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         COMMON_AUDIT_DATA_INIT(&sa, NONE);
  45         sa.aad.op = OP_PTRACE;
  46         sa.aad.target = target;
  47         sa.aad.error = error;
  48
  49         return aa_audit(AUDIT_APPARMOR_AUTO, profile, GFP_ATOMIC, &sa,
  50                         audit_cb);
  51 }
  52
  53 /**
  54  * aa_may_ptrace - test if tracer task can trace the tracee
  55  * @tracer_task: task who will do the tracing  (NOT NULL)
  56  * @tracer: profile of the task doing the tracing  (NOT NULL)
  57  * @tracee: task to be traced
  58  * @mode: whether PTRACE_MODE_READ || PTRACE_MODE_ATTACH
  59  *
  60  * Returns: %0 else error code if permission denied or error
  61  */
  62 int aa_may_ptrace(struct task_struct *tracer_task, struct aa_profile *tracer,
  63                   struct aa_profile *tracee, unsigned int mode)
  64 {
  65         /* TODO: currently only based on capability, not extended ptrace
  66          *       rules,
  67          *       Test mode for PTRACE_MODE_READ || PTRACE_MODE_ATTACH
  68          */
  69
  70         if (unconfined(tracer) || tracer == tracee)
  71                 return 0;
  72         /* log this capability request */
  73         return aa_capable(tracer_task, tracer, CAP_SYS_PTRACE, 1);
  74 }
  75
  76 /**
  77  * aa_ptrace - do ptrace permission check and auditing
  78  * @tracer: task doing the tracing (NOT NULL)
  79  * @tracee: task being traced (NOT NULL)
  80  * @mode: ptrace mode either PTRACE_MODE_READ || PTRACE_MODE_ATTACH
  81  *
  82  * Returns: %0 else error code if permission denied or error
  83  */
  84 int aa_ptrace(struct task_struct *tracer, struct task_struct *tracee,
  85               unsigned int mode)
  86 {
  87         /*
  88          * tracer can ptrace tracee when
  89          * - tracer is unconfined ||
  90          *   - tracer is in complain mode
  91          *   - tracer has rules allowing it to trace tracee currently this is:
  92          *       - confined by the same profile ||
  93          *       - tracer profile has CAP_SYS_PTRACE
  94          */
  95
  96         struct aa_profile *tracer_p;
  97         /* cred released below */
  98         const struct cred *cred = get_task_cred(tracer);
  99         int error = 0;
 100         tracer_p = aa_cred_profile(cred);
 101
 102         if (!unconfined(tracer_p)) {
 103                 /* lcred released below */
 104                 const struct cred *lcred = get_task_cred(tracee);
 105                 struct aa_profile *tracee_p = aa_cred_profile(lcred);
 106
 107                 error = aa_may_ptrace(tracer, tracer_p, tracee_p, mode);
 108                 error = aa_audit_ptrace(tracer_p, tracee_p, error);
 109
 110                 put_cred(lcred);
 111         }
 112         put_cred(cred);
 113
 114         return error;
 115 }