/*
 *  Copyright (C) 2007
 *
 *  Author: Eric Biederman <ebiederm@xmision.com>
 *
 *  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/module.h>
#include <linux/ipc.h>
#include <linux/nsproxy.h>
#include <linux/sysctl.h>
#include <linux/uaccess.h>
#include <linux/ipc_namespace.h>
#include <linux/msg.h>
#include "util.h"

static void *get_ipc(ctl_table *table)
{
        char *which = table->data;
        struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
        which = (which - (char *)&init_ipc_ns) + (char *)ipc_ns;
        return which;
}

/*
 * Routine that is called when the file "auto_msgmni" has successfully been
 * written.
 * Two values are allowed:
 * 0: unregister msgmni's callback routine from the ipc namespace notifier
 *    chain. This means that msgmni won't be recomputed anymore upon memory
 *    add/remove or ipc namespace creation/removal.
 * 1: register back the callback routine.
 */
static void ipc_auto_callback(int val)
{
        if (!val)
                unregister_ipcns_notifier(current->nsproxy->ipc_ns);
        else {
                /*
                 * Re-enable automatic recomputing only if not already
                 * enabled.
                 */
                recompute_msgmni(current->nsproxy->ipc_ns);
                cond_register_ipcns_notifier(current->nsproxy->ipc_ns);
        }
}

#ifdef CONFIG_PROC_FS
static int proc_ipc_dointvec(ctl_table *table, int write, struct file *filp,
        void __user *buffer, size_t *lenp, loff_t *ppos)
{
        struct ctl_table ipc_table;
        memcpy(&ipc_table, table, sizeof(ipc_table));
        ipc_table.data = get_ipc(table);

        return proc_dointvec(&ipc_table, write, filp, buffer, lenp, ppos);
}

static int proc_ipc_callback_dointvec(ctl_table *table, int write,
        struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)
{
        struct ctl_table ipc_table;
        size_t lenp_bef = *lenp;
        int rc;

        memcpy(&ipc_table, table, sizeof(ipc_table));
        ipc_table.data = get_ipc(table);

        rc = proc_dointvec(&ipc_table, write, filp, buffer, lenp, ppos);

        if (write && !rc && lenp_bef == *lenp)
                /*
                 * Tunable has successfully been changed by hand. Disable its
                 * automatic adjustment. This simply requires unregistering
                 * the notifiers that trigger recalculation.
                 */
                unregister_ipcns_notifier(current->nsproxy->ipc_ns);

        return rc;
}

static int proc_ipc_doulongvec_minmax(ctl_table *table, int write,
        struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)
{
        struct ctl_table ipc_table;
        memcpy(&ipc_table, table, sizeof(ipc_table));
        ipc_table.data = get_ipc(table);

        return proc_doulongvec_minmax(&ipc_table, write, filp, buffer,
                                        lenp, ppos);
}

static int proc_ipcauto_dointvec_minmax(ctl_table *table, int write,
        struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos)
{
        struct ctl_table ipc_table;
        size_t lenp_bef = *lenp;
        int oldval;
        int rc;

        memcpy(&ipc_table, table, sizeof(ipc_table));
        ipc_table.data = get_ipc(table);
        oldval = *((int *)(ipc_table.data));

        rc = proc_dointvec_minmax(&ipc_table, write, filp, buffer, lenp, ppos);

        if (write && !rc && lenp_bef == *lenp) {
                int newval = *((int *)(ipc_table.data));
                /*
                 * The file "auto_msgmni" has correctly been set.
                 * React by (un)registering the corresponding tunable, if the
                 * value has changed.
                 */
                if (newval != oldval)
                        ipc_auto_callback(newval);
        }

        return rc;
}

#else
#define proc_ipc_doulongvec_minmax NULL
#define proc_ipc_dointvec          NULL
#define proc_ipc_callback_dointvec NULL
#define proc_ipcauto_dointvec_minmax NULL
#endif

#ifdef CONFIG_SYSCTL_SYSCALL
/* The generic sysctl ipc data routine. */
static int sysctl_ipc_data(ctl_table *table, int __user *name, int nlen,
                void __user *oldval, size_t __user *oldlenp,
                void __user *newval, size_t newlen)
{
        size_t len;
        void *data;

        /* Get out of I don't have a variable */
        if (!table->data || !table->maxlen)
                return -ENOTDIR;

        data = get_ipc(table);
        if (!data)
                return -ENOTDIR;

        if (oldval && oldlenp) {
                if (get_user(len, oldlenp))
                        return -EFAULT;
                if (len) {
                        if (len > table->maxlen)
                                len = table->maxlen;
                        if (copy_to_user(oldval, data, len))
                                return -EFAULT;
                        if (put_user(len, oldlenp))
                                return -EFAULT;
                }
        }

        if (newval && newlen) {
                if (newlen > table->maxlen)
                        newlen = table->maxlen;

                if (copy_from_user(data, newval, newlen))
                        return -EFAULT;
        }
        return 1;
}

static int sysctl_ipc_registered_data(ctl_table *table, int __user *name,
                int nlen, void __user *oldval, size_t __user *oldlenp,
                void __user *newval, size_t newlen)
{
        int rc;

        rc = sysctl_ipc_data(table, name, nlen, oldval, oldlenp, newval,
                newlen);

        if (newval && newlen && rc > 0)
                /*
                 * Tunable has successfully been changed from userland
                 */
                unregister_ipcns_notifier(current->nsproxy->ipc_ns);

        return rc;
}
#else
#define sysctl_ipc_data NULL
#define sysctl_ipc_registered_data NULL
#endif

static int zero;
static int one = 1;

static struct ctl_table ipc_kern_table[] = {
        {
                .ctl_name       = KERN_SHMMAX,
                .procname       = "shmmax",
                .data           = &init_ipc_ns.shm_ctlmax,
                .maxlen         = sizeof (init_ipc_ns.shm_ctlmax),
                .mode           = 0644,
                .proc_handler   = proc_ipc_doulongvec_minmax,
                .strategy       = sysctl_ipc_data,
        },
        {
                .ctl_name       = KERN_SHMALL,
                .procname       = "shmall",
                .data           = &init_ipc_ns.shm_ctlall,
                .maxlen         = sizeof (init_ipc_ns.shm_ctlall),
                .mode           = 0644,
                .proc_handler   = proc_ipc_doulongvec_minmax,
                .strategy       = sysctl_ipc_data,
        },
        {
                .ctl_name       = KERN_SHMMNI,
                .procname       = "shmmni",
                .data           = &init_ipc_ns.shm_ctlmni,
                .maxlen         = sizeof (init_ipc_ns.shm_ctlmni),
                .mode           = 0644,
                .proc_handler   = proc_ipc_dointvec,
                .strategy       = sysctl_ipc_data,
        },
        {
                .ctl_name       = KERN_MSGMAX,
                .procname       = "msgmax",
                .data           = &init_ipc_ns.msg_ctlmax,
                .maxlen         = sizeof (init_ipc_ns.msg_ctlmax),
                .mode           = 0644,
                .proc_handler   = proc_ipc_dointvec,
                .strategy       = sysctl_ipc_data,
        },
        {
                .ctl_name       = KERN_MSGMNI,
                .procname       = "msgmni",
                .data           = &init_ipc_ns.msg_ctlmni,
                .maxlen         = sizeof (init_ipc_ns.msg_ctlmni),
                .mode           = 0644,
                .proc_handler   = proc_ipc_callback_dointvec,
                .strategy       = sysctl_ipc_registered_data,
        },
        {
                .ctl_name       = KERN_MSGMNB,
                .procname       =  "msgmnb",
                .data           = &init_ipc_ns.msg_ctlmnb,
                .maxlen         = sizeof (init_ipc_ns.msg_ctlmnb),
                .mode           = 0644,
                .proc_handler   = proc_ipc_dointvec,
                .strategy       = sysctl_ipc_data,
        },
        {
                .ctl_name       = KERN_SEM,
                .procname       = "sem",
                .data           = &init_ipc_ns.sem_ctls,
                .maxlen         = 4*sizeof (int),
                .mode           = 0644,
                .proc_handler   = proc_ipc_dointvec,
                .strategy       = sysctl_ipc_data,
        },
        {
                .ctl_name       = CTL_UNNUMBERED,
                .procname       = "auto_msgmni",
                .data           = &init_ipc_ns.auto_msgmni,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = proc_ipcauto_dointvec_minmax,
                .extra1         = &zero,
                .extra2         = &one,
        },
        {}
};

static struct ctl_table ipc_root_table[] = {
        {
                .ctl_name       = CTL_KERN,
                .procname       = "kernel",
                .mode           = 0555,
                .child          = ipc_kern_table,
        },
        {}
};

static int __init ipc_sysctl_init(void)
{
        register_sysctl_table(ipc_root_table);
        return 0;
}

__initcall(ipc_sysctl_init);