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 /* assumes check for PROFILE_MEDIATES is already done */
  68 /* TODO: conditionals */
  69 static int profile_ptrace_perm(struct aa_profile *profile,
  70                              struct aa_label *peer, u32 request,
  71                              struct common_audit_data *sa)
  72 {
  73         struct aa_perms perms = { };
  74
  75         aad(sa)->peer = peer;
  76         aa_profile_match_label(profile, peer, AA_CLASS_PTRACE, request,
  77                                &perms);
  78         aa_apply_modes_to_perms(profile, &perms);
  79         return aa_check_perms(profile, &perms, request, sa, audit_ptrace_cb);
  80 }
  81
  82 static int profile_tracee_perm(struct aa_profile *tracee,
  83                                struct aa_label *tracer, u32 request,
  84                                struct common_audit_data *sa)
  85 {
  86         if (profile_unconfined(tracee) || unconfined(tracer) ||
  87             !PROFILE_MEDIATES(tracee, AA_CLASS_PTRACE))
  88                 return 0;
  89
  90         return profile_ptrace_perm(tracee, tracer, request, sa);
  91 }
  92
  93 static int profile_tracer_perm(struct aa_profile *tracer,
  94                                struct aa_label *tracee, u32 request,
  95                                struct common_audit_data *sa)
  96 {
  97         if (profile_unconfined(tracer))
  98                 return 0;
  99
 100         if (PROFILE_MEDIATES(tracer, AA_CLASS_PTRACE))
 101                 return profile_ptrace_perm(tracer, tracee, request, sa);
 102
 103         /* profile uses the old style capability check for ptrace */
 104         if (&tracer->label == tracee)
 105                 return 0;
 106
 107         aad(sa)->label = &tracer->label;
 108         aad(sa)->peer = tracee;
 109         aad(sa)->request = 0;
 110         aad(sa)->error = aa_capable(&tracer->label, CAP_SYS_PTRACE, 1);
 111
 112         return aa_audit(AUDIT_APPARMOR_AUTO, tracer, sa, audit_ptrace_cb);
 113 }
 114
 115 /**
 116  * aa_may_ptrace - test if tracer task can trace the tracee
 117  * @tracer: label of the task doing the tracing  (NOT NULL)
 118  * @tracee: task label to be traced
 119  * @request: permission request
 120  *
 121  * Returns: %0 else error code if permission denied or error
 122  */
 123 int aa_may_ptrace(struct aa_label *tracer, struct aa_label *tracee,
 124                   u32 request)
 125 {
 126         struct aa_profile *profile;
 127         u32 xrequest = request << PTRACE_PERM_SHIFT;
 128         DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_PTRACE);
 129
 130         return xcheck_labels(tracer, tracee, profile,
 131                         profile_tracer_perm(profile, tracee, request, &sa),
 132                         profile_tracee_perm(profile, tracer, xrequest, &sa));
 133 }
 134
 135
 136 static inline int map_signal_num(int sig)
 137 {
 138         if (sig > SIGRTMAX)
 139                 return SIGUNKNOWN;
 140         else if (sig >= SIGRTMIN)
 141                 return sig - SIGRTMIN + 128;    /* rt sigs mapped to 128 */
 142         else if (sig < MAXMAPPED_SIG)
 143                 return sig_map[sig];
 144         return SIGUNKNOWN;
 145 }
 146
 147 /**
 148  * audit_file_mask - convert mask to permission string
 149  * @buffer: buffer to write string to (NOT NULL)
 150  * @mask: permission mask to convert
 151  */
 152 static void audit_signal_mask(struct audit_buffer *ab, u32 mask)
 153 {
 154         if (mask & MAY_READ)
 155                 audit_log_string(ab, "receive");
 156         if (mask & MAY_WRITE)
 157                 audit_log_string(ab, "send");
 158 }
 159
 160 /**
 161  * audit_cb - call back for signal specific audit fields
 162  * @ab: audit_buffer  (NOT NULL)
 163  * @va: audit struct to audit values of  (NOT NULL)
 164  */
 165 static void audit_signal_cb(struct audit_buffer *ab, void *va)
 166 {
 167         struct common_audit_data *sa = va;
 168
 169         if (aad(sa)->request & AA_SIGNAL_PERM_MASK) {
 170                 audit_log_format(ab, " requested_mask=");
 171                 audit_signal_mask(ab, aad(sa)->request);
 172                 if (aad(sa)->denied & AA_SIGNAL_PERM_MASK) {
 173                         audit_log_format(ab, " denied_mask=");
 174                         audit_signal_mask(ab, aad(sa)->denied);
 175                 }
 176         }
 177         if (aad(sa)->signal < MAXMAPPED_SIG)
 178                 audit_log_format(ab, " signal=%s", sig_names[aad(sa)->signal]);
 179         else
 180                 audit_log_format(ab, " signal=rtmin+%d",
 181                                  aad(sa)->signal - 128);
 182         audit_log_format(ab, " peer=");
 183         aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
 184                         FLAGS_NONE, GFP_ATOMIC);
 185 }
 186
 187 /* TODO: update to handle compound name&name2, conditionals */
 188 static void profile_match_signal(struct aa_profile *profile, const char *label,
 189                                  int signal, struct aa_perms *perms)
 190 {
 191         unsigned int state;
 192
 193         /* TODO: secondary cache check <profile, profile, perm> */
 194         state = aa_dfa_next(profile->policy.dfa,
 195                             profile->policy.start[AA_CLASS_SIGNAL],
 196                             signal);
 197         state = aa_dfa_match(profile->policy.dfa, state, label);
 198         aa_compute_perms(profile->policy.dfa, state, perms);
 199 }
 200
 201 static int profile_signal_perm(struct aa_profile *profile,
 202                                struct aa_profile *peer, u32 request,
 203                                struct common_audit_data *sa)
 204 {
 205         struct aa_perms perms;
 206
 207         if (profile_unconfined(profile) ||
 208             !PROFILE_MEDIATES(profile, AA_CLASS_SIGNAL))
 209                 return 0;
 210
 211         aad(sa)->peer = &peer->label;
 212         profile_match_signal(profile, peer->base.hname, aad(sa)->signal,
 213                              &perms);
 214         aa_apply_modes_to_perms(profile, &perms);
 215         return aa_check_perms(profile, &perms, request, sa, audit_signal_cb);
 216 }
 217
 218 static int aa_signal_cross_perm(struct aa_profile *sender,
 219                                 struct aa_profile *target,
 220                                 struct common_audit_data *sa)
 221 {
 222         return xcheck(profile_signal_perm(sender, target, MAY_WRITE, sa),
 223                       profile_signal_perm(target, sender, MAY_READ, sa));
 224 }
 225
 226 int aa_may_signal(struct aa_label *sender, struct aa_label *target, int sig)
 227 {
 228         DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_SIGNAL);
 229
 230         aad(&sa)->signal = map_signal_num(sig);
 231         return xcheck_labels_profiles(sender, target, aa_signal_cross_perm,
 232                                       &sa);
 233 }