apparmor: move ptrace checks to using labels

Signed-off-by: John Johansen <john.johansen@canonical.com>

security/apparmor/domain.c

@@ -51,14 +51,16 @@ void aa_free_domain_entries(struct aa_domain *domain)
 
 /**
  * may_change_ptraced_domain - check if can change profile on ptraced task
- * @to_profile: profile to change to  (NOT NULL)
+ * @to_label: profile to change to  (NOT NULL)
+ * @info: message if there is an error
  *
  * Check if current is ptraced and if so if the tracing task is allowed
  * to trace the new domain
  *
  * Returns: %0 or error if change not allowed
  */
-static int may_change_ptraced_domain(struct aa_profile *to_profile)
+static int may_change_ptraced_domain(struct aa_label *to_label,
+				     const char **info)
 {
 	struct task_struct *tracer;
 	struct aa_label *tracerl = NULL;
@@ -74,13 +76,14 @@ static int may_change_ptraced_domain(struct aa_profile *to_profile)
 	if (!tracer || unconfined(tracerl))
 		goto out;
 
-	error = aa_may_ptrace(labels_profile(tracerl), to_profile,
-			      PTRACE_MODE_ATTACH);
+	error = aa_may_ptrace(tracerl, to_label, PTRACE_MODE_ATTACH);
 
 out:
 	rcu_read_unlock();
 	aa_put_label(tracerl);
 
+	if (error)
+		*info = "ptrace prevents transition";
 	return error;
 }
 
@@ -477,7 +480,7 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
 	}
 
 	if (bprm->unsafe & LSM_UNSAFE_PTRACE) {
-		error = may_change_ptraced_domain(new_profile);
+		error = may_change_ptraced_domain(&new_profile->label, &info);
 		if (error)
 			goto audit;
 	}
@@ -661,7 +664,7 @@ int aa_change_hat(const char *hats[], int count, u64 token, int flags)
 			}
 		}
 
-		error = may_change_ptraced_domain(hat);
+		error = may_change_ptraced_domain(&hat->label, &info);
 		if (error) {
 			info = "ptraced";
 			error = -EPERM;
@@ -782,7 +785,7 @@ int aa_change_profile(const char *fqname, int flags)
 	}
 
 	/* check if tracing task is allowed to trace target domain */
-	error = may_change_ptraced_domain(target);
+	error = may_change_ptraced_domain(&target->label, &info);
 	if (error) {
 		info = "ptrace prevents transition";
 		goto audit;

security/apparmor/include/apparmor.h

@@ -27,6 +27,7 @@
 #define AA_CLASS_NET		4
 #define AA_CLASS_RLIMITS	5
 #define AA_CLASS_DOMAIN		6
+#define AA_CLASS_PTRACE		9
 #define AA_CLASS_LABEL		16
 
 #define AA_CLASS_LAST		AA_CLASS_LABEL

security/apparmor/include/ipc.h

@@ -4,7 +4,7 @@
  * This file contains AppArmor ipc mediation function definitions.
  *
  * Copyright (C) 1998-2008 Novell/SUSE
- * Copyright 2009-2010 Canonical Ltd.
+ * Copyright 2009-2017 Canonical Ltd.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
@@ -19,10 +19,10 @@
 
 struct aa_profile;
 
-int aa_may_ptrace(struct aa_profile *tracer, struct aa_profile *tracee,
-		  unsigned int mode);
+#define AA_PTRACE_TRACE		MAY_WRITE
+#define AA_PTRACE_READ		MAY_READ
 
-int aa_ptrace(struct task_struct *tracer, struct task_struct *tracee,
-	      unsigned int mode);
+int aa_may_ptrace(struct aa_label *tracer, struct aa_label *tracee,
+		  u32 request);
 
 #endif /* __AA_IPC_H */

security/apparmor/ipc.c

@@ -4,7 +4,7 @@
  * This file contains AppArmor ipc mediation
  *
  * Copyright (C) 1998-2008 Novell/SUSE
- * Copyright 2009-2010 Canonical Ltd.
+ * Copyright 2009-2017 Canonical Ltd.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
@@ -25,88 +25,43 @@
 static void audit_ptrace_cb(struct audit_buffer *ab, void *va)
 {
 	struct common_audit_data *sa = va;
+
 	audit_log_format(ab, " peer=");
 	aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
 			FLAGS_NONE, GFP_ATOMIC);
 }
 
-/**
- * aa_audit_ptrace - do auditing for ptrace
- * @profile: profile being enforced  (NOT NULL)
- * @target: profile being traced (NOT NULL)
- * @error: error condition
- *
- * Returns: %0 or error code
- */
-static int aa_audit_ptrace(struct aa_profile *profile,
-			   struct aa_profile *target, int error)
+static int cross_ptrace_perm(struct aa_profile *tracer,
+			     struct aa_profile *tracee, u32 request,
+			     struct common_audit_data *sa)
 {
-	DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_PTRACE);
+	/* policy uses the old style capability check for ptrace */
+	if (profile_unconfined(tracer) || tracer == tracee)
+		return 0;
 
-	aad(&sa)->peer = &target->label;
-	aad(&sa)->error = error;
+	aad(sa)->label = &tracer->label;
+	aad(sa)->peer = &tracee->label;
+	aad(sa)->request = 0;
+	aad(sa)->error = aa_capable(&tracer->label, CAP_SYS_PTRACE, 1);
 
-	return aa_audit(AUDIT_APPARMOR_AUTO, profile, &sa, audit_ptrace_cb);
+	return aa_audit(AUDIT_APPARMOR_AUTO, tracer, sa, audit_ptrace_cb);
 }
 
 /**
  * aa_may_ptrace - test if tracer task can trace the tracee
- * @tracer: profile of the task doing the tracing  (NOT NULL)
- * @tracee: task to be traced
- * @mode: whether PTRACE_MODE_READ || PTRACE_MODE_ATTACH
+ * @tracer: label of the task doing the tracing  (NOT NULL)
+ * @tracee: task label to be traced
+ * @request: permission request
  *
  * Returns: %0 else error code if permission denied or error
  */
-int aa_may_ptrace(struct aa_profile *tracer, struct aa_profile *tracee,
-		  unsigned int mode)
+int aa_may_ptrace(struct aa_label *tracer, struct aa_label *tracee,
+		  u32 request)
 {
-	/* TODO: currently only based on capability, not extended ptrace
-	 *       rules,
-	 *       Test mode for PTRACE_MODE_READ || PTRACE_MODE_ATTACH
-	 */
+	DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_PTRACE);
 
-	if (profile_unconfined(tracer) || tracer == tracee)
-		return 0;
-	/* log this capability request */
-	return aa_capable(&tracer->label, CAP_SYS_PTRACE, 1);
+	return xcheck_labels_profiles(tracer, tracee, cross_ptrace_perm,
+				      request, &sa);
 }
 
-/**
- * aa_ptrace - do ptrace permission check and auditing
- * @tracer: task doing the tracing (NOT NULL)
- * @tracee: task being traced (NOT NULL)
- * @mode: ptrace mode either PTRACE_MODE_READ || PTRACE_MODE_ATTACH
- *
- * Returns: %0 else error code if permission denied or error
- */
-int aa_ptrace(struct task_struct *tracer, struct task_struct *tracee,
-	      unsigned int mode)
-{
-	/*
-	 * tracer can ptrace tracee when
-	 * - tracer is unconfined ||
-	 *   - tracer is in complain mode
-	 *   - tracer has rules allowing it to trace tracee currently this is:
-	 *       - confined by the same profile ||
-	 *       - tracer profile has CAP_SYS_PTRACE
-	 */
 
-	struct aa_label *tracer_l = aa_get_task_label(tracer);
-	int error = 0;
-
-	if (!unconfined(tracer_l)) {
-		struct aa_label *tracee_l = aa_get_task_label(tracee);
-
-		error = aa_may_ptrace(labels_profile(tracer_l),
-				      labels_profile(tracee_l),
-				      mode);
-		error = aa_audit_ptrace(labels_profile(tracer_l),
-					labels_profile(tracee_l),
-					error);
-
-		aa_put_label(tracee_l);
-	}
-	aa_put_label(tracer_l);
-
-	return error;
-}

security/apparmor/lsm.c

@@ -104,12 +104,31 @@ static void apparmor_cred_transfer(struct cred *new, const struct cred *old)
 static int apparmor_ptrace_access_check(struct task_struct *child,
 					unsigned int mode)
 {
-	return aa_ptrace(current, child, mode);
+	struct aa_label *tracer, *tracee;
+	int error;
+
+	tracer = begin_current_label_crit_section();
+	tracee = aa_get_task_label(child);
+	error = aa_may_ptrace(tracer, tracee,
+		  mode == PTRACE_MODE_READ ? AA_PTRACE_READ : AA_PTRACE_TRACE);
+	aa_put_label(tracee);
+	end_current_label_crit_section(tracer);
+
+	return error;
 }
 
 static int apparmor_ptrace_traceme(struct task_struct *parent)
 {
-	return aa_ptrace(parent, current, PTRACE_MODE_ATTACH);
+	struct aa_label *tracer, *tracee;
+	int error;
+
+	tracee = begin_current_label_crit_section();
+	tracer = aa_get_task_label(parent);
+	error = aa_may_ptrace(tracer, tracee, AA_PTRACE_TRACE);
+	aa_put_label(tracer);
+	end_current_label_crit_section(tracee);
+
+	return error;
 }
 
 /* Derived from security/commoncap.c:cap_capget */