (ima_use_secure_boot) add_rules(secure_boot_rules, ARRAY_SIZE(secure_boot_rules), IMA_DEFAULT_POLICY); /* * Insert the build time appraise rules requiring file signatures * for both the initial and custom policies, prior to other appraise * rules. As the secure boot rules includes all of the build time * rules, include either one or the other set of rules, but not both. */ build_appraise_entries = ARRAY_SIZE(build_appraise_rules); if (build_appraise_entries) { if (ima_use_secure_boot) add_rules(build_appraise_rules, build_appraise_entries, IMA_CUSTOM_POLICY); else add_rules(build_appraise_rules, build_appraise_entries, IMA_DEFAULT_POLICY | IMA_CUSTOM_POLICY); } if (ima_use_appraise_tcb) add_rules(default_appraise_rules, ARRAY_SIZE(default_appraise_rules), IMA_DEFAULT_POLICY); if (ima_use_critical_data) add_rules(critical_data_rules, ARRAY_SIZE(critical_data_rules), IMA_DEFAULT_POLICY); atomic_set(&ima_setxattr_allowed_hash_algorithms, 0); ima_update_policy_flags(); } /* Make sure we have a valid policy, at least containing some rules. */ int ima_check_policy(void) { if (list_empty(&ima_temp_rules)) return -EINVAL; return 0; } /** * ima_update_policy - update default_rules with new measure rules * * Called on file .release to update the default rules with a complete new * policy. What we do here is to splice ima_policy_rules and ima_temp_rules so * they make a queue. The policy may be updated multiple times and this is the * RCU updater. * * Policy rules are never deleted so ima_policy_flag gets zeroed only once when * we switch from the default policy to user defined. */ void ima_update_policy(void) { struct list_head *policy = &ima_policy_rules; list_splice_tail_init_rcu(&ima_temp_rules, policy, synchronize_rcu); if (ima_rules != (struct list_head __rcu *)policy) { ima_policy_flag = 0; rcu_assign_pointer(ima_rules, policy); /* * IMA architecture specific policy rules are specified * as strings and converted to an array of ima_entry_rules * on boot. After loading a custom policy, free the * architecture specific rules stored as an array. */ kfree(arch_policy_entry); } ima_update_policy_flags(); /* Custom IMA policy has been loaded */ ima_process_queued_keys(); } /* Keep the enumeration in sync with the policy_tokens! */ enum { Opt_measure, Opt_dont_measure, Opt_appraise, Opt_dont_appraise, Opt_audit, Opt_hash, Opt_dont_hash, Opt_obj_user, Opt_obj_role, Opt_obj_type, Opt_subj_user, Opt_subj_role, Opt_subj_type, Opt_func, Opt_mask, Opt_fsmagic, Opt_fsname, Opt_fsuuid, Opt_uid_eq, Opt_euid_eq, Opt_fowner_eq, Opt_uid_gt, Opt_euid_gt, Opt_fowner_gt, Opt_uid_lt, Opt_euid_lt, Opt_fowner_lt, Opt_appraise_type, Opt_appraise_flag, Opt_appraise_algos, Opt_permit_directio, Opt_pcr, Opt_template, Opt_keyrings, Opt_label, Opt_err }; static const match_table_t policy_tokens = { {Opt_measure, "measure"}, {Opt_dont_measure, "dont_measure"}, {Opt_appraise, "appraise"}, {Opt_dont_appraise, "dont_appraise"}, {Opt_audit, "audit"}, {Opt_hash, "hash"}, {Opt_dont_hash, "dont_hash"}, {Opt_obj_user, "obj_user=%s"}, {Opt_obj_role, "obj_role=%s"}, {Opt_obj_type, "obj_type=%s"}, {Opt_subj_user, "subj_user=%s"}, {Opt_subj_role, "subj_role=%s"}, {Opt_subj_type, "subj_type=%s"}, {Opt_func, "func=%s"}, {Opt_mask, "mask=%s"}, {Opt_fsmagic, "fsmagic=%s"}, {Opt_fsname, "fsname=%s"}, {Opt_fsuuid, "fsuuid=%s"}, {Opt_uid_eq, "uid=%s"}, {Opt_euid_eq, "euid=%s"}, {Opt_fowner_eq, "fowner=%s"}, {Opt_uid_gt, "uid>%s"}, {Opt_euid_gt, "euid>%s"}, {Opt_fowner_gt, "fowner>%s"}, {Opt_uid_lt, "uid<%s"}, {Opt_euid_lt, "euid<%s"}, {Opt_fowner_lt, "fowner<%s"}, {Opt_appraise_type, "appraise_type=%s"}, {Opt_appraise_flag, "appraise_flag=%s"}, {Opt_appraise_algos, "appraise_algos=%s"}, {Opt_permit_directio, "permit_directio"}, {Opt_pcr, "pcr=%s"}, {Opt_template, "template=%s"}, {Opt_keyrings, "keyrings=%s"}, {Opt_label, "label=%s"}, {Opt_err, NULL} }; static int ima_lsm_rule_init(struct ima_rule_entry *entry, substring_t *args, int lsm_rule, int audit_type) { int result; if (entry->lsm[lsm_rule].rule) return -EINVAL; entry->lsm[lsm_rule].args_p = match_strdup(args); if (!entry->lsm[lsm_rule].args_p) return -ENOMEM; entry->lsm[lsm_rule].type = audit_type; result = ima_filter_rule_init(entry->lsm[lsm_rule].type, Audit_equal, entry->lsm[lsm_rule].args_p, &entry->lsm[lsm_rule].rule); if (!entry->lsm[lsm_rule].rule) { pr_warn("rule for LSM \'%s\' is undefined\n", entry->lsm[lsm_rule].args_p); if (ima_rules == (struct list_head __rcu *)(&ima_default_rules)) { kfree(entry->lsm[lsm_rule].args_p); entry->lsm[lsm_rule].args_p = NULL; result = -EINVAL; } else result = 0; } return result; } static void ima_log_string_op(struct audit_buffer *ab, char *key, char *value, bool (*rule_operator)(kuid_t, kuid_t)) { if (!ab) return; if (rule_operator == &uid_gt) audit_log_format(ab, "%s>", key); else if (rule_operator == &uid_lt) audit_log_format(ab, "%s<", key); else audit_log_format(ab, "%s=", key); audit_log_format(ab, "%s ", value); } static void ima_log_string(struct audit_buffer *ab, char *key, char *value) { ima_log_string_op(ab, key, value, NULL); } /* * Validating the appended signature included in the measurement list requires * the file hash calculated without the appended signature (i.e., the 'd-modsig' * field). Therefore, notify the user if they have the 'modsig' field but not * the 'd-modsig' field in the template. */ static void check_template_modsig(const struct ima_template_desc *template) { #define MSG "template with 'modsig' field also needs 'd-modsig' field\n" bool has_modsig, has_dmodsig; static bool checked; int i; /* We only need to notify the user once. */ if (checked) return; has_modsig = has_dmodsig = false; for (i = 0; i < template->num_fields; i++) { if (!strcmp(template->fields[i]->field_id, "modsig")) has_modsig = true; else if (!strcmp(template->fields[i]->field_id, "d-modsig")) has_dmodsig = true; } if (has_modsig && !has_dmodsig) pr_notice(MSG); checked = true; #undef MSG } static bool ima_validate_rule(struct ima_rule_entry *entry) { /* Ensure that the action is set and is compatible with the flags */ if (entry->action == UNKNOWN) return false; if (entry->action != MEASURE && entry->flags & IMA_PCR) return false; if (entry->action != APPRAISE && entry->flags & (IMA_DIGSIG_REQUIRED | IMA_MODSIG_ALLOWED | IMA_CHECK_BLACKLIST | IMA_VALIDATE_ALGOS)) return false; /* * The IMA_FUNC bit must be set if and only if there's a valid hook * function specified, and vice versa. Enforcing this property allows * for the NONE case below to validate a rule without an explicit hook * function. */ if (((entry->flags & IMA_FUNC) && entry->func == NONE) || (!(entry->flags & IMA_FUNC) && entry->func != NONE)) return false; /* * Ensure that the hook function is compatible with the other * components of the rule */ switch (entry->func) { case NONE: case FILE_CHECK: case MMAP_CHECK: case BPRM_CHECK: case CREDS_CHECK: case POST_SETATTR: case FIRMWARE_CHECK: case POLICY_CHECK: if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC | IMA_UID | IMA_FOWNER | IMA_FSUUID | IMA_INMASK | IMA_EUID | IMA_PCR | IMA_FSNAME | IMA_DIGSIG_REQUIRED | IMA_PERMIT_DIRECTIO | IMA_VALIDATE_ALGOS)) return false; break; case MODULE_CHECK: case KEXEC_KERNEL_CHECK: case KEXEC_INITRAMFS_CHECK: if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC | IMA_UID | IMA_FOWNER | IMA_FSUUID | IMA_INMASK | IMA_EUID | IMA_PCR | IMA_FSNAME | IMA_DIGSIG_REQUIRED | IMA_PERMIT_DIRECTIO | IMA_MODSIG_ALLOWED | IMA_CHECK_BLACKLIST | IMA_VALIDATE_ALGOS)) return false; break; case KEXEC_CMDLINE: if (entry->action & ~(MEASURE | DONT_MEASURE)) return false; if (entry->flags & ~(IMA_FUNC | IMA_FSMAGIC | IMA_UID | IMA_FOWNER | IMA_FSUUID | IMA_EUID | IMA_PCR | IMA_FSNAME)) return false; break; case KEY_CHECK: if (entry->action & ~(MEASURE | DONT_MEASURE)) return false; if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_PCR | IMA_KEYRINGS)) return false; if (ima_rule_contains_lsm_cond(entry)) return false; break; case CRITICAL_DATA: if (entry->action & ~(MEASURE | DONT_MEASURE)) return false; if (entry->flags & ~(IMA_FUNC | IMA_UID | IMA_PCR | IMA_LABEL)) return false; if (ima_rule_contains_lsm_cond(entry)) return false; break; case SETXATTR_CHECK: /* any action other than APPRAISE is unsupported */ if (entry->action != APPRAISE) return false; /* SETXATTR_CHECK requires an appraise_algos parameter */ if (!(entry->flags & IMA_VALIDATE_ALGOS)) return false; /* * full policies are not supported, they would have too * much of a performance impact */ if (entry->flags & ~(IMA_FUNC | IMA_VALIDATE_ALGOS)) return false; break; default: return false; } /* Ensure that combinations of flags are compatible with each other */ if (entry->flags & IMA_CHECK_BLACKLIST && !(entry->flags & IMA_MODSIG_ALLOWED)) return false; return true; } static unsigned int ima_parse_appraise_algos(char *arg) { unsigned int res = 0; int idx; char *token; while ((token = strsep(&arg, ",")) != NULL) { idx = match_string(hash_algo_name, HASH_ALGO__LAST, token); if (idx < 0) { pr_err("unknown hash algorithm \"%s\"", token); return 0; } if (!crypto_has_alg(hash_algo_name[idx], 0, 0)) { pr_err("unavailable hash algorithm \"%s\", check your kernel configuration", token); return 0; } /* Add the hash algorithm to the 'allowed' bitfield */ res |= (1U << idx); } return res; } static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) { struct audit_buffer *ab; char *from; char *p; bool uid_token; struct ima_template_desc *template_desc; int result = 0; ab = integrity_audit_log_start(audit_context(), GFP_KERNEL, AUDIT_INTEGRITY_POLICY_RULE); entry->uid = INVALID_UID; entry->fowner = INVALID_UID; entry->uid_op = &uid_eq; entry->fowner_op = &uid_eq; entry->action = UNKNOWN; while ((p = strsep(&rule, " \t")) != NULL) { substring_t args[MAX_OPT_ARGS]; int token; unsigned long lnum; if (result < 0) break; if ((*p == '\0') || (*p == ' ') || (*p == '\t')) continue; token = match_token(p, policy_tokens, args); switch (token) { case Opt_measure: ima_log_string(ab, "action", "measure"); if (entry->action != UNKNOWN) result = -EINVAL; entry->action = MEASURE; break; case Opt_dont_measure: ima_log_string(ab, "action", "dont_measure"); if (entry->action != UNKNOWN) result = -EINVAL; entry->action = DONT_MEASURE; break; case Opt_appraise: ima_log_string(ab, "action", "appraise"); if (entry->action != UNKNOWN) result = -EINVAL; entry->action = APPRAISE; break; case Opt_dont_appraise: ima_log_string(ab, "action", "dont_appraise"); if (entry->action != UNKNOWN) result = -EINVAL; entry->action = DONT_APPRAISE; break; case Opt_audit: ima_log_string(ab, "action", "audit"); if (entry->action != UNKNOWN) result = -EINVAL; entry->action = AUDIT; break; case Opt_hash: ima_log_string(ab, "action", "hash"); if (entry->action != UNKNOWN) result = -EINVAL; entry->action = HASH; break; case Opt_dont_hash: ima_log_string(ab, "action", "dont_hash"); if (entry->action != UNKNOWN) result = -EINVAL; entry->action = DONT_HASH; break; case Opt_func: ima_log_string(ab, "func", args[0].from); if (entry->func) result = -EINVAL; if (strcmp(args[0].from, "FILE_CHECK") == 0) entry->func = FILE_CHECK; /* PATH_CHECK is for backwards compat */ else if (strcmp(args[0].from, "PATH_CHECK") == 0) entry->func = FILE_CHECK; else if (strcmp(args[0].from, "MODULE_CHECK") == 0) entry->func = MODULE_CHECK; else if (strcmp(args[0].from, "FIRMWARE_CHECK") == 0) entry->func = FIRMWARE_CHECK; else if ((strcmp(args[0].from, "FILE_MMAP") == 0) || (strcmp(args[0].from, "MMAP_CHECK") == 0)) entry->func = MMAP_CHECK; else if (strcmp(args[0].from, "BPRM_CHECK") == 0) entry->func = BPRM_CHECK; else if (strcmp(args[0].from, "CREDS_CHECK") == 0) entry->func = CREDS_CHECK; else if (strcmp(args[0].from, "KEXEC_KERNEL_CHECK") == 0) entry->func = KEXEC_KERNEL_CHECK; else if (strcmp(args[0].from, "KEXEC_INITRAMFS_CHECK") == 0) entry->func = KEXEC_INITRAMFS_CHECK; else if (strcmp(args[0].from, "POLICY_CHECK") == 0) entry->func = POLICY_CHECK; else if (strcmp(args[0].from, "KEXEC_CMDLINE") == 0) entry->func = KEXEC_CMDLINE; else if (IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) && strcmp(args[0].from, "KEY_CHECK") == 0) entry->func = KEY_CHECK; else if (strcmp(args[0].from, "CRITICAL_DATA") == 0) entry->func = CRITICAL_DATA; else if (strcmp(args[0].from, "SETXATTR_CHECK") == 0) entry->func = SETXATTR_CHECK; else result = -EINVAL; if (!result) entry->flags |= IMA_FUNC; break; case Opt_mask: ima_log_string(ab, "mask", args[0].from); if (entry->mask) result = -EINVAL; from = args[0].from; if (*from == '^') from++; if ((strcmp(from, "MAY_EXEC")) == 0) entry->mask = MAY_EXEC; else if (strcmp(from, "MAY_WRITE") == 0) entry->mask = MAY_WRITE; else if (strcmp(from, "MAY_READ") == 0) entry->mask = MAY_READ; else if (strcmp(from, "MAY_APPEND") == 0) entry->mask = MAY_APPEND; else result = -EINVAL; if (!result) entry->flags |= (*args[0].from == '^') ? IMA_INMASK : IMA_MASK; break; case Opt_fsmagic: ima_log_string(ab, "fsmagic", args[0].from); if (entry->fsmagic) { result = -EINVAL; break; } result = kstrtoul(args[0].from, 16, &entry->fsmagic); if (!result) entry->flags |= IMA_FSMAGIC; break; case Opt_fsname: ima_log_string(ab, "fsname", args[0].from); entry->fsname = kstrdup(args[0].from, GFP_KERNEL); if (!entry->fsname) { result = -ENOMEM; break; } result = 0; entry->flags |= IMA_FSNAME; break; case Opt_keyrings: ima_log_string(ab, "keyrings", args[0].from); if (!IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) || entry->keyrings) { result = -EINVAL; break; } entry->keyrings = ima_alloc_rule_opt_list(args); if (IS_ERR(entry->keyrings)) { result = PTR_ERR(entry->keyrings); entry->keyrings = NULL; break; } entry->flags |= IMA_KEYRINGS; break; case Opt_label: ima_log_string(ab, "label", args[0].from); if (entry->label) { result = -EINVAL; break; } entry->label = ima_alloc_rule_opt_list(args); if (IS_ERR(entry->label)) { result = PTR_ERR(entry->label); entry->label = NULL; break; } entry->flags |= IMA_LABEL; break; case Opt_fsuuid: ima_log_string(ab, "fsuuid", args[0].from); if (!uuid_is_null(&entry->fsuuid)) { result = -EINVAL; break; } result = uuid_parse(args[0].from, &entry->fsuuid); if (!result) entry->flags |= IMA_FSUUID; break; case Opt_uid_gt: case Opt_euid_gt: entry->uid_op = &uid_gt; fallthrough; case Opt_uid_lt: case Opt_euid_lt: if ((token == Opt_uid_lt) || (token == Opt_euid_lt)) entry->uid_op = &uid_lt; fallthrough; case Opt_uid_eq: case Opt_euid_eq: uid_token = (token == Opt_uid_eq) || (token == Opt_uid_gt) || (token == Opt_uid_lt); ima_log_string_op(ab, uid_token ? "uid" : "euid", args[0].from, entry->uid_op); if (uid_valid(entry->uid)) { result = -EINVAL; break; } result = kstrtoul(args[0].from, 10, &lnum); if (!result) { entry->uid = make_kuid(current_user_ns(), (uid_t) lnum); if (!uid_valid(entry->uid) || (uid_t)lnum != lnum) result = -EINVAL; else entry->flags |= uid_token ? IMA_UID : IMA_EUID; } break; case Opt_fowner_gt: entry->fowner_op = &uid_gt; fallthrough; case Opt_fowner_lt: if (token == Opt_fowner_lt) entry->fowner_op = &uid_lt; fallthrough; case Opt_fowner_eq: ima_log_string_op(ab, "fowner", args[0].from, entry->fowner_op); if (uid_valid(entry->fowner)) { result = -EINVAL; break; } result = kstrtoul(args[0].from, 10, &lnum); if (!result) { entry->fowner = make_kuid(current_user_ns(), (uid_t)lnum); if (!uid_valid(entry->fowner) || (((uid_t)lnum) != lnum)) result = -EINVAL; else entry->flags |= IMA_FOWNER; } break; case Opt_obj_user: ima_log_string(ab, "obj_user", args[0].from); result = ima_lsm_rule_init(entry, args, LSM_OBJ_USER, AUDIT_OBJ_USER); break; case Opt_obj_role: ima_log_string(ab, "obj_role", args[0].from); result = ima_lsm_rule_init(entry, args, LSM_OBJ_ROLE, AUDIT_OBJ_ROLE); break; case Opt_obj_type: ima_log_string(ab, "obj_type", args[0].from); result = ima_lsm_rule_init(entry, args, LSM_OBJ_TYPE, AUDIT_OBJ_TYPE); break; case Opt_subj_user: ima_log_string(ab, "subj_user", args[0].from); result = ima_lsm_rule_init(entry, args, LSM_SUBJ_USER, AUDIT_SUBJ_USER); break; case Opt_subj_role: ima_log_string(ab, "subj_role", args[0].from); result = ima_lsm_rule_init(entry, args, LSM_SUBJ_ROLE, AUDIT_SUBJ_ROLE); break; case Opt_subj_type: ima_log_string(ab, "subj_type", args[0].from); result = ima_lsm_rule_init(entry, args, LSM_SUBJ_TYPE, AUDIT_SUBJ_TYPE); break; case Opt_appraise_type: ima_log_string(ab, "appraise_type", args[0].from); if ((strcmp(args[0].from, "imasig")) == 0) entry->flags |= IMA_DIGSIG_REQUIRED; else if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) && strcmp(args[0].from, "imasig|modsig") == 0) entry->flags |= IMA_DIGSIG_REQUIRED | IMA_MODSIG_ALLOWED; else result = -EINVAL; break; case Opt_appraise_flag: ima_log_string(ab, "appraise_flag", args[0].from); if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) && strstr(args[0].from, "blacklist")) entry->flags |= IMA_CHECK_BLACKLIST; else result = -EINVAL; break; case Opt_appraise_algos: ima_log_string(ab, "appraise_algos", args[0].from); if (entry->allowed_algos) { result = -EINVAL; break; } entry->allowed_algos = ima_parse_appraise_algos(args[0].from); /* invalid or empty list of algorithms */ if (!entry->allowed_algos) { result = -EINVAL; break; } entry->flags |= IMA_VALIDATE_ALGOS; break; case Opt_permit_directio: entry->flags |= IMA_PERMIT_DIRECTIO; break; case Opt_pcr: ima_log_string(ab, "pcr", args[0].from); result = kstrtoint(args[0].from, 10, &entry->pcr); if (result || INVALID_PCR(entry->pcr)) result = -EINVAL; else entry->flags |= IMA_PCR; break; case Opt_template: ima_log_string(ab, "template", args[0].from); if (entry->action != MEASURE) { result = -EINVAL; break; } template_desc = lookup_template_desc(args[0].from); if (!template_desc || entry->template) { result = -EINVAL; break; } /* * template_desc_init_fields() does nothing if * the template is already initialised, so * it's safe to do this unconditionally */ template_desc_init_fields(template_desc->fmt, &(template_desc->fields), &(template_desc->num_fields)); entry->template = template_desc; break; case Opt_err: ima_log_string(ab, "UNKNOWN", p); result = -EINVAL; break; } } if (!result && !ima_validate_rule(entry)) result = -EINVAL; else if (entry->action == APPRAISE) temp_ima_appraise |= ima_appraise_flag(entry->func); if (!result && entry->flags & IMA_MODSIG_ALLOWED) { template_desc = entry->template ? entry->template : ima_template_desc_current(); check_template_modsig(template_desc); } audit_log_format(ab, "res=%d", !result); audit_log_end(ab); return result; } /** * ima_parse_add_rule - add a rule to ima_policy_rules * @rule - ima measurement policy rule * * Avoid locking by allowing just one writer at a time in ima_write_policy() * Returns the length of the rule parsed, an error code on failure */ ssize_t ima_parse_add_rule(char *rule) { static const char op[] = "update_policy"; char *p; struct ima_rule_entry *entry; ssize_t result, len; int audit_info = 0; p = strsep(&rule, "\n"); len = strlen(p) + 1; p += strspn(p, " \t"); if (*p == '#' || *p == '\0') return len; entry = kzalloc(sizeof(*entry), GFP_KERNEL); if (!entry) { integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL, op, "-ENOMEM", -ENOMEM, audit_info); return -ENOMEM; } INIT_LIST_HEAD(&entry->list); result = ima_parse_rule(p, entry); if (result) { ima_free_rule(entry); integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL, NULL, op, "invalid-policy", result, audit_info); return result; } list_add_tail(&entry->list, &ima_temp_rules); return len; } /** * ima_delete_rules() called to cleanup invalid in-flight policy. * We don't need locking as we operate on the temp list, which is * different from the active one. There is also only one user of * ima_delete_rules() at a time. */ void ima_delete_rules(void) { struct ima_rule_entry *entry, *tmp; temp_ima_appraise = 0; list_for_each_entry_safe(entry, tmp, &ima_temp_rules, list) { list_del(&entry->list); ima_free_rule(entry); } } #define __ima_hook_stringify(func, str) (#func), const char *const func_tokens[] = { __ima_hooks(__ima_hook_stringify) }; #ifdef CONFIG_IMA_READ_POLICY enum { mask_exec = 0, mask_write, mask_read, mask_append }; static const char *const mask_tokens[] = { "^MAY_EXEC", "^MAY_WRITE", "^MAY_READ", "^MAY_APPEND" }; void *ima_policy_start(struct seq_file *m, loff_t *pos) { loff_t l = *pos; struct ima_rule_entry *entry; struct list_head *ima_rules_tmp; rcu_read_lock(); ima_rules_tmp = rcu_dereference(ima_rules); list_for_each_entry_rcu(entry, ima_rules_tmp, list) { if (!l--) { rcu_read_unlock(); return entry; } } rcu_read_unlock(); return NULL; } void *ima_policy_next(struct seq_file *m, void *v, loff_t *pos) { struct ima_rule_entry *entry = v; rcu_read_lock(); entry = list_entry_rcu(entry->list.next, struct ima_rule_entry, list); rcu_read_unlock(); (*pos)++; return (&entry->list == &ima_default_rules || &entry->list == &ima_policy_rules) ? NULL : entry; } void ima_policy_stop(struct seq_file *m, void *v) { } #define pt(token) policy_tokens[token].pattern #define mt(token) mask_tokens[token] /* * policy_func_show - display the ima_hooks policy rule */ static void policy_func_show(struct seq_file *m, enum ima_hooks func) { if (func > 0 && func < MAX_CHECK) seq_printf(m, "func=%s ", func_tokens[func]); else seq_printf(m, "func=%d ", func); } static void ima_show_rule_opt_list(struct seq_file *m, const struct ima_rule_opt_list *opt_list) { size_t i; for (i = 0; i < opt_list->count; i++) seq_printf(m, "%s%s", i ? "|" : "", opt_list->items[i]); } static void ima_policy_show_appraise_algos(struct seq_file *m, unsigned int allowed_hashes) { int idx, list_size = 0; for (idx = 0; idx < HASH_ALGO__LAST; idx++) { if (!(allowed_hashes & (1U << idx))) continue; /* only add commas if the list contains multiple entries */ if (list_size++) seq_puts(m, ","); seq_puts(m, hash_algo_name[idx]); } } int ima_policy_show(struct seq_file *m, void *v) { struct ima_rule_entry *entry = v; int i; char tbuf[64] = {0,}; int offset = 0; rcu_read_lock(); /* Do not print rules with inactive LSM labels */ for (i = 0; i < MAX_LSM_RULES; i++) { if (entry->lsm[i].args_p && !entry->lsm[i].rule) { rcu_read_unlock(); return 0; } } if (entry->action & MEASURE) seq_puts(m, pt(Opt_measure)); if (entry->action & DONT_MEASURE) seq_puts(m, pt(Opt_dont_measure)); if (entry->action & APPRAISE) seq_puts(m, pt(Opt_appraise)); if (entry->action & DONT_APPRAISE) seq_puts(m, pt(Opt_dont_appraise)); if (entry->action & AUDIT) seq_puts(m, pt(Opt_audit)); if (entry->action & HASH) seq_puts(m, pt(Opt_hash)); if (entry->action & DONT_HASH) seq_puts(m, pt(Opt_dont_hash)); seq_puts(m, " "); if (entry->flags & IMA_FUNC) policy_func_show(m, entry->func); if ((entry->flags & IMA_MASK) || (entry->flags & IMA_INMASK)) { if (entry->flags & IMA_MASK) offset = 1; if (entry->mask & MAY_EXEC) seq_printf(m, pt(Opt_mask), mt(mask_exec) + offset); if (entry->mask & MAY_WRITE) seq_printf(m, pt(Opt_mask), mt(mask_write) + offset); if (entry->mask & MAY_READ) seq_printf(m, pt(Opt_mask), mt(mask_read) + offset); if (entry->mask & MAY_APPEND) seq_printf(m, pt(Opt_mask), mt(mask_append) + offset); seq_puts(m, " "); } if (entry->flags & IMA_FSMAGIC) { snprintf(tbuf, sizeof(tbuf), "0x%lx", entry->fsmagic); seq_printf(m, pt(Opt_fsmagic), tbuf); seq_puts(m, " "); } if (entry->flags & IMA_FSNAME) { snprintf(tbuf, sizeof(tbuf), "%s", entry->fsname); seq_printf(m, pt(Opt_fsname), tbuf); seq_puts(m, " "); } if (entry->flags & IMA_KEYRINGS) { seq_puts(m, "keyrings="); ima_show_rule_opt_list(m, entry->keyrings); seq_puts(m, " "); } if (entry->flags & IMA_LABEL) { seq_puts(m, "label="); ima_show_rule_opt_list(m, entry->label); seq_puts(m, " "); } if (entry->flags & IMA_PCR) { snprintf(tbuf, sizeof(tbuf), "%d", entry->pcr); seq_printf(m, pt(Opt_pcr), tbuf); seq_puts(m, " "); } if (entry->flags & IMA_FSUUID) { seq_printf(m, "fsuuid=%pU", &entry->fsuuid); seq_puts(m, " "); } if (entry->flags & IMA_UID) { snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid)); if (entry->uid_op == &uid_gt) seq_printf(m, pt(Opt_uid_gt), tbuf); else if (entry->uid_op == &uid_lt) seq_printf(m, pt(Opt_uid_lt), tbuf); else seq_printf(m, pt(Opt_uid_eq), tbuf); seq_puts(m, " "); } if (entry->flags & IMA_EUID) { snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid)); if (entry->uid_op == &uid_gt) seq_printf(m, pt(Opt_euid_gt), tbuf); else if (entry->uid_op == &uid_lt) seq_printf(m, pt(Opt_euid_lt), tbuf); else seq_printf(m, pt(Opt_euid_eq), tbuf); seq_puts(m, " "); } if (entry->flags & IMA_FOWNER) { snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->fowner)); if (entry->fowner_op == &uid_gt) seq_printf(m, pt(Opt_fowner_gt), tbuf); else if (entry->fowner_op == &uid_lt) seq_printf(m, pt(Opt_fowner_lt), tbuf); else seq_printf(m, pt(Opt_fowner_eq), tbuf); seq_puts(m, " "); } if (entry->flags & IMA_VALIDATE_ALGOS) { seq_puts(m, "appraise_algos="); ima_policy_show_appraise_algos(m, entry->allowed_algos); seq_puts(m, " "); } for (i = 0; i < MAX_LSM_RULES; i++) { if (entry->lsm[i].rule) { switch (i) { case LSM_OBJ_USER: seq_printf(m, pt(Opt_obj_user), entry->lsm[i].args_p); break; case LSM_OBJ_ROLE: seq_printf(m, pt(Opt_obj_role), entry->lsm[i].args_p); break; case LSM_OBJ_TYPE: seq_printf(m, pt(Opt_obj_type), entry->lsm[i].args_p); break; case LSM_SUBJ_USER: seq_printf(m, pt(Opt_subj_user), entry->lsm[i].args_p); break; case LSM_SUBJ_ROLE: seq_printf(m, pt(Opt_subj_role), entry->lsm[i].args_p); break; case LSM_SUBJ_TYPE: seq_printf(m, pt(Opt_subj_type), entry->lsm[i].args_p); break; } seq_puts(m, " "); } } if (entry->template) seq_printf(m, "template=%s ", entry->template->name); if (entry->flags & IMA_DIGSIG_REQUIRED) { if (entry->flags & IMA_MODSIG_ALLOWED) seq_puts(m, "appraise_type=imasig|modsig "); else seq_puts(m, "appraise_type=imasig "); } if (entry->flags & IMA_CHECK_BLACKLIST) seq_puts(m, "appraise_flag=check_blacklist "); if (entry->flags & IMA_PERMIT_DIRECTIO) seq_puts(m, "permit_directio "); rcu_read_unlock(); seq_puts(m, "\n"); return 0; } #endif /* CONFIG_IMA_READ_POLICY */ #if defined(CONFIG_IMA_APPRAISE) && defined(CONFIG_INTEGRITY_TRUSTED_KEYRING) /* * ima_appraise_signature: whether IMA will appraise a given function using * an IMA digital signature. This is restricted to cases where the kernel * has a set of built-in trusted keys in order to avoid an attacker simply * loading additional keys. */ bool ima_appraise_signature(enum kernel_read_file_id id) { struct ima_rule_entry *entry; bool found = false; enum ima_hooks func; struct list_head *ima_rules_tmp; if (id >= READING_MAX_ID) return false; if (id == READING_KEXEC_IMAGE && !(ima_appraise & IMA_APPRAISE_ENFORCE) && security_locked_down(LOCKDOWN_KEXEC)) return false; func = read_idmap[id] ?: FILE_CHECK; rcu_read_lock(); ima_rules_tmp = rcu_dereference(ima_rules); list_for_each_entry_rcu(entry, ima_rules_tmp, list) { if (entry->action != APPRAISE) continue; /* * A generic entry will match, but otherwise require that it * match the func we're looking for */ if (entry->func && entry->func != func) continue; /* * We require this to be a digital signature, not a raw IMA * hash. */ if (entry->flags & IMA_DIGSIG_REQUIRED) found = true; /* * We've found a rule that matches, so break now even if it * didn't require a digital signature - a later rule that does * won't override it, so would be a false positive. */ break; } rcu_read_unlock(); return found; } #endif /* CONFIG_IMA_APPRAISE && CONFIG_INTEGRITY_TRUSTED_KEYRING */