nf_sockopt.c

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#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netfilter.h>
#include <linux/mutex.h>
#include <net/sock.h>

#include "nf_internals.h"

/* Sockopts only registered and called from user context, so
   net locking would be overkill.  Also, [gs]etsockopt calls may
   sleep. */
static DEFINE_MUTEX(nf_sockopt_mutex);
static LIST_HEAD(nf_sockopts);

/* Do exclusive ranges overlap? */
static inline int overlap(int min1, int max1, int min2, int max2)
{
    return max1 > min2 && min1 < max2;
}

/* Functions to register sockopt ranges (exclusive). */
int nf_register_sockopt(struct nf_sockopt_ops *reg)
{
    struct nf_sockopt_ops *ops;
    int ret = 0;

    if (mutex_lock_interruptible(&nf_sockopt_mutex) != 0)
        return -EINTR;

    list_for_each_entry(ops, &nf_sockopts, list) {
        if (ops->pf == reg->pf
            && (overlap(ops->set_optmin, ops->set_optmax,
                reg->set_optmin, reg->set_optmax)
            || overlap(ops->get_optmin, ops->get_optmax,
                   reg->get_optmin, reg->get_optmax))) {
            NFDEBUG("nf_sock overlap: %u-%u/%u-%u v %u-%u/%u-%u\n",
                ops->set_optmin, ops->set_optmax,
                ops->get_optmin, ops->get_optmax,
                reg->set_optmin, reg->set_optmax,
                reg->get_optmin, reg->get_optmax);
            ret = -EBUSY;
            goto out;
        }
    }

    list_add(&reg->list, &nf_sockopts);
out:
    mutex_unlock(&nf_sockopt_mutex);
    return ret;
}
EXPORT_SYMBOL(nf_register_sockopt);

void nf_unregister_sockopt(struct nf_sockopt_ops *reg)
{
    mutex_lock(&nf_sockopt_mutex);
    list_del(&reg->list);
    mutex_unlock(&nf_sockopt_mutex);
}
EXPORT_SYMBOL(nf_unregister_sockopt);

static struct nf_sockopt_ops *nf_sockopt_find(struct sock *sk, u_int8_t pf,
        int val, int get)
{
    struct nf_sockopt_ops *ops;

    if (mutex_lock_interruptible(&nf_sockopt_mutex) != 0)
        return ERR_PTR(-EINTR);

    list_for_each_entry(ops, &nf_sockopts, list) {
        if (ops->pf == pf) {
            if (!try_module_get(ops->owner))
                goto out_nosup;

            if (get) {
                if (val >= ops->get_optmin &&
                        val < ops->get_optmax)
                    goto out;
            } else {
                if (val >= ops->set_optmin &&
                        val < ops->set_optmax)
                    goto out;
            }
            module_put(ops->owner);
        }
    }
out_nosup:
    ops = ERR_PTR(-ENOPROTOOPT);
out:
    mutex_unlock(&nf_sockopt_mutex);
    return ops;
}

/* Call get/setsockopt() */
static int nf_sockopt(struct sock *sk, u_int8_t pf, int val,
              char __user *opt, int *len, int get)
{
    struct nf_sockopt_ops *ops;
    int ret;

    ops = nf_sockopt_find(sk, pf, val, get);
    if (IS_ERR(ops))
        return PTR_ERR(ops);

    if (get)
        ret = ops->get(sk, val, opt, len);
    else
        ret = ops->set(sk, val, opt, *len);

    module_put(ops->owner);
    return ret;
}

int nf_setsockopt(struct sock *sk, u_int8_t pf, int val, char __user *opt,
          unsigned int len)
{
    return nf_sockopt(sk, pf, val, opt, &len, 0);
}
EXPORT_SYMBOL(nf_setsockopt);

int nf_getsockopt(struct sock *sk, u_int8_t pf, int val, char __user *opt,
          int *len)
{
    return nf_sockopt(sk, pf, val, opt, len, 1);
}
EXPORT_SYMBOL(nf_getsockopt);

#ifdef CONFIG_COMPAT
static int compat_nf_sockopt(struct sock *sk, u_int8_t pf, int val,
                 char __user *opt, int *len, int get)
{
    struct nf_sockopt_ops *ops;
    int ret;

    ops = nf_sockopt_find(sk, pf, val, get);
    if (IS_ERR(ops))
        return PTR_ERR(ops);

    if (get) {
        if (ops->compat_get)
            ret = ops->compat_get(sk, val, opt, len);
        else
            ret = ops->get(sk, val, opt, len);
    } else {
        if (ops->compat_set)
            ret = ops->compat_set(sk, val, opt, *len);
        else
            ret = ops->set(sk, val, opt, *len);
    }

    module_put(ops->owner);
    return ret;
}

int compat_nf_setsockopt(struct sock *sk, u_int8_t pf,
        int val, char __user *opt, unsigned int len)
{
    return compat_nf_sockopt(sk, pf, val, opt, &len, 0);
}
EXPORT_SYMBOL(compat_nf_setsockopt);

int compat_nf_getsockopt(struct sock *sk, u_int8_t pf,
        int val, char __user *opt, int *len)
{
    return compat_nf_sockopt(sk, pf, val, opt, len, 1);
}
EXPORT_SYMBOL(compat_nf_getsockopt);
#endif