// SPDX-License-Identifier: GPL-2.0+
/*
 *  linux/net/sunrpc/gss_rpc_upcall.c
 *
 *  Copyright (C) 2012 Simo Sorce <simo@redhat.com>
 */

#include <linux/types.h>
#include <linux/un.h>

#include <linux/sunrpc/svcauth.h>
#include "gss_rpc_upcall.h"

#define GSSPROXY_SOCK_PATHNAME  "/var/run/gssproxy.sock"

#define GSSPROXY_PROGRAM        (400112u)
#define GSSPROXY_VERS_1         (1u)

/*
 * Encoding/Decoding functions
 */

enum {
        GSSX_NULL = 0,  /* Unused */
        GSSX_INDICATE_MECHS = 1,
        GSSX_GET_CALL_CONTEXT = 2,
        GSSX_IMPORT_AND_CANON_NAME = 3,
        GSSX_EXPORT_CRED = 4,
        GSSX_IMPORT_CRED = 5,
        GSSX_ACQUIRE_CRED = 6,
        GSSX_STORE_CRED = 7,
        GSSX_INIT_SEC_CONTEXT = 8,
        GSSX_ACCEPT_SEC_CONTEXT = 9,
        GSSX_RELEASE_HANDLE = 10,
        GSSX_GET_MIC = 11,
        GSSX_VERIFY = 12,
        GSSX_WRAP = 13,
        GSSX_UNWRAP = 14,
        GSSX_WRAP_SIZE_LIMIT = 15,
};

#define PROC(proc, name)                                \
[GSSX_##proc] = {                                       \
        .p_proc   = GSSX_##proc,                        \
        .p_encode = gssx_enc_##name,    \
        .p_decode = gssx_dec_##name,    \
        .p_arglen = GSSX_ARG_##name##_sz,               \
        .p_replen = GSSX_RES_##name##_sz,               \
        .p_statidx = GSSX_##proc,                       \
        .p_name   = #proc,                              \
}

static const struct rpc_procinfo gssp_procedures[] = {
        PROC(INDICATE_MECHS, indicate_mechs),
        PROC(GET_CALL_CONTEXT, get_call_context),
        PROC(IMPORT_AND_CANON_NAME, import_and_canon_name),
        PROC(EXPORT_CRED, export_cred),
        PROC(IMPORT_CRED, import_cred),
        PROC(ACQUIRE_CRED, acquire_cred),
        PROC(STORE_CRED, store_cred),
        PROC(INIT_SEC_CONTEXT, init_sec_context),
        PROC(ACCEPT_SEC_CONTEXT, accept_sec_context),
        PROC(RELEASE_HANDLE, release_handle),
        PROC(GET_MIC, get_mic),
        PROC(VERIFY, verify),
        PROC(WRAP, wrap),
        PROC(UNWRAP, unwrap),
        PROC(WRAP_SIZE_LIMIT, wrap_size_limit),
};



/*
 * Common transport functions
 */

static const struct rpc_program gssp_program;

static int gssp_rpc_create(struct net *net, struct rpc_clnt **_clnt)
{
        static const struct sockaddr_un gssp_localaddr = {
                .sun_family             = AF_LOCAL,
                .sun_path               = GSSPROXY_SOCK_PATHNAME,
        };
        struct rpc_create_args args = {
                .net            = net,
                .protocol       = XPRT_TRANSPORT_LOCAL,
                .address        = (struct sockaddr *)&gssp_localaddr,
                .addrsize       = sizeof(gssp_localaddr),
                .servername     = "localhost",
                .program        = &gssp_program,
                .version        = GSSPROXY_VERS_1,
                .authflavor     = RPC_AUTH_NULL,
                /*
                 * Note we want connection to be done in the caller's
                 * filesystem namespace.  We therefore turn off the idle
                 * timeout, which would result in reconnections being
                 * done without the correct namespace:
                 */
                .flags          = RPC_CLNT_CREATE_NOPING |
                                  RPC_CLNT_CREATE_CONNECTED |
                                  RPC_CLNT_CREATE_NO_IDLE_TIMEOUT
        };
        struct rpc_clnt *clnt;
        int result = 0;

        clnt = rpc_create(&args);
        if (IS_ERR(clnt)) {
                dprintk("RPC:       failed to create AF_LOCAL gssproxy "
                                "client (errno %ld).\n", PTR_ERR(clnt));
                result = PTR_ERR(clnt);
                *_clnt = NULL;
                goto out;
        }

        dprintk("RPC:       created new gssp local client (gssp_local_clnt: "
                        "%p)\n", clnt);
        *_clnt = clnt;

out:
        return result;
}

void init_gssp_clnt(struct sunrpc_net *sn)
{
        mutex_init(&sn->gssp_lock);
        sn->gssp_clnt = NULL;
}

int set_gssp_clnt(struct net *net)
{
        struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
        struct rpc_clnt *clnt;
        int ret;

        mutex_lock(&sn->gssp_lock);
        ret = gssp_rpc_create(net, &clnt);
        if (!ret) {
                if (sn->gssp_clnt)
                        rpc_shutdown_client(sn->gssp_clnt);
                sn->gssp_clnt = clnt;
        }
        mutex_unlock(&sn->gssp_lock);
        return ret;
}

void clear_gssp_clnt(struct sunrpc_net *sn)
{
        mutex_lock(&sn->gssp_lock);
        if (sn->gssp_clnt) {
                rpc_shutdown_client(sn->gssp_clnt);
                sn->gssp_clnt = NULL;
        }
        mutex_unlock(&sn->gssp_lock);
}

static struct rpc_clnt *get_gssp_clnt(struct sunrpc_net *sn)
{
        struct rpc_clnt *clnt;

        mutex_lock(&sn->gssp_lock);
        clnt = sn->gssp_clnt;
        if (clnt)
                refcount_inc(&clnt->cl_count);
        mutex_unlock(&sn->gssp_lock);
        return clnt;
}

static int gssp_call(struct net *net, struct rpc_message *msg)
{
        struct sunrpc_net *sn = net_generic(net, sunrpc_net_id);
        struct rpc_clnt *clnt;
        int status;

        clnt = get_gssp_clnt(sn);
        if (!clnt)
                return -EIO;
        status = rpc_call_sync(clnt, msg, 0);
        if (status < 0) {
                dprintk("gssp: rpc_call returned error %d\n", -status);
                switch (status) {
                case -EPROTONOSUPPORT:
                        status = -EINVAL;
                        break;
                case -ECONNREFUSED:
                case -ETIMEDOUT:
                case -ENOTCONN:
                        status = -EAGAIN;
                        break;
                case -ERESTARTSYS:
                        if (signalled ())
                                status = -EINTR;
                        break;
                default:
                        break;
                }
        }
        rpc_release_client(clnt);
        return status;
}

static void gssp_free_receive_pages(struct gssx_arg_accept_sec_context *arg)
{
        unsigned int i;

        for (i = 0; i < arg->npages && arg->pages[i]; i++)
                __free_page(arg->pages[i]);

        kfree(arg->pages);
}

static int gssp_alloc_receive_pages(struct gssx_arg_accept_sec_context *arg)
{
        unsigned int i;

        arg->npages = DIV_ROUND_UP(NGROUPS_MAX * 4, PAGE_SIZE);
        arg->pages = kzalloc_objs(struct page *, arg->npages);
        if (!arg->pages)
                return -ENOMEM;
        for (i = 0; i < arg->npages; i++) {
                arg->pages[i] = alloc_page(GFP_KERNEL);
                if (!arg->pages[i]) {
                        gssp_free_receive_pages(arg);
                        return -ENOMEM;
                }
        }
        return 0;
}

static char *gssp_stringify(struct xdr_netobj *netobj)
{
        return kmemdup_nul(netobj->data, netobj->len, GFP_KERNEL);
}

static void gssp_hostbased_service(char **principal)
{
        char *c;

        if (!*principal)
                return;

        /* terminate and remove realm part */
        c = strchr(*principal, '@');
        if (c) {
                *c = '\0';

                /* change service-hostname delimiter */
                c = strchr(*principal, '/');
                if (c)
                        *c = '@';
        }
        if (!c) {
                /* not a service principal */
                kfree(*principal);
                *principal = NULL;
        }
}

/*
 * Public functions
 */

/* numbers somewhat arbitrary but large enough for current needs */
#define GSSX_MAX_OUT_HANDLE     128
#define GSSX_MAX_SRC_PRINC      256
#define GSSX_KMEMBUF (GSSX_max_output_handle_sz + \
                        GSSX_max_oid_sz + \
                        GSSX_max_princ_sz + \
                        sizeof(struct svc_cred))

int gssp_accept_sec_context_upcall(struct net *net,
                                struct gssp_upcall_data *data)
{
        struct gssx_ctx ctxh = {
                .state = data->in_handle
        };
        struct gssx_arg_accept_sec_context arg = {
                .input_token = data->in_token,
        };
        struct gssx_ctx rctxh = {
                /*
                 * pass in the max length we expect for each of these
                 * buffers but let the xdr code kmalloc them:
                 */
                .exported_context_token.len = GSSX_max_output_handle_sz,
                .mech.len = GSS_OID_MAX_LEN,
                .targ_name.display_name.len = GSSX_max_princ_sz,
                .src_name.display_name.len = GSSX_max_princ_sz
        };
        struct gssx_res_accept_sec_context res = {
                .context_handle = &rctxh,
                .output_token = &data->out_token
        };
        struct rpc_message msg = {
                .rpc_proc = &gssp_procedures[GSSX_ACCEPT_SEC_CONTEXT],
                .rpc_argp = &arg,
                .rpc_resp = &res,
                .rpc_cred = NULL, /* FIXME ? */
        };
        struct xdr_netobj client_name = { 0 , NULL };
        struct xdr_netobj target_name = { 0, NULL };
        int ret;

        if (data->in_handle.len != 0)
                arg.context_handle = &ctxh;
        res.output_token->len = GSSX_max_output_token_sz;

        ret = gssp_alloc_receive_pages(&arg);
        if (ret)
                return ret;

        ret = gssp_call(net, &msg);

        gssp_free_receive_pages(&arg);

        /* we need to fetch all data even in case of error so
         * that we can free special strctures is they have been allocated */
        data->major_status = res.status.major_status;
        data->minor_status = res.status.minor_status;
        if (res.context_handle) {
                data->out_handle = rctxh.exported_context_token;
                data->mech_oid.len = rctxh.mech.len;
                if (rctxh.mech.data) {
                        memcpy(data->mech_oid.data, rctxh.mech.data,
                                                data->mech_oid.len);
                        kfree(rctxh.mech.data);
                }
                client_name = rctxh.src_name.display_name;
                target_name = rctxh.targ_name.display_name;
        }

        if (res.options.count == 1) {
                gssx_buffer *value = &res.options.data[0].value;
                /* Currently we only decode CREDS_VALUE, if we add
                 * anything else we'll have to loop and match on the
                 * option name */
                if (value->len == 1) {
                        /* steal group info from struct svc_cred */
                        data->creds = *(struct svc_cred *)value->data;
                        data->found_creds = 1;
                }
                /* whether we use it or not, free data */
                kfree(value->data);
        }

        if (res.options.count != 0) {
                kfree(res.options.data);
        }

        /* convert to GSS_NT_HOSTBASED_SERVICE form and set into creds */
        if (data->found_creds) {
                if (client_name.data) {
                        data->creds.cr_raw_principal =
                                        gssp_stringify(&client_name);
                        data->creds.cr_principal =
                                        gssp_stringify(&client_name);
                        gssp_hostbased_service(&data->creds.cr_principal);
                }
                if (target_name.data) {
                        data->creds.cr_targ_princ =
                                        gssp_stringify(&target_name);
                        gssp_hostbased_service(&data->creds.cr_targ_princ);
                }
        }
        kfree(client_name.data);
        kfree(target_name.data);

        return ret;
}

void gssp_free_upcall_data(struct gssp_upcall_data *data)
{
        kfree(data->in_handle.data);
        kfree(data->out_handle.data);
        kfree(data->out_token.data);
        free_svc_cred(&data->creds);
}

/*
 * Initialization stuff
 */
static unsigned int gssp_version1_counts[ARRAY_SIZE(gssp_procedures)];
static const struct rpc_version gssp_version1 = {
        .number         = GSSPROXY_VERS_1,
        .nrprocs        = ARRAY_SIZE(gssp_procedures),
        .procs          = gssp_procedures,
        .counts         = gssp_version1_counts,
};

static const struct rpc_version *gssp_version[] = {
        NULL,
        &gssp_version1,
};

static struct rpc_stat gssp_stats;

static const struct rpc_program gssp_program = {
        .name           = "gssproxy",
        .number         = GSSPROXY_PROGRAM,
        .nrvers         = ARRAY_SIZE(gssp_version),
        .version        = gssp_version,
        .stats          = &gssp_stats,
};