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 #include "include/sig_names.h"
  24
  25 /**
  26  * audit_ptrace_mask - convert mask to permission string
  27  * @buffer: buffer to write string to (NOT NULL)
  28  * @mask: permission mask to convert
  29  */
  30 static void audit_ptrace_mask(struct audit_buffer *ab, u32 mask)
  31 {
  32         switch (mask) {
  33         case MAY_READ:
  34                 audit_log_string(ab, "read");
  35                 break;
  36         case MAY_WRITE:
  37                 audit_log_string(ab, "trace");
  38                 break;
  39         case AA_MAY_BE_READ:
  40                 audit_log_string(ab, "readby");
  41                 break;
  42         case AA_MAY_BE_TRACED:
  43                 audit_log_string(ab, "tracedby");
  44                 break;
  45         }
  46 }
  47
  48 /* call back to audit ptrace fields */
  49 static void audit_ptrace_cb(struct audit_buffer *ab, void *va)
  50 {
  51         struct common_audit_data *sa = va;
  52
  53         if (aad(sa)->request & AA_PTRACE_PERM_MASK) {
  54                 audit_log_format(ab, " requested_mask=");
  55                 audit_ptrace_mask(ab, aad(sa)->request);
  56
  57                 if (aad(sa)->denied & AA_PTRACE_PERM_MASK) {
  58                         audit_log_format(ab, " denied_mask=");
  59                         audit_ptrace_mask(ab, aad(sa)->denied);
  60                 }
  61         }
  62         audit_log_format(ab, " peer=");
  63         aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
  64                         FLAGS_NONE, GFP_ATOMIC);
  65 }
  66
  67 /* TODO: conditionals */
  68 static int profile_ptrace_perm(struct aa_profile *profile,
  69                                struct aa_profile *peer, u32 request,
  70                                struct common_audit_data *sa)
  71 {
  72         struct aa_perms perms = { };
  73
  74         /* need because of peer in cross check */
  75         if (profile_unconfined(profile) ||
  76             !PROFILE_MEDIATES(profile, AA_CLASS_PTRACE))
  77                 return 0;
  78
  79         aad(sa)->peer = &peer->label;
  80         aa_profile_match_label(profile, &peer->label, AA_CLASS_PTRACE, request,
  81                                &perms);
  82         aa_apply_modes_to_perms(profile, &perms);
  83         return aa_check_perms(profile, &perms, request, sa, audit_ptrace_cb);
  84 }
  85
  86 static int cross_ptrace_perm(struct aa_profile *tracer,
  87                              struct aa_profile *tracee, u32 request,
  88                              struct common_audit_data *sa)
  89 {
  90         if (PROFILE_MEDIATES(tracer, AA_CLASS_PTRACE))
  91                 return xcheck(profile_ptrace_perm(tracer, tracee, request, sa),
  92                               profile_ptrace_perm(tracee, tracer,
  93                                                   request << PTRACE_PERM_SHIFT,
  94                                                   sa));
  95         /* policy uses the old style capability check for ptrace */
  96         if (profile_unconfined(tracer) || tracer == tracee)
  97                 return 0;
  98
  99         aad(sa)->label = &tracer->label;
 100         aad(sa)->peer = &tracee->label;
 101         aad(sa)->request = 0;
 102         aad(sa)->error = aa_capable(&tracer->label, CAP_SYS_PTRACE, 1);
 103
 104         return aa_audit(AUDIT_APPARMOR_AUTO, tracer, sa, audit_ptrace_cb);
 105 }
 106
 107 /**
 108  * aa_may_ptrace - test if tracer task can trace the tracee
 109  * @tracer: label of the task doing the tracing  (NOT NULL)
 110  * @tracee: task label to be traced
 111  * @request: permission request
 112  *
 113  * Returns: %0 else error code if permission denied or error
 114  */
 115 int aa_may_ptrace(struct aa_label *tracer, struct aa_label *tracee,
 116                   u32 request)
 117 {
 118         DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_PTRACE);
 119
 120         return xcheck_labels_profiles(tracer, tracee, cross_ptrace_perm,
 121                                       request, &sa);
 122 }
 123
 124
 125 static inline int map_signal_num(int sig)
 126 {
 127         if (sig > SIGRTMAX)
 128                 return SIGUNKNOWN;
 129         else if (sig >= SIGRTMIN)
 130                 return sig - SIGRTMIN + 128;    /* rt sigs mapped to 128 */
 131         else if (sig <= MAXMAPPED_SIG)
 132                 return sig_map[sig];
 133         return SIGUNKNOWN;
 134 }
 135
 136 /**
 137  * audit_file_mask - convert mask to permission string
 138  * @buffer: buffer to write string to (NOT NULL)
 139  * @mask: permission mask to convert
 140  */
 141 static void audit_signal_mask(struct audit_buffer *ab, u32 mask)
 142 {
 143         if (mask & MAY_READ)
 144                 audit_log_string(ab, "receive");
 145         if (mask & MAY_WRITE)
 146                 audit_log_string(ab, "send");
 147 }
 148
 149 /**
 150  * audit_cb - call back for signal specific audit fields
 151  * @ab: audit_buffer  (NOT NULL)
 152  * @va: audit struct to audit values of  (NOT NULL)
 153  */
 154 static void audit_signal_cb(struct audit_buffer *ab, void *va)
 155 {
 156         struct common_audit_data *sa = va;
 157
 158         if (aad(sa)->request & AA_SIGNAL_PERM_MASK) {
 159                 audit_log_format(ab, " requested_mask=");
 160                 audit_signal_mask(ab, aad(sa)->request);
 161                 if (aad(sa)->denied & AA_SIGNAL_PERM_MASK) {
 162                         audit_log_format(ab, " denied_mask=");
 163                         audit_signal_mask(ab, aad(sa)->denied);
 164                 }
 165         }
 166         if (aad(sa)->signal <= MAXMAPPED_SIG)
 167                 audit_log_format(ab, " signal=%s", sig_names[aad(sa)->signal]);
 168         else
 169                 audit_log_format(ab, " signal=rtmin+%d",
 170                                  aad(sa)->signal - 128);
 171         audit_log_format(ab, " peer=");
 172         aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
 173                         FLAGS_NONE, GFP_ATOMIC);
 174 }
 175
 176 /* TODO: update to handle compound name&name2, conditionals */
 177 static void profile_match_signal(struct aa_profile *profile, const char *label,
 178                                  int signal, struct aa_perms *perms)
 179 {
 180         unsigned int state;
 181
 182         /* TODO: secondary cache check <profile, profile, perm> */
 183         state = aa_dfa_next(profile->policy.dfa,
 184                             profile->policy.start[AA_CLASS_SIGNAL],
 185                             signal);
 186         state = aa_dfa_match(profile->policy.dfa, state, label);
 187         aa_compute_perms(profile->policy.dfa, state, perms);
 188 }
 189
 190 static int profile_signal_perm(struct aa_profile *profile,
 191                                struct aa_profile *peer, u32 request,
 192                                struct common_audit_data *sa)
 193 {
 194         struct aa_perms perms;
 195
 196         if (profile_unconfined(profile) ||
 197             !PROFILE_MEDIATES(profile, AA_CLASS_SIGNAL))
 198                 return 0;
 199
 200         aad(sa)->peer = &peer->label;
 201         profile_match_signal(profile, peer->base.hname, aad(sa)->signal,
 202                              &perms);
 203         aa_apply_modes_to_perms(profile, &perms);
 204         return aa_check_perms(profile, &perms, request, sa, audit_signal_cb);
 205 }
 206
 207 static int aa_signal_cross_perm(struct aa_profile *sender,
 208                                 struct aa_profile *target,
 209                                 struct common_audit_data *sa)
 210 {
 211         return xcheck(profile_signal_perm(sender, target, MAY_WRITE, sa),
 212                       profile_signal_perm(target, sender, MAY_READ, sa));
 213 }
 214
 215 int aa_may_signal(struct aa_label *sender, struct aa_label *target, int sig)
 216 {
 217         DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_SIGNAL);
 218
 219         aad(&sa)->signal = map_signal_num(sig);
 220         return xcheck_labels_profiles(sender, target, aa_signal_cross_perm,
 221                                       &sa);
 222 }