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linux/security/integrity/ima/ima_policy.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2008 IBM Corporation
* Author: Mimi Zohar <zohar@us.ibm.com>
*
* ima_policy.c
* - initialize default measure policy rules
*/
#include <linux/init.h>
#include <linux/list.h>
#include <linux/kernel_read_file.h>
#include <linux/fs.h>
#include <linux/security.h>
#include <linux/magic.h>
#include <linux/parser.h>
#include <linux/slab.h>
#include <linux/rculist.h>
#include <linux/genhd.h>
#include <linux/seq_file.h>
#include <linux/ima.h>
#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 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;
#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;
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_template_desc *template;
};
/*
* 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},
};
/* 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 *ima_rules = &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_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, "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;
/*
* Remove the reference from entry so that the associated
* memory will not be freed during a later call to
* ima_lsm_free_rule(entry).
*/
entry->lsm[i].args_p = NULL;
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)
{
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.
*/
ima_lsm_free_rule(entry);
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_keyring - determine whether the keyring matches the measure rule
* @rule: a pointer to a rule
* @keyring: name of the keyring to match against the measure rule
* @cred: a pointer to a credentials structure for user validation
*
* Returns true if keyring matches one in the rule, false otherwise.
*/
static bool ima_match_keyring(struct ima_rule_entry *rule,
const char *keyring, const struct cred *cred)
{
bool matched = false;
size_t i;
if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid))
return false;
if (!rule->keyrings)
return true;
if (!keyring)
return false;
for (i = 0; i < rule->keyrings->count; i++) {
if (!strcmp(rule->keyrings->items[i], keyring)) {
matched = true;
break;
}
}
return matched;
}
/**
* ima_match_rules - determine whether an inode matches the policy rule.
* @rule: a pointer to a rule
* @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)
* @keyring: keyring name to check in policy for KEY_CHECK func
*
* Returns true on rule match, false on failure.
*/
static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
const struct cred *cred, u32 secid,
enum ima_hooks func, int mask,
const char *keyring)
{
int i;
if (func == KEY_CHECK) {
return (rule->flags & IMA_FUNC) && (rule->func == func) &&
ima_match_keyring(rule, keyring, cred);
}
if ((rule->flags & IMA_FUNC) &&
(rule->func != func && func != POST_SETATTR))
return false;
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(inode->i_uid, rule->fowner))
return false;
for (i = 0; i < MAX_LSM_RULES; i++) {
int rc = 0;
u32 osid;
if (!rule->lsm[i].rule) {
if (!rule->lsm[i].args_p)
continue;
else
return false;
}
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, rule->lsm[i].type,
Audit_equal,
rule->lsm[i].rule);
break;
case LSM_SUBJ_USER:
case LSM_SUBJ_ROLE:
case LSM_SUBJ_TYPE:
rc = ima_filter_rule_match(secid, rule->lsm[i].type,
Audit_equal,
rule->lsm[i].rule);
default:
break;
}
if (!rc)
return false;
}
return true;
}
/*
* 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
* @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
* @keyring: the keyring name, if given, to be used to check in the policy.
* keyring can be NULL if func is anything other than KEY_CHECK.
*
* 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 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 *keyring)
{
struct ima_rule_entry *entry;
int action = 0, actmask = flags | (flags << 1);
if (template_desc)
*template_desc = ima_template_desc_current();
rcu_read_lock();
list_for_each_entry_rcu(entry, ima_rules, list) {
if (!(entry->action & actmask))
continue;
if (!ima_match_rules(entry, inode, cred, secid, func, mask,
keyring))
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 (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;
}
/*
* Initialize the ima_policy_flag variable based on the currently
* loaded policy. Based on this flag, the decision to short circuit
* out of a function or not call the function in the first place
* can be made earlier.
*/
void ima_update_policy_flag(void)
{
struct ima_rule_entry *entry;
list_for_each_entry(entry, ima_rules, list) {
if (entry->action & IMA_DO_MASK)
ima_policy_flag |= entry->action;
}
ima_appraise |= (build_ima_appraise | temp_ima_appraise);
if (!ima_appraise)
ima_policy_flag &= ~IMA_APPRAISE;
}
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);
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);
ima_update_policy_flag();
}
/* 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 != policy) {
ima_policy_flag = 0;
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_flag();
/* 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_permit_directio, Opt_pcr, Opt_template, Opt_keyrings,
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_permit_directio, "permit_directio"},
{Opt_pcr, "pcr=%s"},
{Opt_template, "template=%s"},
{Opt_keyrings, "keyrings=%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 == &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))
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))
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))
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;
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 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
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_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_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;
rcu_read_lock();
list_for_each_entry_rcu(entry, ima_rules, 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_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]);
}
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();
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_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, " ");
}
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;
if (id >= READING_MAX_ID)
return false;
func = read_idmap[id] ?: FILE_CHECK;
rcu_read_lock();
list_for_each_entry_rcu(entry, ima_rules, 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 */
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