af_alg.c

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/*
 * af_alg: User-space algorithm interface
 *
 * This file provides the user-space API for algorithms.
 *
 * Copyright (c) 2010 Herbert Xu <[email protected]>
 *
 * 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; either version 2 of the License, or (at your option)
 * any later version.
 *
 */

#include <linux/atomic.h>
#include <crypto/if_alg.h>
#include <linux/crypto.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/net.h>
#include <linux/rwsem.h>

struct alg_type_list {
    const struct af_alg_type *type;
    struct list_head list;
};

static atomic_long_t alg_memory_allocated;

static struct proto alg_proto = {
    .name           = "ALG",
    .owner          = THIS_MODULE,
    .memory_allocated   = &alg_memory_allocated,
    .obj_size       = sizeof(struct alg_sock),
};

static LIST_HEAD(alg_types);
static DECLARE_RWSEM(alg_types_sem);

static const struct af_alg_type *alg_get_type(const char *name)
{
    const struct af_alg_type *type = ERR_PTR(-ENOENT);
    struct alg_type_list *node;

    down_read(&alg_types_sem);
    list_for_each_entry(node, &alg_types, list) {
        if (strcmp(node->type->name, name))
            continue;

        if (try_module_get(node->type->owner))
            type = node->type;
        break;
    }
    up_read(&alg_types_sem);

    return type;
}

int af_alg_register_type(const struct af_alg_type *type)
{
    struct alg_type_list *node;
    int err = -EEXIST;

    down_write(&alg_types_sem);
    list_for_each_entry(node, &alg_types, list) {
        if (!strcmp(node->type->name, type->name))
            goto unlock;
    }

    node = kmalloc(sizeof(*node), GFP_KERNEL);
    err = -ENOMEM;
    if (!node)
        goto unlock;

    type->ops->owner = THIS_MODULE;
    node->type = type;
    list_add(&node->list, &alg_types);
    err = 0;

unlock:
    up_write(&alg_types_sem);

    return err;
}
EXPORT_SYMBOL_GPL(af_alg_register_type);

int af_alg_unregister_type(const struct af_alg_type *type)
{
    struct alg_type_list *node;
    int err = -ENOENT;

    down_write(&alg_types_sem);
    list_for_each_entry(node, &alg_types, list) {
        if (strcmp(node->type->name, type->name))
            continue;

        list_del(&node->list);
        kfree(node);
        err = 0;
        break;
    }
    up_write(&alg_types_sem);

    return err;
}
EXPORT_SYMBOL_GPL(af_alg_unregister_type);

static void alg_do_release(const struct af_alg_type *type, void *private)
{
    if (!type)
        return;

    type->release(private);
    module_put(type->owner);
}

int af_alg_release(struct socket *sock)
{
    if (sock->sk)
        sock_put(sock->sk);
    return 0;
}
EXPORT_SYMBOL_GPL(af_alg_release);

static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
{
    struct sock *sk = sock->sk;
    struct alg_sock *ask = alg_sk(sk);
    struct sockaddr_alg *sa = (void *)uaddr;
    const struct af_alg_type *type;
    void *private;

    if (sock->state == SS_CONNECTED)
        return -EINVAL;

    if (addr_len != sizeof(*sa))
        return -EINVAL;

    sa->salg_type[sizeof(sa->salg_type) - 1] = 0;
    sa->salg_name[sizeof(sa->salg_name) - 1] = 0;

    type = alg_get_type(sa->salg_type);
    if (IS_ERR(type) && PTR_ERR(type) == -ENOENT) {
        request_module("algif-%s", sa->salg_type);
        type = alg_get_type(sa->salg_type);
    }

    if (IS_ERR(type))
        return PTR_ERR(type);

    private = type->bind(sa->salg_name, sa->salg_feat, sa->salg_mask);
    if (IS_ERR(private)) {
        module_put(type->owner);
        return PTR_ERR(private);
    }

    lock_sock(sk);

    swap(ask->type, type);
    swap(ask->private, private);

    release_sock(sk);

    alg_do_release(type, private);

    return 0;
}

static int alg_setkey(struct sock *sk, char __user *ukey,
              unsigned int keylen)
{
    struct alg_sock *ask = alg_sk(sk);
    const struct af_alg_type *type = ask->type;
    u8 *key;
    int err;

    key = sock_kmalloc(sk, keylen, GFP_KERNEL);
    if (!key)
        return -ENOMEM;

    err = -EFAULT;
    if (copy_from_user(key, ukey, keylen))
        goto out;

    err = type->setkey(ask->private, key, keylen);

out:
    sock_kfree_s(sk, key, keylen);

    return err;
}

static int alg_setsockopt(struct socket *sock, int level, int optname,
              char __user *optval, unsigned int optlen)
{
    struct sock *sk = sock->sk;
    struct alg_sock *ask = alg_sk(sk);
    const struct af_alg_type *type;
    int err = -ENOPROTOOPT;

    lock_sock(sk);
    type = ask->type;

    if (level != SOL_ALG || !type)
        goto unlock;

    switch (optname) {
    case ALG_SET_KEY:
        if (sock->state == SS_CONNECTED)
            goto unlock;
        if (!type->setkey)
            goto unlock;

        err = alg_setkey(sk, optval, optlen);
    }

unlock:
    release_sock(sk);

    return err;
}

int af_alg_accept(struct sock *sk, struct socket *newsock)
{
    struct alg_sock *ask = alg_sk(sk);
    const struct af_alg_type *type;
    struct sock *sk2;
    int err;

    lock_sock(sk);
    type = ask->type;

    err = -EINVAL;
    if (!type)
        goto unlock;

    sk2 = sk_alloc(sock_net(sk), PF_ALG, GFP_KERNEL, &alg_proto);
    err = -ENOMEM;
    if (!sk2)
        goto unlock;

    sock_init_data(newsock, sk2);
    sock_graft(sk2, newsock);

    err = type->accept(ask->private, sk2);
    if (err) {
        sk_free(sk2);
        goto unlock;
    }

    sk2->sk_family = PF_ALG;

    sock_hold(sk);
    alg_sk(sk2)->parent = sk;
    alg_sk(sk2)->type = type;

    newsock->ops = type->ops;
    newsock->state = SS_CONNECTED;

    err = 0;

unlock:
    release_sock(sk);

    return err;
}
EXPORT_SYMBOL_GPL(af_alg_accept);

static int alg_accept(struct socket *sock, struct socket *newsock, int flags)
{
    return af_alg_accept(sock->sk, newsock);
}

static const struct proto_ops alg_proto_ops = {
    .family     =   PF_ALG,
    .owner      =   THIS_MODULE,

    .connect    =   sock_no_connect,
    .socketpair =   sock_no_socketpair,
    .getname    =   sock_no_getname,
    .ioctl      =   sock_no_ioctl,
    .listen     =   sock_no_listen,
    .shutdown   =   sock_no_shutdown,
    .getsockopt =   sock_no_getsockopt,
    .mmap       =   sock_no_mmap,
    .sendpage   =   sock_no_sendpage,
    .sendmsg    =   sock_no_sendmsg,
    .recvmsg    =   sock_no_recvmsg,
    .poll       =   sock_no_poll,

    .bind       =   alg_bind,
    .release    =   af_alg_release,
    .setsockopt =   alg_setsockopt,
    .accept     =   alg_accept,
};

static void alg_sock_destruct(struct sock *sk)
{
    struct alg_sock *ask = alg_sk(sk);

    alg_do_release(ask->type, ask->private);
}

static int alg_create(struct net *net, struct socket *sock, int protocol,
              int kern)
{
    struct sock *sk;
    int err;

    if (sock->type != SOCK_SEQPACKET)
        return -ESOCKTNOSUPPORT;
    if (protocol != 0)
        return -EPROTONOSUPPORT;

    err = -ENOMEM;
    sk = sk_alloc(net, PF_ALG, GFP_KERNEL, &alg_proto);
    if (!sk)
        goto out;

    sock->ops = &alg_proto_ops;
    sock_init_data(sock, sk);

    sk->sk_family = PF_ALG;
    sk->sk_destruct = alg_sock_destruct;

    return 0;
out:
    return err;
}

static const struct net_proto_family alg_family = {
    .family =   PF_ALG,
    .create =   alg_create,
    .owner  =   THIS_MODULE,
};

int af_alg_make_sg(struct af_alg_sgl *sgl, void __user *addr, int len,
           int write)
{
    unsigned long from = (unsigned long)addr;
    unsigned long npages;
    unsigned off;
    int err;
    int i;

    err = -EFAULT;
    if (!access_ok(write ? VERIFY_READ : VERIFY_WRITE, addr, len))
        goto out;

    off = from & ~PAGE_MASK;
    npages = (off + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
    if (npages > ALG_MAX_PAGES)
        npages = ALG_MAX_PAGES;

    err = get_user_pages_fast(from, npages, write, sgl->pages);
    if (err < 0)
        goto out;

    npages = err;
    err = -EINVAL;
    if (WARN_ON(npages == 0))
        goto out;

    err = 0;

    sg_init_table(sgl->sg, npages);

    for (i = 0; i < npages; i++) {
        int plen = min_t(int, len, PAGE_SIZE - off);

        sg_set_page(sgl->sg + i, sgl->pages[i], plen, off);

        off = 0;
        len -= plen;
        err += plen;
    }

out:
    return err;
}
EXPORT_SYMBOL_GPL(af_alg_make_sg);

void af_alg_free_sg(struct af_alg_sgl *sgl)
{
    int i;

    i = 0;
    do {
        put_page(sgl->pages[i]);
    } while (!sg_is_last(sgl->sg + (i++)));
}
EXPORT_SYMBOL_GPL(af_alg_free_sg);

int af_alg_cmsg_send(struct msghdr *msg, struct af_alg_control *con)
{
    struct cmsghdr *cmsg;

    for (cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
        if (!CMSG_OK(msg, cmsg))
            return -EINVAL;
        if (cmsg->cmsg_level != SOL_ALG)
            continue;

        switch(cmsg->cmsg_type) {
        case ALG_SET_IV:
            if (cmsg->cmsg_len < CMSG_LEN(sizeof(*con->iv)))
                return -EINVAL;
            con->iv = (void *)CMSG_DATA(cmsg);
            if (cmsg->cmsg_len < CMSG_LEN(con->iv->ivlen +
                              sizeof(*con->iv)))
                return -EINVAL;
            break;

        case ALG_SET_OP:
            if (cmsg->cmsg_len < CMSG_LEN(sizeof(u32)))
                return -EINVAL;
            con->op = *(u32 *)CMSG_DATA(cmsg);
            break;

        default:
            return -EINVAL;
        }
    }

    return 0;
}
EXPORT_SYMBOL_GPL(af_alg_cmsg_send);

int af_alg_wait_for_completion(int err, struct af_alg_completion *completion)
{
    switch (err) {
    case -EINPROGRESS:
    case -EBUSY:
        wait_for_completion(&completion->completion);
        INIT_COMPLETION(completion->completion);
        err = completion->err;
        break;
    };

    return err;
}
EXPORT_SYMBOL_GPL(af_alg_wait_for_completion);

void af_alg_complete(struct crypto_async_request *req, int err)
{
    struct af_alg_completion *completion = req->data;

    completion->err = err;
    complete(&completion->completion);
}
EXPORT_SYMBOL_GPL(af_alg_complete);

static int __init af_alg_init(void)
{
    int err = proto_register(&alg_proto, 0);

    if (err)
        goto out;

    err = sock_register(&alg_family);
    if (err != 0)
        goto out_unregister_proto;

out:
    return err;

out_unregister_proto:
    proto_unregister(&alg_proto);
    goto out;
}

static void __exit af_alg_exit(void)
{
    sock_unregister(PF_ALG);
    proto_unregister(&alg_proto);
}

module_init(af_alg_init);
module_exit(af_alg_exit);
MODULE_LICENSE("GPL");
MODULE_ALIAS_NETPROTO(AF_ALG);