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[zen-stable.git] / fs / nfsd / nfs4acl.c

/*
 *  Common NFSv4 ACL handling code.
 *
 *  Copyright (c) 2002, 2003 The Regents of the University of Michigan.
 *  All rights reserved.
 *
 *  Marius Aamodt Eriksen <marius@umich.edu>
 *  Jeff Sedlak <jsedlak@umich.edu>
 *  J. Bruce Fields <bfields@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 <linux/slab.h>
#include <linux/nfs_fs.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;
                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 = deny_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;
        struct posix_ace_state group;
        struct posix_ace_state other;
        struct posix_ace_state everyone;
        struct posix_ace_state mask; /* Deny unused in this case */
        struct posix_ace_state_array *users;
        struct posix_ace_state_array *groups;
};

static int
init_state(struct posix_acl_state *state, int cnt)
{
        int alloc;

        memset(state, 0, sizeof(struct posix_acl_state));
        state->empty = 1;
        /*
         * In the worst case, each individual acl could be for a distinct
         * named user or group, but we don't no which, so we allocate
         * enough space for either:
         */
        alloc = sizeof(struct posix_ace_state_array)
                + cnt*sizeof(struct posix_user_ace_state);
        state->users = kzalloc(alloc, GFP_KERNEL);
        if (!state->users)
                return -ENOMEM;
        state->groups = kzalloc(alloc, GFP_KERNEL);
        if (!state->groups) {
                kfree(state->users);
                return -ENOMEM;
        }
        return 0;
}

static void
free_state(struct posix_acl_state *state) {
        kfree(state->users);
        kfree(state->groups);
}

static inline void add_to_mask(struct posix_acl_state *state, struct posix_ace_state *astate)
{
        state->mask.allow |= astate->allow;
}

/*
 * Certain bits (SYNCHRONIZE, DELETE, WRITE_OWNER, READ/WRITE_NAMED_ATTRS,
 * READ_ATTRIBUTES, READ_ACL) are currently unenforceable and don't translate
 * to traditional read/write/execute permissions.
 *
 * It's problematic to reject acls that use certain mode bits, because it
 * places the burden on users to learn the rules about which bits one
 * particular server sets, without giving the user a lot of help--we return an
 * error that could mean any number of different things.  To make matters
 * worse, the problematic bits might be introduced by some application that's
 * automatically mapping from some other acl model.
 *
 * So wherever possible we accept anything, possibly erring on the side of
 * denying more permissions than necessary.
 *
 * However we do reject *explicit* DENY's of a few bits representing
 * permissions we could never deny:
 */

static inline int check_deny(u32 mask, int isowner)
{
        if (mask & (NFS4_ACE_READ_ATTRIBUTES | NFS4_ACE_READ_ACL))
                return -EINVAL;
        if (!isowner)
                return 0;
        if (mask & (NFS4_ACE_WRITE_ATTRIBUTES | NFS4_ACE_WRITE_ACL))
                return -EINVAL;
        return 0;
}

static struct posix_acl *
posix_state_to_acl(struct posix_acl_state *state, unsigned int flags)
{
        struct posix_acl_entry *pace;
        struct posix_acl *pacl;
        int nace;
        int i, error = 0;

        /*
         * ACLs with no ACEs are treated differently in the inheritable
         * and effective cases: when there are no inheritable ACEs, we
         * set a zero-length default posix acl:
         */
        if (state->empty && (flags & NFS4_ACL_TYPE_DEFAULT)) {
                pacl = posix_acl_alloc(0, GFP_KERNEL);
                return pacl ? pacl : ERR_PTR(-ENOMEM);
        }
        /*
         * When there are no effective ACEs, the following will end
         * up setting a 3-element effective posix ACL with all
         * permissions zero.
         */
        nace = 4 + state->users->n + state->groups->n;
        pacl = posix_acl_alloc(nace, GFP_KERNEL);
        if (!pacl)
                return ERR_PTR(-ENOMEM);

        pace = pacl->a_entries;
        pace->e_tag = ACL_USER_OBJ;
        error = check_deny(state->owner.deny, 1);
        if (error)
                goto out_err;
        low_mode_from_nfs4(state->owner.allow, &pace->e_perm, flags);
        pace->e_id = ACL_UNDEFINED_ID;

        for (i=0; i < state->users->n; i++) {
                pace++;
                pace->e_tag = ACL_USER;
                error = check_deny(state->users->aces[i].perms.deny, 0);
                if (error)
                        goto out_err;
                low_mode_from_nfs4(state->users->aces[i].perms.allow,
                                        &pace->e_perm, flags);
                pace->e_id = state->users->aces[i].uid;
                add_to_mask(state, &state->users->aces[i].perms);
        }

        pace++;
        pace->e_tag = ACL_GROUP_OBJ;
        error = check_deny(state->group.deny, 0);
        if (error)
                goto out_err;
        low_mode_from_nfs4(state->group.allow, &pace->e_perm, flags);
        pace->e_id = ACL_UNDEFINED_ID;
        add_to_mask(state, &state->group);

        for (i=0; i < state->groups->n; i++) {
                pace++;
                pace->e_tag = ACL_GROUP;
                error = check_deny(state->groups->aces[i].perms.deny, 0);
                if (error)
                        goto out_err;
                low_mode_from_nfs4(state->groups->aces[i].perms.allow,
                                        &pace->e_perm, flags);
                pace->e_id = state->groups->aces[i].uid;
                add_to_mask(state, &state->groups->aces[i].perms);
        }

        pace++;
        pace->e_tag = ACL_MASK;
        low_mode_from_nfs4(state->mask.allow, &pace->e_perm, flags);
        pace->e_id = ACL_UNDEFINED_ID;

        pace++;
        pace->e_tag = ACL_OTHER;
        error = check_deny(state->other.deny, 0);
        if (error)
                goto out_err;
        low_mode_from_nfs4(state->other.allow, &pace->e_perm, flags);
        pace->e_id = ACL_UNDEFINED_ID;

        return pacl;
out_err:
        posix_acl_release(pacl);
        return ERR_PTR(error);
}

static inline void allow_bits(struct posix_ace_state *astate, u32 mask)
{
        /* Allow all bits in the mask not already denied: */
        astate->allow |= mask & ~astate->deny;
}

static inline void deny_bits(struct posix_ace_state *astate, u32 mask)
{
        /* Deny all bits in the mask not already allowed: */
        astate->deny |= mask & ~astate->allow;
}

static int find_uid(struct posix_acl_state *state, struct posix_ace_state_array *a, uid_t uid)
{
        int i;

        for (i = 0; i < a->n; i++)
                if (a->aces[i].uid == uid)
                        return i;
        /* Not found: */
        a->n++;
        a->aces[i].uid = uid;
        a->aces[i].perms.allow = state->everyone.allow;
        a->aces[i].perms.deny  = state->everyone.deny;

        return i;
}

static void deny_bits_array(struct posix_ace_state_array *a, u32 mask)
{
        int i;

        for (i=0; i < a->n; i++)
                deny_bits(&a->aces[i].perms, mask);
}

static void allow_bits_array(struct posix_ace_state_array *a, u32 mask)
{
        int i;

        for (i=0; i < a->n; i++)
                allow_bits(&a->aces[i].perms, mask);
}

static void process_one_v4_ace(struct posix_acl_state *state,
                                struct nfs4_ace *ace)
{
        u32 mask = ace->access_mask;
        int i;

        state->empty = 0;

        switch (ace2type(ace)) {
        case ACL_USER_OBJ:
                if (ace->type == NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE) {
                        allow_bits(&state->owner, mask);
                } else {
                        deny_bits(&state->owner, mask);
                }
                break;
        case ACL_USER:
                i = find_uid(state, state->users, ace->who);
                if (ace->type == NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE) {
                        allow_bits(&state->users->aces[i].perms, mask);
                } else {
                        deny_bits(&state->users->aces[i].perms, mask);
                        mask = state->users->aces[i].perms.deny;
                        deny_bits(&state->owner, mask);
                }
                break;
        case ACL_GROUP_OBJ:
                if (ace->type == NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE) {
                        allow_bits(&state->group, mask);
                } else {
                        deny_bits(&state->group, mask);
                        mask = state->group.deny;
                        deny_bits(&state->owner, mask);
                        deny_bits(&state->everyone, mask);
                        deny_bits_array(state->users, mask);
                        deny_bits_array(state->groups, mask);
                }
                break;
        case ACL_GROUP:
                i = find_uid(state, state->groups, ace->who);
                if (ace->type == NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE) {
                        allow_bits(&state->groups->aces[i].perms, mask);
                } else {
                        deny_bits(&state->groups->aces[i].perms, mask);
                        mask = state->groups->aces[i].perms.deny;
                        deny_bits(&state->owner, mask);
                        deny_bits(&state->group, mask);
                        deny_bits(&state->everyone, mask);
                        deny_bits_array(state->users, mask);
                        deny_bits_array(state->groups, mask);
                }
                break;
        case ACL_OTHER:
                if (ace->type == NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE) {
                        allow_bits(&state->owner, mask);
                        allow_bits(&state->group, mask);
                        allow_bits(&state->other, mask);
                        allow_bits(&state->everyone, mask);
                        allow_bits_array(state->users, mask);
                        allow_bits_array(state->groups, mask);
                } else {
                        deny_bits(&state->owner, mask);
                        deny_bits(&state->group, mask);
                        deny_bits(&state->other, mask);
                        deny_bits(&state->everyone, mask);
                        deny_bits_array(state->users, mask);
                        deny_bits_array(state->groups, mask);
                }
        }
}

int nfs4_acl_nfsv4_to_posix(struct nfs4_acl *acl, struct posix_acl **pacl,
                            struct posix_acl **dpacl, unsigned int flags)
{
        struct posix_acl_state effective_acl_state, default_acl_state;
        struct nfs4_ace *ace;
        int ret;

        ret = init_state(&effective_acl_state, acl->naces);
        if (ret)
                return ret;
        ret = init_state(&default_acl_state, acl->naces);
        if (ret)
                goto out_estate;
        ret = -EINVAL;
        for (ace = acl->aces; ace < acl->aces + acl->naces; ace++) {
                if (ace->type != NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE &&
                    ace->type != NFS4_ACE_ACCESS_DENIED_ACE_TYPE)
                        goto out_dstate;
                if (ace->flag & ~NFS4_SUPPORTED_FLAGS)
                        goto out_dstate;
                if ((ace->flag & NFS4_INHERITANCE_FLAGS) == 0) {
                        process_one_v4_ace(&effective_acl_state, ace);
                        continue;
                }
                if (!(flags & NFS4_ACL_DIR))
                        goto out_dstate;
                /*
                 * Note that when only one of FILE_INHERIT or DIRECTORY_INHERIT
                 * is set, we're effectively turning on the other.  That's OK,
                 * according to rfc 3530.
                 */
                process_one_v4_ace(&default_acl_state, ace);

                if (!(ace->flag & NFS4_ACE_INHERIT_ONLY_ACE))
                        process_one_v4_ace(&effective_acl_state, ace);
        }
        *pacl = posix_state_to_acl(&effective_acl_state, flags);
        if (IS_ERR(*pacl)) {
                ret = PTR_ERR(*pacl);
                *pacl = NULL;
                goto out_dstate;
        }
        *dpacl = posix_state_to_acl(&default_acl_state,
                                                flags | NFS4_ACL_TYPE_DEFAULT);
        if (IS_ERR(*dpacl)) {
                ret = PTR_ERR(*dpacl);
                *dpacl = NULL;
                posix_acl_release(*pacl);
                *pacl = NULL;
                goto out_dstate;
        }
        sort_pacl(*pacl);
        sort_pacl(*dpacl);
        ret = 0;
out_dstate:
        free_state(&default_acl_state);
out_estate:
        free_state(&effective_acl_state);
        return ret;
}

static short
ace2type(struct nfs4_ace *ace)
{
        switch (ace->whotype) {
                case NFS4_ACL_WHO_NAMED:
                        return (ace->flag & NFS4_ACE_IDENTIFIER_GROUP ?
                                        ACL_GROUP : ACL_USER);
                case NFS4_ACL_WHO_OWNER:
                        return ACL_USER_OBJ;
                case NFS4_ACL_WHO_GROUP:
                        return ACL_GROUP_OBJ;
                case NFS4_ACL_WHO_EVERYONE:
                        return ACL_OTHER;
        }
        BUG();
        return -1;
}

EXPORT_SYMBOL(nfs4_acl_posix_to_nfsv4);
EXPORT_SYMBOL(nfs4_acl_nfsv4_to_posix);

struct nfs4_acl *
nfs4_acl_new(int n)
{
        struct nfs4_acl *acl;

        acl = kmalloc(sizeof(*acl) + n*sizeof(struct nfs4_ace), GFP_KERNEL);
        if (acl == NULL)
                return NULL;
        acl->naces = 0;
        return acl;
}

static struct {
        char *string;
        int   stringlen;
        int type;
} s2t_map[] = {
        {
                .string    = "OWNER@",
                .stringlen = sizeof("OWNER@") - 1,
                .type      = NFS4_ACL_WHO_OWNER,
        },
        {
                .string    = "GROUP@",
                .stringlen = sizeof("GROUP@") - 1,
                .type      = NFS4_ACL_WHO_GROUP,
        },
        {
                .string    = "EVERYONE@",
                .stringlen = sizeof("EVERYONE@") - 1,
                .type      = NFS4_ACL_WHO_EVERYONE,
        },
};

int
nfs4_acl_get_whotype(char *p, u32 len)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(s2t_map); i++) {
                if (s2t_map[i].stringlen == len &&
                                0 == memcmp(s2t_map[i].string, p, len))
                        return s2t_map[i].type;
        }
        return NFS4_ACL_WHO_NAMED;
}

int
nfs4_acl_write_who(int who, char *p)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(s2t_map); i++) {
                if (s2t_map[i].type == who) {
                        memcpy(p, s2t_map[i].string, s2t_map[i].stringlen);
                        return s2t_map[i].stringlen;
                }
        }
        BUG();
        return -1;
}

EXPORT_SYMBOL(nfs4_acl_new);
EXPORT_SYMBOL(nfs4_acl_get_whotype);
EXPORT_SYMBOL(nfs4_acl_write_who);