/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 1999-2003 Robert N. M. Watson
 * All rights reserved.
 *
 * This software was developed by Robert Watson for the TrustedBSD Project.
 *
 * 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 AUTHOR 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 AUTHOR 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.
 */

/*
 * Support for POSIX.1e access control lists: UFS-specific support functions.
 */

#include <sys/cdefs.h>
#include "opt_ufs.h"
#include "opt_quota.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/stat.h>
#include <sys/mount.h>
#include <sys/vnode.h>
#include <sys/types.h>
#include <sys/acl.h>
#include <sys/event.h>
#include <sys/extattr.h>
#include <sys/proc.h>

#include <ufs/ufs/quota.h>
#include <ufs/ufs/inode.h>
#include <ufs/ufs/acl.h>
#include <ufs/ufs/extattr.h>
#include <ufs/ufs/dir.h>
#include <ufs/ufs/ufsmount.h>
#include <ufs/ufs/ufs_extern.h>
#include <ufs/ffs/fs.h>

#ifdef UFS_ACL

FEATURE(ufs_acl, "ACL support for UFS");

/*
 * Synchronize an ACL and an inode by copying over appropriate inode fields
 * to the passed ACL.  Assumes an ACL that would satisfy acl_posix1e_check(),
 * and may panic if not.
 */
void
ufs_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("ufs_sync_acl_from_inode(): bad ae_tag");
                }
        }

        if (acl_group_obj == NULL)
                panic("ufs_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);
        }
}

/*
 * Calculate what the inode mode should look like based on an authoritative
 * ACL for the inode.  Replace only the fields in the inode that the ACL
 * can represent.
 */
void
ufs_sync_inode_from_acl(struct acl *acl, struct inode *ip)
{
        int newmode;

        newmode = ip->i_mode & ACL_PRESERVE_MASK;
        newmode |= acl_posix1e_acl_to_mode(acl);
        UFS_INODE_SET_MODE(ip, newmode);
        DIP_SET(ip, i_mode, ip->i_mode);
}

/*
 * Retrieve NFSv4 ACL, skipping access checks.  Must be used in UFS code
 * instead of VOP_GETACL() when we don't want to be restricted by the user
 * not having ACL_READ_ACL permission, e.g. when calculating inherited ACL
 * or in ufs_vnops.c:ufs_accessx().
 */
int
ufs_getacl_nfs4_internal(struct vnode *vp, struct acl *aclp, struct thread *td)
{
        int error, len;
        struct inode *ip = VTOI(vp);

        len = sizeof(*aclp);
        bzero(aclp, len);

        error = vn_extattr_get(vp, IO_NODELOCKED,
            NFS4_ACL_EXTATTR_NAMESPACE, NFS4_ACL_EXTATTR_NAME,
            &len, (char *) aclp, td);
        aclp->acl_maxcnt = ACL_MAX_ENTRIES;
        if (error == ENOATTR) {
                /*
                 * Legitimately no ACL set on object, purely
                 * emulate it through the inode.
                 */
                acl_nfs4_sync_acl_from_mode(aclp, ip->i_mode, ip->i_uid);

                return (0);
        }

        if (error)
                return (error);

        if (len != sizeof(*aclp)) {
                /*
                 * A short (or long) read, meaning that for
                 * some reason the ACL is corrupted.  Return
                 * EPERM since the object DAC protections
                 * are unsafe.
                 */
                printf("ufs_getacl_nfs4(): Loaded invalid ACL ("
                    "%d bytes), inumber %ju on %s\n", len,
                    (uintmax_t)ip->i_number, ITOFS(ip)->fs_fsmnt);

                return (EPERM);
        }

        error = acl_nfs4_check(aclp, vp->v_type == VDIR);
        if (error) {
                printf("ufs_getacl_nfs4(): Loaded invalid ACL "
                    "(failed acl_nfs4_check), inumber %ju on %s\n",
                    (uintmax_t)ip->i_number, ITOFS(ip)->fs_fsmnt);

                return (EPERM);
        }

        return (0);
}

static int
ufs_getacl_nfs4(struct vop_getacl_args *ap)
{
        int error;

        if ((ap->a_vp->v_mount->mnt_flag & MNT_NFS4ACLS) == 0)
                return (EINVAL);

        error = VOP_ACCESSX(ap->a_vp, VREAD_ACL, ap->a_td->td_ucred, ap->a_td);
        if (error)
                return (error);

        error = ufs_getacl_nfs4_internal(ap->a_vp, ap->a_aclp, ap->a_td);

        return (error);
}

/*
 * Read POSIX.1e ACL from an EA.  Return error if its not found
 * or if any other error has occurred.
 */
static int
ufs_get_oldacl(acl_type_t type, struct oldacl *old, struct vnode *vp,
    struct thread *td)
{
        int error, len;
        struct inode *ip = VTOI(vp);

        len = sizeof(*old);

        switch (type) {
        case ACL_TYPE_ACCESS:
                error = vn_extattr_get(vp, IO_NODELOCKED,
                    POSIX1E_ACL_ACCESS_EXTATTR_NAMESPACE,
                    POSIX1E_ACL_ACCESS_EXTATTR_NAME, &len, (char *) old,
                    td);
                break;
        case ACL_TYPE_DEFAULT:
                if (vp->v_type != VDIR)
                        return (EINVAL);
                error = vn_extattr_get(vp, IO_NODELOCKED,
                    POSIX1E_ACL_DEFAULT_EXTATTR_NAMESPACE,
                    POSIX1E_ACL_DEFAULT_EXTATTR_NAME, &len, (char *) old,
                    td);
                break;
        default:
                return (EINVAL);
        }

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

        if (len != sizeof(*old)) {
                /*
                 * A short (or long) read, meaning that for some reason
                 * the ACL is corrupted.  Return EPERM since the object
                 * DAC protections are unsafe.
                 */
                printf("ufs_get_oldacl(): Loaded invalid ACL "
                    "(len = %d), inumber %ju on %s\n", len,
                    (uintmax_t)ip->i_number, ITOFS(ip)->fs_fsmnt);
                return (EPERM);
        }

        return (0);
}

/*
 * Retrieve the ACL on a file.
 *
 * As part of the ACL is stored in the inode, and the rest in an EA,
 * assemble both into a final ACL product.  Right now this is not done
 * very efficiently.
 */
static int
ufs_getacl_posix1e(struct vop_getacl_args *ap)
{
        struct inode *ip = VTOI(ap->a_vp);
        int error;
        struct oldacl *old;

        /*
         * XXX: If ufs_getacl() should work on file systems not supporting
         * ACLs, remove this check.
         */
        if ((ap->a_vp->v_mount->mnt_flag & MNT_ACLS) == 0)
                return (EINVAL);

        old = malloc(sizeof(*old), M_ACL, M_WAITOK | M_ZERO);

        /*
         * Attempt to retrieve the ACL from the extended attributes.
         */
        error = ufs_get_oldacl(ap->a_type, old, ap->a_vp, ap->a_td);
        switch (error) {
        /*
         * XXX: If ufs_getacl() should work on filesystems
         * without the EA configured, add case EOPNOTSUPP here.
         */
        case ENOATTR:
                switch (ap->a_type) {
                case ACL_TYPE_ACCESS:
                        /*
                         * Legitimately no ACL set on object, purely
                         * emulate it through the inode.  These fields will
                         * be updated when the ACL is synchronized with
                         * the inode later.
                         */
                        old->acl_cnt = 3;
                        old->acl_entry[0].ae_tag = ACL_USER_OBJ;
                        old->acl_entry[0].ae_id = ACL_UNDEFINED_ID;
                        old->acl_entry[0].ae_perm = ACL_PERM_NONE;
                        old->acl_entry[1].ae_tag = ACL_GROUP_OBJ;
                        old->acl_entry[1].ae_id = ACL_UNDEFINED_ID;
                        old->acl_entry[1].ae_perm = ACL_PERM_NONE;
                        old->acl_entry[2].ae_tag = ACL_OTHER;
                        old->acl_entry[2].ae_id = ACL_UNDEFINED_ID;
                        old->acl_entry[2].ae_perm = ACL_PERM_NONE;
                        break;

                case ACL_TYPE_DEFAULT:
                        /*
                         * Unlike ACL_TYPE_ACCESS, there is no relationship
                         * between the inode contents and the ACL, and it is
                         * therefore possible for the request for the ACL
                         * to fail since the ACL is undefined.  In this
                         * situation, return success and an empty ACL,
                         * as required by POSIX.1e.
                         */
                        old->acl_cnt = 0;
                        break;
                }
                /* FALLTHROUGH */
        case 0:
                error = acl_copy_oldacl_into_acl(old, ap->a_aclp);
                if (error != 0)
                        break;

                if (ap->a_type == ACL_TYPE_ACCESS)
                        ufs_sync_acl_from_inode(ip, ap->a_aclp);
        default:
                break;
        }

        free(old, M_ACL);
        return (error);
}

int
ufs_getacl(struct vop_getacl_args *ap)
{

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

        if (ap->a_type == ACL_TYPE_NFS4)
                return (ufs_getacl_nfs4(ap));

        return (ufs_getacl_posix1e(ap));
}

/*
 * Set NFSv4 ACL without doing any access checking.  This is required
 * e.g. by the UFS code that implements ACL inheritance, or from
 * ufs_vnops.c:ufs_chmod(), as some of the checks have to be skipped
 * in that case, and others are redundant.
 */
int
ufs_setacl_nfs4_internal(struct vnode *vp, struct acl *aclp, struct thread *td)
{
        int error;
        mode_t mode, newmode;
        struct inode *ip = VTOI(vp);

        KASSERT(acl_nfs4_check(aclp, vp->v_type == VDIR) == 0,
            ("invalid ACL passed to ufs_setacl_nfs4_internal"));

        if (acl_nfs4_is_trivial(aclp, ip->i_uid)) {
                error = vn_extattr_rm(vp, IO_NODELOCKED,
                    NFS4_ACL_EXTATTR_NAMESPACE, NFS4_ACL_EXTATTR_NAME, td);

                /*
                 * An attempt to remove ACL from a file that didn't have
                 * any extended entries is not an error.
                 */
                if (error == ENOATTR)
                        error = 0;

        } else {
                error = vn_extattr_set(vp, IO_NODELOCKED,
                    NFS4_ACL_EXTATTR_NAMESPACE, NFS4_ACL_EXTATTR_NAME,
                    sizeof(*aclp), (char *) aclp, td);
        }

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

        if (error)
                return (error);

        mode = ip->i_mode;

        acl_nfs4_sync_mode_from_acl(&mode, aclp);

        newmode = ip->i_mode & ACL_PRESERVE_MASK;
        newmode |= mode;
        UFS_INODE_SET_MODE(ip, newmode);
        DIP_SET(ip, i_mode, ip->i_mode);
        UFS_INODE_SET_FLAG(ip, IN_CHANGE);

        VN_KNOTE_UNLOCKED(vp, NOTE_ATTRIB);

        error = UFS_UPDATE(vp, 0);
        return (error);
}

static int
ufs_setacl_nfs4(struct vop_setacl_args *ap)
{
        int error;
        struct inode *ip = VTOI(ap->a_vp);

        if ((ap->a_vp->v_mount->mnt_flag & MNT_NFS4ACLS) == 0)
                return (EINVAL);

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

        if (ap->a_aclp == NULL)
                return (EINVAL);

        error = VOP_ACLCHECK(ap->a_vp, ap->a_type, ap->a_aclp, ap->a_cred,
            ap->a_td);
        if (error)
                return (error);

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

        /*
         * Must hold VWRITE_ACL or have appropriate privilege.
         */
        if ((error = VOP_ACCESSX(ap->a_vp, VWRITE_ACL, ap->a_cred, ap->a_td)))
                return (error);

        /*
         * With NFSv4 ACLs, chmod(2) may need to add additional entries.
         * Make sure it has enough room for that - splitting every entry
         * into two and appending "canonical six" entries at the end.
         */
        if (ap->a_aclp->acl_cnt > (ACL_MAX_ENTRIES - 6) / 2)
                return (ENOSPC);

        error = ufs_setacl_nfs4_internal(ap->a_vp, ap->a_aclp, ap->a_td);

        return (error);
}

/*
 * Set the ACL on a file.
 *
 * As part of the ACL is stored in the inode, and the rest in an EA,
 * this is necessarily non-atomic, and has complex authorization.
 * As ufs_setacl() includes elements of ufs_chown() and ufs_chmod(),
 * a fair number of different access checks may be required to go ahead
 * with the operation at all.
 */
static int
ufs_setacl_posix1e(struct vop_setacl_args *ap)
{
        struct inode *ip = VTOI(ap->a_vp);
        int error;
        struct oldacl *old;

        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 != 0)
                        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:
                old = malloc(sizeof(*old), M_ACL, M_WAITOK | M_ZERO);
                error = acl_copy_acl_into_oldacl(ap->a_aclp, old);
                if (error == 0) {
                        error = vn_extattr_set(ap->a_vp, IO_NODELOCKED,
                            POSIX1E_ACL_ACCESS_EXTATTR_NAMESPACE,
                            POSIX1E_ACL_ACCESS_EXTATTR_NAME, sizeof(*old),
                            (char *) old, ap->a_td);
                }
                free(old, 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 {
                        old = malloc(sizeof(*old), M_ACL, M_WAITOK | M_ZERO);
                        error = acl_copy_acl_into_oldacl(ap->a_aclp, old);
                        if (error == 0) {
                                error = vn_extattr_set(ap->a_vp, IO_NODELOCKED,
                                    POSIX1E_ACL_DEFAULT_EXTATTR_NAMESPACE,
                                    POSIX1E_ACL_DEFAULT_EXTATTR_NAME,
                                    sizeof(*old), (char *) old, ap->a_td);
                        }
                        free(old, 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.
                 */
                ufs_sync_inode_from_acl(ap->a_aclp, ip);
                UFS_INODE_SET_FLAG(ip, IN_CHANGE);
                error = UFS_UPDATE(ap->a_vp, 0);
        }

        VN_KNOTE_UNLOCKED(ap->a_vp, NOTE_ATTRIB);
        return (error);
}

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

        if (ap->a_type == ACL_TYPE_NFS4)
                return (ufs_setacl_nfs4(ap));

        return (ufs_setacl_posix1e(ap));
}

static int
ufs_aclcheck_nfs4(struct vop_aclcheck_args *ap, struct mount *mp)
{
        int is_directory = 0;

        if ((mp->mnt_flag & MNT_NFS4ACLS) == 0)
                return (EINVAL);

        /*
         * With NFSv4 ACLs, chmod(2) may need to add additional entries.
         * Make sure it has enough room for that - splitting every entry
         * into two and appending "canonical six" entries at the end.
         */
        if (ap->a_aclp->acl_cnt > (ACL_MAX_ENTRIES - 6) / 2)
                return (ENOSPC);

        if (ap->a_vp->v_type == VDIR)
                is_directory = 1;

        return (acl_nfs4_check(ap->a_aclp, is_directory));
}

static int
ufs_aclcheck_posix1e(struct vop_aclcheck_args *ap, struct mount *mp)
{
        if ((mp->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);
        }

        if (ap->a_aclp->acl_cnt > OLDACL_MAX_ENTRIES)
                return (EINVAL);

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

/*
 * Check the validity of an ACL for a file.
 */
int
ufs_aclcheck(struct vop_aclcheck_args *ap)
{
        struct mount *mp;

        mp = atomic_load_ptr(&ap->a_vp->v_mount);
        if (mp == NULL)
                return (EBADF);
        if ((mp->mnt_flag & (MNT_ACLS | MNT_NFS4ACLS)) == 0)
                return (EOPNOTSUPP);

        if (ap->a_type == ACL_TYPE_NFS4)
                return (ufs_aclcheck_nfs4(ap, mp));

        return (ufs_aclcheck_posix1e(ap, mp));
}

#endif /* !UFS_ACL */