security/apparmor/ipc.c

   1 /*
   2  * AppArmor security module
   3  *
   4  * This file contains AppArmor ipc mediation
   5  *
   6  * Copyright (C) 1998-2008 Novell/SUSE
   7  * Copyright 2009-2010 Canonical Ltd.
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License as
  11  * published by the Free Software Foundation, version 2 of the
  12  * License.
  13  */
  14
  15 #include <linux/gfp.h>
  16 #include <linux/ptrace.h>
  17
  18 #include "include/audit.h"
  19 #include "include/capability.h"
  20 #include "include/context.h"
  21 #include "include/policy.h"
  22 #include "include/ipc.h"
  23
  24 /* call back to audit ptrace fields */
  25 static void audit_cb(struct audit_buffer *ab, void *va)
  26 {
  27         struct common_audit_data *sa = va;
  28         audit_log_format(ab, " target=");
  29         audit_log_untrustedstring(ab, sa->aad->target);
  30 }
  31
  32 /**
  33  * aa_audit_ptrace - do auditing for ptrace
  34  * @profile: profile being enforced  (NOT NULL)
  35  * @target: profile being traced (NOT NULL)
  36  * @error: error condition
  37  *
  38  * Returns: %0 or error code
  39  */
  40 static int aa_audit_ptrace(struct aa_profile *profile,
  41                            struct aa_profile *target, int error)
  42 {
  43         struct common_audit_data sa;
  44         struct apparmor_audit_data aad = {0,};
  45         sa.type = LSM_AUDIT_DATA_NONE;
  46         sa.aad = &aad;
  47         aad.op = OP_PTRACE;
  48         aad.target = target;
  49         aad.error = error;
  50
  51         return aa_audit(AUDIT_APPARMOR_AUTO, profile, GFP_ATOMIC, &sa,
  52                         audit_cb);
  53 }
  54
  55 /**
  56  * aa_may_ptrace - test if tracer task can trace the tracee
  57  * @tracer_task: task who will do the tracing  (NOT NULL)
  58  * @tracer: profile of the task doing the tracing  (NOT NULL)
  59  * @tracee: task to be traced
  60  * @mode: whether PTRACE_MODE_READ || PTRACE_MODE_ATTACH
  61  *
  62  * Returns: %0 else error code if permission denied or error
  63  */
  64 int aa_may_ptrace(struct task_struct *tracer_task, struct aa_profile *tracer,
  65                   struct aa_profile *tracee, unsigned int mode)
  66 {
  67         /* TODO: currently only based on capability, not extended ptrace
  68          *       rules,
  69          *       Test mode for PTRACE_MODE_READ || PTRACE_MODE_ATTACH
  70          */
  71
  72         if (unconfined(tracer) || tracer == tracee)
  73                 return 0;
  74         /* log this capability request */
  75         return aa_capable(tracer_task, tracer, CAP_SYS_PTRACE, 1);
  76 }
  77
  78 /**
  79  * aa_ptrace - do ptrace permission check and auditing
  80  * @tracer: task doing the tracing (NOT NULL)
  81  * @tracee: task being traced (NOT NULL)
  82  * @mode: ptrace mode either PTRACE_MODE_READ || PTRACE_MODE_ATTACH
  83  *
  84  * Returns: %0 else error code if permission denied or error
  85  */
  86 int aa_ptrace(struct task_struct *tracer, struct task_struct *tracee,
  87               unsigned int mode)
  88 {
  89         /*
  90          * tracer can ptrace tracee when
  91          * - tracer is unconfined ||
  92          *   - tracer is in complain mode
  93          *   - tracer has rules allowing it to trace tracee currently this is:
  94          *       - confined by the same profile ||
  95          *       - tracer profile has CAP_SYS_PTRACE
  96          */
  97
  98         struct aa_profile *tracer_p;
  99         /* cred released below */
 100         const struct cred *cred = get_task_cred(tracer);
 101         int error = 0;
 102         tracer_p = aa_cred_profile(cred);
 103
 104         if (!unconfined(tracer_p)) {
 105                 /* lcred released below */
 106                 const struct cred *lcred = get_task_cred(tracee);
 107                 struct aa_profile *tracee_p = aa_cred_profile(lcred);
 108
 109                 error = aa_may_ptrace(tracer, tracer_p, tracee_p, mode);
 110                 error = aa_audit_ptrace(tracer_p, tracee_p, error);
 111
 112                 put_cred(lcred);
 113         }
 114         put_cred(cred);
 115
 116         return error;
 117 }