security/apparmor/capability.c

Source file repositories/reference/linux-study-clean/security/apparmor/capability.c

File Facts

System
Linux kernel
Corpus path
security/apparmor/capability.c
Extension
.c
Size
6170 bytes
Lines
224
Domain
Core OS
Bucket
Security And Isolation
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

struct audit_cache {
	const struct cred *ad_subj_cred;
	/* Capabilities go from 0 to CAP_LAST_CAP */
	u64 ktime_ns_expiration[CAP_LAST_CAP+1];
};

static DEFINE_PER_CPU(struct audit_cache, audit_cache);

/**
 * audit_cb - call back for capability components of audit struct
 * @ab: audit buffer   (NOT NULL)
 * @va: audit struct to audit data from  (NOT NULL)
 */
static void audit_cb(struct audit_buffer *ab, void *va)
{
	struct common_audit_data *sa = va;

	audit_log_format(ab, " capname=");
	audit_log_untrustedstring(ab, capability_names[sa->u.cap]);
}

/**
 * audit_caps - audit a capability
 * @ad: audit data
 * @profile: profile being tested for confinement (NOT NULL)
 * @cap: capability tested
 * @error: error code returned by test
 *
 * Do auditing of capability and handle, audit/complain/kill modes switching
 * and duplicate message elimination.
 *
 * Returns: 0 or ad->error on success,  error code on failure
 */
static int audit_caps(struct apparmor_audit_data *ad, struct aa_profile *profile,
		      int cap, int error)
{
	const u64 AUDIT_CACHE_TIMEOUT_NS = 1000*1000*1000; /* 1 second */

	struct aa_ruleset *rules = profile->label.rules[0];
	struct audit_cache *ent;
	int type = AUDIT_APPARMOR_AUTO;

	ad->error = error;

	if (likely(!error)) {
		/* test if auditing is being forced */
		if (likely((AUDIT_MODE(profile) != AUDIT_ALL) &&
			   !cap_raised(rules->caps.audit, cap)))
			return 0;
		type = AUDIT_APPARMOR_AUDIT;
	} else if (KILL_MODE(profile) ||
		   cap_raised(rules->caps.kill, cap)) {
		type = AUDIT_APPARMOR_KILL;
	} else if (cap_raised(rules->caps.quiet, cap) &&
		   AUDIT_MODE(profile) != AUDIT_NOQUIET &&
		   AUDIT_MODE(profile) != AUDIT_ALL) {
		/* quiet auditing */
		return error;
	}

	/* Do simple duplicate message elimination */
	ent = &get_cpu_var(audit_cache);
	/* If the capability was never raised the timestamp check would also catch that */
	if (ad->subj_cred == ent->ad_subj_cred && ktime_get_ns() <= ent->ktime_ns_expiration[cap]) {
		put_cpu_var(audit_cache);
		if (COMPLAIN_MODE(profile))
			return complain_error(error);
		return error;
	} else {
		put_cred(ent->ad_subj_cred);
		ent->ad_subj_cred = get_cred(ad->subj_cred);
		ent->ktime_ns_expiration[cap] = ktime_get_ns() + AUDIT_CACHE_TIMEOUT_NS;
	}
	put_cpu_var(audit_cache);

	return aa_audit(type, profile, ad, audit_cb);
}

/**
 * profile_capable - test if profile allows use of capability @cap
 * @profile: profile being enforced    (NOT NULL, NOT unconfined)
 * @cap: capability to test if allowed
 * @opts: CAP_OPT_NOAUDIT bit determines whether audit record is generated
 * @ad: audit data (NOT NULL)
 *
 * Returns: 0 if allowed else -EPERM
 */
static int profile_capable(struct aa_profile *profile, int cap,
			   unsigned int opts, struct apparmor_audit_data *ad)
{

Annotation

Implementation Notes