libsmb/common/smb_acl.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <stddef.h>
#include <strings.h>
#include <assert.h>

#include <smbsrv/smb.h>
#include <smbsrv/smb_sid.h>
#include <smbsrv/smb_idmap.h>

#define ACE_ALL_TYPES   0x001F

/*
 * ACE groups within a DACL
 *
 * This is from lower to higher ACE order priority
 */
#define SMB_AG_START        0
#define SMB_AG_ALW_INHRT    0
#define SMB_AG_DNY_INHRT    1
#define SMB_AG_ALW_DRCT     2
#define SMB_AG_DNY_DRCT     3
#define SMB_AG_NUM      4

#define DEFAULT_DACL_ACENUM 2
acl_t *acl_alloc(enum acl_type);

static idmap_stat smb_fsacl_getsids(smb_idmap_batch_t *, acl_t *);
static acl_t *smb_fsacl_null_empty(boolean_t);
static uint16_t smb_ace_len(smb_ace_t *);
static uint32_t smb_ace_mask_g2s(uint32_t);
static uint16_t smb_ace_flags_tozfs(uint8_t);
static uint8_t smb_ace_flags_fromzfs(uint16_t);
static boolean_t smb_ace_wellknown_update(const char *, ace_t *);

smb_acl_t *
smb_acl_alloc(uint8_t revision, uint16_t bsize, uint16_t acecnt)
{
    smb_acl_t *acl;
    int size;

    size = sizeof (smb_acl_t) + (acecnt * sizeof (smb_ace_t));
    if ((acl = malloc(size)) == NULL)
        return (NULL);

    acl->sl_revision = revision;
    acl->sl_bsize = bsize;
    acl->sl_acecnt = acecnt;
    acl->sl_aces = (smb_ace_t *)(acl + 1);

    list_create(&acl->sl_sorted, sizeof (smb_ace_t),
        offsetof(smb_ace_t, se_sln));
    return (acl);
}

void
smb_acl_free(smb_acl_t *acl)
{
    int i;
    void *ace;

    if (acl == NULL)
        return;

    for (i = 0; i < acl->sl_acecnt; i++)
        smb_sid_free(acl->sl_aces[i].se_sid);

    while ((ace = list_head(&acl->sl_sorted)) != NULL)
        list_remove(&acl->sl_sorted, ace);
    list_destroy(&acl->sl_sorted);
    free(acl);

}

/*
 * smb_acl_len
 *
 * Returns the size of given ACL in bytes. Note that this
 * is not an in-memory size, it's the ACL's size as it would
 * appear on the wire
 */
uint16_t
smb_acl_len(smb_acl_t *acl)
{
    return ((acl) ? acl->sl_bsize : 0);
}

/*ARGSUSED*/
boolean_t
smb_acl_isvalid(smb_acl_t *acl, int which_acl)
{
    if (acl->sl_bsize < SMB_ACL_HDRSIZE)
        return (B_FALSE);

    if (acl->sl_revision != ACL_REVISION) {
        /*
         * we are rejecting ACLs with object-specific ACEs for now
         */
        return (B_FALSE);
    }

    return (B_TRUE);
}

/*
 * smb_acl_sort
 *
 * Sorts the given ACL in place if it needs to be sorted.
 *
 * The following is an excerpt from MSDN website.
 *
 * Order of ACEs in a DACL
 *
 * For Windows NT versions 4.0 and earlier, the preferred order of ACEs
 * is simple: In a DACL, all access-denied ACEs should precede any
 * access-allowed ACEs.
 *
 * For Windows 2000 or later, the proper order of ACEs is more complicated
 * because of the introduction of object-specific ACEs and automatic
 * inheritance.
 *
 * The following describes the preferred order:
 *
 * To ensure that noninherited ACEs have precedence over inherited ACEs,
 * place all noninherited ACEs in a group before any inherited ACEs. This
 * ordering ensures, for example, that a noninherited access-denied ACE
 * is enforced regardless of any inherited ACE that allows access.
 * Within the groups of noninherited ACEs and inherited ACEs, order ACEs
 * according to ACE type, as the following shows:
 *  . Access-denied ACEs that apply to the object itself
 *  . Access-denied ACEs that apply to a subobject of the
 *    object, such as a property set or property
 *  . Access-allowed ACEs that apply to the object itself
 *  . Access-allowed ACEs that apply to a subobject of the object
 *
 * So, here is the desired ACE order
 *
 * deny-direct, allow-direct, deny-inherited, allow-inherited
 *
 * Of course, not all ACE types are required in an ACL.
 */
void
smb_acl_sort(smb_acl_t *acl)
{
    list_t ace_grps[SMB_AG_NUM];
    list_t *alist;
    smb_ace_t *ace;
    uint8_t ace_flags;
    int ag, i;

    assert(acl);

    if (acl->sl_acecnt == 0) {
        /*
         * ACL with no entry is a valid ACL and it means
         * no access for anybody.
         */
        return;
    }

    for (i = SMB_AG_START; i < SMB_AG_NUM; i++) {
        list_create(&ace_grps[i], sizeof (smb_ace_t),
            offsetof(smb_ace_t, se_sln));
    }

    for (i = 0, ace = acl->sl_aces; i < acl->sl_acecnt; ++i, ace++) {
        ace_flags = ace->se_hdr.se_flags;

        switch (ace->se_hdr.se_type) {
        case ACCESS_DENIED_ACE_TYPE:
            ag = (ace_flags & INHERITED_ACE) ?
                SMB_AG_DNY_INHRT : SMB_AG_DNY_DRCT;
            break;

        case ACCESS_ALLOWED_ACE_TYPE:
            ag = (ace_flags & INHERITED_ACE) ?
                SMB_AG_ALW_INHRT : SMB_AG_ALW_DRCT;
            break;

        default:
            /*
             * This is the lowest priority group so we put
             * evertything unknown here.
             */
            ag = SMB_AG_ALW_INHRT;
            break;
        }

        /* Add the ACE to the selected group */
        list_insert_tail(&ace_grps[ag], ace);
    }

    /*
     * start with highest priority ACE group and append
     * the ACEs to the ACL.
     */
    for (i = SMB_AG_NUM - 1; i >= SMB_AG_START; i--) {
        alist = &ace_grps[i];
        while ((ace = list_head(alist)) != NULL) {
            list_remove(alist, ace);
            list_insert_tail(&acl->sl_sorted, ace);
        }
        list_destroy(alist);
    }
}

/*
 * smb_acl_from_zfs
 *
 * Converts given ZFS ACL to a Windows ACL.
 *
 * A pointer to allocated memory for the Windows ACL will be
 * returned upon successful conversion.
 */
smb_acl_t *
smb_acl_from_zfs(acl_t *zacl)
{
    ace_t *zace;
    int numaces;
    smb_acl_t *acl;
    smb_ace_t *ace;
    smb_idmap_batch_t sib;
    smb_idmap_t *sim;
    idmap_stat idm_stat;

    idm_stat = smb_idmap_batch_create(&sib, zacl->acl_cnt,
        SMB_IDMAP_ID2SID);
    if (idm_stat != IDMAP_SUCCESS)
        return (NULL);

    if (smb_fsacl_getsids(&sib, zacl) != IDMAP_SUCCESS) {
        smb_idmap_batch_destroy(&sib);
        return (NULL);
    }

    acl = smb_acl_alloc(ACL_REVISION, SMB_ACL_HDRSIZE, zacl->acl_cnt);

    sim = sib.sib_maps;
    for (numaces = 0, zace = zacl->acl_aclp;
        numaces < zacl->acl_cnt;
        zace++, numaces++, sim++) {
        assert(sim->sim_sid);
        if (sim->sim_sid == NULL) {
            smb_acl_free(acl);
            acl = NULL;
            break;
        }

        ace = &acl->sl_aces[numaces];
        ace->se_hdr.se_type = zace->a_type;
        ace->se_hdr.se_flags = smb_ace_flags_fromzfs(zace->a_flags);
        ace->se_mask = zace->a_access_mask;
        ace->se_sid = smb_sid_dup(sim->sim_sid);
        ace->se_hdr.se_bsize = smb_ace_len(ace);

        acl->sl_bsize += ace->se_hdr.se_bsize;
    }

    smb_idmap_batch_destroy(&sib);
    return (acl);
}

/*
 * smb_acl_to_zfs
 *
 * Converts given Windows ACL to a ZFS ACL.
 *
 * fs_acl will contain a pointer to the created ZFS ACL.
 * The allocated memory should be freed by calling
 * smb_fsacl_free().
 *
 * Since the output parameter, fs_acl, is allocated in this
 * function, the caller has to make sure *fs_acl is NULL which
 * means it's not pointing to any memory.
 */
uint32_t
smb_acl_to_zfs(smb_acl_t *acl, uint32_t flags, int which_acl, acl_t **fs_acl)
{
    char sidstr[SMB_SID_STRSZ];
    smb_ace_t *ace;
    acl_t *zacl;
    ace_t *zace;
    smb_idmap_batch_t sib;
    smb_idmap_t *sim;
    idmap_stat idm_stat;
    int i;

    assert(fs_acl);
    assert(*fs_acl == NULL);

    if (acl && !smb_acl_isvalid(acl, which_acl))
        return (NT_STATUS_INVALID_ACL);

    if ((acl == NULL) || (acl->sl_acecnt == 0)) {
        if (which_acl == SMB_DACL_SECINFO) {
            *fs_acl = smb_fsacl_null_empty(acl == NULL);
        }

        return (NT_STATUS_SUCCESS);
    }

    idm_stat = smb_idmap_batch_create(&sib, acl->sl_acecnt,
        SMB_IDMAP_SID2ID);
    if (idm_stat != IDMAP_SUCCESS)
        return (NT_STATUS_INTERNAL_ERROR);

    zacl = smb_fsacl_alloc(acl->sl_acecnt, flags);

    zace = zacl->acl_aclp;
    ace = acl->sl_aces;
    sim = sib.sib_maps;

    for (i = 0; i < acl->sl_acecnt; i++, zace++, ace++, sim++) {
        zace->a_type = ace->se_hdr.se_type & ACE_ALL_TYPES;
        zace->a_access_mask = smb_ace_mask_g2s(ace->se_mask);
        zace->a_flags = smb_ace_flags_tozfs(ace->se_hdr.se_flags);
        zace->a_who = (uid_t)-1;

        smb_sid_tostr(ace->se_sid, sidstr);

        if (!smb_ace_wellknown_update(sidstr, zace)) {
            sim->sim_id = &zace->a_who;
            idm_stat = smb_idmap_batch_getid(sib.sib_idmaph, sim,
                ace->se_sid, SMB_IDMAP_UNKNOWN);

            if (idm_stat != IDMAP_SUCCESS) {
                smb_fsacl_free(zacl);
                smb_idmap_batch_destroy(&sib);
                return (NT_STATUS_INTERNAL_ERROR);
            }
        }
    }

    idm_stat = smb_idmap_batch_getmappings(&sib);
    if (idm_stat != IDMAP_SUCCESS) {
        smb_fsacl_free(zacl);
        smb_idmap_batch_destroy(&sib);
        return (NT_STATUS_NONE_MAPPED);
    }

    /*
     * Set the ACEs group flag based on the type of ID returned.
     */
    zace = zacl->acl_aclp;
    ace = acl->sl_aces;
    sim = sib.sib_maps;
    for (i = 0; i < acl->sl_acecnt; i++, zace++, ace++, sim++) {
        if (zace->a_who == (uid_t)-1)
            continue;

        if (sim->sim_idtype == SMB_IDMAP_GROUP)
            zace->a_flags |= ACE_IDENTIFIER_GROUP;
    }

    smb_idmap_batch_destroy(&sib);

    *fs_acl = zacl;
    return (NT_STATUS_SUCCESS);
}

static boolean_t
smb_ace_wellknown_update(const char *sid, ace_t *zace)
{
    struct {
        char        *sid;
        uint16_t    flags;
    } map[] = {
        { NT_WORLD_SIDSTR,          ACE_EVERYONE },
        { NT_BUILTIN_CURRENT_OWNER_SIDSTR,  ACE_OWNER },
        { NT_BUILTIN_CURRENT_GROUP_SIDSTR,
            (ACE_GROUP | ACE_IDENTIFIER_GROUP) },
    };

    int i;

    for (i = 0; i < (sizeof (map) / sizeof (map[0])); ++i) {
        if (strcmp(sid, map[i].sid) == 0) {
            zace->a_flags |= map[i].flags;
            return (B_TRUE);
        }
    }

    return (B_FALSE);
}

/*
 * smb_fsacl_getsids
 *
 * Batch all the uid/gid in given ZFS ACL to get their corresponding SIDs.
 */
static idmap_stat
smb_fsacl_getsids(smb_idmap_batch_t *sib, acl_t *zacl)
{
    ace_t *zace;
    idmap_stat idm_stat;
    smb_idmap_t *sim;
    uid_t id;
    int i, idtype;

    sim = sib->sib_maps;

    for (i = 0, zace = zacl->acl_aclp; i < zacl->acl_cnt;
        zace++, i++, sim++) {
        switch (zace->a_flags & ACE_TYPE_FLAGS) {
        case ACE_OWNER:
            idtype = SMB_IDMAP_OWNERAT;
            break;

        case (ACE_GROUP | ACE_IDENTIFIER_GROUP):
            /* owning group */
            idtype = SMB_IDMAP_GROUPAT;
            break;

        case ACE_IDENTIFIER_GROUP:
            /* regular group */
            id = zace->a_who;
            idtype = SMB_IDMAP_GROUP;
            break;

        case ACE_EVERYONE:
            idtype = SMB_IDMAP_EVERYONE;
            break;

        default:
            /* user entry */
            id = zace->a_who;
            idtype = SMB_IDMAP_USER;
        }

        idm_stat = smb_idmap_batch_getsid(sib->sib_idmaph, sim,
            id, idtype);

        if (idm_stat != IDMAP_SUCCESS) {
            return (idm_stat);
        }
    }

    idm_stat = smb_idmap_batch_getmappings(sib);
    return (idm_stat);
}

/*
 * smb_fsacl_null_empty
 *
 * NULL DACL means everyone full-access
 * Empty DACL means everyone full-deny
 *
 * ZFS ACL must have at least one entry so smb server has
 * to simulate the aforementioned expected behavior by adding
 * an entry in case the requested DACL is null or empty. Adding
 * a everyone full-deny entry has proved to be problematic in
 * tests since a deny entry takes precedence over allow entries.
 * So, instead of adding a everyone full-deny, an owner ACE with
 * owner implicit permissions will be set.
 */
static acl_t *
smb_fsacl_null_empty(boolean_t null)
{
    acl_t *zacl;
    ace_t *zace;

    zacl = smb_fsacl_alloc(1, ACL_AUTO_INHERIT);
    zace = zacl->acl_aclp;

    zace->a_type = ACE_ACCESS_ALLOWED_ACE_TYPE;
    if (null) {
        zace->a_access_mask = ACE_ALL_PERMS;
        zace->a_flags = ACE_EVERYONE;
    } else {
        zace->a_access_mask = ACE_READ_ACL | ACE_WRITE_ACL |
            ACE_READ_ATTRIBUTES;
        zace->a_flags = ACE_OWNER;
    }

    return (zacl);
}

/*
 * FS ACL (acl_t) Functions
 */
acl_t *
smb_fsacl_alloc(int acenum, int flags)
{
    acl_t *acl;

    acl = acl_alloc(ACE_T);
    acl->acl_cnt = acenum;
    if ((acl->acl_aclp = malloc(acl->acl_entry_size * acenum)) == NULL)
        return (NULL);

    acl->acl_flags = flags;
    return (acl);
}

void
smb_fsacl_free(acl_t *acl)
{
    if (acl)
        acl_free(acl);
}

/*
 * ACE Functions
 */

/*
 * smb_ace_len
 *
 * Returns the length of the given ACE as it appears in an
 * ACL on the wire (i.e. a flat buffer which contains the SID)
 */
static uint16_t
smb_ace_len(smb_ace_t *ace)
{
    assert(ace);
    assert(ace->se_sid);

    if (ace == NULL)
        return (0);

    return (SMB_ACE_HDRSIZE + sizeof (ace->se_mask) +
        smb_sid_len(ace->se_sid));
}

/*
 * smb_ace_mask_g2s
 *
 * Converts generic access bits in the given mask (if any)
 * to file specific bits. Generic access masks shouldn't be
 * stored in filesystem ACEs.
 */
static uint32_t
smb_ace_mask_g2s(uint32_t mask)
{
    if (mask & GENERIC_ALL) {
        mask &= ~(GENERIC_ALL | GENERIC_READ | GENERIC_WRITE
            | GENERIC_EXECUTE);

        mask |= FILE_ALL_ACCESS;
        return (mask);
    }

    if (mask & GENERIC_READ) {
        mask &= ~GENERIC_READ;
        mask |= FILE_GENERIC_READ;
    }

    if (mask & GENERIC_WRITE) {
        mask &= ~GENERIC_WRITE;
        mask |= FILE_GENERIC_WRITE;
    }

    if (mask & GENERIC_EXECUTE) {
        mask &= ~GENERIC_EXECUTE;
        mask |= FILE_GENERIC_EXECUTE;
    }

    return (mask);
}

/*
 * smb_ace_flags_tozfs
 *
 * This function maps the flags which have different values
 * in Windows and Solaris. The ones with the same value are
 * transferred untouched.
 */
static uint16_t
smb_ace_flags_tozfs(uint8_t c_flags)
{
    uint16_t z_flags = 0;

    if (c_flags & SUCCESSFUL_ACCESS_ACE_FLAG)
        z_flags |= ACE_SUCCESSFUL_ACCESS_ACE_FLAG;

    if (c_flags & FAILED_ACCESS_ACE_FLAG)
        z_flags |= ACE_FAILED_ACCESS_ACE_FLAG;

    if (c_flags & INHERITED_ACE)
        z_flags |= ACE_INHERITED_ACE;

    z_flags |= (c_flags & ACE_INHERIT_FLAGS);

    return (z_flags);
}

static uint8_t
smb_ace_flags_fromzfs(uint16_t z_flags)
{
    uint8_t c_flags;

    c_flags = z_flags & ACE_INHERIT_FLAGS;

    if (z_flags & ACE_SUCCESSFUL_ACCESS_ACE_FLAG)
        c_flags |= SUCCESSFUL_ACCESS_ACE_FLAG;

    if (z_flags & ACE_FAILED_ACCESS_ACE_FLAG)
        c_flags |= FAILED_ACCESS_ACE_FLAG;

    if (z_flags & ACE_INHERITED_ACE)
        c_flags |= INHERITED_ACE;

    return (c_flags);
}