nfs4acl.c

linux 内核源代码

/*
 *  fs/nfs4acl/acl.c
 *
 *  Common NFSv4 ACL handling code.
 *
 *  Copyright (c) 2002, 2003 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Marius Aamodt Eriksen <[e-mail]>
 *  Jeff Sedlak <[e-mail]>
 *  J. Bruce Fields <[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.
 */

#include <linux/string.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/nfs_fs.h>
#include <linux/posix_acl.h>
#include <linux/nfs4.h>
#include <linux/nfs4_acl.h>


/* mode bit translations: */
#define NFS4_READ_MODE (NFS4_ACE_READ_DATA)
#define NFS4_WRITE_MODE (NFS4_ACE_WRITE_DATA | NFS4_ACE_APPEND_DATA)
#define NFS4_EXECUTE_MODE NFS4_ACE_EXECUTE
#define NFS4_ANYONE_MODE (NFS4_ACE_READ_ATTRIBUTES | NFS4_ACE_READ_ACL | NFS4_ACE_SYNCHRONIZE)
#define NFS4_OWNER_MODE (NFS4_ACE_WRITE_ATTRIBUTES | NFS4_ACE_WRITE_ACL)

/* We don't support these bits; insist they be neither allowed nor denied */
#define NFS4_MASK_UNSUPP (NFS4_ACE_DELETE | NFS4_ACE_WRITE_OWNER \
		| NFS4_ACE_READ_NAMED_ATTRS | NFS4_ACE_WRITE_NAMED_ATTRS)

/* flags used to simulate posix default ACLs */
#define NFS4_INHERITANCE_FLAGS (NFS4_ACE_FILE_INHERIT_ACE \
		| NFS4_ACE_DIRECTORY_INHERIT_ACE)

#define NFS4_SUPPORTED_FLAGS (NFS4_INHERITANCE_FLAGS \
		| NFS4_ACE_INHERIT_ONLY_ACE \
		| NFS4_ACE_IDENTIFIER_GROUP)

#define MASK_EQUAL(mask1, mask2) \
	( ((mask1) & NFS4_ACE_MASK_ALL) == ((mask2) & NFS4_ACE_MASK_ALL) )

static u32
mask_from_posix(unsigned short perm, unsigned int flags)
{
	int mask = NFS4_ANYONE_MODE;

	if (flags & NFS4_ACL_OWNER)
		mask |= NFS4_OWNER_MODE;
	if (perm & ACL_READ)
		mask |= NFS4_READ_MODE;
	if (perm & ACL_WRITE)
		mask |= NFS4_WRITE_MODE;
	if ((perm & ACL_WRITE) && (flags & NFS4_ACL_DIR))
		mask |= NFS4_ACE_DELETE_CHILD;
	if (perm & ACL_EXECUTE)
		mask |= NFS4_EXECUTE_MODE;
	return mask;
}

static u32
deny_mask_from_posix(unsigned short perm, u32 flags)
{
	u32 mask = 0;

	if (perm & ACL_READ)
		mask |= NFS4_READ_MODE;
	if (perm & ACL_WRITE)
		mask |= NFS4_WRITE_MODE;
	if ((perm & ACL_WRITE) && (flags & NFS4_ACL_DIR))
		mask |= NFS4_ACE_DELETE_CHILD;
	if (perm & ACL_EXECUTE)
		mask |= NFS4_EXECUTE_MODE;
	return mask;
}

/* XXX: modify functions to return NFS errors; they're only ever
 * used by nfs code, after all.... */

/* We only map from NFSv4 to POSIX ACLs when setting ACLs, when we err on the
 * side of being more restrictive, so the mode bit mapping below is
 * pessimistic.  An optimistic version would be needed to handle DENY's,
 * but we espect to coalesce all ALLOWs and DENYs before mapping to mode
 * bits. */

static void
low_mode_from_nfs4(u32 perm, unsigned short *mode, unsigned int flags)
{
	u32 write_mode = NFS4_WRITE_MODE;

	if (flags & NFS4_ACL_DIR)
		write_mode |= NFS4_ACE_DELETE_CHILD;
	*mode = 0;
	if ((perm & NFS4_READ_MODE) == NFS4_READ_MODE)
		*mode |= ACL_READ;
	if ((perm & write_mode) == write_mode)
		*mode |= ACL_WRITE;
	if ((perm & NFS4_EXECUTE_MODE) == NFS4_EXECUTE_MODE)
		*mode |= ACL_EXECUTE;
}

struct ace_container {
	struct nfs4_ace  *ace;
	struct list_head  ace_l;
};

static short ace2type(struct nfs4_ace *);
static void _posix_to_nfsv4_one(struct posix_acl *, struct nfs4_acl *,
				unsigned int);

struct nfs4_acl *
nfs4_acl_posix_to_nfsv4(struct posix_acl *pacl, struct posix_acl *dpacl,
			unsigned int flags)
{
	struct nfs4_acl *acl;
	int size = 0;

	if (pacl) {
		if (posix_acl_valid(pacl) < 0)
			return ERR_PTR(-EINVAL);
		size += 2*pacl->a_count;
	}
	if (dpacl) {
		if (posix_acl_valid(dpacl) < 0)
			return ERR_PTR(-EINVAL);
		size += 2*dpacl->a_count;
	}

	/* Allocate for worst case: one (deny, allow) pair each: */
	acl = nfs4_acl_new(size);
	if (acl == NULL)
		return ERR_PTR(-ENOMEM);

	if (pacl)
		_posix_to_nfsv4_one(pacl, acl, flags & ~NFS4_ACL_TYPE_DEFAULT);

	if (dpacl)
		_posix_to_nfsv4_one(dpacl, acl, flags | NFS4_ACL_TYPE_DEFAULT);

	return acl;
}

struct posix_acl_summary {
	unsigned short owner;
	unsigned short users;
	unsigned short group;
	unsigned short groups;
	unsigned short other;
	unsigned short mask;
};

static void
summarize_posix_acl(struct posix_acl *acl, struct posix_acl_summary *pas)
{
	struct posix_acl_entry *pa, *pe;

	/*
	 * Only pas.users and pas.groups need initialization; previous
	 * posix_acl_valid() calls ensure that the other fields will be
	 * initialized in the following loop.  But, just to placate gcc:
	 */
	memset(pas, 0, sizeof(*pas));
	pas->mask = 07;

	pe = acl->a_entries + acl->a_count;

	FOREACH_ACL_ENTRY(pa, acl, pe) {
		switch (pa->e_tag) {
			case ACL_USER_OBJ:
				pas->owner = pa->e_perm;
				break;
			case ACL_GROUP_OBJ:
				pas->group = pa->e_perm;
				break;
			case ACL_USER:
				pas->users |= pa->e_perm;
				break;
			case ACL_GROUP:
				pas->groups |= pa->e_perm;
				break;
			case ACL_OTHER:
				pas->other = pa->e_perm;
				break;
			case ACL_MASK:
				pas->mask = pa->e_perm;
				break;
		}
	}
	/* We'll only care about effective permissions: */
	pas->users &= pas->mask;
	pas->group &= pas->mask;
	pas->groups &= pas->mask;
}

/* We assume the acl has been verified with posix_acl_valid. */
static void
_posix_to_nfsv4_one(struct posix_acl *pacl, struct nfs4_acl *acl,
						unsigned int flags)
{
	struct posix_acl_entry *pa, *group_owner_entry;
	struct nfs4_ace *ace;
	struct posix_acl_summary pas;
	unsigned short deny;
	int eflag = ((flags & NFS4_ACL_TYPE_DEFAULT) ?
		NFS4_INHERITANCE_FLAGS | NFS4_ACE_INHERIT_ONLY_ACE : 0);

	BUG_ON(pacl->a_count < 3);
	summarize_posix_acl(pacl, &pas);

	pa = pacl->a_entries;
	ace = acl->aces + acl->naces;

	/* We could deny everything not granted by the owner: */
	deny = ~pas.owner;
	/*
	 * but it is equivalent (and simpler) to deny only what is not
	 * granted by later entries:
	 */
	deny &= pas.users | pas.group | pas.groups | pas.other;
	if (deny) {
		ace->type = NFS4_ACE_ACCESS_DENIED_ACE_TYPE;
		ace->flag = eflag;
		ace->access_mask = deny_mask_from_posix(deny, flags);
		ace->whotype = NFS4_ACL_WHO_OWNER;
		ace++;
		acl->naces++;
	}

	ace->type = NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE;
	ace->flag = eflag;
	ace->access_mask = mask_from_posix(pa->e_perm, flags | NFS4_ACL_OWNER);
	ace->whotype = NFS4_ACL_WHO_OWNER;
	ace++;
	acl->naces++;
	pa++;

	while (pa->e_tag == ACL_USER) {
		deny = ~(pa->e_perm & pas.mask);
		deny &= pas.groups | pas.group | pas.other;
		if (deny) {
			ace->type = NFS4_ACE_ACCESS_DENIED_ACE_TYPE;
			ace->flag = eflag;
			ace->access_mask = deny_mask_from_posix(deny, flags);
			ace->whotype = NFS4_ACL_WHO_NAMED;
			ace->who = pa->e_id;
			ace++;
			acl->naces++;
		}
		ace->type = NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE;
		ace->flag = eflag;
		ace->access_mask = mask_from_posix(pa->e_perm & pas.mask,
						   flags);
		ace->whotype = NFS4_ACL_WHO_NAMED;
		ace->who = pa->e_id;
		ace++;
		acl->naces++;
		pa++;
	}

	/* In the case of groups, we apply allow ACEs first, then deny ACEs,
	 * since a user can be in more than one group.  */

	/* allow ACEs */

	group_owner_entry = pa;

	ace->type = NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE;
	ace->flag = eflag;
	ace->access_mask = mask_from_posix(pas.group, flags);
	ace->whotype = NFS4_ACL_WHO_GROUP;
	ace++;
	acl->naces++;
	pa++;

	while (pa->e_tag == ACL_GROUP) {
		ace->type = NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE;
		ace->flag = eflag | NFS4_ACE_IDENTIFIER_GROUP;
		ace->access_mask = mask_from_posix(pa->e_perm & pas.mask,
						   flags);
		ace->whotype = NFS4_ACL_WHO_NAMED;
		ace->who = pa->e_id;
		ace++;
		acl->naces++;
		pa++;
	}

	/* deny ACEs */

	pa = group_owner_entry;

	deny = ~pas.group & pas.other;
	if (deny) {
		ace->type = NFS4_ACE_ACCESS_DENIED_ACE_TYPE;
		ace->flag = eflag | NFS4_ACE_IDENTIFIER_GROUP;
		ace->access_mask = deny_mask_from_posix(deny, flags);
		ace->whotype = NFS4_ACL_WHO_GROUP;
		ace++;
		acl->naces++;
	}
	pa++;

	while (pa->e_tag == ACL_GROUP) {
		deny = ~(pa->e_perm & pas.mask);
		deny &= pas.other;
		if (deny) {
			ace->type = NFS4_ACE_ACCESS_DENIED_ACE_TYPE;
			ace->flag = eflag | NFS4_ACE_IDENTIFIER_GROUP;
			ace->access_mask = mask_from_posix(deny, flags);
			ace->whotype = NFS4_ACL_WHO_NAMED;
			ace->who = pa->e_id;
			ace++;
			acl->naces++;
		}
		pa++;
	}

	if (pa->e_tag == ACL_MASK)
		pa++;
	ace->type = NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE;
	ace->flag = eflag;
	ace->access_mask = mask_from_posix(pa->e_perm, flags);
	ace->whotype = NFS4_ACL_WHO_EVERYONE;
	acl->naces++;
}

static void
sort_pacl_range(struct posix_acl *pacl, int start, int end) {
	int sorted = 0, i;
	struct posix_acl_entry tmp;

	/* We just do a bubble sort; easy to do in place, and we're not
	 * expecting acl's to be long enough to justify anything more. */
	while (!sorted) {
		sorted = 1;
		for (i = start; i < end; i++) {
			if (pacl->a_entries[i].e_id
					> pacl->a_entries[i+1].e_id) {
				sorted = 0;
				tmp = pacl->a_entries[i];
				pacl->a_entries[i] = pacl->a_entries[i+1];
				pacl->a_entries[i+1] = tmp;
			}
		}
	}
}

static void
sort_pacl(struct posix_acl *pacl)
{
	/* posix_acl_valid requires that users and groups be in order
	 * by uid/gid. */
	int i, j;

	if (pacl->a_count <= 4)
		return; /* no users or groups */
	i = 1;
	while (pacl->a_entries[i].e_tag == ACL_USER)
		i++;
	sort_pacl_range(pacl, 1, i-1);

	BUG_ON(pacl->a_entries[i].e_tag != ACL_GROUP_OBJ);
	j = i++;
	while (pacl->a_entries[j].e_tag == ACL_GROUP)
		j++;
	sort_pacl_range(pacl, i, j-1);
	return;
}

/*
 * While processing the NFSv4 ACE, this maintains bitmasks representing
 * which permission bits have been allowed and which denied to a given
 * entity: */
struct posix_ace_state {
	u32 allow;
	u32 deny;
};

struct posix_user_ace_state {
	uid_t uid;
	struct posix_ace_state perms;
};

struct posix_ace_state_array {
	int n;
	struct posix_user_ace_state aces[];
};

/*
 * While processing the NFSv4 ACE, this maintains the partial permissions
 * calculated so far: */

struct posix_acl_state {
	int empty;
	struct posix_ace_state owner;