path: root/fs/nfsd/nfs4recover.c

/*
*  Copyright (c) 2004 The Regents of the University of Michigan.
*  Copyright (c) 2012 Jeff Layton <jlayton@redhat.com>
*  All rights reserved.
*
*  Andy Adamson <andros@citi.umich.edu>
*
*  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.
*
*/

#include <crypto/hash.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/namei.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <net/net_namespace.h>
#include <linux/sunrpc/rpc_pipe_fs.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfsd/cld.h>

#include "nfsd.h"
#include "state.h"
#include "vfs.h"
#include "netns.h"

#define NFSDDBG_FACILITY                NFSDDBG_PROC

/* Declarations */
struct nfsd4_client_tracking_ops {
	int (*init)(struct net *);
	void (*exit)(struct net *);
	void (*create)(struct nfs4_client *);
	void (*remove)(struct nfs4_client *);
	int (*check)(struct nfs4_client *);
	void (*grace_done)(struct nfsd_net *);
};

/* Globals */
static char user_recovery_dirname[PATH_MAX] = "/var/lib/nfs/v4recovery";

static int
nfs4_save_creds(const struct cred **original_creds)
{
	struct cred *new;

	new = prepare_creds();
	if (!new)
		return -ENOMEM;

	new->fsuid = GLOBAL_ROOT_UID;
	new->fsgid = GLOBAL_ROOT_GID;
	*original_creds = override_creds(new);
	put_cred(new);
	return 0;
}

static void
nfs4_reset_creds(const struct cred *original)
{
	revert_creds(original);
}

static void
md5_to_hex(char *out, char *md5)
{
	int i;

	for (i=0; i<16; i++) {
		unsigned char c = md5[i];

		*out++ = '0' + ((c&0xf0)>>4) + (c>=0xa0)*('a'-'9'-1);
		*out++ = '0' + (c&0x0f) + ((c&0x0f)>=0x0a)*('a'-'9'-1);
	}
	*out = '\0';
}

static int
nfs4_make_rec_clidname(char *dname, const struct xdr_netobj *clname)
{
	struct xdr_netobj cksum;
	struct crypto_shash *tfm;
	int status;

	dprintk("NFSD: nfs4_make_rec_clidname for %.*s\n",
			clname->len, clname->data);
	tfm = crypto_alloc_shash("md5", 0, 0);
	if (IS_ERR(tfm)) {
		status = PTR_ERR(tfm);
		goto out_no_tfm;
	}

	cksum.len = crypto_shash_digestsize(tfm);
	cksum.data = kmalloc(cksum.len, GFP_KERNEL);
	if (cksum.data == NULL) {
		status = -ENOMEM;
 		goto out;
	}

	{
		SHASH_DESC_ON_STACK(desc, tfm);

		desc->tfm = tfm;
		desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;

		status = crypto_shash_digest(desc, clname->data, clname->len,
					     cksum.data);
		shash_desc_zero(desc);
	}

	if (status)
		goto out;

	md5_to_hex(dname, cksum.data);

	status = 0;
out:
	kfree(cksum.data);
	crypto_free_shash(tfm);
out_no_tfm:
	return status;
}

/*
 * If we had an error generating the recdir name for the legacy tracker
 * then warn the admin. If the error doesn't appear to be transient,
 * then disable recovery tracking.
 */
static void
legacy_recdir_name_error(struct nfs4_client *clp, int error)
{
	printk(KERN_ERR "NFSD: unable to generate recoverydir "
			"name (%d).\n", error);

	/*
	 * if the algorithm just doesn't exist, then disable the recovery
	 * tracker altogether. The crypto libs will generally return this if
	 * FIPS is enabled as well.
	 */
	if (error == -ENOENT) {
		printk(KERN_ERR "NFSD: disabling legacy clientid tracking. "
			"Reboot recovery will not function correctly!\n");
		nfsd4_client_tracking_exit(clp->net);
	}
}

static void
nfsd4_create_clid_dir(struct nfs4_client *clp)
{
	const struct cred *original_cred;
	char dname[HEXDIR_LEN];
	struct dentry *dir, *dentry;
	struct nfs4_client_reclaim *crp;
	int status;
	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);

	if (test_and_set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags))
		return;
	if (!nn->rec_file)
		return;

	status = nfs4_make_rec_clidname(dname, &clp->cl_name);
	if (status)
		return legacy_recdir_name_error(clp, status);

	status = nfs4_save_creds(&original_cred);
	if (status < 0)
		return;

	status = mnt_want_write_file(nn->rec_file);
	if (status)
		goto out_creds;

	dir = nn->rec_file->f_path.dentry;
	/* lock the parent */
	inode_lock(d_inode(dir));

	dentry = lookup_one_len(dname, dir, HEXDIR_LEN-1);
	if (IS_ERR(dentry)) {
		status = PTR_ERR(dentry);
		goto out_unlock;
	}
	if (d_really_is_positive(dentry))
		/*
		 * In the 4.1 case, where we're called from
		 * reclaim_complete(), records from the previous reboot
		 * may still be left, so this is OK.
		 *
		 * In the 4.0 case, we should never get here; but we may
		 * as well be forgiving and just succeed silently.
		 */
		goto out_put;
	status = vfs_mkdir(d_inode(dir), dentry, S_IRWXU);
out_put:
	dput(dentry);
out_unlock:
	inode_unlock(d_inode(dir));
	if (status == 0) {
		if (nn->in_grace) {
			crp = nfs4_client_to_reclaim(dname, nn);
			if (crp)
				crp->cr_clp = clp;
		}
		vfs_fsync(nn->rec_file, 0);
	} else {
		printk(KERN_ERR "NFSD: failed to write recovery record"
				" (err %d); please check that %s exists"
				" and is writeable", status,
				user_recovery_dirname);
	}
	mnt_drop_write_file(nn->rec_file);
out_creds:
	nfs4_reset_creds(original_cred);