From: Janne Karhunen janne.karhunen@gmail.com
[ Upstream commit b169424551930a9325f700f502802f4d515194e5 ]
Don't do lazy policy updates while running the rule matching, run the updates as they happen.
Depends on commit f242064c5df3 ("LSM: switch to blocking policy update notifiers")
Signed-off-by: Janne Karhunen janne.karhunen@gmail.com Signed-off-by: Mimi Zohar zohar@linux.ibm.com Signed-off-by: GUO Zihua guozihua@huawei.com --- security/integrity/ima/ima.h | 2 + security/integrity/ima/ima_main.c | 8 ++ security/integrity/ima/ima_policy.c | 118 ++++++++++++++++++++++------ 3 files changed, 106 insertions(+), 22 deletions(-)
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index e2916b115b93..dc564ed9a790 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -154,6 +154,8 @@ int ima_measurements_show(struct seq_file *m, void *v); unsigned long ima_get_binary_runtime_size(void); int ima_init_template(void); void ima_init_template_list(void); +int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event, + void *lsm_data);
/* * used to protect h_table and sha_table diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 2d31921fbda4..55681872c6ce 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -41,6 +41,10 @@ int ima_appraise; int ima_hash_algo = HASH_ALGO_SHA1; static int hash_setup_done;
+static struct notifier_block ima_lsm_policy_notifier = { + .notifier_call = ima_lsm_policy_change, +}; + static int __init hash_setup(char *str) { struct ima_template_desc *template_desc = ima_template_desc_current(); @@ -553,6 +557,10 @@ static int __init init_ima(void) error = ima_init(); }
+ error = register_blocking_lsm_notifier(&ima_lsm_policy_notifier); + if (error) + pr_warn("Couldn't register LSM notifier, error %d\n", error); + if (!error) ima_update_policy_flag();
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index b2dadff3626b..d9ff46780976 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -241,6 +241,16 @@ static int __init default_appraise_policy_setup(char *str) } __setup("ima_appraise_tcb", default_appraise_policy_setup);
+static void ima_lsm_free_rule(struct ima_rule_entry *entry) +{ + int i; + + for (i = 0; i < MAX_LSM_RULES; i++) { + security_filter_rule_free(entry->lsm[i].rule); + kfree(entry->lsm[i].args_p); + } +} + static void ima_free_rule(struct ima_rule_entry *entry) { int i; @@ -249,38 +259,108 @@ static void ima_free_rule(struct ima_rule_entry *entry) return;
kfree(entry->fsname); + 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, result; + + nentry = kmalloc(sizeof(*nentry), GFP_KERNEL); + if (!nentry) + return NULL; + + /* + * Immutable elements are copied over as pointers and data; only + * lsm rules can change + */ + memcpy(nentry, entry, sizeof(*nentry)); + memset(nentry->lsm, 0, FIELD_SIZEOF(struct ima_rule_entry, lsm)); + for (i = 0; i < MAX_LSM_RULES; i++) { - security_filter_rule_free(entry->lsm[i].rule); - kfree(entry->lsm[i].args_p); + if (!entry->lsm[i].rule) + continue; + + nentry->lsm[i].type = entry->lsm[i].type; + nentry->lsm[i].args_p = kstrdup(entry->lsm[i].args_p, + GFP_KERNEL); + if (!nentry->lsm[i].args_p) + goto out_err; + + result = security_filter_rule_init(nentry->lsm[i].type, + Audit_equal, + nentry->lsm[i].args_p, + &nentry->lsm[i].rule); + if (result == -EINVAL) + pr_warn("ima: rule for LSM '%d' is undefined\n", + entry->lsm[i].type); } + return nentry; + +out_err: + ima_lsm_free_rule(entry); kfree(entry); + return NULL; +} + +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_free_rule(entry); + kfree(entry); + + return 0; }
/* * 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 reloaded LSM policy. */ static void ima_lsm_update_rules(void) { - struct ima_rule_entry *entry; - int result; - int i; + struct ima_rule_entry *entry, *e; + int i, result, needs_update;
- list_for_each_entry(entry, &ima_policy_rules, list) { + list_for_each_entry_safe(entry, e, &ima_policy_rules, list) { + needs_update = 0; 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); + if (entry->lsm[i].rule) { + needs_update = 1; + break; + } + } + if (!needs_update) + continue; + + result = ima_lsm_update_rule(entry); + if (result) { + pr_err("ima: 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_rules - determine whether an inode matches the measure rule. * @rule: a pointer to a rule @@ -334,11 +414,10 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode, 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: @@ -361,11 +440,6 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode, default: break; } - if ((rc < 0) && (!retried)) { - retried = 1; - ima_lsm_update_rules(); - goto retry; - } if (!rc) return false; }