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
  23 /* call back to audit ptrace fields */
  24 static void audit_cb(struct audit_buffer *ab, void *va)
  25 {
  26         struct common_audit_data *sa = va;
  27         audit_log_format(ab, " target=");
  28         audit_log_untrustedstring(ab, sa->aad.target);
  29 }
  30
  31 /**
  32  * aa_audit_ptrace - do auditing for ptrace
  33  * @profile: profile being enforced  (NOT NULL)
  34  * @target: profile being traced (NOT NULL)
  35  * @error: error condition
  36  *
  37  * Returns: %0 or error code
  38  */
  39 static int aa_audit_ptrace(struct aa_profile *profile,
  40                            struct aa_profile *target, int error)
  41 {
  42         struct common_audit_data sa;
  43         COMMON_AUDIT_DATA_INIT(&sa, NONE);
  44         sa.aad.op = OP_PTRACE;
  45         sa.aad.target = target;
  46         sa.aad.error = error;
  47
  48         return aa_audit(AUDIT_APPARMOR_AUTO, profile, GFP_ATOMIC, &sa,
  49                         audit_cb);
  50 }
  51
  52 /**
  53  * aa_may_ptrace - test if tracer task can trace the tracee
  54  * @tracer_task: task who will do the tracing  (NOT NULL)
  55  * @tracer: profile of the task doing the tracing  (NOT NULL)
  56  * @tracee: task to be traced
  57  * @mode: whether PTRACE_MODE_READ || PTRACE_MODE_ATTACH
  58  *
  59  * Returns: %0 else error code if permission denied or error
  60  */
  61 int aa_may_ptrace(struct task_struct *tracer_task, struct aa_profile *tracer,
  62                   struct aa_profile *tracee, unsigned int mode)
  63 {
  64         /* TODO: currently only based on capability, not extended ptrace
  65          *       rules,
  66          *       Test mode for PTRACE_MODE_READ || PTRACE_MODE_ATTACH
  67          */
  68
  69         if (unconfined(tracer) || tracer == tracee)
  70                 return 0;
  71         /* log this capability request */
  72         return aa_capable(tracer_task, tracer, CAP_SYS_PTRACE, 1);
  73 }
  74
  75 /**
  76  * aa_ptrace - do ptrace permission check and auditing
  77  * @tracer: task doing the tracing (NOT NULL)
  78  * @tracee: task being traced (NOT NULL)
  79  * @mode: ptrace mode either PTRACE_MODE_READ || PTRACE_MODE_ATTACH
  80  *
  81  * Returns: %0 else error code if permission denied or error
  82  */
  83 int aa_ptrace(struct task_struct *tracer, struct task_struct *tracee,
  84               unsigned int mode)
  85 {
  86         /*
  87          * tracer can ptrace tracee when
  88          * - tracer is unconfined ||
  89          *   - tracer is in complain mode
  90          *   - tracer has rules allowing it to trace tracee currently this is:
  91          *       - confined by the same profile ||
  92          *       - tracer profile has CAP_SYS_PTRACE
  93          */
  94
  95         struct aa_profile *tracer_p;
  96         /* cred released below */
  97         const struct cred *cred = get_task_cred(tracer);
  98         int error = 0;
  99         tracer_p = aa_cred_profile(cred);
 100
 101         if (!unconfined(tracer_p)) {
 102                 /* lcred released below */
 103                 const struct cred *lcred = get_task_cred(tracee);
 104                 struct aa_profile *tracee_p = aa_cred_profile(lcred);
 105
 106                 error = aa_may_ptrace(tracer, tracer_p, tracee_p, mode);
 107                 error = aa_audit_ptrace(tracer_p, tracee_p, error);
 108
 109                 put_cred(lcred);
 110         }
 111         put_cred(cred);
 112
 113         return error;
 114 }