diff options
Diffstat (limited to 'security/integrity/ima/ima_policy.c')
-rw-r--r-- | security/integrity/ima/ima_policy.c | 358 |
1 files changed, 318 insertions, 40 deletions
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 3997e206f82d..be09e2cacf82 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -12,11 +12,14 @@ */ #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" @@ -38,6 +41,7 @@ #define AUDIT 0x0040 int ima_policy_flag; +static int temp_ima_appraise; #define MAX_LSM_RULES 6 enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE, @@ -110,6 +114,7 @@ static struct ima_rule_entry default_measurement_rules[] = { .uid = GLOBAL_ROOT_UID, .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[] = { @@ -124,6 +129,10 @@ static struct ima_rule_entry default_appraise_rules[] = { {.action = DONT_APPRAISE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC}, {.action = DONT_APPRAISE, .fsmagic = CGROUP_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, .flags = IMA_FOWNER}, #else @@ -135,11 +144,11 @@ static struct ima_rule_entry default_appraise_rules[] = { 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 DEFINE_MUTEX(ima_rules_mutex); - static int ima_policy __initdata; + static int __init default_measure_policy_setup(char *str) { if (ima_policy) @@ -171,21 +180,18 @@ static int __init default_appraise_policy_setup(char *str) __setup("ima_appraise_tcb", default_appraise_policy_setup); /* - * Although the IMA policy does not change, 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. + * 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, *tmp; + struct ima_rule_entry *entry; int result; int i; - mutex_lock(&ima_rules_mutex); - list_for_each_entry_safe(entry, tmp, &ima_policy_rules, list) { + list_for_each_entry(entry, &ima_policy_rules, list) { for (i = 0; i < MAX_LSM_RULES; i++) { if (!entry->lsm[i].rule) continue; @@ -196,7 +202,6 @@ static void ima_lsm_update_rules(void) BUG_ON(!entry->lsm[i].rule); } } - mutex_unlock(&ima_rules_mutex); } /** @@ -208,8 +213,8 @@ static void ima_lsm_update_rules(void) * * Returns true on rule match, false on failure. */ -static bool ima_match_rules(struct ima_rule_entry *rule, - struct inode *inode, enum ima_hooks func, int mask) +static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode, + enum ima_hooks func, int mask) { struct task_struct *tsk = current; const struct cred *cred = current_cred(); @@ -290,7 +295,7 @@ retry: * 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, int func) +static int get_subaction(struct ima_rule_entry *rule, enum ima_hooks func) { if (!(rule->flags & IMA_FUNC)) return IMA_FILE_APPRAISE; @@ -300,13 +305,12 @@ static int get_subaction(struct ima_rule_entry *rule, int func) return IMA_MMAP_APPRAISE; case BPRM_CHECK: return IMA_BPRM_APPRAISE; - case MODULE_CHECK: - return IMA_MODULE_APPRAISE; - case FIRMWARE_CHECK: - return IMA_FIRMWARE_APPRAISE; case FILE_CHECK: - default: + case POST_SETATTR: return IMA_FILE_APPRAISE; + case MODULE_CHECK ... MAX_CHECK - 1: + default: + return IMA_READ_APPRAISE; } } @@ -319,9 +323,9 @@ static int get_subaction(struct ima_rule_entry *rule, int func) * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type) * conditions. * - * (There is no need for locking when walking the policy list, - * as elements in the list are never deleted, nor does the list - * change.) + * 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, enum ima_hooks func, int mask, int flags) @@ -329,7 +333,8 @@ int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask, struct ima_rule_entry *entry; int action = 0, actmask = flags | (flags << 1); - list_for_each_entry(entry, ima_rules, list) { + rcu_read_lock(); + list_for_each_entry_rcu(entry, ima_rules, list) { if (!(entry->action & actmask)) continue; @@ -351,6 +356,7 @@ int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask, if (!actmask) break; } + rcu_read_unlock(); return action; } @@ -365,12 +371,12 @@ void ima_update_policy_flag(void) { struct ima_rule_entry *entry; - ima_policy_flag = 0; list_for_each_entry(entry, ima_rules, list) { if (entry->action & IMA_DO_MASK) ima_policy_flag |= entry->action; } + ima_appraise |= temp_ima_appraise; if (!ima_appraise) ima_policy_flag &= ~IMA_APPRAISE; } @@ -410,21 +416,56 @@ void __init ima_init_policy(void) 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. Once updated, the policy is locked, no additional rules can be - * added to the policy. + * 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) { - ima_rules = &ima_policy_rules; + struct list_head *first, *last, *policy; + + /* append current policy with the new rules */ + first = (&ima_temp_rules)->next; + last = (&ima_temp_rules)->prev; + policy = &ima_policy_rules; + + synchronize_rcu(); + + last->next = policy; + rcu_assign_pointer(list_next_rcu(policy->prev), first); + first->prev = policy->prev; + policy->prev = last; + + /* prepare for the next policy rules addition */ + INIT_LIST_HEAD(&ima_temp_rules); + + if (ima_rules != policy) { + ima_policy_flag = 0; + ima_rules = policy; + } ima_update_policy_flag(); } @@ -436,8 +477,8 @@ enum { 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_uid, Opt_euid, Opt_fowner, - Opt_appraise_type, Opt_fsuuid, Opt_permit_directio + Opt_fsuuid, Opt_uid, Opt_euid, Opt_fowner, + Opt_appraise_type, Opt_permit_directio }; static match_table_t policy_tokens = { @@ -579,6 +620,14 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) entry->func = MMAP_CHECK; else if (strcmp(args[0].from, "BPRM_CHECK") == 0) entry->func = BPRM_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) @@ -734,9 +783,11 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) if (!result && (entry->action == UNKNOWN)) result = -EINVAL; else if (entry->func == MODULE_CHECK) - ima_appraise |= IMA_APPRAISE_MODULES; + temp_ima_appraise |= IMA_APPRAISE_MODULES; else if (entry->func == FIRMWARE_CHECK) - ima_appraise |= IMA_APPRAISE_FIRMWARE; + temp_ima_appraise |= IMA_APPRAISE_FIRMWARE; + else if (entry->func == POLICY_CHECK) + temp_ima_appraise |= IMA_APPRAISE_POLICY; audit_log_format(ab, "res=%d", !result); audit_log_end(ab); return result; @@ -746,7 +797,7 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) * ima_parse_add_rule - add a rule to ima_policy_rules * @rule - ima measurement policy rule * - * Uses a mutex to protect the policy list from multiple concurrent writers. + * 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) @@ -782,26 +833,253 @@ ssize_t ima_parse_add_rule(char *rule) return result; } - mutex_lock(&ima_rules_mutex); - list_add_tail(&entry->list, &ima_policy_rules); - mutex_unlock(&ima_rules_mutex); + list_add_tail(&entry->list, &ima_temp_rules); return len; } -/* ima_delete_rules called to cleanup invalid policy */ +/** + * 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; - mutex_lock(&ima_rules_mutex); - list_for_each_entry_safe(entry, tmp, &ima_policy_rules, list) { + 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); } - mutex_unlock(&ima_rules_mutex); } + +#ifdef CONFIG_IMA_READ_POLICY +enum { + mask_exec = 0, mask_write, mask_read, mask_append +}; + +static char *mask_tokens[] = { + "MAY_EXEC", + "MAY_WRITE", + "MAY_READ", + "MAY_APPEND" +}; + +enum { + func_file = 0, func_mmap, func_bprm, + func_module, func_firmware, func_post, + func_kexec_kernel, func_kexec_initramfs, + func_policy +}; + +static char *func_tokens[] = { + "FILE_CHECK", + "MMAP_CHECK", + "BPRM_CHECK", + "MODULE_CHECK", + "FIRMWARE_CHECK", + "KEXEC_KERNEL_CHECK", + "KEXEC_INITRAMFS_CHECK", + "POLICY_CHECK", + "POST_SETATTR" +}; + +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] +#define ft(token) func_tokens[token] + +/* + * policy_func_show - display the ima_hooks policy rule + */ +static void policy_func_show(struct seq_file *m, enum ima_hooks func) +{ + char tbuf[64] = {0,}; + + switch (func) { + case FILE_CHECK: + seq_printf(m, pt(Opt_func), ft(func_file)); + break; + case MMAP_CHECK: + seq_printf(m, pt(Opt_func), ft(func_mmap)); + break; + case BPRM_CHECK: + seq_printf(m, pt(Opt_func), ft(func_bprm)); + break; + case MODULE_CHECK: + seq_printf(m, pt(Opt_func), ft(func_module)); + break; + case FIRMWARE_CHECK: + seq_printf(m, pt(Opt_func), ft(func_firmware)); + break; + case POST_SETATTR: + seq_printf(m, pt(Opt_func), ft(func_post)); + break; + case KEXEC_KERNEL_CHECK: + seq_printf(m, pt(Opt_func), ft(func_kexec_kernel)); + break; + case KEXEC_INITRAMFS_CHECK: + seq_printf(m, pt(Opt_func), ft(func_kexec_initramfs)); + break; + case POLICY_CHECK: + seq_printf(m, pt(Opt_func), ft(func_policy)); + break; + default: + snprintf(tbuf, sizeof(tbuf), "%d", func); + seq_printf(m, pt(Opt_func), tbuf); + break; + } + seq_puts(m, " "); +} + +int ima_policy_show(struct seq_file *m, void *v) +{ + struct ima_rule_entry *entry = v; + int i = 0; + 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)); + + 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_FSUUID) { + seq_puts(m, "fsuuid="); + for (i = 0; i < ARRAY_SIZE(entry->fsuuid); ++i) { + switch (i) { + case 4: + case 6: + case 8: + case 10: + seq_puts(m, "-"); + } + seq_printf(m, "%x", entry->fsuuid[i]); + } + seq_puts(m, " "); + } + + if (entry->flags & IMA_UID) { + snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid)); + seq_printf(m, pt(Opt_uid), tbuf); + seq_puts(m, " "); + } + + if (entry->flags & IMA_EUID) { + snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid)); + seq_printf(m, pt(Opt_euid), tbuf); + seq_puts(m, " "); + } + + if (entry->flags & IMA_FOWNER) { + snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->fowner)); + seq_printf(m, pt(Opt_fowner), 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 */ |