// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *
 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
 */

#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <net/ax25.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <linux/uaccess.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/notifier.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/stat.h>
#include <linux/sysctl.h>
#include <linux/export.h>
#include <net/ip.h>
#include <net/arp.h>

/*
 *      Callsign/UID mapper. This is in kernel space for security on multi-amateur machines.
 */

static HLIST_HEAD(ax25_uid_list);
static DEFINE_RWLOCK(ax25_uid_lock);

int ax25_uid_policy;

EXPORT_SYMBOL(ax25_uid_policy);

ax25_uid_assoc *ax25_findbyuid(kuid_t uid)
{
        ax25_uid_assoc *ax25_uid, *res = NULL;

        read_lock(&ax25_uid_lock);
        ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
                if (uid_eq(ax25_uid->uid, uid)) {
                        ax25_uid_hold(ax25_uid);
                        res = ax25_uid;
                        break;
                }
        }
        read_unlock(&ax25_uid_lock);

        return res;
}

EXPORT_SYMBOL(ax25_findbyuid);

int ax25_uid_ioctl(int cmd, struct sockaddr_ax25 *sax)
{
        ax25_uid_assoc *ax25_uid;
        ax25_uid_assoc *user;
        unsigned long res;

        switch (cmd) {
        case SIOCAX25GETUID:
                res = -ENOENT;
                read_lock(&ax25_uid_lock);
                ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
                        if (ax25cmp(&sax->sax25_call, &ax25_uid->call) == 0) {
                                res = from_kuid_munged(current_user_ns(), ax25_uid->uid);
                                break;
                        }
                }
                read_unlock(&ax25_uid_lock);

                return res;

        case SIOCAX25ADDUID:
        {
                kuid_t sax25_kuid;
                if (!capable(CAP_NET_ADMIN))
                        return -EPERM;
                sax25_kuid = make_kuid(current_user_ns(), sax->sax25_uid);
                if (!uid_valid(sax25_kuid))
                        return -EINVAL;
                user = ax25_findbyuid(sax25_kuid);
                if (user) {
                        ax25_uid_put(user);
                        return -EEXIST;
                }
                if (sax->sax25_uid == 0)
                        return -EINVAL;
                if ((ax25_uid = kmalloc_obj(*ax25_uid)) == NULL)
                        return -ENOMEM;

                refcount_set(&ax25_uid->refcount, 1);
                ax25_uid->uid  = sax25_kuid;
                ax25_uid->call = sax->sax25_call;

                write_lock(&ax25_uid_lock);
                hlist_add_head(&ax25_uid->uid_node, &ax25_uid_list);
                write_unlock(&ax25_uid_lock);

                return 0;
        }
        case SIOCAX25DELUID:
                if (!capable(CAP_NET_ADMIN))
                        return -EPERM;

                ax25_uid = NULL;
                write_lock(&ax25_uid_lock);
                ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
                        if (ax25cmp(&sax->sax25_call, &ax25_uid->call) == 0)
                                break;
                }
                if (ax25_uid == NULL) {
                        write_unlock(&ax25_uid_lock);
                        return -ENOENT;
                }
                hlist_del_init(&ax25_uid->uid_node);
                ax25_uid_put(ax25_uid);
                write_unlock(&ax25_uid_lock);

                return 0;

        default:
                return -EINVAL;
        }

        return -EINVAL; /*NOTREACHED */
}

#ifdef CONFIG_PROC_FS

static void *ax25_uid_seq_start(struct seq_file *seq, loff_t *pos)
        __acquires(ax25_uid_lock)
{
        read_lock(&ax25_uid_lock);
        return seq_hlist_start_head(&ax25_uid_list, *pos);
}

static void *ax25_uid_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
        return seq_hlist_next(v, &ax25_uid_list, pos);
}

static void ax25_uid_seq_stop(struct seq_file *seq, void *v)
        __releases(ax25_uid_lock)
{
        read_unlock(&ax25_uid_lock);
}

static int ax25_uid_seq_show(struct seq_file *seq, void *v)
{
        char buf[11];

        if (v == SEQ_START_TOKEN)
                seq_printf(seq, "Policy: %d\n", ax25_uid_policy);
        else {
                struct ax25_uid_assoc *pt;

                pt = hlist_entry(v, struct ax25_uid_assoc, uid_node);
                seq_printf(seq, "%6d %s\n",
                        from_kuid_munged(seq_user_ns(seq), pt->uid),
                        ax2asc(buf, &pt->call));
        }
        return 0;
}

const struct seq_operations ax25_uid_seqops = {
        .start = ax25_uid_seq_start,
        .next = ax25_uid_seq_next,
        .stop = ax25_uid_seq_stop,
        .show = ax25_uid_seq_show,
};
#endif

/*
 *      Free all memory associated with UID/Callsign structures.
 */
void __exit ax25_uid_free(void)
{
        ax25_uid_assoc *ax25_uid;

        write_lock(&ax25_uid_lock);
again:
        ax25_uid_for_each(ax25_uid, &ax25_uid_list) {
                hlist_del_init(&ax25_uid->uid_node);
                ax25_uid_put(ax25_uid);
                goto again;
        }
        write_unlock(&ax25_uid_lock);
}