/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2017, Fedor Uporov
 * All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 <sys/param.h>
#include <sys/systm.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/vnode.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/endian.h>
#include <sys/conf.h>
#include <sys/mount.h>
#include <sys/extattr.h>

#include <fs/ext2fs/fs.h>
#include <fs/ext2fs/ext2fs.h>
#include <fs/ext2fs/inode.h>
#include <fs/ext2fs/ext2_acl.h>
#include <fs/ext2fs/ext2_extattr.h>
#include <fs/ext2fs/ext2_extern.h>
#include <fs/ext2fs/ext2_dinode.h>
#include <fs/ext2fs/ext2_mount.h>

#ifdef UFS_ACL

void
ext2_sync_acl_from_inode(struct inode *ip, struct acl *acl)
{
        struct acl_entry        *acl_mask, *acl_group_obj;
        int     i;

        /*
         * Update ACL_USER_OBJ, ACL_OTHER, but simply identify ACL_MASK
         * and ACL_GROUP_OBJ for use after we know whether ACL_MASK is
         * present.
         */
        acl_mask = NULL;
        acl_group_obj = NULL;
        for (i = 0; i < acl->acl_cnt; i++) {
                switch (acl->acl_entry[i].ae_tag) {
                case ACL_USER_OBJ:
                        acl->acl_entry[i].ae_perm = acl_posix1e_mode_to_perm(
                            ACL_USER_OBJ, ip->i_mode);
                        acl->acl_entry[i].ae_id = ACL_UNDEFINED_ID;
                        break;

                case ACL_GROUP_OBJ:
                        acl_group_obj = &acl->acl_entry[i];
                        acl->acl_entry[i].ae_id = ACL_UNDEFINED_ID;
                        break;

                case ACL_OTHER:
                        acl->acl_entry[i].ae_perm = acl_posix1e_mode_to_perm(
                            ACL_OTHER, ip->i_mode);
                        acl->acl_entry[i].ae_id = ACL_UNDEFINED_ID;
                        break;

                case ACL_MASK:
                        acl_mask = &acl->acl_entry[i];
                        acl->acl_entry[i].ae_id = ACL_UNDEFINED_ID;
                        break;

                case ACL_USER:
                case ACL_GROUP:
                        break;

                default:
                        panic("ext2_sync_acl_from_inode(): bad ae_tag");
                }
        }

        if (acl_group_obj == NULL)
                panic("ext2_sync_acl_from_inode(): no ACL_GROUP_OBJ");

        if (acl_mask == NULL) {
                /*
                 * There is no ACL_MASK, so update ACL_GROUP_OBJ.
                 */
                acl_group_obj->ae_perm = acl_posix1e_mode_to_perm(
                    ACL_GROUP_OBJ, ip->i_mode);
        } else {
                /*
                 * Update the ACL_MASK entry instead of ACL_GROUP_OBJ.
                 */
                acl_mask->ae_perm = acl_posix1e_mode_to_perm(ACL_GROUP_OBJ,
                    ip->i_mode);
        }
}

static void
ext2_sync_inode_from_acl(struct acl *acl, struct inode *ip)
{

        ip->i_mode &= ACL_PRESERVE_MASK;
        ip->i_mode |= acl_posix1e_acl_to_mode(acl);
}

/*
 * Convert from filesystem to in-memory representation.
 */
static int
ext4_acl_from_disk(char *value, size_t size, struct acl *acl)
{
        const char *end;
        int n, count, s;

        if (value == NULL)
                return (EINVAL);

        end = value + size;

        if (((struct ext2_acl_header *)value)->a_version != EXT4_ACL_VERSION)
                return (EINVAL);

        if (size < sizeof(struct ext2_acl_header))
                return (EINVAL);

        s = size - sizeof(struct ext2_acl_header);
        s -= 4 * sizeof(struct ext2_acl_entry_short);
        if (s < 0)
                if ((size - sizeof(struct ext2_acl_header)) %
                    sizeof(struct ext2_acl_entry_short))
                        count = -1;
                else
                        count = (size - sizeof(struct ext2_acl_header)) /
                            sizeof(struct ext2_acl_entry_short);
        else
                if (s % sizeof(struct ext2_acl_entry))
                        count = -1;
                else
                        count = s / sizeof(struct ext2_acl_entry) + 4;

        if (count <= 0 || count > acl->acl_maxcnt)
                return (EINVAL);

        value = value + sizeof(struct ext2_acl_header);

        for (n = 0; n < count; n++) {
                struct ext2_acl_entry *entry = (struct ext2_acl_entry *)value;
                if ((char *)value + sizeof(struct ext2_acl_entry_short) > end)
                        return (EINVAL);

                acl->acl_entry[n].ae_tag  = entry->ae_tag;
                acl->acl_entry[n].ae_perm = entry->ae_perm;

                switch (acl->acl_entry[n].ae_tag) {
                case ACL_USER_OBJ:
                case ACL_GROUP_OBJ:
                case ACL_MASK:
                case ACL_OTHER:
                        value = (char *)value + sizeof(struct ext2_acl_entry_short);
                        break;

                case ACL_USER:
                        value = (char *)value + sizeof(struct ext2_acl_entry);
                        if ((char *)value > end)
                                return (EINVAL);

                        acl->acl_entry[n].ae_id = entry->ae_id;
                        break;

                case ACL_GROUP:
                        value = (char *)value + sizeof(struct ext2_acl_entry);
                        if ((char *)value > end)
                                return (EINVAL);

                        acl->acl_entry[n].ae_id = entry->ae_id;
                        break;

                default:
                        return (EINVAL);
                }
        }

        if (value != end)
                return (EINVAL);

        acl->acl_cnt = count;

        return (0);
}

static int
ext2_getacl_posix1e(struct vop_getacl_args *ap)
{
        int attrnamespace;
        const char *attrname;
        char *value;
        int len;
        int error;

        switch (ap->a_type) {
        case ACL_TYPE_DEFAULT:
                attrnamespace = POSIX1E_ACL_DEFAULT_EXTATTR_NAMESPACE;
                attrname = POSIX1E_ACL_DEFAULT_EXTATTR_NAME;
                break;
        case ACL_TYPE_ACCESS:
                attrnamespace = POSIX1E_ACL_ACCESS_EXTATTR_NAMESPACE;
                attrname = POSIX1E_ACL_ACCESS_EXTATTR_NAME;
                break;
        default:
                return (EINVAL);
        }

        len = sizeof(*ap->a_aclp) + sizeof(struct ext2_acl_header);
        value = malloc(len, M_ACL, M_WAITOK);

        error = vn_extattr_get(ap->a_vp, IO_NODELOCKED, attrnamespace, attrname,
            &len, value, ap->a_td);
        if (error == ENOATTR) {
                switch (ap->a_type) {
                case ACL_TYPE_ACCESS:
                        ap->a_aclp->acl_cnt = 3;
                        ap->a_aclp->acl_entry[0].ae_tag = ACL_USER_OBJ;
                        ap->a_aclp->acl_entry[0].ae_id = ACL_UNDEFINED_ID;
                        ap->a_aclp->acl_entry[0].ae_perm = ACL_PERM_NONE;
                        ap->a_aclp->acl_entry[1].ae_tag = ACL_GROUP_OBJ;
                        ap->a_aclp->acl_entry[1].ae_id = ACL_UNDEFINED_ID;
                        ap->a_aclp->acl_entry[1].ae_perm = ACL_PERM_NONE;
                        ap->a_aclp->acl_entry[2].ae_tag = ACL_OTHER;
                        ap->a_aclp->acl_entry[2].ae_id = ACL_UNDEFINED_ID;
                        ap->a_aclp->acl_entry[2].ae_perm = ACL_PERM_NONE;
                        break;

                case ACL_TYPE_DEFAULT:
                        ap->a_aclp->acl_cnt = 0;
                        break;
                }
        } else if (error != 0)
                goto out;

        if (!error) {
                error = ext4_acl_from_disk(value, len, ap->a_aclp);
                if (error)
                        goto out;
        }

        if (error == ENOATTR)
                error = 0;

        if (ap->a_type == ACL_TYPE_ACCESS)
                ext2_sync_acl_from_inode(VTOI(ap->a_vp), ap->a_aclp);

out:
        free(value, M_TEMP);
        return (error);
}

int
ext2_getacl(struct vop_getacl_args *ap)
{

        if (((ap->a_vp->v_mount->mnt_flag & MNT_ACLS) == 0) ||
            ((ap->a_vp->v_mount->mnt_flag & MNT_NFS4ACLS) != 0))
                return (EOPNOTSUPP);

        if (ap->a_type == ACL_TYPE_NFS4)
                return (ENOTSUP);

        return (ext2_getacl_posix1e(ap));
}

/*
 * Convert from in-memory to filesystem representation.
 */
static int
ext4_acl_to_disk(const struct acl *acl, size_t *size, char *value)
{
        struct ext2_acl_header *ext_acl;
        int disk_size;
        char *e;
        size_t n;

        if (acl->acl_cnt <= 4)
                disk_size = sizeof(struct ext2_acl_header) +
                   acl->acl_cnt * sizeof(struct ext2_acl_entry_short);
        else
                disk_size = sizeof(struct ext2_acl_header) +
                    4 * sizeof(struct ext2_acl_entry_short) +
                    (acl->acl_cnt - 4) * sizeof(struct ext2_acl_entry);

        if (disk_size > *size)
                return (EINVAL);

        *size = disk_size;
        ext_acl = (struct ext2_acl_header *)value;

        ext_acl->a_version = EXT4_ACL_VERSION;
        e = (char *)ext_acl + sizeof(struct ext2_acl_header);
        for (n = 0; n < acl->acl_cnt; n++) {
                const struct acl_entry *acl_e = &acl->acl_entry[n];
                struct ext2_acl_entry *entry = (struct ext2_acl_entry *)e;
                entry->ae_tag  = acl_e->ae_tag;
                entry->ae_perm = acl_e->ae_perm;
                switch (acl_e->ae_tag) {
                case ACL_USER:
                        entry->ae_id = acl_e->ae_id;
                        e += sizeof(struct ext2_acl_entry);
                        break;

                case ACL_GROUP:
                        entry->ae_id = acl_e->ae_id;
                        e += sizeof(struct ext2_acl_entry);
                        break;

                case ACL_USER_OBJ:
                case ACL_GROUP_OBJ:
                case ACL_MASK:
                case ACL_OTHER:
                        e += sizeof(struct ext2_acl_entry_short);
                        break;

                default:
                        return (EINVAL);
                }
        }

        return (0);
}

static int
ext2_setacl_posix1e(struct vop_setacl_args *ap)
{
        struct inode *ip = VTOI(ap->a_vp);
        char *value;
        size_t len;
        int error;

        if ((ap->a_vp->v_mount->mnt_flag & MNT_ACLS) == 0)
                return (EINVAL);

        /*
         * If this is a set operation rather than a delete operation,
         * invoke VOP_ACLCHECK() on the passed ACL to determine if it is
         * valid for the target.  This will include a check on ap->a_type.
         */
        if (ap->a_aclp != NULL) {
                /*
                 * Set operation.
                 */
                error = VOP_ACLCHECK(ap->a_vp, ap->a_type, ap->a_aclp,
                    ap->a_cred, ap->a_td);
                if (error)
                        return (error);
        } else {
                /*
                 * Delete operation.
                 * POSIX.1e allows only deletion of the default ACL on a
                 * directory (ACL_TYPE_DEFAULT).
                 */
                if (ap->a_type != ACL_TYPE_DEFAULT)
                        return (EINVAL);
                if (ap->a_vp->v_type != VDIR)
                        return (ENOTDIR);
        }

        if (ap->a_vp->v_mount->mnt_flag & MNT_RDONLY)
                return (EROFS);

        /*
         * Authorize the ACL operation.
         */
        if (ip->i_flags & (IMMUTABLE | APPEND))
                return (EPERM);

        /*
         * Must hold VADMIN (be file owner) or have appropriate privilege.
         */
        if ((error = VOP_ACCESS(ap->a_vp, VADMIN, ap->a_cred, ap->a_td)))
                return (error);

        switch (ap->a_type) {
        case ACL_TYPE_ACCESS:
                len = sizeof(*ap->a_aclp) + sizeof(struct ext2_acl_header);
                value = malloc(len, M_ACL, M_WAITOK | M_ZERO);
                error = ext4_acl_to_disk(ap->a_aclp, &len, value);
                if (error == 0)
                        error = vn_extattr_set(ap->a_vp, IO_NODELOCKED,
                            POSIX1E_ACL_ACCESS_EXTATTR_NAMESPACE,
                            POSIX1E_ACL_ACCESS_EXTATTR_NAME, len,
                            value, ap->a_td);

                free(value, M_ACL);
                break;

        case ACL_TYPE_DEFAULT:
                if (ap->a_aclp == NULL) {
                        error = vn_extattr_rm(ap->a_vp, IO_NODELOCKED,
                            POSIX1E_ACL_DEFAULT_EXTATTR_NAMESPACE,
                            POSIX1E_ACL_DEFAULT_EXTATTR_NAME, ap->a_td);

                        /*
                         * Attempting to delete a non-present default ACL
                         * will return success for portability purposes.
                         * (TRIX)
                         *
                         * XXX: Note that since we can't distinguish
                         * "that EA is not supported" from "that EA is not
                         * defined", the success case here overlaps the
                         * the ENOATTR->EOPNOTSUPP case below.
                         */
                        if (error == ENOATTR)
                                error = 0;
                } else {
                        len = sizeof(*ap->a_aclp) + sizeof(struct ext2_acl_header);
                        value = malloc(len, M_ACL, M_WAITOK | M_ZERO);
                        error = ext4_acl_to_disk(ap->a_aclp, &len, value);
                        if (error == 0)
                                error = vn_extattr_set(ap->a_vp, IO_NODELOCKED,
                                    POSIX1E_ACL_DEFAULT_EXTATTR_NAMESPACE,
                                    POSIX1E_ACL_DEFAULT_EXTATTR_NAME, len,
                                    value, ap->a_td);

                        free(value, M_ACL);
                }
                break;

        default:
                error = EINVAL;
        }

        /*
         * Map lack of attribute definition in UFS_EXTATTR into lack of
         * support for ACLs on the filesystem.
         */
        if (error == ENOATTR)
                return (EOPNOTSUPP);

        if (error != 0)
                return (error);

        if (ap->a_type == ACL_TYPE_ACCESS) {
                /*
                 * Now that the EA is successfully updated, update the
                 * inode and mark it as changed.
                 */
                ext2_sync_inode_from_acl(ap->a_aclp, ip);
                ip->i_flag |= IN_CHANGE;
                error = ext2_update(ip->i_vnode, 1);
        }

        VN_KNOTE_UNLOCKED(ap->a_vp, NOTE_ATTRIB);

        return (error);
}

int
ext2_setacl(struct vop_setacl_args *ap)
{
        if (((ap->a_vp->v_mount->mnt_flag & MNT_ACLS) == 0) ||
            ((ap->a_vp->v_mount->mnt_flag & MNT_NFS4ACLS) != 0))
                return (EOPNOTSUPP);

        if (ap->a_type == ACL_TYPE_NFS4)
                return (ENOTSUP);

        return (ext2_setacl_posix1e(ap));
}

/*
 * Check the validity of an ACL for a file.
 */
int
ext2_aclcheck(struct vop_aclcheck_args *ap)
{

        if (((ap->a_vp->v_mount->mnt_flag & MNT_ACLS) == 0) ||
            ((ap->a_vp->v_mount->mnt_flag & MNT_NFS4ACLS) != 0))
                return (EOPNOTSUPP);

        if (ap->a_type == ACL_TYPE_NFS4)
                return (ENOTSUP);

        if ((ap->a_vp->v_mount->mnt_flag & MNT_ACLS) == 0)
                return (EINVAL);

        /*
         * Verify we understand this type of ACL, and that it applies
         * to this kind of object.
         * Rely on the acl_posix1e_check() routine to verify the contents.
         */
        switch (ap->a_type) {
                case ACL_TYPE_ACCESS:
                break;

                case ACL_TYPE_DEFAULT:
                        if (ap->a_vp->v_type != VDIR)
                                return (EINVAL);
                break;

                default:
                        return (EINVAL);
        }

        return (acl_posix1e_check(ap->a_aclp));
}

#endif /* UFS_ACL */