auth_gss.c

out_err:
	dprintk("RPC:       gss_create_cred failed with error %d\n", err);
	return ERR_PTR(err);
}

static int
gss_cred_init(struct rpc_auth *auth, struct rpc_cred *cred)
{
	struct gss_auth *gss_auth = container_of(auth, struct gss_auth, rpc_auth);
	struct gss_cred *gss_cred = container_of(cred,struct gss_cred, gc_base);
	int err;

	do {
		err = gss_create_upcall(gss_auth, gss_cred);
	} while (err == -EAGAIN);
	return err;
}

static int
gss_match(struct auth_cred *acred, struct rpc_cred *rc, int flags)
{
	struct gss_cred *gss_cred = container_of(rc, struct gss_cred, gc_base);

	if (test_bit(RPCAUTH_CRED_NEW, &rc->cr_flags))
		goto out;
	/* Don't match with creds that have expired. */
	if (time_after(jiffies, gss_cred->gc_ctx->gc_expiry))
		return 0;
	if (!test_bit(RPCAUTH_CRED_UPTODATE, &rc->cr_flags))
		return 0;
out:
	if (acred->machine_cred != gss_cred->gc_machine_cred)
		return 0;
	return rc->cr_uid == acred->uid;
}

/*
* Marshal credentials.
* Maybe we should keep a cached credential for performance reasons.
*/
static __be32 *
gss_marshal(struct rpc_task *task, __be32 *p)
{
	struct rpc_rqst *req = task->tk_rqstp;
	struct rpc_cred *cred = req->rq_cred;
	struct gss_cred	*gss_cred = container_of(cred, struct gss_cred,
						 gc_base);
	struct gss_cl_ctx	*ctx = gss_cred_get_ctx(cred);
	__be32		*cred_len;
	u32             maj_stat = 0;
	struct xdr_netobj mic;
	struct kvec	iov;
	struct xdr_buf	verf_buf;

	dprintk("RPC: %5u gss_marshal\n", task->tk_pid);

	*p++ = htonl(RPC_AUTH_GSS);
	cred_len = p++;

	spin_lock(&ctx->gc_seq_lock);
	req->rq_seqno = ctx->gc_seq++;
	spin_unlock(&ctx->gc_seq_lock);

	*p++ = htonl((u32) RPC_GSS_VERSION);
	*p++ = htonl((u32) ctx->gc_proc);
	*p++ = htonl((u32) req->rq_seqno);
	*p++ = htonl((u32) gss_cred->gc_service);
	p = xdr_encode_netobj(p, &ctx->gc_wire_ctx);
	*cred_len = htonl((p - (cred_len + 1)) << 2);

	/* We compute the checksum for the verifier over the xdr-encoded bytes
	 * starting with the xid and ending at the end of the credential: */
	iov.iov_base = xprt_skip_transport_header(task->tk_xprt,
					req->rq_snd_buf.head[0].iov_base);
	iov.iov_len = (u8 *)p - (u8 *)iov.iov_base;
	xdr_buf_from_iov(&iov, &verf_buf);

	/* set verifier flavor*/
	*p++ = htonl(RPC_AUTH_GSS);

	mic.data = (u8 *)(p + 1);
	maj_stat = gss_get_mic(ctx->gc_gss_ctx, &verf_buf, &mic);
	if (maj_stat == GSS_S_CONTEXT_EXPIRED) {
		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
	} else if (maj_stat != 0) {
		printk("gss_marshal: gss_get_mic FAILED (%d)\n", maj_stat);
		goto out_put_ctx;
	}
	p = xdr_encode_opaque(p, NULL, mic.len);
	gss_put_ctx(ctx);
	return p;
out_put_ctx:
	gss_put_ctx(ctx);
	return NULL;
}

static int gss_renew_cred(struct rpc_task *task)
{
	struct rpc_cred *oldcred = task->tk_rqstp->rq_cred;
	struct gss_cred *gss_cred = container_of(oldcred,
						 struct gss_cred,
						 gc_base);
	struct rpc_auth *auth = oldcred->cr_auth;
	struct auth_cred acred = {
		.uid = oldcred->cr_uid,
		.machine_cred = gss_cred->gc_machine_cred,
	};
	struct rpc_cred *new;

	new = gss_lookup_cred(auth, &acred, RPCAUTH_LOOKUP_NEW);
	if (IS_ERR(new))
		return PTR_ERR(new);
	task->tk_rqstp->rq_cred = new;
	put_rpccred(oldcred);
	return 0;
}

static int gss_cred_is_negative_entry(struct rpc_cred *cred)
{
	if (test_bit(RPCAUTH_CRED_NEGATIVE, &cred->cr_flags)) {
		unsigned long now = jiffies;
		unsigned long begin, expire;
		struct gss_cred *gss_cred; 

		gss_cred = container_of(cred, struct gss_cred, gc_base);
		begin = gss_cred->gc_upcall_timestamp;
		expire = begin + gss_expired_cred_retry_delay * HZ;

		if (time_in_range_open(now, begin, expire))
			return 1;
	}
	return 0;
}

/*
* Refresh credentials. XXX - finish
*/
static int
gss_refresh(struct rpc_task *task)
{
	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
	int ret = 0;

	if (gss_cred_is_negative_entry(cred))
		return -EKEYEXPIRED;

	if (!test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags) &&
			!test_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags)) {
		ret = gss_renew_cred(task);
		if (ret < 0)
			goto out;
		cred = task->tk_rqstp->rq_cred;
	}

	if (test_bit(RPCAUTH_CRED_NEW, &cred->cr_flags))
		ret = gss_refresh_upcall(task);
out:
	return ret;
}

/* Dummy refresh routine: used only when destroying the context */
static int
gss_refresh_null(struct rpc_task *task)
{
	return -EACCES;
}

static __be32 *
gss_validate(struct rpc_task *task, __be32 *p)
{
	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
	struct gss_cl_ctx *ctx = gss_cred_get_ctx(cred);
	__be32		seq;
	struct kvec	iov;
	struct xdr_buf	verf_buf;
	struct xdr_netobj mic;
	u32		flav,len;
	u32		maj_stat;

	dprintk("RPC: %5u gss_validate\n", task->tk_pid);

	flav = ntohl(*p++);
	if ((len = ntohl(*p++)) > RPC_MAX_AUTH_SIZE)
		goto out_bad;
	if (flav != RPC_AUTH_GSS)
		goto out_bad;
	seq = htonl(task->tk_rqstp->rq_seqno);
	iov.iov_base = &seq;
	iov.iov_len = sizeof(seq);
	xdr_buf_from_iov(&iov, &verf_buf);
	mic.data = (u8 *)p;
	mic.len = len;

	maj_stat = gss_verify_mic(ctx->gc_gss_ctx, &verf_buf, &mic);
	if (maj_stat == GSS_S_CONTEXT_EXPIRED)
		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
	if (maj_stat) {
		dprintk("RPC: %5u gss_validate: gss_verify_mic returned "
				"error 0x%08x\n", task->tk_pid, maj_stat);
		goto out_bad;
	}
	/* We leave it to unwrap to calculate au_rslack. For now we just
	 * calculate the length of the verifier: */
	cred->cr_auth->au_verfsize = XDR_QUADLEN(len) + 2;
	gss_put_ctx(ctx);
	dprintk("RPC: %5u gss_validate: gss_verify_mic succeeded.\n",
			task->tk_pid);
	return p + XDR_QUADLEN(len);
out_bad:
	gss_put_ctx(ctx);
	dprintk("RPC: %5u gss_validate failed.\n", task->tk_pid);
	return NULL;
}

static void gss_wrap_req_encode(kxdreproc_t encode, struct rpc_rqst *rqstp,
				__be32 *p, void *obj)
{
	struct xdr_stream xdr;

	xdr_init_encode(&xdr, &rqstp->rq_snd_buf, p);
	encode(rqstp, &xdr, obj);
}

static inline int
gss_wrap_req_integ(struct rpc_cred *cred, struct gss_cl_ctx *ctx,
		   kxdreproc_t encode, struct rpc_rqst *rqstp,
		   __be32 *p, void *obj)
{
	struct xdr_buf	*snd_buf = &rqstp->rq_snd_buf;
	struct xdr_buf	integ_buf;
	__be32          *integ_len = NULL;
	struct xdr_netobj mic;
	u32		offset;
	__be32		*q;
	struct kvec	*iov;
	u32             maj_stat = 0;
	int		status = -EIO;

	integ_len = p++;
	offset = (u8 *)p - (u8 *)snd_buf->head[0].iov_base;
	*p++ = htonl(rqstp->rq_seqno);

	gss_wrap_req_encode(encode, rqstp, p, obj);

	if (xdr_buf_subsegment(snd_buf, &integ_buf,
				offset, snd_buf->len - offset))
		return status;
	*integ_len = htonl(integ_buf.len);

	/* guess whether we're in the head or the tail: */
	if (snd_buf->page_len || snd_buf->tail[0].iov_len)
		iov = snd_buf->tail;
	else
		iov = snd_buf->head;
	p = iov->iov_base + iov->iov_len;
	mic.data = (u8 *)(p + 1);

	maj_stat = gss_get_mic(ctx->gc_gss_ctx, &integ_buf, &mic);
	status = -EIO; /* XXX? */
	if (maj_stat == GSS_S_CONTEXT_EXPIRED)
		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
	else if (maj_stat)
		return status;
	q = xdr_encode_opaque(p, NULL, mic.len);

	offset = (u8 *)q - (u8 *)p;
	iov->iov_len += offset;
	snd_buf->len += offset;
	return 0;
}

static void
priv_release_snd_buf(struct rpc_rqst *rqstp)
{
	int i;

	for (i=0; i < rqstp->rq_enc_pages_num; i++)
		__free_page(rqstp->rq_enc_pages[i]);
	kfree(rqstp->rq_enc_pages);
}

static int
alloc_enc_pages(struct rpc_rqst *rqstp)
{
	struct xdr_buf *snd_buf = &rqstp->rq_snd_buf;
	int first, last, i;

	if (snd_buf->page_len == 0) {
		rqstp->rq_enc_pages_num = 0;
		return 0;
	}

	first = snd_buf->page_base >> PAGE_CACHE_SHIFT;
	last = (snd_buf->page_base + snd_buf->page_len - 1) >> PAGE_CACHE_SHIFT;
	rqstp->rq_enc_pages_num = last - first + 1 + 1;
	rqstp->rq_enc_pages
		= kmalloc(rqstp->rq_enc_pages_num * sizeof(struct page *),
				GFP_NOFS);
	if (!rqstp->rq_enc_pages)
		goto out;
	for (i=0; i < rqstp->rq_enc_pages_num; i++) {
		rqstp->rq_enc_pages[i] = alloc_page(GFP_NOFS);
		if (rqstp->rq_enc_pages[i] == NULL)
			goto out_free;
	}
	rqstp->rq_release_snd_buf = priv_release_snd_buf;
	return 0;
out_free:
	rqstp->rq_enc_pages_num = i;
	priv_release_snd_buf(rqstp);
out:
	return -EAGAIN;
}

static inline int
gss_wrap_req_priv(struct rpc_cred *cred, struct gss_cl_ctx *ctx,
		  kxdreproc_t encode, struct rpc_rqst *rqstp,
		  __be32 *p, void *obj)
{
	struct xdr_buf	*snd_buf = &rqstp->rq_snd_buf;
	u32		offset;
	u32             maj_stat;
	int		status;
	__be32		*opaque_len;
	struct page	**inpages;
	int		first;
	int		pad;
	struct kvec	*iov;
	char		*tmp;

	opaque_len = p++;
	offset = (u8 *)p - (u8 *)snd_buf->head[0].iov_base;
	*p++ = htonl(rqstp->rq_seqno);

	gss_wrap_req_encode(encode, rqstp, p, obj);

	status = alloc_enc_pages(rqstp);
	if (status)
		return status;
	first = snd_buf->page_base >> PAGE_CACHE_SHIFT;
	inpages = snd_buf->pages + first;
	snd_buf->pages = rqstp->rq_enc_pages;
	snd_buf->page_base -= first << PAGE_CACHE_SHIFT;
	/*
	 * Give the tail its own page, in case we need extra space in the
	 * head when wrapping:
	 *
	 * call_allocate() allocates twice the slack space required
	 * by the authentication flavor to rq_callsize.
	 * For GSS, slack is GSS_CRED_SLACK.
	 */
	if (snd_buf->page_len || snd_buf->tail[0].iov_len) {
		tmp = page_address(rqstp->rq_enc_pages[rqstp->rq_enc_pages_num - 1]);
		memcpy(tmp, snd_buf->tail[0].iov_base, snd_buf->tail[0].iov_len);
		snd_buf->tail[0].iov_base = tmp;
	}
	maj_stat = gss_wrap(ctx->gc_gss_ctx, offset, snd_buf, inpages);
	/* slack space should prevent this ever happening: */
	BUG_ON(snd_buf->len > snd_buf->buflen);
	status = -EIO;
	/* We're assuming that when GSS_S_CONTEXT_EXPIRED, the encryption was
	 * done anyway, so it's safe to put the request on the wire: */
	if (maj_stat == GSS_S_CONTEXT_EXPIRED)
		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
	else if (maj_stat)
		return status;

	*opaque_len = htonl(snd_buf->len - offset);
	/* guess whether we're in the head or the tail: */
	if (snd_buf->page_len || snd_buf->tail[0].iov_len)
		iov = snd_buf->tail;
	else
		iov = snd_buf->head;
	p = iov->iov_base + iov->iov_len;
	pad = 3 - ((snd_buf->len - offset - 1) & 3);
	memset(p, 0, pad);
	iov->iov_len += pad;
	snd_buf->len += pad;

	return 0;
}

static int
gss_wrap_req(struct rpc_task *task,
	     kxdreproc_t encode, void *rqstp, __be32 *p, void *obj)
{
	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
	struct gss_cred	*gss_cred = container_of(cred, struct gss_cred,
			gc_base);
	struct gss_cl_ctx *ctx = gss_cred_get_ctx(cred);
	int             status = -EIO;

	dprintk("RPC: %5u gss_wrap_req\n", task->tk_pid);
	if (ctx->gc_proc != RPC_GSS_PROC_DATA) {
		/* The spec seems a little ambiguous here, but I think that not
		 * wrapping context destruction requests makes the most sense.
		 */
		gss_wrap_req_encode(encode, rqstp, p, obj);
		status = 0;
		goto out;
	}
	switch (gss_cred->gc_service) {
	case RPC_GSS_SVC_NONE:
		gss_wrap_req_encode(encode, rqstp, p, obj);
		status = 0;
		break;
	case RPC_GSS_SVC_INTEGRITY:
		status = gss_wrap_req_integ(cred, ctx, encode, rqstp, p, obj);
		break;
	case RPC_GSS_SVC_PRIVACY:
		status = gss_wrap_req_priv(cred, ctx, encode, rqstp, p, obj);
		break;
	}
out:
	gss_put_ctx(ctx);
	dprintk("RPC: %5u gss_wrap_req returning %d\n", task->tk_pid, status);
	return status;
}

static inline int
gss_unwrap_resp_integ(struct rpc_cred *cred, struct gss_cl_ctx *ctx,
		struct rpc_rqst *rqstp, __be32 **p)
{
	struct xdr_buf	*rcv_buf = &rqstp->rq_rcv_buf;
	struct xdr_buf integ_buf;
	struct xdr_netobj mic;
	u32 data_offset, mic_offset;
	u32 integ_len;
	u32 maj_stat;
	int status = -EIO;

	integ_len = ntohl(*(*p)++);
	if (integ_len & 3)
		return status;
	data_offset = (u8 *)(*p) - (u8 *)rcv_buf->head[0].iov_base;
	mic_offset = integ_len + data_offset;
	if (mic_offset > rcv_buf->len)
		return status;
	if (ntohl(*(*p)++) != rqstp->rq_seqno)
		return status;

	if (xdr_buf_subsegment(rcv_buf, &integ_buf, data_offset,
				mic_offset - data_offset))
		return status;

	if (xdr_buf_read_netobj(rcv_buf, &mic, mic_offset))
		return status;

	maj_stat = gss_verify_mic(ctx->gc_gss_ctx, &integ_buf, &mic);
	if (maj_stat == GSS_S_CONTEXT_EXPIRED)
		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
	if (maj_stat != GSS_S_COMPLETE)
		return status;
	return 0;
}

static inline int
gss_unwrap_resp_priv(struct rpc_cred *cred, struct gss_cl_ctx *ctx,
		struct rpc_rqst *rqstp, __be32 **p)
{
	struct xdr_buf  *rcv_buf = &rqstp->rq_rcv_buf;
	u32 offset;
	u32 opaque_len;
	u32 maj_stat;
	int status = -EIO;

	opaque_len = ntohl(*(*p)++);
	offset = (u8 *)(*p) - (u8 *)rcv_buf->head[0].iov_base;
	if (offset + opaque_len > rcv_buf->len)
		return status;
	/* remove padding: */
	rcv_buf->len = offset + opaque_len;

	maj_stat = gss_unwrap(ctx->gc_gss_ctx, offset, rcv_buf);
	if (maj_stat == GSS_S_CONTEXT_EXPIRED)
		clear_bit(RPCAUTH_CRED_UPTODATE, &cred->cr_flags);
	if (maj_stat != GSS_S_COMPLETE)
		return status;
	if (ntohl(*(*p)++) != rqstp->rq_seqno)
		return status;

	return 0;
}

static int
gss_unwrap_req_decode(kxdrdproc_t decode, struct rpc_rqst *rqstp,
		      __be32 *p, void *obj)
{
	struct xdr_stream xdr;

	xdr_init_decode(&xdr, &rqstp->rq_rcv_buf, p);
	return decode(rqstp, &xdr, obj);
}

static int
gss_unwrap_resp(struct rpc_task *task,
		kxdrdproc_t decode, void *rqstp, __be32 *p, void *obj)
{
	struct rpc_cred *cred = task->tk_rqstp->rq_cred;
	struct gss_cred *gss_cred = container_of(cred, struct gss_cred,
			gc_base);
	struct gss_cl_ctx *ctx = gss_cred_get_ctx(cred);
	__be32		*savedp = p;
	struct kvec	*head = ((struct rpc_rqst *)rqstp)->rq_rcv_buf.head;
	int		savedlen = head->iov_len;
	int             status = -EIO;

	if (ctx->gc_proc != RPC_GSS_PROC_DATA)
		goto out_decode;
	switch (gss_cred->gc_service) {
	case RPC_GSS_SVC_NONE:
		break;
	case RPC_GSS_SVC_INTEGRITY:
		status = gss_unwrap_resp_integ(cred, ctx, rqstp, &p);
		if (status)
			goto out;
		break;
	case RPC_GSS_SVC_PRIVACY:
		status = gss_unwrap_resp_priv(cred, ctx, rqstp, &p);
		if (status)
			goto out;
		break;
	}
	/* take into account extra slack for integrity and privacy cases: */
	cred->cr_auth->au_rslack = cred->cr_auth->au_verfsize + (p - savedp)
						+ (savedlen - head->iov_len);
out_decode:
	status = gss_unwrap_req_decode(decode, rqstp, p, obj);
out:
	gss_put_ctx(ctx);
	dprintk("RPC: %5u gss_unwrap_resp returning %d\n", task->tk_pid,
			status);
	return status;
}

static const struct rpc_authops authgss_ops = {
	.owner		= THIS_MODULE,
	.au_flavor	= RPC_AUTH_GSS,
	.au_name	= "RPCSEC_GSS",
	.create		= gss_create,
	.destroy	= gss_destroy,
	.lookup_cred	= gss_lookup_cred,
	.crcreate	= gss_create_cred
};

static const struct rpc_credops gss_credops = {
	.cr_name	= "AUTH_GSS",
	.crdestroy	= gss_destroy_cred,
	.cr_init	= gss_cred_init,
	.crbind		= rpcauth_generic_bind_cred,
	.crmatch	= gss_match,
	.crmarshal	= gss_marshal,
	.crrefresh	= gss_refresh,
	.crvalidate	= gss_validate,
	.crwrap_req	= gss_wrap_req,
	.crunwrap_resp	= gss_unwrap_resp,
};

static const struct rpc_credops gss_nullops = {
	.cr_name	= "AUTH_GSS",
	.crdestroy	= gss_destroy_nullcred,
	.crbind		= rpcauth_generic_bind_cred,
	.crmatch	= gss_match,
	.crmarshal	= gss_marshal,
	.crrefresh	= gss_refresh_null,
	.crvalidate	= gss_validate,
	.crwrap_req	= gss_wrap_req,
	.crunwrap_resp	= gss_unwrap_resp,
};

static const struct rpc_pipe_ops gss_upcall_ops_v0 = {
	.upcall		= rpc_pipe_generic_upcall,
	.downcall	= gss_pipe_downcall,
	.destroy_msg	= gss_pipe_destroy_msg,
	.open_pipe	= gss_pipe_open_v0,
	.release_pipe	= gss_pipe_release,
};

static const struct rpc_pipe_ops gss_upcall_ops_v1 = {
	.upcall		= rpc_pipe_generic_upcall,
	.downcall	= gss_pipe_downcall,
	.destroy_msg	= gss_pipe_destroy_msg,
	.open_pipe	= gss_pipe_open_v1,
	.release_pipe	= gss_pipe_release,
};

/*
 * Initialize RPCSEC_GSS module
 */
static int __init init_rpcsec_gss(void)
{
	int err = 0;

	err = rpcauth_register(&authgss_ops);
	if (err)
		goto out;
	err = gss_svc_init();
	if (err)
		goto out_unregister;
	rpc_init_wait_queue(&pipe_version_rpc_waitqueue, "gss pipe version");
	return 0;
out_unregister:
	rpcauth_unregister(&authgss_ops);
out:
	return err;
}

static void __exit exit_rpcsec_gss(void)
{
	gss_svc_shutdown();
	rpcauth_unregister(&authgss_ops);
	rcu_barrier(); /* Wait for completion of call_rcu()'s */
}

MODULE_LICENSE("GPL");
module_param_named(expired_cred_retry_delay,
		   gss_expired_cred_retry_delay,
		   uint, 0644);
MODULE_PARM_DESC(expired_cred_retry_delay, "Timeout (in seconds) until "
		"the RPC engine retries an expired credential");

module_init(init_rpcsec_gss)
module_exit(exit_rpcsec_gss)