// SPDX-License-Identifier: GPL-2.0-only
/*
 * AppArmor security module
 *
 * This file contains AppArmor ipc mediation
 *
 * Copyright (C) 1998-2008 Novell/SUSE
 * Copyright 2009-2017 Canonical Ltd.
 */

#include <linux/gfp.h>

#include "include/audit.h"
#include "include/capability.h"
#include "include/cred.h"
#include "include/policy.h"
#include "include/ipc.h"
#include "include/sig_names.h"


static inline int map_signal_num(int sig)
{
        if (sig > SIGRTMAX)
                return SIGUNKNOWN;
        else if (sig >= SIGRTMIN)
                return sig - SIGRTMIN + SIGRT_BASE;
        else if (sig < MAXMAPPED_SIG)
                return sig_map[sig];
        return SIGUNKNOWN;
}

/**
 * audit_signal_mask - convert mask to permission string
 * @mask: permission mask to convert
 *
 * Returns: pointer to static string
 */
static const char *audit_signal_mask(u32 mask)
{
        if (mask & MAY_READ)
                return "receive";
        if (mask & MAY_WRITE)
                return "send";
        return "";
}

/**
 * audit_signal_cb() - call back for signal specific audit fields
 * @ab: audit_buffer  (NOT NULL)
 * @va: audit struct to audit values of  (NOT NULL)
 */
static void audit_signal_cb(struct audit_buffer *ab, void *va)
{
        struct common_audit_data *sa = va;
        struct apparmor_audit_data *ad = aad(sa);

        if (ad->request & AA_SIGNAL_PERM_MASK) {
                audit_log_format(ab, " requested_mask=\"%s\"",
                                 audit_signal_mask(ad->request));
                if (ad->denied & AA_SIGNAL_PERM_MASK) {
                        audit_log_format(ab, " denied_mask=\"%s\"",
                                         audit_signal_mask(ad->denied));
                }
        }
        if (ad->signal == SIGUNKNOWN)
                audit_log_format(ab, "signal=unknown(%d)",
                                 ad->unmappedsig);
        else if (ad->signal < MAXMAPPED_SIGNAME)
                audit_log_format(ab, " signal=%s", sig_names[ad->signal]);
        else
                audit_log_format(ab, " signal=rtmin+%d",
                                 ad->signal - SIGRT_BASE);
        audit_log_format(ab, " peer=");
        aa_label_xaudit(ab, labels_ns(ad->subj_label), ad->peer,
                        FLAGS_NONE, GFP_ATOMIC);
}

static int profile_signal_perm(const struct cred *cred,
                               struct aa_profile *profile,
                               struct aa_label *peer, u32 request,
                               struct apparmor_audit_data *ad)
{
        struct aa_ruleset *rules = profile->label.rules[0];
        struct aa_perms perms;
        aa_state_t state;

        if (profile_unconfined(profile))
                return 0;

        ad->subj_cred = cred;
        ad->peer = peer;
        /* TODO: secondary cache check <profile, profile, perm> */
        state = RULE_MEDIATES(rules, AA_CLASS_SIGNAL);
        if (!state)
                return 0;
        state = aa_dfa_next(rules->policy->dfa, state, ad->signal);
        aa_label_match(profile, rules, peer, state, false, request, &perms);
        aa_apply_modes_to_perms(profile, &perms);
        return aa_check_perms(profile, &perms, request, ad, audit_signal_cb);
}

int aa_may_signal(const struct cred *subj_cred, struct aa_label *sender,
                  const struct cred *target_cred, struct aa_label *target,
                  int sig)
{
        struct aa_profile *profile;
        DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_NONE, AA_CLASS_SIGNAL, OP_SIGNAL);

        ad.signal = map_signal_num(sig);
        ad.unmappedsig = sig;
        return xcheck_labels(sender, target, profile,
                             profile_signal_perm(subj_cred, profile, target,
                                                 MAY_WRITE, &ad),
                             profile_signal_perm(target_cred, profile, sender,
                                                 MAY_READ, &ad));
}