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 2009-2017 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 /**
  25  * audit_ptrace_mask - convert mask to permission string
  26  * @buffer: buffer to write string to (NOT NULL)
  27  * @mask: permission mask to convert
  28  */
  29 static void audit_ptrace_mask(struct audit_buffer *ab, u32 mask)
  30 {
  31         switch (mask) {
  32         case MAY_READ:
  33                 audit_log_string(ab, "read");
  34                 break;
  35         case MAY_WRITE:
  36                 audit_log_string(ab, "trace");
  37                 break;
  38         case AA_MAY_BE_READ:
  39                 audit_log_string(ab, "readby");
  40                 break;
  41         case AA_MAY_BE_TRACED:
  42                 audit_log_string(ab, "tracedby");
  43                 break;
  44         }
  45 }
  46
  47 /* call back to audit ptrace fields */
  48 static void audit_ptrace_cb(struct audit_buffer *ab, void *va)
  49 {
  50         struct common_audit_data *sa = va;
  51
  52         if (aad(sa)->request & AA_PTRACE_PERM_MASK) {
  53                 audit_log_format(ab, " requested_mask=");
  54                 audit_ptrace_mask(ab, aad(sa)->request);
  55
  56                 if (aad(sa)->denied & AA_PTRACE_PERM_MASK) {
  57                         audit_log_format(ab, " denied_mask=");
  58                         audit_ptrace_mask(ab, aad(sa)->denied);
  59                 }
  60         }
  61         audit_log_format(ab, " peer=");
  62         aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
  63                         FLAGS_NONE, GFP_ATOMIC);
  64 }
  65
  66 /* TODO: conditionals */
  67 static int profile_ptrace_perm(struct aa_profile *profile,
  68                                struct aa_profile *peer, u32 request,
  69                                struct common_audit_data *sa)
  70 {
  71         struct aa_perms perms = { };
  72
  73         /* need because of peer in cross check */
  74         if (profile_unconfined(profile) ||
  75             !PROFILE_MEDIATES(profile, AA_CLASS_PTRACE))
  76                 return 0;
  77
  78         aad(sa)->peer = &peer->label;
  79         aa_profile_match_label(profile, &peer->label, AA_CLASS_PTRACE, request,
  80                                &perms);
  81         aa_apply_modes_to_perms(profile, &perms);
  82         return aa_check_perms(profile, &perms, request, sa, audit_ptrace_cb);
  83 }
  84
  85 static int cross_ptrace_perm(struct aa_profile *tracer,
  86                              struct aa_profile *tracee, u32 request,
  87                              struct common_audit_data *sa)
  88 {
  89         if (PROFILE_MEDIATES(tracer, AA_CLASS_PTRACE))
  90                 return xcheck(profile_ptrace_perm(tracer, tracee, request, sa),
  91                               profile_ptrace_perm(tracee, tracer,
  92                                                   request << PTRACE_PERM_SHIFT,
  93                                                   sa));
  94         /* policy uses the old style capability check for ptrace */
  95         if (profile_unconfined(tracer) || tracer == tracee)
  96                 return 0;
  97
  98         aad(sa)->label = &tracer->label;
  99         aad(sa)->peer = &tracee->label;
 100         aad(sa)->request = 0;
 101         aad(sa)->error = aa_capable(&tracer->label, CAP_SYS_PTRACE, 1);
 102
 103         return aa_audit(AUDIT_APPARMOR_AUTO, tracer, sa, audit_ptrace_cb);
 104 }
 105
 106 /**
 107  * aa_may_ptrace - test if tracer task can trace the tracee
 108  * @tracer: label of the task doing the tracing  (NOT NULL)
 109  * @tracee: task label to be traced
 110  * @request: permission request
 111  *
 112  * Returns: %0 else error code if permission denied or error
 113  */
 114 int aa_may_ptrace(struct aa_label *tracer, struct aa_label *tracee,
 115                   u32 request)
 116 {
 117         DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_PTRACE);
 118
 119         return xcheck_labels_profiles(tracer, tracee, cross_ptrace_perm,
 120                                       request, &sa);
 121 }
 122
 123