diff options
Diffstat (limited to 'security/integrity/ima')
| -rw-r--r-- | security/integrity/ima/Kconfig | 10 | ||||
| -rw-r--r-- | security/integrity/ima/ima_appraise.c | 14 | ||||
| -rw-r--r-- | security/integrity/ima/ima_main.c | 21 | ||||
| -rw-r--r-- | security/integrity/ima/ima_policy.c | 171 |
4 files changed, 163 insertions, 53 deletions
diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig index 13b446328dda..a18f8c6d13b5 100644 --- a/security/integrity/ima/Kconfig +++ b/security/integrity/ima/Kconfig @@ -157,6 +157,14 @@ config IMA_APPRAISE <http://linux-ima.sourceforge.net> If unsure, say N. +config IMA_ARCH_POLICY + bool "Enable loading an IMA architecture specific policy" + depends on KEXEC_VERIFY_SIG || IMA_APPRAISE && INTEGRITY_ASYMMETRIC_KEYS + default n + help + This option enables loading an IMA architecture specific policy + based on run time secure boot flags. + config IMA_APPRAISE_BUILD_POLICY bool "IMA build time configured policy rules" depends on IMA_APPRAISE && INTEGRITY_ASYMMETRIC_KEYS @@ -217,7 +225,7 @@ config IMA_APPRAISE_REQUIRE_POLICY_SIGS config IMA_APPRAISE_BOOTPARAM bool "ima_appraise boot parameter" - depends on IMA_APPRAISE + depends on IMA_APPRAISE && !IMA_ARCH_POLICY default y help This option enables the different "ima_appraise=" modes diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index 2e11e750a067..a2baa85ea2f5 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -289,12 +289,22 @@ int ima_appraise_measurement(enum ima_hooks func, case EVM_IMA_XATTR_DIGSIG: set_bit(IMA_DIGSIG, &iint->atomic_flags); rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA, - (const char *)xattr_value, rc, + (const char *)xattr_value, + xattr_len, iint->ima_hash->digest, iint->ima_hash->length); if (rc == -EOPNOTSUPP) { status = INTEGRITY_UNKNOWN; - } else if (rc) { + break; + } + if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc && + func == KEXEC_KERNEL_CHECK) + rc = integrity_digsig_verify(INTEGRITY_KEYRING_PLATFORM, + (const char *)xattr_value, + xattr_len, + iint->ima_hash->digest, + iint->ima_hash->length); + if (rc) { cause = "invalid-signature"; status = INTEGRITY_FAIL; } else { diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 616a88f95b92..4ffac4f5c647 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -105,7 +105,7 @@ static void ima_rdwr_violation_check(struct file *file, } else { if (must_measure) set_bit(IMA_MUST_MEASURE, &iint->atomic_flags); - if ((atomic_read(&inode->i_writecount) > 0) && must_measure) + if (inode_is_open_for_write(inode) && must_measure) send_writers = true; } @@ -507,20 +507,26 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size, */ int ima_load_data(enum kernel_load_data_id id) { - bool sig_enforce; + bool ima_enforce, sig_enforce; - if ((ima_appraise & IMA_APPRAISE_ENFORCE) != IMA_APPRAISE_ENFORCE) - return 0; + ima_enforce = + (ima_appraise & IMA_APPRAISE_ENFORCE) == IMA_APPRAISE_ENFORCE; switch (id) { case LOADING_KEXEC_IMAGE: - if (ima_appraise & IMA_APPRAISE_KEXEC) { + if (IS_ENABLED(CONFIG_KEXEC_VERIFY_SIG) + && arch_ima_get_secureboot()) { + pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n"); + return -EACCES; + } + + if (ima_enforce && (ima_appraise & IMA_APPRAISE_KEXEC)) { pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n"); return -EACCES; /* INTEGRITY_UNKNOWN */ } break; case LOADING_FIRMWARE: - if (ima_appraise & IMA_APPRAISE_FIRMWARE) { + if (ima_enforce && (ima_appraise & IMA_APPRAISE_FIRMWARE)) { pr_err("Prevent firmware sysfs fallback loading.\n"); return -EACCES; /* INTEGRITY_UNKNOWN */ } @@ -528,7 +534,8 @@ int ima_load_data(enum kernel_load_data_id id) case LOADING_MODULE: sig_enforce = is_module_sig_enforced(); - if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES)) { + if (ima_enforce && (!sig_enforce + && (ima_appraise & IMA_APPRAISE_MODULES))) { pr_err("impossible to appraise a module without a file descriptor. sig_enforce kernel parameter might help\n"); return -EACCES; /* INTEGRITY_UNKNOWN */ } diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index fcf5b2729063..8bc8a1c8cb3f 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -20,6 +20,7 @@ #include <linux/rculist.h> #include <linux/genhd.h> #include <linux/seq_file.h> +#include <linux/ima.h> #include "ima.h" @@ -58,6 +59,8 @@ enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE, enum policy_types { ORIGINAL_TCB = 1, DEFAULT_TCB }; +enum policy_rule_list { IMA_DEFAULT_POLICY = 1, IMA_CUSTOM_POLICY }; + struct ima_rule_entry { struct list_head list; int action; @@ -104,7 +107,8 @@ static struct ima_rule_entry dont_measure_rules[] __ro_after_init = { .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 = 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 = { @@ -147,6 +151,7 @@ static struct ima_rule_entry default_appraise_rules[] __ro_after_init = { {.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 @@ -193,6 +198,9 @@ static struct ima_rule_entry secure_boot_rules[] __ro_after_init = { .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED}, }; +/* An array of architecture specific rules */ +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); @@ -473,6 +481,75 @@ static int ima_appraise_flag(enum ima_hooks func) 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) + temp_ima_appraise |= ima_appraise_flag(entries[i].func); + if (entries[i].func == POLICY_CHECK) + temp_ima_appraise |= IMA_APPRAISE_POLICY; + } +} + +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. * @@ -481,68 +558,68 @@ static int ima_appraise_flag(enum ima_hooks func) */ void __init ima_init_policy(void) { - int i, measure_entries, appraise_entries, secure_boot_entries; + int build_appraise_entries, arch_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); + /* 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: - for (i = 0; i < ARRAY_SIZE(original_measurement_rules); i++) - list_add_tail(&original_measurement_rules[i].list, - &ima_default_rules); + add_rules(original_measurement_rules, + ARRAY_SIZE(original_measurement_rules), + IMA_DEFAULT_POLICY); 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); + 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 any other appraise rules. + * signatures, prior to 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); - } + 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. + * 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. */ - 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); + 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); } - 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; - } + if (ima_use_appraise_tcb) + add_rules(default_appraise_rules, + ARRAY_SIZE(default_appraise_rules), + IMA_DEFAULT_POLICY); ima_rules = &ima_default_rules; ima_update_policy_flag(); @@ -576,6 +653,14 @@ void ima_update_policy(void) 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(); } |