security/apparmor/ipc.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * AppArmor security module
   4  *
   5  * This file contains AppArmor ipc mediation
   6  *
   7  * Copyright (C) 1998-2008 Novell/SUSE
   8  * Copyright 2009-2017 Canonical Ltd.
   9  */
  10
  11 #include <linux/gfp.h>
  12
  13 #include "include/audit.h"
  14 #include "include/capability.h"
  15 #include "include/cred.h"
  16 #include "include/policy.h"
  17 #include "include/ipc.h"
  18 #include "include/sig_names.h"
  19
  20
  21 static inline int map_signal_num(int sig)
  22 {
  23         if (sig > SIGRTMAX)
  24                 return SIGUNKNOWN;
  25         else if (sig >= SIGRTMIN)
  26                 return sig - SIGRTMIN + SIGRT_BASE;
  27         else if (sig < MAXMAPPED_SIG)
  28                 return sig_map[sig];
  29         return SIGUNKNOWN;
  30 }
  31
  32 /**
  33  * audit_signal_mask - convert mask to permission string
  34  * @mask: permission mask to convert
  35  *
  36  * Returns: pointer to static string
  37  */
  38 static const char *audit_signal_mask(u32 mask)
  39 {
  40         if (mask & MAY_READ)
  41                 return "receive";
  42         if (mask & MAY_WRITE)
  43                 return "send";
  44         return "";
  45 }
  46
  47 /**
  48  * audit_signal_cb() - call back for signal specific audit fields
  49  * @ab: audit_buffer  (NOT NULL)
  50  * @va: audit struct to audit values of  (NOT NULL)
  51  */
  52 static void audit_signal_cb(struct audit_buffer *ab, void *va)
  53 {
  54         struct common_audit_data *sa = va;
  55         struct apparmor_audit_data *ad = aad(sa);
  56
  57         if (ad->request & AA_SIGNAL_PERM_MASK) {
  58                 audit_log_format(ab, " requested_mask=\"%s\"",
  59                                  audit_signal_mask(ad->request));
  60                 if (ad->denied & AA_SIGNAL_PERM_MASK) {
  61                         audit_log_format(ab, " denied_mask=\"%s\"",
  62                                          audit_signal_mask(ad->denied));
  63                 }
  64         }
  65         if (ad->signal == SIGUNKNOWN)
  66                 audit_log_format(ab, "signal=unknown(%d)",
  67                                  ad->unmappedsig);
  68         else if (ad->signal < MAXMAPPED_SIGNAME)
  69                 audit_log_format(ab, " signal=%s", sig_names[ad->signal]);
  70         else
  71                 audit_log_format(ab, " signal=rtmin+%d",
  72                                  ad->signal - SIGRT_BASE);
  73         audit_log_format(ab, " peer=");
  74         aa_label_xaudit(ab, labels_ns(ad->subj_label), ad->peer,
  75                         FLAGS_NONE, GFP_ATOMIC);
  76 }
  77
  78 static int profile_signal_perm(const struct cred *cred,
  79                                struct aa_profile *profile,
  80                                struct aa_label *peer, u32 request,
  81                                struct apparmor_audit_data *ad)
  82 {
  83         struct aa_ruleset *rules = list_first_entry(&profile->rules,
  84                                                     typeof(*rules), list);
  85         struct aa_perms perms;
  86         aa_state_t state;
  87
  88         if (profile_unconfined(profile) ||
  89             !ANY_RULE_MEDIATES(&profile->rules, AA_CLASS_SIGNAL))
  90                 return 0;
  91
  92         ad->subj_cred = cred;
  93         ad->peer = peer;
  94         /* TODO: secondary cache check <profile, profile, perm> */
  95         state = aa_dfa_next(rules->policy->dfa,
  96                             rules->policy->start[AA_CLASS_SIGNAL],
  97                             ad->signal);
  98         aa_label_match(profile, rules, peer, state, false, request, &perms);
  99         aa_apply_modes_to_perms(profile, &perms);
 100         return aa_check_perms(profile, &perms, request, ad, audit_signal_cb);
 101 }
 102
 103 int aa_may_signal(const struct cred *subj_cred, struct aa_label *sender,
 104                   const struct cred *target_cred, struct aa_label *target,
 105                   int sig)
 106 {
 107         struct aa_profile *profile;
 108         DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_NONE, AA_CLASS_SIGNAL, OP_SIGNAL);
 109
 110         ad.signal = map_signal_num(sig);
 111         ad.unmappedsig = sig;
 112         return xcheck_labels(sender, target, profile,
 113                              profile_signal_perm(subj_cred, profile, target,
 114                                                  MAY_WRITE, &ad),
 115                              profile_signal_perm(target_cred, profile, sender,
 116                                                  MAY_READ, &ad));
 117 }