crypto_user.c

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/*
 * Crypto user configuration API.
 *
 * Copyright (C) 2011 secunet Security Networks AG
 * Copyright (C) 2011 Steffen Klassert <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <linux/module.h>
#include <linux/crypto.h>
#include <linux/cryptouser.h>
#include <linux/sched.h>
#include <net/netlink.h>
#include <linux/security.h>
#include <net/net_namespace.h>
#include <crypto/internal/aead.h>
#include <crypto/internal/skcipher.h>

#include "internal.h"

static DEFINE_MUTEX(crypto_cfg_mutex);

/* The crypto netlink socket */
static struct sock *crypto_nlsk;

struct crypto_dump_info {
    struct sk_buff *in_skb;
    struct sk_buff *out_skb;
    u32 nlmsg_seq;
    u16 nlmsg_flags;
};

static struct crypto_alg *crypto_alg_match(struct crypto_user_alg *p, int exact)
{
    struct crypto_alg *q, *alg = NULL;

    down_read(&crypto_alg_sem);

    list_for_each_entry(q, &crypto_alg_list, cra_list) {
        int match = 0;

        if ((q->cra_flags ^ p->cru_type) & p->cru_mask)
            continue;

        if (strlen(p->cru_driver_name))
            match = !strcmp(q->cra_driver_name,
                    p->cru_driver_name);
        else if (!exact)
            match = !strcmp(q->cra_name, p->cru_name);

        if (match) {
            alg = q;
            break;
        }
    }

    up_read(&crypto_alg_sem);

    return alg;
}

static int crypto_report_cipher(struct sk_buff *skb, struct crypto_alg *alg)
{
    struct crypto_report_cipher rcipher;

    snprintf(rcipher.type, CRYPTO_MAX_ALG_NAME, "%s", "cipher");

    rcipher.blocksize = alg->cra_blocksize;
    rcipher.min_keysize = alg->cra_cipher.cia_min_keysize;
    rcipher.max_keysize = alg->cra_cipher.cia_max_keysize;

    if (nla_put(skb, CRYPTOCFGA_REPORT_CIPHER,
            sizeof(struct crypto_report_cipher), &rcipher))
        goto nla_put_failure;
    return 0;

nla_put_failure:
    return -EMSGSIZE;
}

static int crypto_report_comp(struct sk_buff *skb, struct crypto_alg *alg)
{
    struct crypto_report_comp rcomp;

    snprintf(rcomp.type, CRYPTO_MAX_ALG_NAME, "%s", "compression");

    if (nla_put(skb, CRYPTOCFGA_REPORT_COMPRESS,
            sizeof(struct crypto_report_comp), &rcomp))
        goto nla_put_failure;
    return 0;

nla_put_failure:
    return -EMSGSIZE;
}

static int crypto_report_one(struct crypto_alg *alg,
                 struct crypto_user_alg *ualg, struct sk_buff *skb)
{
    memcpy(&ualg->cru_name, &alg->cra_name, sizeof(ualg->cru_name));
    memcpy(&ualg->cru_driver_name, &alg->cra_driver_name,
           sizeof(ualg->cru_driver_name));
    memcpy(&ualg->cru_module_name, module_name(alg->cra_module),
           CRYPTO_MAX_ALG_NAME);

    ualg->cru_flags = alg->cra_flags;
    ualg->cru_refcnt = atomic_read(&alg->cra_refcnt);

    if (nla_put_u32(skb, CRYPTOCFGA_PRIORITY_VAL, alg->cra_priority))
        goto nla_put_failure;
    if (alg->cra_flags & CRYPTO_ALG_LARVAL) {
        struct crypto_report_larval rl;

        snprintf(rl.type, CRYPTO_MAX_ALG_NAME, "%s", "larval");

        if (nla_put(skb, CRYPTOCFGA_REPORT_LARVAL,
                sizeof(struct crypto_report_larval), &rl))
            goto nla_put_failure;
        goto out;
    }

    if (alg->cra_type && alg->cra_type->report) {
        if (alg->cra_type->report(skb, alg))
            goto nla_put_failure;

        goto out;
    }

    switch (alg->cra_flags & (CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_LARVAL)) {
    case CRYPTO_ALG_TYPE_CIPHER:
        if (crypto_report_cipher(skb, alg))
            goto nla_put_failure;

        break;
    case CRYPTO_ALG_TYPE_COMPRESS:
        if (crypto_report_comp(skb, alg))
            goto nla_put_failure;

        break;
    }

out:
    return 0;

nla_put_failure:
    return -EMSGSIZE;
}

static int crypto_report_alg(struct crypto_alg *alg,
                 struct crypto_dump_info *info)
{
    struct sk_buff *in_skb = info->in_skb;
    struct sk_buff *skb = info->out_skb;
    struct nlmsghdr *nlh;
    struct crypto_user_alg *ualg;
    int err = 0;

    nlh = nlmsg_put(skb, NETLINK_CB(in_skb).portid, info->nlmsg_seq,
            CRYPTO_MSG_GETALG, sizeof(*ualg), info->nlmsg_flags);
    if (!nlh) {
        err = -EMSGSIZE;
        goto out;
    }

    ualg = nlmsg_data(nlh);

    err = crypto_report_one(alg, ualg, skb);
    if (err) {
        nlmsg_cancel(skb, nlh);
        goto out;
    }

    nlmsg_end(skb, nlh);

out:
    return err;
}

static int crypto_report(struct sk_buff *in_skb, struct nlmsghdr *in_nlh,
             struct nlattr **attrs)
{
    struct crypto_user_alg *p = nlmsg_data(in_nlh);
    struct crypto_alg *alg;
    struct sk_buff *skb;
    struct crypto_dump_info info;
    int err;

    if (!p->cru_driver_name)
        return -EINVAL;

    alg = crypto_alg_match(p, 1);
    if (!alg)
        return -ENOENT;

    skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
    if (!skb)
        return -ENOMEM;

    info.in_skb = in_skb;
    info.out_skb = skb;
    info.nlmsg_seq = in_nlh->nlmsg_seq;
    info.nlmsg_flags = 0;

    err = crypto_report_alg(alg, &info);
    if (err)
        return err;

    return nlmsg_unicast(crypto_nlsk, skb, NETLINK_CB(in_skb).portid);
}

static int crypto_dump_report(struct sk_buff *skb, struct netlink_callback *cb)
{
    struct crypto_alg *alg;
    struct crypto_dump_info info;
    int err;

    if (cb->args[0])
        goto out;

    cb->args[0] = 1;

    info.in_skb = cb->skb;
    info.out_skb = skb;
    info.nlmsg_seq = cb->nlh->nlmsg_seq;
    info.nlmsg_flags = NLM_F_MULTI;

    list_for_each_entry(alg, &crypto_alg_list, cra_list) {
        err = crypto_report_alg(alg, &info);
        if (err)
            goto out_err;
    }

out:
    return skb->len;
out_err:
    return err;
}

static int crypto_dump_report_done(struct netlink_callback *cb)
{
    return 0;
}

static int crypto_update_alg(struct sk_buff *skb, struct nlmsghdr *nlh,
                 struct nlattr **attrs)
{
    struct crypto_alg *alg;
    struct crypto_user_alg *p = nlmsg_data(nlh);
    struct nlattr *priority = attrs[CRYPTOCFGA_PRIORITY_VAL];
    LIST_HEAD(list);

    if (priority && !strlen(p->cru_driver_name))
        return -EINVAL;

    alg = crypto_alg_match(p, 1);
    if (!alg)
        return -ENOENT;

    down_write(&crypto_alg_sem);

    crypto_remove_spawns(alg, &list, NULL);

    if (priority)
        alg->cra_priority = nla_get_u32(priority);

    up_write(&crypto_alg_sem);

    crypto_remove_final(&list);

    return 0;
}

static int crypto_del_alg(struct sk_buff *skb, struct nlmsghdr *nlh,
              struct nlattr **attrs)
{
    struct crypto_alg *alg;
    struct crypto_user_alg *p = nlmsg_data(nlh);

    alg = crypto_alg_match(p, 1);
    if (!alg)
        return -ENOENT;

    /* We can not unregister core algorithms such as aes-generic.
     * We would loose the reference in the crypto_alg_list to this algorithm
     * if we try to unregister. Unregistering such an algorithm without
     * removing the module is not possible, so we restrict to crypto
     * instances that are build from templates. */
    if (!(alg->cra_flags & CRYPTO_ALG_INSTANCE))
        return -EINVAL;

    if (atomic_read(&alg->cra_refcnt) != 1)
        return -EBUSY;

    return crypto_unregister_instance(alg);
}

static struct crypto_alg *crypto_user_skcipher_alg(const char *name, u32 type,
                           u32 mask)
{
    int err;
    struct crypto_alg *alg;

    type = crypto_skcipher_type(type);
    mask = crypto_skcipher_mask(mask);

    for (;;) {
        alg = crypto_lookup_skcipher(name,  type, mask);
        if (!IS_ERR(alg))
            return alg;

        err = PTR_ERR(alg);
        if (err != -EAGAIN)
            break;
        if (signal_pending(current)) {
            err = -EINTR;
            break;
        }
    }

    return ERR_PTR(err);
}

static struct crypto_alg *crypto_user_aead_alg(const char *name, u32 type,
                           u32 mask)
{
    int err;
    struct crypto_alg *alg;

    type &= ~(CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_GENIV);
    type |= CRYPTO_ALG_TYPE_AEAD;
    mask &= ~(CRYPTO_ALG_TYPE_MASK | CRYPTO_ALG_GENIV);
    mask |= CRYPTO_ALG_TYPE_MASK;

    for (;;) {
        alg = crypto_lookup_aead(name,  type, mask);
        if (!IS_ERR(alg))
            return alg;

        err = PTR_ERR(alg);
        if (err != -EAGAIN)
            break;
        if (signal_pending(current)) {
            err = -EINTR;
            break;
        }
    }

    return ERR_PTR(err);
}

static int crypto_add_alg(struct sk_buff *skb, struct nlmsghdr *nlh,
              struct nlattr **attrs)
{
    int exact = 0;
    const char *name;
    struct crypto_alg *alg;
    struct crypto_user_alg *p = nlmsg_data(nlh);
    struct nlattr *priority = attrs[CRYPTOCFGA_PRIORITY_VAL];

    if (strlen(p->cru_driver_name))
        exact = 1;

    if (priority && !exact)
        return -EINVAL;

    alg = crypto_alg_match(p, exact);
    if (alg)
        return -EEXIST;

    if (strlen(p->cru_driver_name))
        name = p->cru_driver_name;
    else
        name = p->cru_name;

    switch (p->cru_type & p->cru_mask & CRYPTO_ALG_TYPE_MASK) {
    case CRYPTO_ALG_TYPE_AEAD:
        alg = crypto_user_aead_alg(name, p->cru_type, p->cru_mask);
        break;
    case CRYPTO_ALG_TYPE_GIVCIPHER:
    case CRYPTO_ALG_TYPE_BLKCIPHER:
    case CRYPTO_ALG_TYPE_ABLKCIPHER:
        alg = crypto_user_skcipher_alg(name, p->cru_type, p->cru_mask);
        break;
    default:
        alg = crypto_alg_mod_lookup(name, p->cru_type, p->cru_mask);
    }

    if (IS_ERR(alg))
        return PTR_ERR(alg);

    down_write(&crypto_alg_sem);

    if (priority)
        alg->cra_priority = nla_get_u32(priority);

    up_write(&crypto_alg_sem);

    crypto_mod_put(alg);

    return 0;
}

#define MSGSIZE(type) sizeof(struct type)

static const int crypto_msg_min[CRYPTO_NR_MSGTYPES] = {
    [CRYPTO_MSG_NEWALG  - CRYPTO_MSG_BASE] = MSGSIZE(crypto_user_alg),
    [CRYPTO_MSG_DELALG  - CRYPTO_MSG_BASE] = MSGSIZE(crypto_user_alg),
    [CRYPTO_MSG_UPDATEALG   - CRYPTO_MSG_BASE] = MSGSIZE(crypto_user_alg),
    [CRYPTO_MSG_GETALG  - CRYPTO_MSG_BASE] = MSGSIZE(crypto_user_alg),
};

static const struct nla_policy crypto_policy[CRYPTOCFGA_MAX+1] = {
    [CRYPTOCFGA_PRIORITY_VAL]   = { .type = NLA_U32},
};

#undef MSGSIZE

static struct crypto_link {
    int (*doit)(struct sk_buff *, struct nlmsghdr *, struct nlattr **);
    int (*dump)(struct sk_buff *, struct netlink_callback *);
    int (*done)(struct netlink_callback *);
} crypto_dispatch[CRYPTO_NR_MSGTYPES] = {
    [CRYPTO_MSG_NEWALG  - CRYPTO_MSG_BASE] = { .doit = crypto_add_alg},
    [CRYPTO_MSG_DELALG  - CRYPTO_MSG_BASE] = { .doit = crypto_del_alg},
    [CRYPTO_MSG_UPDATEALG   - CRYPTO_MSG_BASE] = { .doit = crypto_update_alg},
    [CRYPTO_MSG_GETALG  - CRYPTO_MSG_BASE] = { .doit = crypto_report,
                               .dump = crypto_dump_report,
                               .done = crypto_dump_report_done},
};

static int crypto_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
{
    struct nlattr *attrs[CRYPTOCFGA_MAX+1];
    struct crypto_link *link;
    int type, err;

    type = nlh->nlmsg_type;
    if (type > CRYPTO_MSG_MAX)
        return -EINVAL;

    type -= CRYPTO_MSG_BASE;
    link = &crypto_dispatch[type];

    if (!capable(CAP_NET_ADMIN))
        return -EPERM;

    if ((type == (CRYPTO_MSG_GETALG - CRYPTO_MSG_BASE) &&
        (nlh->nlmsg_flags & NLM_F_DUMP))) {
        struct crypto_alg *alg;
        u16 dump_alloc = 0;

        if (link->dump == NULL)
            return -EINVAL;

        list_for_each_entry(alg, &crypto_alg_list, cra_list)
            dump_alloc += CRYPTO_REPORT_MAXSIZE;

        {
            struct netlink_dump_control c = {
                .dump = link->dump,
                .done = link->done,
                .min_dump_alloc = dump_alloc,
            };
            return netlink_dump_start(crypto_nlsk, skb, nlh, &c);
        }
    }

    err = nlmsg_parse(nlh, crypto_msg_min[type], attrs, CRYPTOCFGA_MAX,
              crypto_policy);
    if (err < 0)
        return err;

    if (link->doit == NULL)
        return -EINVAL;

    return link->doit(skb, nlh, attrs);
}

static void crypto_netlink_rcv(struct sk_buff *skb)
{
    mutex_lock(&crypto_cfg_mutex);
    netlink_rcv_skb(skb, &crypto_user_rcv_msg);
    mutex_unlock(&crypto_cfg_mutex);
}

static int __init crypto_user_init(void)
{
    struct netlink_kernel_cfg cfg = {
        .input  = crypto_netlink_rcv,
    };

    crypto_nlsk = netlink_kernel_create(&init_net, NETLINK_CRYPTO, &cfg);
    if (!crypto_nlsk)
        return -ENOMEM;

    return 0;
}

static void __exit crypto_user_exit(void)
{
    netlink_kernel_release(crypto_nlsk);
}

module_init(crypto_user_init);
module_exit(crypto_user_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Steffen Klassert <[email protected]>");
MODULE_DESCRIPTION("Crypto userspace configuration API");