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linux/security/integrity/ima/ima_policy.c

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/*
* Copyright (C) 2008 IBM Corporation
* Author: Mimi Zohar <zohar@us.ibm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, version 2 of the License.
*
* ima_policy.c
* - initialize default measure policy rules
*
*/
#include <linux/module.h>
#include <linux/list.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 "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 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) >= (FIELD_SIZEOF(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 };
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 */
void *args_p; /* audit value */
int type; /* audit type */
} lsm[MAX_LSM_RULES];
char *fsname;
};
/*
* 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}
};
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 = 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 LIST_HEAD(ima_default_rules);
static LIST_HEAD(ima_policy_rules);
static LIST_HEAD(ima_temp_rules);
static struct list_head *ima_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;
}
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);
/*
* 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. We assume the rules still exist; and BUG_ON() if
* they don't.
*/
static void ima_lsm_update_rules(void)
{
struct ima_rule_entry *entry;
int result;
int i;
list_for_each_entry(entry, &ima_policy_rules, list) {
for (i = 0; i < MAX_LSM_RULES; i++) {
if (!entry->lsm[i].rule)
continue;
result = security_filter_rule_init(entry->lsm[i].type,
Audit_equal,
entry->lsm[i].args_p,
&entry->lsm[i].rule);
BUG_ON(!entry->lsm[i].rule);
}
}
}
/**
* ima_match_rules - determine whether an inode matches the measure 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)
*
* 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)
{
int i;
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;
int retried = 0;
if (!rule->lsm[i].rule)
continue;
retry:
switch (i) {
case LSM_OBJ_USER:
case LSM_OBJ_ROLE:
case LSM_OBJ_TYPE:
security_inode_getsecid(inode, &osid);
rc = security_filter_rule_match(osid,
rule->lsm[i].type,
Audit_equal,
rule->lsm[i].rule,
NULL);
break;
case LSM_SUBJ_USER:
case LSM_SUBJ_ROLE:
case LSM_SUBJ_TYPE:
rc = security_filter_rule_match(secid,
rule->lsm[i].type,
Audit_equal,
rule->lsm[i].rule,
NULL);
default:
break;
}
if ((rc < 0) && (!retried)) {
retried = 1;
ima_lsm_update_rules();
goto retry;
}
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
*
* 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_rule_entry *entry;
int action = 0, actmask = flags | (flags << 1);
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))
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 (!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;
}
/**
* 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 i, measure_entries, appraise_entries, secure_boot_entries;
/* if !ima_policy set entries = 0 so we load NO default rules */
measure_entries = ima_policy ? ARRAY_SIZE(dont_measure_rules) : 0;
appraise_entries = ima_use_appraise_tcb ?
ARRAY_SIZE(default_appraise_rules) : 0;
secure_boot_entries = ima_use_secure_boot ?
ARRAY_SIZE(secure_boot_rules) : 0;
for (i = 0; i < measure_entries; i++)
list_add_tail(&dont_measure_rules[i].list, &ima_default_rules);
switch (ima_policy) {
case ORIGINAL_TCB:
for (i = 0; i < ARRAY_SIZE(original_measurement_rules); i++)
list_add_tail(&original_measurement_rules[i].list,
&ima_default_rules);
break;
case DEFAULT_TCB:
for (i = 0; i < ARRAY_SIZE(default_measurement_rules); i++)
list_add_tail(&default_measurement_rules[i].list,
&ima_default_rules);
default:
break;
}
/*
* Insert the builtin "secure_boot" policy rules requiring file
* signatures, prior to any other appraise rules.
*/
for (i = 0; i < secure_boot_entries; i++) {
list_add_tail(&secure_boot_rules[i].list, &ima_default_rules);
temp_ima_appraise |=
ima_appraise_flag(secure_boot_rules[i].func);
}
/*
* Insert the build time appraise rules requiring file signatures
* for both the initial and custom policies, prior to other appraise
* rules.
*/
for (i = 0; i < ARRAY_SIZE(build_appraise_rules); i++) {
struct ima_rule_entry *entry;
if (!secure_boot_entries)
list_add_tail(&build_appraise_rules[i].list,
&ima_default_rules);
entry = kmemdup(&build_appraise_rules[i], sizeof(*entry),
GFP_KERNEL);
if (entry)
list_add_tail(&entry->list, &ima_policy_rules);
build_ima_appraise |=
ima_appraise_flag(build_appraise_rules[i].func);
}
for (i = 0; i < appraise_entries; i++) {
list_add_tail(&default_appraise_rules[i].list,
&ima_default_rules);
if (default_appraise_rules[i].func == POLICY_CHECK)
temp_ima_appraise |= IMA_APPRAISE_POLICY;
}
ima_rules = &ima_default_rules;
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_update_policy_flag();
}
enum {
Opt_err = -1,
Opt_measure = 1, 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_permit_directio,
Opt_pcr
};
static 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_permit_directio, "permit_directio"},
{Opt_pcr, "pcr=%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 = security_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) {
kfree(entry->lsm[lsm_rule].args_p);
return -EINVAL;
}
return result;
}
static void ima_log_string_op(struct audit_buffer *ab, char *key, char *value,
bool (*rule_operator)(kuid_t, kuid_t))
{
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_untrustedstring(ab, value);
audit_log_format(ab, " ");
}
static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
{
ima_log_string_op(ab, key, value, NULL);
}
static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
{
struct audit_buffer *ab;
char *from;
char *p;
bool uid_token;
int result = 0;
ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_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
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_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;
case Opt_uid_lt:
case Opt_euid_lt:
if ((token == Opt_uid_lt) || (token == Opt_euid_lt))
entry->uid_op = &uid_lt;
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;
case Opt_fowner_lt:
if (token == Opt_fowner_lt)
entry->fowner_op = &uid_lt;
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:
if (entry->action != APPRAISE) {
result = -EINVAL;
break;
}
ima_log_string(ab, "appraise_type", args[0].from);
if ((strcmp(args[0].from, "imasig")) == 0)
entry->flags |= IMA_DIGSIG_REQUIRED;
else
result = -EINVAL;
break;
case Opt_permit_directio:
entry->flags |= IMA_PERMIT_DIRECTIO;
break;
case Opt_pcr:
if (entry->action != MEASURE) {
result = -EINVAL;
break;
}
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_err:
ima_log_string(ab, "UNKNOWN", p);
result = -EINVAL;
break;
}
}
if (!result && (entry->action == UNKNOWN))
result = -EINVAL;
else if (entry->action == APPRAISE)
temp_ima_appraise |= ima_appraise_flag(entry->func);
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) {
kfree(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;
int i;
temp_ima_appraise = 0;
list_for_each_entry_safe(entry, tmp, &ima_temp_rules, list) {
for (i = 0; i < MAX_LSM_RULES; i++)
kfree(entry->lsm[i].args_p);
list_del(&entry->list);
kfree(entry);
}
}
#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"
};
#define __ima_hook_stringify(str) (#str),
static const char *const func_tokens[] = {
__ima_hooks(__ima_hook_stringify)
};
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 + Opt_err].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);
}
int ima_policy_show(struct seq_file *m, void *v)
{
struct ima_rule_entry *entry = v;
int i;
char tbuf[64] = {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) {
if (entry->mask & MAY_EXEC)
seq_printf(m, pt(Opt_mask), mt(mask_exec));
if (entry->mask & MAY_WRITE)
seq_printf(m, pt(Opt_mask), mt(mask_write));
if (entry->mask & MAY_READ)
seq_printf(m, pt(Opt_mask), mt(mask_read));
if (entry->mask & MAY_APPEND)
seq_printf(m, pt(Opt_mask), mt(mask_append));
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_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),
(char *)entry->lsm[i].args_p);
break;
case LSM_OBJ_ROLE:
seq_printf(m, pt(Opt_obj_role),
(char *)entry->lsm[i].args_p);
break;
case LSM_OBJ_TYPE:
seq_printf(m, pt(Opt_obj_type),
(char *)entry->lsm[i].args_p);
break;
case LSM_SUBJ_USER:
seq_printf(m, pt(Opt_subj_user),
(char *)entry->lsm[i].args_p);
break;
case LSM_SUBJ_ROLE:
seq_printf(m, pt(Opt_subj_role),
(char *)entry->lsm[i].args_p);
break;
case LSM_SUBJ_TYPE:
seq_printf(m, pt(Opt_subj_type),
(char *)entry->lsm[i].args_p);
break;
}
}
}
if (entry->flags & IMA_DIGSIG_REQUIRED)
seq_puts(m, "appraise_type=imasig ");
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 */
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