// SPDX-License-Identifier: GPL-2.0-only
/*
 * AppArmor security module
 *
 * This file contains AppArmor resource mediation and attachment
 *
 * Copyright (C) 1998-2008 Novell/SUSE
 * Copyright 2009-2010 Canonical Ltd.
 */

#include <linux/audit.h>
#include <linux/security.h>

#include "include/audit.h"
#include "include/cred.h"
#include "include/resource.h"
#include "include/policy.h"

/*
 * Table of rlimit names: we generate it from resource.h.
 */
#include "rlim_names.h"

struct aa_sfs_entry aa_sfs_entry_rlimit[] = {
        AA_SFS_FILE_STRING("mask", AA_SFS_RLIMIT_MASK),
        { }
};

/* audit callback for resource specific fields */
static void audit_cb(struct audit_buffer *ab, void *va)
{
        struct common_audit_data *sa = va;
        struct apparmor_audit_data *ad = aad(sa);

        audit_log_format(ab, " rlimit=%s value=%lu",
                         rlim_names[ad->rlim.rlim], ad->rlim.max);
        if (ad->peer) {
                audit_log_format(ab, " peer=");
                aa_label_xaudit(ab, labels_ns(ad->subj_label), ad->peer,
                                FLAGS_NONE, GFP_ATOMIC);
        }
}

/**
 * audit_resource - audit setting resource limit
 * @subj_cred: cred setting the resource
 * @profile: profile being enforced  (NOT NULL)
 * @resource: rlimit being auditing
 * @value: value being set
 * @peer: aa_albel of the task being set
 * @info: info being auditing
 * @error: error value
 *
 * Returns: 0 or ad->error else other error code on failure
 */
static int audit_resource(const struct cred *subj_cred,
                          struct aa_profile *profile, unsigned int resource,
                          unsigned long value, struct aa_label *peer,
                          const char *info, int error)
{
        DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_NONE, AA_CLASS_RLIMITS,
                          OP_SETRLIMIT);

        ad.subj_cred = subj_cred;
        ad.rlim.rlim = resource;
        ad.rlim.max = value;
        ad.peer = peer;
        ad.info = info;
        ad.error = error;

        return aa_audit(AUDIT_APPARMOR_AUTO, profile, &ad, audit_cb);
}

/**
 * aa_map_resource - map compiled policy resource to internal #
 * @resource: flattened policy resource number
 *
 * Returns: resource # for the current architecture.
 *
 * rlimit resource can vary based on architecture, map the compiled policy
 * resource # to the internal representation for the architecture.
 */
int aa_map_resource(int resource)
{
        return rlim_map[resource];
}

static int profile_setrlimit(const struct cred *subj_cred,
                             struct aa_profile *profile, unsigned int resource,
                             struct rlimit *new_rlim)
{
        struct aa_ruleset *rules = profile->label.rules[0];
        int e = 0;

        if (rules->rlimits.mask & (1 << resource) && new_rlim->rlim_max >
            rules->rlimits.limits[resource].rlim_max)
                e = -EACCES;
        return audit_resource(subj_cred, profile, resource, new_rlim->rlim_max,
                              NULL, NULL, e);
}

/**
 * aa_task_setrlimit - test permission to set an rlimit
 * @subj_cred: cred setting the limit
 * @label: label confining the task  (NOT NULL)
 * @task: task the resource is being set on
 * @resource: the resource being set
 * @new_rlim: the new resource limit  (NOT NULL)
 *
 * Control raising the processes hard limit.
 *
 * Returns: 0 or error code if setting resource failed
 */
int aa_task_setrlimit(const struct cred *subj_cred, struct aa_label *label,
                      struct task_struct *task,
                      unsigned int resource, struct rlimit *new_rlim)
{
        struct aa_profile *profile;
        struct aa_label *peer;
        int error = 0;

        rcu_read_lock();
        peer = aa_get_newest_cred_label(__task_cred(task));
        rcu_read_unlock();

        /* TODO: extend resource control to handle other (non current)
         * profiles.  AppArmor rules currently have the implicit assumption
         * that the task is setting the resource of a task confined with
         * the same profile or that the task setting the resource of another
         * task has CAP_SYS_RESOURCE.
         */

        if (label != peer &&
            aa_capable(subj_cred, label, CAP_SYS_RESOURCE, CAP_OPT_NOAUDIT) != 0)
                error = fn_for_each(label, profile,
                                audit_resource(subj_cred, profile, resource,
                                               new_rlim->rlim_max, peer,
                                               "cap_sys_resource", -EACCES));
        else
                error = fn_for_each_confined(label, profile,
                                profile_setrlimit(subj_cred, profile, resource,
                                                  new_rlim));
        aa_put_label(peer);

        return error;
}

/**
 * __aa_transition_rlimits - apply new profile rlimits
 * @old_l: old label on task  (NOT NULL)
 * @new_l: new label with rlimits to apply  (NOT NULL)
 */
void __aa_transition_rlimits(struct aa_label *old_l, struct aa_label *new_l)
{
        unsigned int mask = 0;
        struct rlimit *rlim, *initrlim;
        struct aa_profile *old, *new;
        struct label_it i;

        old = labels_profile(old_l);
        new = labels_profile(new_l);

        /* for any rlimits the profile controlled, reset the soft limit
         * to the lesser of the tasks hard limit and the init tasks soft limit
         */
        label_for_each_confined(i, old_l, old) {
                struct aa_ruleset *rules = old->label.rules[0];
                if (rules->rlimits.mask) {
                        int j;

                        for (j = 0, mask = 1; j < RLIM_NLIMITS; j++,
                                     mask <<= 1) {
                                if (rules->rlimits.mask & mask) {
                                        rlim = current->signal->rlim + j;
                                        initrlim = init_task.signal->rlim + j;
                                        rlim->rlim_cur = min(rlim->rlim_max,
                                                            initrlim->rlim_cur);
                                }
                        }
                }
        }

        /* set any new hard limits as dictated by the new profile */
        label_for_each_confined(i, new_l, new) {
                struct aa_ruleset *rules = new->label.rules[0];
                int j;

                if (!rules->rlimits.mask)
                        continue;
                for (j = 0, mask = 1; j < RLIM_NLIMITS; j++, mask <<= 1) {
                        if (!(rules->rlimits.mask & mask))
                                continue;

                        rlim = current->signal->rlim + j;
                        rlim->rlim_max = min(rlim->rlim_max,
                                             rules->rlimits.limits[j].rlim_max);
                        /* soft limit should not exceed hard limit */
                        rlim->rlim_cur = min(rlim->rlim_cur, rlim->rlim_max);
                        if (j == RLIMIT_CPU &&
                            rlim->rlim_cur != RLIM_INFINITY &&
                            IS_ENABLED(CONFIG_POSIX_TIMERS))
                                (void) update_rlimit_cpu(current->group_leader,
                                                         rlim->rlim_cur);
                }
        }
}