// SPDX-License-Identifier: BSD-3-Clause
/*
 *  linux/net/sunrpc/gss_mech_switch.c
 *
 *  Copyright (c) 2001 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  J. Bruce Fields   <bfields@umich.edu>
 */

#include <linux/types.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/oid_registry.h>
#include <linux/sunrpc/msg_prot.h>
#include <linux/sunrpc/auth_gss.h>
#include <linux/sunrpc/svcauth_gss.h>
#include <linux/sunrpc/gss_err.h>
#include <linux/sunrpc/sched.h>
#include <linux/sunrpc/gss_api.h>
#include <linux/sunrpc/clnt.h>
#include <trace/events/rpcgss.h>

#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
# define RPCDBG_FACILITY        RPCDBG_AUTH
#endif

static LIST_HEAD(registered_mechs);
static DEFINE_SPINLOCK(registered_mechs_lock);

static void
gss_mech_free(struct gss_api_mech *gm)
{
        struct pf_desc *pf;
        int i;

        for (i = 0; i < gm->gm_pf_num; i++) {
                pf = &gm->gm_pfs[i];
                if (pf->domain)
                        auth_domain_put(pf->domain);
                kfree(pf->auth_domain_name);
                pf->auth_domain_name = NULL;
        }
}

static inline char *
make_auth_domain_name(char *name)
{
        static char     *prefix = "gss/";
        char            *new;

        new = kmalloc(strlen(name) + strlen(prefix) + 1, GFP_KERNEL);
        if (new) {
                strcpy(new, prefix);
                strcat(new, name);
        }
        return new;
}

static int
gss_mech_svc_setup(struct gss_api_mech *gm)
{
        struct auth_domain *dom;
        struct pf_desc *pf;
        int i, status;

        for (i = 0; i < gm->gm_pf_num; i++) {
                pf = &gm->gm_pfs[i];
                pf->auth_domain_name = make_auth_domain_name(pf->name);
                status = -ENOMEM;
                if (pf->auth_domain_name == NULL)
                        goto out;
                dom = svcauth_gss_register_pseudoflavor(
                        pf->pseudoflavor, pf->auth_domain_name);
                if (IS_ERR(dom)) {
                        status = PTR_ERR(dom);
                        goto out;
                }
                pf->domain = dom;
        }
        return 0;
out:
        gss_mech_free(gm);
        return status;
}

/**
 * gss_mech_register - register a GSS mechanism
 * @gm: GSS mechanism handle
 *
 * Returns zero if successful, or a negative errno.
 */
int gss_mech_register(struct gss_api_mech *gm)
{
        int status;

        status = gss_mech_svc_setup(gm);
        if (status)
                return status;
        spin_lock(&registered_mechs_lock);
        list_add_rcu(&gm->gm_list, &registered_mechs);
        spin_unlock(&registered_mechs_lock);
        dprintk("RPC:       registered gss mechanism %s\n", gm->gm_name);
        return 0;
}
EXPORT_SYMBOL_GPL(gss_mech_register);

/**
 * gss_mech_unregister - release a GSS mechanism
 * @gm: GSS mechanism handle
 *
 */
void gss_mech_unregister(struct gss_api_mech *gm)
{
        spin_lock(&registered_mechs_lock);
        list_del_rcu(&gm->gm_list);
        spin_unlock(&registered_mechs_lock);
        dprintk("RPC:       unregistered gss mechanism %s\n", gm->gm_name);
        gss_mech_free(gm);
}
EXPORT_SYMBOL_GPL(gss_mech_unregister);

struct gss_api_mech *gss_mech_get(struct gss_api_mech *gm)
{
        __module_get(gm->gm_owner);
        return gm;
}
EXPORT_SYMBOL(gss_mech_get);

static struct gss_api_mech *
_gss_mech_get_by_name(const char *name)
{
        struct gss_api_mech     *pos, *gm = NULL;

        rcu_read_lock();
        list_for_each_entry_rcu(pos, &registered_mechs, gm_list) {
                if (0 == strcmp(name, pos->gm_name)) {
                        if (try_module_get(pos->gm_owner))
                                gm = pos;
                        break;
                }
        }
        rcu_read_unlock();
        return gm;

}

struct gss_api_mech * gss_mech_get_by_name(const char *name)
{
        struct gss_api_mech *gm = NULL;

        gm = _gss_mech_get_by_name(name);
        if (!gm) {
                request_module("rpc-auth-gss-%s", name);
                gm = _gss_mech_get_by_name(name);
        }
        return gm;
}

struct gss_api_mech *gss_mech_get_by_OID(struct rpcsec_gss_oid *obj)
{
        struct gss_api_mech     *pos, *gm = NULL;
        char buf[32];

        if (sprint_oid(obj->data, obj->len, buf, sizeof(buf)) < 0)
                return NULL;
        request_module("rpc-auth-gss-%s", buf);

        rcu_read_lock();
        list_for_each_entry_rcu(pos, &registered_mechs, gm_list) {
                if (obj->len == pos->gm_oid.len) {
                        if (0 == memcmp(obj->data, pos->gm_oid.data, obj->len)) {
                                if (try_module_get(pos->gm_owner))
                                        gm = pos;
                                break;
                        }
                }
        }
        rcu_read_unlock();
        if (!gm)
                trace_rpcgss_oid_to_mech(buf);
        return gm;
}

static inline int
mech_supports_pseudoflavor(struct gss_api_mech *gm, u32 pseudoflavor)
{
        int i;

        for (i = 0; i < gm->gm_pf_num; i++) {
                if (gm->gm_pfs[i].pseudoflavor == pseudoflavor)
                        return 1;
        }
        return 0;
}

static struct gss_api_mech *_gss_mech_get_by_pseudoflavor(u32 pseudoflavor)
{
        struct gss_api_mech *gm = NULL, *pos;

        rcu_read_lock();
        list_for_each_entry_rcu(pos, &registered_mechs, gm_list) {
                if (!mech_supports_pseudoflavor(pos, pseudoflavor))
                        continue;
                if (try_module_get(pos->gm_owner))
                        gm = pos;
                break;
        }
        rcu_read_unlock();
        return gm;
}

struct gss_api_mech *
gss_mech_get_by_pseudoflavor(u32 pseudoflavor)
{
        struct gss_api_mech *gm;

        gm = _gss_mech_get_by_pseudoflavor(pseudoflavor);

        if (!gm) {
                request_module("rpc-auth-gss-%u", pseudoflavor);
                gm = _gss_mech_get_by_pseudoflavor(pseudoflavor);
        }
        return gm;
}

/**
 * gss_svc_to_pseudoflavor - map a GSS service number to a pseudoflavor
 * @gm: GSS mechanism handle
 * @qop: GSS quality-of-protection value
 * @service: GSS service value
 *
 * Returns a matching security flavor, or RPC_AUTH_MAXFLAVOR if none is found.
 */
rpc_authflavor_t gss_svc_to_pseudoflavor(struct gss_api_mech *gm, u32 qop,
                                         u32 service)
{
        int i;

        for (i = 0; i < gm->gm_pf_num; i++) {
                if (gm->gm_pfs[i].qop == qop &&
                    gm->gm_pfs[i].service == service) {
                        return gm->gm_pfs[i].pseudoflavor;
                }
        }
        return RPC_AUTH_MAXFLAVOR;
}

/**
 * gss_mech_info2flavor - look up a pseudoflavor given a GSS tuple
 * @info: a GSS mech OID, quality of protection, and service value
 *
 * Returns a matching pseudoflavor, or RPC_AUTH_MAXFLAVOR if the tuple is
 * not supported.
 */
rpc_authflavor_t gss_mech_info2flavor(struct rpcsec_gss_info *info)
{
        rpc_authflavor_t pseudoflavor;
        struct gss_api_mech *gm;

        gm = gss_mech_get_by_OID(&info->oid);
        if (gm == NULL)
                return RPC_AUTH_MAXFLAVOR;

        pseudoflavor = gss_svc_to_pseudoflavor(gm, info->qop, info->service);

        gss_mech_put(gm);
        return pseudoflavor;
}

/**
 * gss_mech_flavor2info - look up a GSS tuple for a given pseudoflavor
 * @pseudoflavor: GSS pseudoflavor to match
 * @info: rpcsec_gss_info structure to fill in
 *
 * Returns zero and fills in "info" if pseudoflavor matches a
 * supported mechanism.  Otherwise a negative errno is returned.
 */
int gss_mech_flavor2info(rpc_authflavor_t pseudoflavor,
                         struct rpcsec_gss_info *info)
{
        struct gss_api_mech *gm;
        int i;

        gm = gss_mech_get_by_pseudoflavor(pseudoflavor);
        if (gm == NULL)
                return -ENOENT;

        for (i = 0; i < gm->gm_pf_num; i++) {
                if (gm->gm_pfs[i].pseudoflavor == pseudoflavor) {
                        memcpy(info->oid.data, gm->gm_oid.data, gm->gm_oid.len);
                        info->oid.len = gm->gm_oid.len;
                        info->qop = gm->gm_pfs[i].qop;
                        info->service = gm->gm_pfs[i].service;
                        gss_mech_put(gm);
                        return 0;
                }
        }

        gss_mech_put(gm);
        return -ENOENT;
}

u32
gss_pseudoflavor_to_service(struct gss_api_mech *gm, u32 pseudoflavor)
{
        int i;

        for (i = 0; i < gm->gm_pf_num; i++) {
                if (gm->gm_pfs[i].pseudoflavor == pseudoflavor)
                        return gm->gm_pfs[i].service;
        }
        return 0;
}
EXPORT_SYMBOL(gss_pseudoflavor_to_service);

bool
gss_pseudoflavor_to_datatouch(struct gss_api_mech *gm, u32 pseudoflavor)
{
        int i;

        for (i = 0; i < gm->gm_pf_num; i++) {
                if (gm->gm_pfs[i].pseudoflavor == pseudoflavor)
                        return gm->gm_pfs[i].datatouch;
        }
        return false;
}

char *
gss_service_to_auth_domain_name(struct gss_api_mech *gm, u32 service)
{
        int i;

        for (i = 0; i < gm->gm_pf_num; i++) {
                if (gm->gm_pfs[i].service == service)
                        return gm->gm_pfs[i].auth_domain_name;
        }
        return NULL;
}

void
gss_mech_put(struct gss_api_mech * gm)
{
        if (gm)
                module_put(gm->gm_owner);
}
EXPORT_SYMBOL(gss_mech_put);

/* The mech could probably be determined from the token instead, but it's just
 * as easy for now to pass it in. */
int
gss_import_sec_context(const void *input_token, size_t bufsize,
                       struct gss_api_mech      *mech,
                       struct gss_ctx           **ctx_id,
                       time64_t                 *endtime,
                       gfp_t gfp_mask)
{
        if (!(*ctx_id = kzalloc_obj(**ctx_id, gfp_mask)))
                return -ENOMEM;
        (*ctx_id)->mech_type = gss_mech_get(mech);

        return mech->gm_ops->gss_import_sec_context(input_token, bufsize,
                                                *ctx_id, endtime, gfp_mask);
}

/* gss_get_mic: compute a mic over message and return mic_token. */

u32
gss_get_mic(struct gss_ctx      *context_handle,
            struct xdr_buf      *message,
            struct xdr_netobj   *mic_token)
{
         return context_handle->mech_type->gm_ops
                ->gss_get_mic(context_handle,
                              message,
                              mic_token);
}

/* gss_verify_mic: check whether the provided mic_token verifies message. */

u32
gss_verify_mic(struct gss_ctx           *context_handle,
               struct xdr_buf           *message,
               struct xdr_netobj        *mic_token)
{
        return context_handle->mech_type->gm_ops
                ->gss_verify_mic(context_handle,
                                 message,
                                 mic_token);
}

/*
 * This function is called from both the client and server code.
 * Each makes guarantees about how much "slack" space is available
 * for the underlying function in "buf"'s head and tail while
 * performing the wrap.
 *
 * The client and server code allocate RPC_MAX_AUTH_SIZE extra
 * space in both the head and tail which is available for use by
 * the wrap function.
 *
 * Underlying functions should verify they do not use more than
 * RPC_MAX_AUTH_SIZE of extra space in either the head or tail
 * when performing the wrap.
 */
u32
gss_wrap(struct gss_ctx *ctx_id,
         int            offset,
         struct xdr_buf *buf,
         struct page    **inpages)
{
        return ctx_id->mech_type->gm_ops
                ->gss_wrap(ctx_id, offset, buf, inpages);
}

u32
gss_unwrap(struct gss_ctx       *ctx_id,
           int                  offset,
           int                  len,
           struct xdr_buf       *buf)
{
        return ctx_id->mech_type->gm_ops
                ->gss_unwrap(ctx_id, offset, len, buf);
}


/* gss_delete_sec_context: free all resources associated with context_handle.
 * Note this differs from the RFC 2744-specified prototype in that we don't
 * bother returning an output token, since it would never be used anyway. */

u32
gss_delete_sec_context(struct gss_ctx   **context_handle)
{
        dprintk("RPC:       gss_delete_sec_context deleting %p\n",
                        *context_handle);

        if (!*context_handle)
                return GSS_S_NO_CONTEXT;
        if ((*context_handle)->internal_ctx_id)
                (*context_handle)->mech_type->gm_ops
                        ->gss_delete_sec_context((*context_handle)
                                                        ->internal_ctx_id);
        gss_mech_put((*context_handle)->mech_type);
        kfree(*context_handle);
        *context_handle=NULL;
        return GSS_S_COMPLETE;
}