export.c

linux 内核源代码

#define MSNFS	/* HACK HACK */
/*
 * linux/fs/nfsd/export.c
 *
 * NFS exporting and validation.
 *
 * We maintain a list of clients, each of which has a list of
 * exports. To export an fs to a given client, you first have
 * to create the client entry with NFSCTL_ADDCLIENT, which
 * creates a client control block and adds it to the hash
 * table. Then, you call NFSCTL_EXPORT for each fs.
 *
 *
 * Copyright (C) 1995, 1996 Olaf Kirch, <[e-mail]>
 */

#include <linux/unistd.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/in.h>
#include <linux/seq_file.h>
#include <linux/syscalls.h>
#include <linux/rwsem.h>
#include <linux/dcache.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/hash.h>
#include <linux/module.h>
#include <linux/exportfs.h>

#include <linux/sunrpc/svc.h>
#include <linux/nfsd/nfsd.h>
#include <linux/nfsd/nfsfh.h>
#include <linux/nfsd/syscall.h>
#include <linux/lockd/bind.h>
#include <linux/sunrpc/msg_prot.h>
#include <linux/sunrpc/gss_api.h>

#define NFSDDBG_FACILITY	NFSDDBG_EXPORT

typedef struct auth_domain	svc_client;
typedef struct svc_export	svc_export;

static void		exp_do_unexport(svc_export *unexp);
static int		exp_verify_string(char *cp, int max);

/*
 * We have two caches.
 * One maps client+vfsmnt+dentry to export options - the export map
 * The other maps client+filehandle-fragment to export options. - the expkey map
 *
 * The export options are actually stored in the first map, and the
 * second map contains a reference to the entry in the first map.
 */

#define	EXPKEY_HASHBITS		8
#define	EXPKEY_HASHMAX		(1 << EXPKEY_HASHBITS)
#define	EXPKEY_HASHMASK		(EXPKEY_HASHMAX -1)
static struct cache_head *expkey_table[EXPKEY_HASHMAX];

static void expkey_put(struct kref *ref)
{
	struct svc_expkey *key = container_of(ref, struct svc_expkey, h.ref);

	if (test_bit(CACHE_VALID, &key->h.flags) &&
	    !test_bit(CACHE_NEGATIVE, &key->h.flags)) {
		dput(key->ek_dentry);
		mntput(key->ek_mnt);
	}
	auth_domain_put(key->ek_client);
	kfree(key);
}

static void expkey_request(struct cache_detail *cd,
			   struct cache_head *h,
			   char **bpp, int *blen)
{
	/* client fsidtype \xfsid */
	struct svc_expkey *ek = container_of(h, struct svc_expkey, h);
	char type[5];

	qword_add(bpp, blen, ek->ek_client->name);
	snprintf(type, 5, "%d", ek->ek_fsidtype);
	qword_add(bpp, blen, type);
	qword_addhex(bpp, blen, (char*)ek->ek_fsid, key_len(ek->ek_fsidtype));
	(*bpp)[-1] = '\n';
}

static struct svc_expkey *svc_expkey_update(struct svc_expkey *new, struct svc_expkey *old);
static struct svc_expkey *svc_expkey_lookup(struct svc_expkey *);
static struct cache_detail svc_expkey_cache;

static int expkey_parse(struct cache_detail *cd, char *mesg, int mlen)
{
	/* client fsidtype fsid [path] */
	char *buf;
	int len;
	struct auth_domain *dom = NULL;
	int err;
	int fsidtype;
	char *ep;
	struct svc_expkey key;
	struct svc_expkey *ek;

	if (mesg[mlen-1] != '\n')
		return -EINVAL;
	mesg[mlen-1] = 0;

	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
	err = -ENOMEM;
	if (!buf) goto out;

	err = -EINVAL;
	if ((len=qword_get(&mesg, buf, PAGE_SIZE)) <= 0)
		goto out;

	err = -ENOENT;
	dom = auth_domain_find(buf);
	if (!dom)
		goto out;
	dprintk("found domain %s\n", buf);

	err = -EINVAL;
	if ((len=qword_get(&mesg, buf, PAGE_SIZE)) <= 0)
		goto out;
	fsidtype = simple_strtoul(buf, &ep, 10);
	if (*ep)
		goto out;
	dprintk("found fsidtype %d\n", fsidtype);
	if (key_len(fsidtype)==0) /* invalid type */
		goto out;
	if ((len=qword_get(&mesg, buf, PAGE_SIZE)) <= 0)
		goto out;
	dprintk("found fsid length %d\n", len);
	if (len != key_len(fsidtype))
		goto out;

	/* OK, we seem to have a valid key */
	key.h.flags = 0;
	key.h.expiry_time = get_expiry(&mesg);
	if (key.h.expiry_time == 0)
		goto out;

	key.ek_client = dom;	
	key.ek_fsidtype = fsidtype;
	memcpy(key.ek_fsid, buf, len);

	ek = svc_expkey_lookup(&key);
	err = -ENOMEM;
	if (!ek)
		goto out;

	/* now we want a pathname, or empty meaning NEGATIVE  */
	err = -EINVAL;
	if ((len=qword_get(&mesg, buf, PAGE_SIZE)) < 0)
		goto out;
	dprintk("Path seems to be <%s>\n", buf);
	err = 0;
	if (len == 0) {
		set_bit(CACHE_NEGATIVE, &key.h.flags);
		ek = svc_expkey_update(&key, ek);
		if (ek)
			cache_put(&ek->h, &svc_expkey_cache);
		else err = -ENOMEM;
	} else {
		struct nameidata nd;
		err = path_lookup(buf, 0, &nd);
		if (err)
			goto out;

		dprintk("Found the path %s\n", buf);
		key.ek_mnt = nd.mnt;
		key.ek_dentry = nd.dentry;
		
		ek = svc_expkey_update(&key, ek);
		if (ek)
			cache_put(&ek->h, &svc_expkey_cache);
		else
			err = -ENOMEM;
		path_release(&nd);
	}
	cache_flush();
 out:
	if (dom)
		auth_domain_put(dom);
	kfree(buf);
	return err;
}

static int expkey_show(struct seq_file *m,
		       struct cache_detail *cd,
		       struct cache_head *h)
{
	struct svc_expkey *ek ;
	int i;

	if (h ==NULL) {
		seq_puts(m, "#domain fsidtype fsid [path]\n");
		return 0;
	}
	ek = container_of(h, struct svc_expkey, h);
	seq_printf(m, "%s %d 0x", ek->ek_client->name,
		   ek->ek_fsidtype);
	for (i=0; i < key_len(ek->ek_fsidtype)/4; i++)
		seq_printf(m, "%08x", ek->ek_fsid[i]);
	if (test_bit(CACHE_VALID, &h->flags) && 
	    !test_bit(CACHE_NEGATIVE, &h->flags)) {
		seq_printf(m, " ");
		seq_path(m, ek->ek_mnt, ek->ek_dentry, "\\ \t\n");
	}
	seq_printf(m, "\n");
	return 0;
}

static inline int expkey_match (struct cache_head *a, struct cache_head *b)
{
	struct svc_expkey *orig = container_of(a, struct svc_expkey, h);
	struct svc_expkey *new = container_of(b, struct svc_expkey, h);

	if (orig->ek_fsidtype != new->ek_fsidtype ||
	    orig->ek_client != new->ek_client ||
	    memcmp(orig->ek_fsid, new->ek_fsid, key_len(orig->ek_fsidtype)) != 0)
		return 0;
	return 1;
}

static inline void expkey_init(struct cache_head *cnew,
				   struct cache_head *citem)
{
	struct svc_expkey *new = container_of(cnew, struct svc_expkey, h);
	struct svc_expkey *item = container_of(citem, struct svc_expkey, h);

	kref_get(&item->ek_client->ref);
	new->ek_client = item->ek_client;
	new->ek_fsidtype = item->ek_fsidtype;

	memcpy(new->ek_fsid, item->ek_fsid, sizeof(new->ek_fsid));
}

static inline void expkey_update(struct cache_head *cnew,
				   struct cache_head *citem)
{
	struct svc_expkey *new = container_of(cnew, struct svc_expkey, h);
	struct svc_expkey *item = container_of(citem, struct svc_expkey, h);

	new->ek_mnt = mntget(item->ek_mnt);
	new->ek_dentry = dget(item->ek_dentry);
}

static struct cache_head *expkey_alloc(void)
{
	struct svc_expkey *i = kmalloc(sizeof(*i), GFP_KERNEL);
	if (i)
		return &i->h;
	else
		return NULL;
}

static struct cache_detail svc_expkey_cache = {
	.owner		= THIS_MODULE,
	.hash_size	= EXPKEY_HASHMAX,
	.hash_table	= expkey_table,
	.name		= "nfsd.fh",
	.cache_put	= expkey_put,
	.cache_request	= expkey_request,
	.cache_parse	= expkey_parse,
	.cache_show	= expkey_show,
	.match		= expkey_match,
	.init		= expkey_init,
	.update       	= expkey_update,
	.alloc		= expkey_alloc,
};

static struct svc_expkey *
svc_expkey_lookup(struct svc_expkey *item)
{
	struct cache_head *ch;
	int hash = item->ek_fsidtype;
	char * cp = (char*)item->ek_fsid;
	int len = key_len(item->ek_fsidtype);

	hash ^= hash_mem(cp, len, EXPKEY_HASHBITS);
	hash ^= hash_ptr(item->ek_client, EXPKEY_HASHBITS);
	hash &= EXPKEY_HASHMASK;

	ch = sunrpc_cache_lookup(&svc_expkey_cache, &item->h,
				 hash);
	if (ch)
		return container_of(ch, struct svc_expkey, h);
	else
		return NULL;
}

static struct svc_expkey *
svc_expkey_update(struct svc_expkey *new, struct svc_expkey *old)
{
	struct cache_head *ch;
	int hash = new->ek_fsidtype;
	char * cp = (char*)new->ek_fsid;
	int len = key_len(new->ek_fsidtype);

	hash ^= hash_mem(cp, len, EXPKEY_HASHBITS);
	hash ^= hash_ptr(new->ek_client, EXPKEY_HASHBITS);
	hash &= EXPKEY_HASHMASK;

	ch = sunrpc_cache_update(&svc_expkey_cache, &new->h,
				 &old->h, hash);
	if (ch)
		return container_of(ch, struct svc_expkey, h);
	else
		return NULL;
}


#define	EXPORT_HASHBITS		8
#define	EXPORT_HASHMAX		(1<< EXPORT_HASHBITS)
#define	EXPORT_HASHMASK		(EXPORT_HASHMAX -1)

static struct cache_head *export_table[EXPORT_HASHMAX];

static void nfsd4_fslocs_free(struct nfsd4_fs_locations *fsloc)
{
	int i;

	for (i = 0; i < fsloc->locations_count; i++) {
		kfree(fsloc->locations[i].path);
		kfree(fsloc->locations[i].hosts);
	}
	kfree(fsloc->locations);
}

static void svc_export_put(struct kref *ref)
{
	struct svc_export *exp = container_of(ref, struct svc_export, h.ref);
	dput(exp->ex_dentry);
	mntput(exp->ex_mnt);
	auth_domain_put(exp->ex_client);
	kfree(exp->ex_path);
	nfsd4_fslocs_free(&exp->ex_fslocs);
	kfree(exp);
}

static void svc_export_request(struct cache_detail *cd,
			       struct cache_head *h,
			       char **bpp, int *blen)
{
	/*  client path */
	struct svc_export *exp = container_of(h, struct svc_export, h);
	char *pth;

	qword_add(bpp, blen, exp->ex_client->name);
	pth = d_path(exp->ex_dentry, exp->ex_mnt, *bpp, *blen);
	if (IS_ERR(pth)) {
		/* is this correct? */
		(*bpp)[0] = '\n';
		return;
	}
	qword_add(bpp, blen, pth);
	(*bpp)[-1] = '\n';
}

static struct svc_export *svc_export_update(struct svc_export *new,
					    struct svc_export *old);
static struct svc_export *svc_export_lookup(struct svc_export *);

static int check_export(struct inode *inode, int flags, unsigned char *uuid)
{

	/* We currently export only dirs and regular files.
	 * This is what umountd does.
	 */
	if (!S_ISDIR(inode->i_mode) &&
	    !S_ISREG(inode->i_mode))
		return -ENOTDIR;

	/* There are two requirements on a filesystem to be exportable.
	 * 1:  We must be able to identify the filesystem from a number.
	 *       either a device number (so FS_REQUIRES_DEV needed)
	 *       or an FSID number (so NFSEXP_FSID or ->uuid is needed).
	 * 2:  We must be able to find an inode from a filehandle.
	 *       This means that s_export_op must be set.
	 */
	if (!(inode->i_sb->s_type->fs_flags & FS_REQUIRES_DEV) &&
	    !(flags & NFSEXP_FSID) &&
	    uuid == NULL) {
		dprintk("exp_export: export of non-dev fs without fsid\n");
		return -EINVAL;
	}

	if (!inode->i_sb->s_export_op ||
	    !inode->i_sb->s_export_op->fh_to_dentry) {
		dprintk("exp_export: export of invalid fs type.\n");
		return -EINVAL;
	}

	return 0;

}

#ifdef CONFIG_NFSD_V4

static int
fsloc_parse(char **mesg, char *buf, struct nfsd4_fs_locations *fsloc)
{
	int len;
	int migrated, i, err;

	/* listsize */
	err = get_int(mesg, &fsloc->locations_count);
	if (err)
		return err;
	if (fsloc->locations_count > MAX_FS_LOCATIONS)
		return -EINVAL;
	if (fsloc->locations_count == 0)
		return 0;

	fsloc->locations = kzalloc(fsloc->locations_count
			* sizeof(struct nfsd4_fs_location), GFP_KERNEL);
	if (!fsloc->locations)
		return -ENOMEM;
	for (i=0; i < fsloc->locations_count; i++) {
		/* colon separated host list */
		err = -EINVAL;
		len = qword_get(mesg, buf, PAGE_SIZE);
		if (len <= 0)
			goto out_free_all;
		err = -ENOMEM;
		fsloc->locations[i].hosts = kstrdup(buf, GFP_KERNEL);
		if (!fsloc->locations[i].hosts)
			goto out_free_all;
		err = -EINVAL;
		/* slash separated path component list */
		len = qword_get(mesg, buf, PAGE_SIZE);
		if (len <= 0)
			goto out_free_all;
		err = -ENOMEM;
		fsloc->locations[i].path = kstrdup(buf, GFP_KERNEL);
		if (!fsloc->locations[i].path)
			goto out_free_all;
	}
	/* migrated */
	err = get_int(mesg, &migrated);
	if (err)
		goto out_free_all;
	err = -EINVAL;
	if (migrated < 0 || migrated > 1)
		goto out_free_all;
	fsloc->migrated = migrated;
	return 0;
out_free_all:
	nfsd4_fslocs_free(fsloc);
	return err;
}

static int secinfo_parse(char **mesg, char *buf, struct svc_export *exp)
{
	int listsize, err;
	struct exp_flavor_info *f;

	err = get_int(mesg, &listsize);
	if (err)
		return err;
	if (listsize < 0 || listsize > MAX_SECINFO_LIST)
		return -EINVAL;

	for (f = exp->ex_flavors; f < exp->ex_flavors + listsize; f++) {
		err = get_int(mesg, &f->pseudoflavor);
		if (err)
			return err;
		/*
		 * Just a quick sanity check; we could also try to check
		 * whether this pseudoflavor is supported, but at worst
		 * an unsupported pseudoflavor on the export would just
		 * be a pseudoflavor that won't match the flavor of any
		 * authenticated request.  The administrator will
		 * probably discover the problem when someone fails to
		 * authenticate.
		 */
		if (f->pseudoflavor < 0)
			return -EINVAL;
		err = get_int(mesg, &f->flags);
		if (err)
			return err;
		/* Only some flags are allowed to differ between flavors: */
		if (~NFSEXP_SECINFO_FLAGS & (f->flags ^ exp->ex_flags))
			return -EINVAL;
	}
	exp->ex_nflavors = listsize;
	return 0;
}

#else /* CONFIG_NFSD_V4 */
static inline int
fsloc_parse(char **mesg, char *buf, struct nfsd4_fs_locations *fsloc){return 0;}
static inline int
secinfo_parse(char **mesg, char *buf, struct svc_export *exp) { return 0; }
#endif

static int svc_export_parse(struct cache_detail *cd, char *mesg, int mlen)
{
	/* client path expiry [flags anonuid anongid fsid] */
	char *buf;
	int len;
	int err;
	struct auth_domain *dom = NULL;
	struct nameidata nd;
	struct svc_export exp, *expp;
	int an_int;

	nd.dentry = NULL;
	exp.ex_path = NULL;

	/* fs locations */
	exp.ex_fslocs.locations = NULL;
	exp.ex_fslocs.locations_count = 0;
	exp.ex_fslocs.migrated = 0;

	exp.ex_uuid = NULL;

	/* secinfo */
	exp.ex_nflavors = 0;

	if (mesg[mlen-1] != '\n')
		return -EINVAL;
	mesg[mlen-1] = 0;

	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
	err = -ENOMEM;
	if (!buf) goto out;

	/* client */
	len = qword_get(&mesg, buf, PAGE_SIZE);
	err = -EINVAL;
	if (len <= 0) goto out;

	err = -ENOENT;
	dom = auth_domain_find(buf);
	if (!dom)
		goto out;

	/* path */
	err = -EINVAL;
	if ((len=qword_get(&mesg, buf, PAGE_SIZE)) <= 0)
		goto out;
	err = path_lookup(buf, 0, &nd);
	if (err) goto out_no_path;

	exp.h.flags = 0;
	exp.ex_client = dom;
	exp.ex_mnt = nd.mnt;
	exp.ex_dentry = nd.dentry;
	exp.ex_path = kstrdup(buf, GFP_KERNEL);
	err = -ENOMEM;
	if (!exp.ex_path)
		goto out;

	/* expiry */
	err = -EINVAL;
	exp.h.expiry_time = get_expiry(&mesg);
	if (exp.h.expiry_time == 0)
		goto out;