auth_gss.c

h内核

/*
 * linux/net/sunrpc/auth_gss.c
 *
 * RPCSEC_GSS client authentication.
 * 
 *  Copyright (c) 2000 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Dug Song       <[e-mail]>
 *  Andy Adamson   <[e-mail]>
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. Neither the name of the University nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * $Id$
 */


#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/sched.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/auth.h>
#include <linux/sunrpc/auth_gss.h>
#include <linux/sunrpc/svcauth_gss.h>
#include <linux/sunrpc/gss_err.h>
#include <linux/workqueue.h>
#include <linux/sunrpc/rpc_pipe_fs.h>
#include <linux/sunrpc/gss_api.h>
#include <asm/uaccess.h>

static struct rpc_authops authgss_ops;

static struct rpc_credops gss_credops;

#ifdef RPC_DEBUG
# define RPCDBG_FACILITY	RPCDBG_AUTH
#endif

#define NFS_NGROUPS	16

#define GSS_CRED_EXPIRE		(60 * HZ)	/* XXX: reasonable? */
#define GSS_CRED_SLACK		1024		/* XXX: unused */
/* length of a krb5 verifier (48), plus data added before arguments when
 * using integrity (two 4-byte integers): */
#define GSS_VERF_SLACK		56

/* XXX this define must match the gssd define
* as it is passed to gssd to signal the use of
* machine creds should be part of the shared rpc interface */

#define CA_RUN_AS_MACHINE  0x00000200 

/* dump the buffer in `emacs-hexl' style */
#define isprint(c)      ((c > 0x1f) && (c < 0x7f))

static DEFINE_RWLOCK(gss_ctx_lock);

struct gss_auth {
	struct rpc_auth rpc_auth;
	struct gss_api_mech *mech;
	struct list_head upcalls;
	struct dentry *dentry;
	char path[48];
	spinlock_t lock;
};

static void gss_destroy_ctx(struct gss_cl_ctx *);
static struct rpc_pipe_ops gss_upcall_ops;

void
print_hexl(u32 *p, u_int length, u_int offset)
{
	u_int i, j, jm;
	u8 c, *cp;
	
	dprintk("RPC: print_hexl: length %d\n",length);
	dprintk("\n");
	cp = (u8 *) p;
	
	for (i = 0; i < length; i += 0x10) {
		dprintk("  %04x: ", (u_int)(i + offset));
		jm = length - i;
		jm = jm > 16 ? 16 : jm;
		
		for (j = 0; j < jm; j++) {
			if ((j % 2) == 1)
				dprintk("%02x ", (u_int)cp[i+j]);
			else
				dprintk("%02x", (u_int)cp[i+j]);
		}
		for (; j < 16; j++) {
			if ((j % 2) == 1)
				dprintk("   ");
			else
				dprintk("  ");
		}
		dprintk(" ");
		
		for (j = 0; j < jm; j++) {
			c = cp[i+j];
			c = isprint(c) ? c : '.';
			dprintk("%c", c);
		}
		dprintk("\n");
	}
}

EXPORT_SYMBOL(print_hexl);

static inline struct gss_cl_ctx *
gss_get_ctx(struct gss_cl_ctx *ctx)
{
	atomic_inc(&ctx->count);
	return ctx;
}

static inline void
gss_put_ctx(struct gss_cl_ctx *ctx)
{
	if (atomic_dec_and_test(&ctx->count))
		gss_destroy_ctx(ctx);
}

static void
gss_cred_set_ctx(struct rpc_cred *cred, struct gss_cl_ctx *ctx)
{
	struct gss_cred *gss_cred = container_of(cred, struct gss_cred, gc_base);
	struct gss_cl_ctx *old;
	write_lock(&gss_ctx_lock);
	old = gss_cred->gc_ctx;
	gss_cred->gc_ctx = ctx;
	cred->cr_flags |= RPCAUTH_CRED_UPTODATE;
	write_unlock(&gss_ctx_lock);
	if (old)
		gss_put_ctx(old);
}

static int
gss_cred_is_uptodate_ctx(struct rpc_cred *cred)
{
	struct gss_cred *gss_cred = container_of(cred, struct gss_cred, gc_base);
	int res = 0;

	read_lock(&gss_ctx_lock);
	if ((cred->cr_flags & RPCAUTH_CRED_UPTODATE) && gss_cred->gc_ctx)
		res = 1;
	read_unlock(&gss_ctx_lock);
	return res;
}

static inline int
simple_get_bytes(char **ptr, const char *end, void *res, int len)
{
	char *p, *q;
	p = *ptr;
	q = p + len;
	if (q > end || q < p)
		return -1;
	memcpy(res, p, len);
	*ptr = q;
	return 0;
}

static inline int
simple_get_netobj(char **ptr, const char *end, struct xdr_netobj *res)
{
	char *p, *q;
	p = *ptr;
	if (simple_get_bytes(&p, end, &res->len, sizeof(res->len)))
		return -1;
	q = p + res->len;
	if (q > end || q < p)
		return -1;
	res->data = p;
	*ptr = q;
	return 0;
}

static int
dup_netobj(struct xdr_netobj *source, struct xdr_netobj *dest)
{
	dest->len = source->len;
	if (!(dest->data = kmalloc(dest->len, GFP_KERNEL)))
		return -1;
	memcpy(dest->data, source->data, dest->len);
	return 0;
}

static struct gss_cl_ctx *
gss_cred_get_ctx(struct rpc_cred *cred)
{
	struct gss_cred *gss_cred = container_of(cred, struct gss_cred, gc_base);
	struct gss_cl_ctx *ctx = NULL;

	read_lock(&gss_ctx_lock);
	if (gss_cred->gc_ctx)
		ctx = gss_get_ctx(gss_cred->gc_ctx);
	read_unlock(&gss_ctx_lock);
	return ctx;
}

static int
gss_parse_init_downcall(struct gss_api_mech *gm, struct xdr_netobj *buf,
		struct gss_cl_ctx **gc, uid_t *uid, int *gss_err)
{
	char *end = buf->data + buf->len;
	char *p = buf->data;
	struct gss_cl_ctx *ctx;
	struct xdr_netobj tmp_buf;
	unsigned int timeout;
	int err = -EIO;

	if (!(ctx = kmalloc(sizeof(*ctx), GFP_KERNEL))) {
		err = -ENOMEM;
		goto err;
	}
	ctx->gc_proc = RPC_GSS_PROC_DATA;
	ctx->gc_seq = 1;	/* NetApp 6.4R1 doesn't accept seq. no. 0 */
	spin_lock_init(&ctx->gc_seq_lock);
	atomic_set(&ctx->count,1);

	if (simple_get_bytes(&p, end, uid, sizeof(*uid)))
		goto err_free_ctx;
	/* FIXME: discarded timeout for now */
	if (simple_get_bytes(&p, end, &timeout, sizeof(timeout)))
		goto err_free_ctx;
	*gss_err = 0;
	if (simple_get_bytes(&p, end, &ctx->gc_win, sizeof(ctx->gc_win)))
		goto err_free_ctx;
	/* gssd signals an error by passing ctx->gc_win = 0: */
	if (!ctx->gc_win) {
		/* in which case the next int is an error code: */
		if (simple_get_bytes(&p, end, gss_err, sizeof(*gss_err)))
			goto err_free_ctx;
		err = 0;
		goto err_free_ctx;
	}
	if (simple_get_netobj(&p, end, &tmp_buf))
		goto err_free_ctx;
	if (dup_netobj(&tmp_buf, &ctx->gc_wire_ctx)) {
		err = -ENOMEM;
		goto err_free_ctx;
	}
	if (simple_get_netobj(&p, end, &tmp_buf))
		goto err_free_wire_ctx;
	if (p != end)
		goto err_free_wire_ctx;
	if (gss_import_sec_context(&tmp_buf, gm, &ctx->gc_gss_ctx))
		goto err_free_wire_ctx;
	*gc = ctx;
	return 0;
err_free_wire_ctx:
	kfree(ctx->gc_wire_ctx.data);
err_free_ctx:
	kfree(ctx);
err:
	*gc = NULL;
	dprintk("RPC:      gss_parse_init_downcall returning %d\n", err);
	return err;
}


struct gss_upcall_msg {
	struct rpc_pipe_msg msg;
	struct list_head list;
	struct gss_auth *auth;
	struct rpc_wait_queue waitq;
	uid_t	uid;
	atomic_t count;
};

static void
gss_release_msg(struct gss_upcall_msg *gss_msg)
{
	if (!atomic_dec_and_test(&gss_msg->count))
		return;
	BUG_ON(!list_empty(&gss_msg->list));
	kfree(gss_msg);
}

static struct gss_upcall_msg *
__gss_find_upcall(struct gss_auth *gss_auth, uid_t uid)
{
	struct gss_upcall_msg *pos;
	list_for_each_entry(pos, &gss_auth->upcalls, list) {
		if (pos->uid != uid)
			continue;
		atomic_inc(&pos->count);
		dprintk("RPC:      gss_find_upcall found msg %p\n", pos);
		return pos;
	}
	dprintk("RPC:      gss_find_upcall found nothing\n");
	return NULL;
}

static void
__gss_unhash_msg(struct gss_upcall_msg *gss_msg)
{
	if (list_empty(&gss_msg->list))
		return;
	list_del_init(&gss_msg->list);
	if (gss_msg->msg.errno < 0)
		rpc_wake_up_status(&gss_msg->waitq, gss_msg->msg.errno);
	else
		rpc_wake_up(&gss_msg->waitq);
	atomic_dec(&gss_msg->count);
}

static void
gss_unhash_msg(struct gss_upcall_msg *gss_msg)
{
	struct gss_auth *gss_auth = gss_msg->auth;

	spin_lock(&gss_auth->lock);
	__gss_unhash_msg(gss_msg);
	spin_unlock(&gss_auth->lock);
}

static int
gss_upcall(struct rpc_clnt *clnt, struct rpc_task *task, struct rpc_cred *cred)
{
	struct gss_auth *gss_auth = container_of(clnt->cl_auth,
			struct gss_auth, rpc_auth);
	struct gss_upcall_msg *gss_msg, *gss_new = NULL;
	struct rpc_pipe_msg *msg;
	struct dentry *dentry = gss_auth->dentry;
	uid_t uid = cred->cr_uid;
	int res = 0;

	dprintk("RPC: %4u gss_upcall for uid %u\n", task->tk_pid, uid);

retry:
	spin_lock(&gss_auth->lock);
	gss_msg = __gss_find_upcall(gss_auth, uid);
	if (gss_msg)
		goto out_sleep;
	if (gss_new == NULL) {
		spin_unlock(&gss_auth->lock);
		gss_new = kmalloc(sizeof(*gss_new), GFP_KERNEL);
		if (!gss_new) {
			dprintk("RPC: %4u gss_upcall -ENOMEM\n", task->tk_pid);
			return -ENOMEM;
		}
		goto retry;
	}
	gss_msg = gss_new;
	memset(gss_new, 0, sizeof(*gss_new));
	INIT_LIST_HEAD(&gss_new->list);
	rpc_init_wait_queue(&gss_new->waitq, "RPCSEC_GSS upcall waitq");
	atomic_set(&gss_new->count, 2);
	msg = &gss_new->msg;
	msg->data = &gss_new->uid;
	msg->len = sizeof(gss_new->uid);
	gss_new->uid = uid;
	gss_new->auth = gss_auth;
	list_add(&gss_new->list, &gss_auth->upcalls);
	gss_new = NULL;
	/* Has someone updated the credential behind our back? */
	if (!gss_cred_is_uptodate_ctx(cred)) {
		/* No, so do upcall and sleep */
		task->tk_timeout = 0;
		rpc_sleep_on(&gss_msg->waitq, task, NULL, NULL);
		spin_unlock(&gss_auth->lock);
		res = rpc_queue_upcall(dentry->d_inode, msg);
		if (res)
			gss_unhash_msg(gss_msg);
	} else {
		/* Yes, so cancel upcall */
		__gss_unhash_msg(gss_msg);
		spin_unlock(&gss_auth->lock);
	}
	gss_release_msg(gss_msg);
	dprintk("RPC: %4u gss_upcall for uid %u result %d\n", task->tk_pid,
			uid, res);
	return res;
out_sleep:
	task->tk_timeout = 0;
	rpc_sleep_on(&gss_msg->waitq, task, NULL, NULL);
	spin_unlock(&gss_auth->lock);
	dprintk("RPC: %4u gss_upcall  sleeping\n", task->tk_pid);
	if (gss_new)
		kfree(gss_new);
	/* Note: we drop the reference here: we are automatically removed
	 * from the queue when we're woken up, and we should in any case
	 * have no further responsabilities w.r.t. the upcall.
	 */
	gss_release_msg(gss_msg);
	return 0;
}

static ssize_t
gss_pipe_upcall(struct file *filp, struct rpc_pipe_msg *msg,
		char __user *dst, size_t buflen)
{
	char *data = (char *)msg->data + msg->copied;
	ssize_t mlen = msg->len;
	ssize_t left;

	if (mlen > buflen)
		mlen = buflen;
	left = copy_to_user(dst, data, mlen);
	if (left < 0) {
		msg->errno = left;
		return left;
	}
	mlen -= left;
	msg->copied += mlen;
	msg->errno = 0;
	return mlen;
}

#define MSG_BUF_MAXSIZE 1024

static ssize_t
gss_pipe_downcall(struct file *filp, const char __user *src, size_t mlen)
{
	struct xdr_netobj obj = {
		.len	= mlen,
	};
	struct inode *inode = filp->f_dentry->d_inode;
	struct rpc_inode *rpci = RPC_I(inode);
	struct rpc_clnt *clnt;
	struct rpc_auth *auth;
	struct gss_auth *gss_auth;
	struct gss_api_mech *mech;
	struct auth_cred acred = { 0 };
	struct rpc_cred *cred;
	struct gss_upcall_msg *gss_msg;
	struct gss_cl_ctx *ctx = NULL;
	ssize_t left;
	int err;
	int gss_err;

	if (mlen > MSG_BUF_MAXSIZE)
		return -EFBIG;
	obj.data = kmalloc(mlen, GFP_KERNEL);
	if (!obj.data)
		return -ENOMEM;
	left = copy_from_user(obj.data, src, mlen);
	if (left) {
		err = -EFAULT;
		goto out;
	}
	clnt = rpci->private;
	atomic_inc(&clnt->cl_users);
	auth = clnt->cl_auth;
	gss_auth = container_of(auth, struct gss_auth, rpc_auth);
	mech = gss_auth->mech;
	err = gss_parse_init_downcall(mech, &obj, &ctx, &acred.uid, &gss_err);
	if (err)
		goto err;
	cred = rpcauth_lookup_credcache(auth, &acred, 0);
	if (!cred)
		goto err;
	if (gss_err)
		cred->cr_flags &= ~RPCAUTH_CRED_UPTODATE;
	else
		gss_cred_set_ctx(cred, ctx);
	spin_lock(&gss_auth->lock);
	gss_msg = __gss_find_upcall(gss_auth, acred.uid);
	if (gss_msg) {
		if (gss_err)
			gss_msg->msg.errno = -EACCES;
		__gss_unhash_msg(gss_msg);
		spin_unlock(&gss_auth->lock);
		gss_release_msg(gss_msg);
	} else
		spin_unlock(&gss_auth->lock);
	rpc_release_client(clnt);
	kfree(obj.data);
	dprintk("RPC:      gss_pipe_downcall returning length %Zu\n", mlen);
	return mlen;
err:
	if (ctx)
		gss_destroy_ctx(ctx);
	rpc_release_client(clnt);
out:
	kfree(obj.data);
	dprintk("RPC:      gss_pipe_downcall returning %d\n", err);
	return err;
}

static void
gss_pipe_release(struct inode *inode)
{
	struct rpc_inode *rpci = RPC_I(inode);
	struct rpc_clnt *clnt;
	struct rpc_auth *auth;
	struct gss_auth *gss_auth;

	clnt = rpci->private;
	auth = clnt->cl_auth;
	gss_auth = container_of(auth, struct gss_auth, rpc_auth);
	spin_lock(&gss_auth->lock);
	while (!list_empty(&gss_auth->upcalls)) {
		struct gss_upcall_msg *gss_msg;

		gss_msg = list_entry(gss_auth->upcalls.next,
				struct gss_upcall_msg, list);
		gss_msg->msg.errno = -EPIPE;