/*
 * AppArmor security module
 *
 * This file contains AppArmor ipc mediation
 *
 * Copyright (C) 1998-2008 Novell/SUSE
 * Copyright 2009-2017 Canonical Ltd.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, version 2 of the
 * License.
 */

#include <linux/gfp.h>
#include <linux/ptrace.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"

/**
 * audit_ptrace_mask - convert mask to permission string
 * @buffer: buffer to write string to (NOT NULL)
 * @mask: permission mask to convert
 */
static void audit_ptrace_mask(struct audit_buffer *ab, u32 mask)
{
        switch (mask) {
        case MAY_READ:
                audit_log_string(ab, "read");
                break;
        case MAY_WRITE:
                audit_log_string(ab, "trace");
                break;
        case AA_MAY_BE_READ:
                audit_log_string(ab, "readby");
                break;
        case AA_MAY_BE_TRACED:
                audit_log_string(ab, "tracedby");
                break;
        }
}

/* call back to audit ptrace fields */
static void audit_ptrace_cb(struct audit_buffer *ab, void *va)
{
        struct common_audit_data *sa = va;

        if (aad(sa)->request & AA_PTRACE_PERM_MASK) {
                audit_log_format(ab, " requested_mask=");
                audit_ptrace_mask(ab, aad(sa)->request);

                if (aad(sa)->denied & AA_PTRACE_PERM_MASK) {
                        audit_log_format(ab, " denied_mask=");
                        audit_ptrace_mask(ab, aad(sa)->denied);
                }
        }
        audit_log_format(ab, " peer=");
        aa_label_xaudit(ab, labels_ns(aad(sa)->label), aad(sa)->peer,
                        FLAGS_NONE, GFP_ATOMIC);
}

/* assumes check for PROFILE_MEDIATES is already done */
/* TODO: conditionals */
static int profile_ptrace_perm(struct aa_profile *profile,
                             struct aa_label *peer, u32 request,
                             struct common_audit_data *sa)
{
        struct aa_perms perms = { };

        aad(sa)->peer = peer;
        aa_profile_match_label(profile, peer, AA_CLASS_PTRACE, request,
                               &perms);
        aa_apply_modes_to_perms(profile, &perms);
        return aa_check_perms(profile, &perms, request, sa, audit_ptrace_cb);
}

static int profile_tracee_perm(struct aa_profile *tracee,
                               struct aa_label *tracer, u32 request,
                               struct common_audit_data *sa)
{
        if (profile_unconfined(tracee) || unconfined(tracer) ||
            !PROFILE_MEDIATES(tracee, AA_CLASS_PTRACE))
                return 0;

        return profile_ptrace_perm(tracee, tracer, request, sa);
}

static int profile_tracer_perm(struct aa_profile *tracer,
                               struct aa_label *tracee, u32 request,
                               struct common_audit_data *sa)
{
        if (profile_unconfined(tracer))
                return 0;

        if (PROFILE_MEDIATES(tracer, AA_CLASS_PTRACE))
                return profile_ptrace_perm(tracer, tracee, request, sa);

        /* profile uses the old style capability check for ptrace */
        if (&tracer->label == tracee)
                return 0;

        aad(sa)->label = &tracer->label;
        aad(sa)->peer = tracee;
        aad(sa)->request = 0;
        aad(sa)->error = aa_capable(&tracer->label, CAP_SYS_PTRACE, 1);

        return aa_audit(AUDIT_APPARMOR_AUTO, tracer, sa, audit_ptrace_cb);
}

/**
 * aa_may_ptrace - test if tracer task can trace the tracee
 * @tracer: label of the task doing the tracing  (NOT NULL)
 * @tracee: task label to be traced
 * @request: permission request
 *
 * Returns: %0 else error code if permission denied or error
 */
int aa_may_ptrace(struct aa_label *tracer, struct aa_label *tracee,
                  u32 request)
{
        struct aa_profile *profile;
        u32 xrequest = request << PTRACE_PERM_SHIFT;
        DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_PTRACE);

        return xcheck_labels(tracer, tracee, profile,
                        profile_tracer_perm(profile, tracee, request, &sa),
                        profile_tracee_perm(profile, tracer, xrequest, &sa));
}


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_file_mask - convert mask to permission string
 * @buffer: buffer to write string to (NOT NULL)
 * @mask: permission mask to convert
 */
static void audit_signal_mask(struct audit_buffer *ab, u32 mask)
{
        if (mask & MAY_READ)
                audit_log_string(ab, "receive");
        if (mask & MAY_WRITE)
                audit_log_string(ab, "send");
}

/**
 * audit_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;

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

static int profile_signal_perm(struct aa_profile *profile,
                               struct aa_label *peer, u32 request,
                               struct common_audit_data *sa)
{
        struct aa_perms perms;
        unsigned int state;

        if (profile_unconfined(profile) ||
            !PROFILE_MEDIATES(profile, AA_CLASS_SIGNAL))
                return 0;

        aad(sa)->peer = peer;
        /* TODO: secondary cache check <profile, profile, perm> */
        state = aa_dfa_next(profile->policy.dfa,
                            profile->policy.start[AA_CLASS_SIGNAL],
                            aad(sa)->signal);
        aa_label_match(profile, peer, state, false, request, &perms);
        aa_apply_modes_to_perms(profile, &perms);
        return aa_check_perms(profile, &perms, request, sa, audit_signal_cb);
}

int aa_may_signal(struct aa_label *sender, struct aa_label *target, int sig)
{
        struct aa_profile *profile;
        DEFINE_AUDIT_DATA(sa, LSM_AUDIT_DATA_NONE, OP_SIGNAL);

        aad(&sa)->signal = map_signal_num(sig);
        aad(&sa)->unmappedsig = sig;
        return xcheck_labels(sender, target, profile,
                        profile_signal_perm(profile, target, MAY_WRITE, &sa),
                        profile_signal_perm(profile, sender, MAY_READ, &sa));
}