IMA: Add audit log for failure conditions

process_buffer_measurement() and ima_alloc_key_entry() functions need to
log an audit message for auditing integrity measurement failures.

Add audit message in these two functions. Remove "pr_devel" log message
in process_buffer_measurement().

Sample audit messages:

[    6.303048] audit: type=1804 audit(1592506281.627:2): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=kernel op=measuring_key cause=ENOMEM comm="swapper/0" name=".builtin_trusted_keys" res=0 errno=-12

[    8.019432] audit: type=1804 audit(1592506283.344:10): pid=1 uid=0 auid=4294967295 ses=4294967295 subj=system_u:system_r:init_t:s0 op=measuring_kexec_cmdline cause=hashing_error comm="systemd" name="kexec-cmdline" res=0 errno=-22

Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
This commit is contained in:
Lakshmi Ramasubramanian 2020-06-18 14:10:12 -07:00 committed by Mimi Zohar
parent 2f845882ec
commit 34e980bb83
4 changed files with 51 additions and 22 deletions

View File

@ -186,27 +186,43 @@ static inline unsigned int ima_hash_key(u8 *digest)
return (digest[0] | digest[1] << 8) % IMA_MEASURE_HTABLE_SIZE;
}
#define __ima_hooks(hook) \
hook(NONE) \
hook(FILE_CHECK) \
hook(MMAP_CHECK) \
hook(BPRM_CHECK) \
hook(CREDS_CHECK) \
hook(POST_SETATTR) \
hook(MODULE_CHECK) \
hook(FIRMWARE_CHECK) \
hook(KEXEC_KERNEL_CHECK) \
hook(KEXEC_INITRAMFS_CHECK) \
hook(POLICY_CHECK) \
hook(KEXEC_CMDLINE) \
hook(KEY_CHECK) \
hook(MAX_CHECK)
#define __ima_hook_enumify(ENUM) ENUM,
#define __ima_hooks(hook) \
hook(NONE, none) \
hook(FILE_CHECK, file) \
hook(MMAP_CHECK, mmap) \
hook(BPRM_CHECK, bprm) \
hook(CREDS_CHECK, creds) \
hook(POST_SETATTR, post_setattr) \
hook(MODULE_CHECK, module) \
hook(FIRMWARE_CHECK, firmware) \
hook(KEXEC_KERNEL_CHECK, kexec_kernel) \
hook(KEXEC_INITRAMFS_CHECK, kexec_initramfs) \
hook(POLICY_CHECK, policy) \
hook(KEXEC_CMDLINE, kexec_cmdline) \
hook(KEY_CHECK, key) \
hook(MAX_CHECK, none)
#define __ima_hook_enumify(ENUM, str) ENUM,
#define __ima_stringify(arg) (#arg)
#define __ima_hook_measuring_stringify(ENUM, str) \
(__ima_stringify(measuring_ ##str)),
enum ima_hooks {
__ima_hooks(__ima_hook_enumify)
};
static const char * const ima_hooks_measure_str[] = {
__ima_hooks(__ima_hook_measuring_stringify)
};
static inline const char *func_measure_str(enum ima_hooks func)
{
if (func >= MAX_CHECK)
return ima_hooks_measure_str[NONE];
return ima_hooks_measure_str[func];
}
extern const char *const func_tokens[];
struct modsig;

View File

@ -740,6 +740,7 @@ void process_buffer_measurement(const void *buf, int size,
int pcr, const char *keyring)
{
int ret = 0;
const char *audit_cause = "ENOMEM";
struct ima_template_entry *entry = NULL;
struct integrity_iint_cache iint = {};
struct ima_event_data event_data = {.iint = &iint,
@ -794,21 +795,28 @@ void process_buffer_measurement(const void *buf, int size,
iint.ima_hash->length = hash_digest_size[ima_hash_algo];
ret = ima_calc_buffer_hash(buf, size, iint.ima_hash);
if (ret < 0)
if (ret < 0) {
audit_cause = "hashing_error";
goto out;
}
ret = ima_alloc_init_template(&event_data, &entry, template);
if (ret < 0)
if (ret < 0) {
audit_cause = "alloc_entry";
goto out;
}
ret = ima_store_template(entry, violation, NULL, buf, pcr);
if (ret < 0)
if (ret < 0) {
audit_cause = "store_entry";
ima_free_template_entry(entry);
}
out:
if (ret < 0)
pr_devel("%s: failed, result: %d\n", __func__, ret);
integrity_audit_message(AUDIT_INTEGRITY_PCR, NULL, eventname,
func_measure_str(func),
audit_cause, ret, 0, ret);
return;
}

View File

@ -1414,7 +1414,7 @@ void ima_delete_rules(void)
}
}
#define __ima_hook_stringify(str) (#str),
#define __ima_hook_stringify(func, str) (#func),
const char *const func_tokens[] = {
__ima_hooks(__ima_hook_stringify)

View File

@ -68,6 +68,7 @@ static struct ima_key_entry *ima_alloc_key_entry(struct key *keyring,
size_t payload_len)
{
int rc = 0;
const char *audit_cause = "ENOMEM";
struct ima_key_entry *entry;
entry = kzalloc(sizeof(*entry), GFP_KERNEL);
@ -88,6 +89,10 @@ static struct ima_key_entry *ima_alloc_key_entry(struct key *keyring,
out:
if (rc) {
integrity_audit_message(AUDIT_INTEGRITY_PCR, NULL,
keyring->description,
func_measure_str(KEY_CHECK),
audit_cause, rc, 0, rc);
ima_free_key_entry(entry);
entry = NULL;
}