sys/kern/subr_acl_nfs4.c

root/sys/kern/subr_acl_nfs4.c
/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2008-2010 Edward Tomasz Napierała <trasz@FreeBSD.org>
 * 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 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.
 */

/*
 * ACL support routines specific to NFSv4 access control lists.  These are
 * utility routines for code common across file systems implementing NFSv4
 * ACLs.
 */

#ifdef _KERNEL
#include <sys/cdefs.h>
#if 0
__FBSDID("$FreeBSD: head/sys/kern/subr_acl_nfs4.c 341827 2018-12-11 19:32:16Z mjg $");
#endif
__KERNEL_RCSID(0, "$NetBSD: subr_acl_nfs4.c,v 1.4 2026/01/04 02:10:18 riastradh Exp $");

#include <sys/param.h>
#include <sys/types.h>

#include <sys/acl.h>
#include <sys/errno.h>
#include <sys/kauth.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/mount.h>
#include <sys/sdt.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/vnode.h>

static void     acl_nfs4_trivial_from_mode(struct acl *aclp, mode_t mode);

#else

#include <sys/acl.h>
#include <sys/stat.h>

#include <assert.h>
#include <errno.h>

#define KASSERT(a) assert(a)

#endif /* !_KERNEL */

#if 0
static int
_acl_entry_matches(struct acl_entry *ae, acl_tag_t tag, acl_perm_t perm,
    acl_entry_type_t entry_type)
{
        if (ae->ae_tag != tag)
                return (0);

        if (ae->ae_id != ACL_UNDEFINED_ID)
                return (0);

        if (ae->ae_perm != perm)
                return (0);

        if (ae->ae_entry_type != entry_type)
                return (0);

        if (ae->ae_flags != 0)
                return (0);

        return (1);
}
#endif

static struct acl_entry *
_acl_append(struct acl *aclp, acl_tag_t tag, acl_perm_t perm,
    acl_entry_type_t entry_type)
{
        struct acl_entry *ae;

        KASSERT(aclp->acl_cnt + 1 <= ACL_MAX_ENTRIES);

        ae = &(aclp->acl_entry[aclp->acl_cnt]);
        aclp->acl_cnt++;

        ae->ae_tag = tag;
        ae->ae_id = ACL_UNDEFINED_ID;
        ae->ae_perm = perm;
        ae->ae_entry_type = entry_type;
        ae->ae_flags = 0;

        return (ae);
}

#if 0
static struct acl_entry *
_acl_duplicate_entry(struct acl *aclp, unsigned int entry_index)
{
        size_t i;

        KASSERT(aclp->acl_cnt + 1 <= ACL_MAX_ENTRIES);

        for (i = aclp->acl_cnt; i > entry_index; i--)
                aclp->acl_entry[i] = aclp->acl_entry[i - 1];

        aclp->acl_cnt++;

        return (&(aclp->acl_entry[entry_index + 1]));
}
#endif


#ifdef _KERNEL
void
acl_nfs4_sync_acl_from_mode(struct acl *aclp, mode_t mode,
    int file_owner_id)
{

        acl_nfs4_trivial_from_mode(aclp, mode);
}
#endif /* _KERNEL */

void
__acl_nfs4_sync_mode_from_acl(mode_t *_mode, const struct acl *aclp)
{
        size_t i;
        mode_t old_mode = *_mode, mode = 0, seen = 0;
        const struct acl_entry *ae;

        KASSERT(aclp->acl_cnt <= ACL_MAX_ENTRIES);

        /*
         * NFSv4 Minor Version 1, draft-ietf-nfsv4-minorversion1-03.txt
         *
         * 3.16.6.1. Recomputing mode upon SETATTR of ACL
         */

        for (i = 0; i < aclp->acl_cnt; i++) {
                ae = &(aclp->acl_entry[i]);

                if (ae->ae_entry_type != ACL_ENTRY_TYPE_ALLOW &&
                    ae->ae_entry_type != ACL_ENTRY_TYPE_DENY)
                        continue;

                if (ae->ae_flags & ACL_ENTRY_INHERIT_ONLY)
                        continue;

                if (ae->ae_tag == ACL_USER_OBJ) {
                        if ((ae->ae_perm & ACL_READ_DATA) &&
                            ((seen & S_IRUSR) == 0)) {
                                seen |= S_IRUSR;
                                if (ae->ae_entry_type == ACL_ENTRY_TYPE_ALLOW)
                                        mode |= S_IRUSR;
                        }
                        if ((ae->ae_perm & ACL_WRITE_DATA) &&
                             ((seen & S_IWUSR) == 0)) {
                                seen |= S_IWUSR;
                                if (ae->ae_entry_type == ACL_ENTRY_TYPE_ALLOW)
                                        mode |= S_IWUSR;
                        }
                        if ((ae->ae_perm & ACL_EXECUTE) &&
                            ((seen & S_IXUSR) == 0)) {
                                seen |= S_IXUSR;
                                if (ae->ae_entry_type == ACL_ENTRY_TYPE_ALLOW)
                                        mode |= S_IXUSR;
                        }
                } else if (ae->ae_tag == ACL_GROUP_OBJ) {
                        if ((ae->ae_perm & ACL_READ_DATA) &&
                            ((seen & S_IRGRP) == 0)) {
                                seen |= S_IRGRP;
                                if (ae->ae_entry_type == ACL_ENTRY_TYPE_ALLOW)
                                        mode |= S_IRGRP;
                        }
                        if ((ae->ae_perm & ACL_WRITE_DATA) &&
                            ((seen & S_IWGRP) == 0)) {
                                seen |= S_IWGRP;
                                if (ae->ae_entry_type == ACL_ENTRY_TYPE_ALLOW)
                                        mode |= S_IWGRP;
                        }
                        if ((ae->ae_perm & ACL_EXECUTE) &&
                            ((seen & S_IXGRP) == 0)) {
                                seen |= S_IXGRP;
                                if (ae->ae_entry_type == ACL_ENTRY_TYPE_ALLOW)
                                        mode |= S_IXGRP;
                        }
                } else if (ae->ae_tag == ACL_EVERYONE) {
                        if (ae->ae_perm & ACL_READ_DATA) {
                                if ((seen & S_IRUSR) == 0) {
                                        seen |= S_IRUSR;
                                        if (ae->ae_entry_type == ACL_ENTRY_TYPE_ALLOW)
                                                mode |= S_IRUSR;
                                }
                                if ((seen & S_IRGRP) == 0) {
                                        seen |= S_IRGRP;
                                        if (ae->ae_entry_type == ACL_ENTRY_TYPE_ALLOW)
                                                mode |= S_IRGRP;
                                }
                                if ((seen & S_IROTH) == 0) {
                                        seen |= S_IROTH;
                                        if (ae->ae_entry_type == ACL_ENTRY_TYPE_ALLOW)
                                                mode |= S_IROTH;
                                }
                        }
                        if (ae->ae_perm & ACL_WRITE_DATA) {
                                if ((seen & S_IWUSR) == 0) {
                                        seen |= S_IWUSR;
                                        if (ae->ae_entry_type == ACL_ENTRY_TYPE_ALLOW)
                                                mode |= S_IWUSR;
                                }
                                if ((seen & S_IWGRP) == 0) {
                                        seen |= S_IWGRP;
                                        if (ae->ae_entry_type == ACL_ENTRY_TYPE_ALLOW)
                                                mode |= S_IWGRP;
                                }
                                if ((seen & S_IWOTH) == 0) {
                                        seen |= S_IWOTH;
                                        if (ae->ae_entry_type == ACL_ENTRY_TYPE_ALLOW)
                                                mode |= S_IWOTH;
                                }
                        }
                        if (ae->ae_perm & ACL_EXECUTE) {
                                if ((seen & S_IXUSR) == 0) {
                                        seen |= S_IXUSR;
                                        if (ae->ae_entry_type == ACL_ENTRY_TYPE_ALLOW)
                                                mode |= S_IXUSR;
                                }
                                if ((seen & S_IXGRP) == 0) {
                                        seen |= S_IXGRP;
                                        if (ae->ae_entry_type == ACL_ENTRY_TYPE_ALLOW)
                                                mode |= S_IXGRP;
                                }
                                if ((seen & S_IXOTH) == 0) {
                                        seen |= S_IXOTH;
                                        if (ae->ae_entry_type == ACL_ENTRY_TYPE_ALLOW)
                                                mode |= S_IXOTH;
                                }
                        }
                }
        }

        *_mode = mode | (old_mode & ACL_PRESERVE_MASK);
}

/*
 * Populate the ACL with entries inherited from parent_aclp.
 */
static void             
/*ARGSUSED*/
acl_nfs4_inherit_entries(const struct acl *parent_aclp,
    struct acl *child_aclp, mode_t mode, int file_owner_id,
    int is_directory)
{
        int flags, tag;
        size_t i;
        const struct acl_entry *parent_entry;
        struct acl_entry *ae;

        KASSERT(parent_aclp->acl_cnt <= ACL_MAX_ENTRIES);

        for (i = 0; i < parent_aclp->acl_cnt; i++) {
                parent_entry = &(parent_aclp->acl_entry[i]);
                flags = parent_entry->ae_flags;
                tag = parent_entry->ae_tag;

                /*
                 * Don't inherit owner@, group@, or everyone@ entries.
                 */
                if (tag == ACL_USER_OBJ || tag == ACL_GROUP_OBJ ||
                    tag == ACL_EVERYONE)
                        continue;

                /*
                 * Entry is not inheritable at all.
                 */
                if ((flags & (ACL_ENTRY_DIRECTORY_INHERIT |
                    ACL_ENTRY_FILE_INHERIT)) == 0)
                        continue;

                /*
                 * We're creating a file, but ae is not inheritable
                 * by files.
                 */
                if (!is_directory && (flags & ACL_ENTRY_FILE_INHERIT) == 0)
                        continue;

                /*
                 * Entry is inheritable only by files, but has NO_PROPAGATE
                 * flag set, and we're creating a directory, so it wouldn't
                 * propagate to any file in that directory anyway.
                 */
                if (is_directory &&
                    (flags & ACL_ENTRY_DIRECTORY_INHERIT) == 0 &&
                    (flags & ACL_ENTRY_NO_PROPAGATE_INHERIT))
                        continue;

                /*
                 * Entry qualifies for being inherited.
                 */
                KASSERT(child_aclp->acl_cnt + 1 <= ACL_MAX_ENTRIES);
                ae = &(child_aclp->acl_entry[child_aclp->acl_cnt]);
                *ae = *parent_entry;
                child_aclp->acl_cnt++;

                ae->ae_flags &= ~ACL_ENTRY_INHERIT_ONLY;
                ae->ae_flags |= ACL_ENTRY_INHERITED;

                /*
                 * If the type of the ACE is neither ALLOW nor DENY,
                 * then leave it as it is and proceed to the next one.
                 */
                if (ae->ae_entry_type != ACL_ENTRY_TYPE_ALLOW &&
                    ae->ae_entry_type != ACL_ENTRY_TYPE_DENY)
                        continue;

                /*
                 * If the ACL_ENTRY_NO_PROPAGATE_INHERIT is set, or if
                 * the object being created is not a directory, then clear
                 * the following flags: ACL_ENTRY_NO_PROPAGATE_INHERIT,
                 * ACL_ENTRY_FILE_INHERIT, ACL_ENTRY_DIRECTORY_INHERIT,
                 * ACL_ENTRY_INHERIT_ONLY.
                 */
                if (ae->ae_flags & ACL_ENTRY_NO_PROPAGATE_INHERIT ||
                    !is_directory) {
                        ae->ae_flags &= ~(ACL_ENTRY_NO_PROPAGATE_INHERIT |
                        ACL_ENTRY_FILE_INHERIT | ACL_ENTRY_DIRECTORY_INHERIT |
                        ACL_ENTRY_INHERIT_ONLY);
                }

                /*
                 * If the object is a directory and ACL_ENTRY_FILE_INHERIT
                 * is set, but ACL_ENTRY_DIRECTORY_INHERIT is not set, ensure
                 * that ACL_ENTRY_INHERIT_ONLY is set.
                 */
                if (is_directory &&
                    (ae->ae_flags & ACL_ENTRY_FILE_INHERIT) &&
                    ((ae->ae_flags & ACL_ENTRY_DIRECTORY_INHERIT) == 0)) {
                        ae->ae_flags |= ACL_ENTRY_INHERIT_ONLY;
                }

                if (ae->ae_entry_type == ACL_ENTRY_TYPE_ALLOW &&
                    (ae->ae_flags & ACL_ENTRY_INHERIT_ONLY) == 0) {
                        /*
                         * Some permissions must never be inherited.
                         */
                        ae->ae_perm &= ~(ACL_WRITE_ACL | ACL_WRITE_OWNER |
                            ACL_WRITE_NAMED_ATTRS | ACL_WRITE_ATTRIBUTES);

                        /*
                         * Others must be masked according to the file mode.
                         */
                        if ((mode & S_IRGRP) == 0)
                                ae->ae_perm &= ~ACL_READ_DATA;
                        if ((mode & S_IWGRP) == 0)
                                ae->ae_perm &=
                                    ~(ACL_WRITE_DATA | ACL_APPEND_DATA);
                        if ((mode & S_IXGRP) == 0)
                                ae->ae_perm &= ~ACL_EXECUTE;
                }
        }
}

/*
 * Calculate inherited ACL in a manner compatible with PSARC/2010/029.
 * It's also being used to calculate a trivial ACL, by inheriting from
 * a NULL ACL.
 */
static void             
acl_nfs4_compute_inherited_acl_psarc(const struct acl *parent_aclp,
    struct acl *aclp, mode_t mode, int file_owner_id, int is_directory)
{
        acl_perm_t user_allow_first = 0, user_deny = 0, group_deny = 0;
        acl_perm_t user_allow, group_allow, everyone_allow;

        KASSERT(aclp->acl_cnt == 0);

        user_allow = group_allow = everyone_allow = ACL_READ_ACL |
            ACL_READ_ATTRIBUTES | ACL_READ_NAMED_ATTRS | ACL_SYNCHRONIZE;
        user_allow |= ACL_WRITE_ACL | ACL_WRITE_OWNER | ACL_WRITE_ATTRIBUTES |
            ACL_WRITE_NAMED_ATTRS;

        if (mode & S_IRUSR)
                user_allow |= ACL_READ_DATA;
        if (mode & S_IWUSR)
                user_allow |= (ACL_WRITE_DATA | ACL_APPEND_DATA);
        if (mode & S_IXUSR)
                user_allow |= ACL_EXECUTE;

        if (mode & S_IRGRP)
                group_allow |= ACL_READ_DATA;
        if (mode & S_IWGRP)
                group_allow |= (ACL_WRITE_DATA | ACL_APPEND_DATA);
        if (mode & S_IXGRP)
                group_allow |= ACL_EXECUTE;

        if (mode & S_IROTH)
                everyone_allow |= ACL_READ_DATA;
        if (mode & S_IWOTH)
                everyone_allow |= (ACL_WRITE_DATA | ACL_APPEND_DATA);
        if (mode & S_IXOTH)
                everyone_allow |= ACL_EXECUTE;

        user_deny = ((group_allow | everyone_allow) & ~user_allow);
        group_deny = everyone_allow & ~group_allow;
        user_allow_first = group_deny & ~user_deny;

        if (user_allow_first != 0)
                _acl_append(aclp, ACL_USER_OBJ, user_allow_first,
                    ACL_ENTRY_TYPE_ALLOW);
        if (user_deny != 0)
                _acl_append(aclp, ACL_USER_OBJ, user_deny,
                    ACL_ENTRY_TYPE_DENY);
        if (group_deny != 0)
                _acl_append(aclp, ACL_GROUP_OBJ, group_deny,
                    ACL_ENTRY_TYPE_DENY);

        if (parent_aclp != NULL)
                acl_nfs4_inherit_entries(parent_aclp, aclp, mode,
                    file_owner_id, is_directory);

        _acl_append(aclp, ACL_USER_OBJ, user_allow, ACL_ENTRY_TYPE_ALLOW);
        _acl_append(aclp, ACL_GROUP_OBJ, group_allow, ACL_ENTRY_TYPE_ALLOW);
        _acl_append(aclp, ACL_EVERYONE, everyone_allow, ACL_ENTRY_TYPE_ALLOW);
}

#ifdef _KERNEL
void            
acl_nfs4_compute_inherited_acl(const struct acl *parent_aclp,
    struct acl *child_aclp, mode_t mode, int file_owner_id,
    int is_directory)
{

        acl_nfs4_compute_inherited_acl_psarc(parent_aclp, child_aclp,
            mode, file_owner_id, is_directory);
}
#endif /* _KERNEL */

/*
 * Calculate trivial ACL in a manner compatible with PSARC/2010/029.
 * Note that this results in an ACL different from (but semantically
 * equal to) the "canonical six" trivial ACL computed using algorithm
 * described in draft-ietf-nfsv4-minorversion1-03.txt, 3.16.6.2.
 */
static void
acl_nfs4_trivial_from_mode(struct acl *aclp, mode_t mode)
{

        aclp->acl_cnt = 0;
        acl_nfs4_compute_inherited_acl_psarc(NULL, aclp, mode, -1, -1);
}

#ifndef _KERNEL
/*
 * This routine is used by libc to implement acl_strip_np(3)
 * and acl_is_trivial_np(3).
 */
void
/*ARGSUSED*/
__acl_nfs4_trivial_from_mode_libc(struct acl *aclp, int mode, int canonical_six)
{

        aclp->acl_cnt = 0;
        acl_nfs4_trivial_from_mode(aclp, mode);
}
#endif /* !_KERNEL */

#ifdef _KERNEL
static int
_acls_are_equal(const struct acl *a, const struct acl *b)
{
        int i;
        const struct acl_entry *entrya, *entryb;

        if (a->acl_cnt != b->acl_cnt)
                return (0);

        for (i = 0; i < b->acl_cnt; i++) {
                entrya = &(a->acl_entry[i]);
                entryb = &(b->acl_entry[i]);

                if (entrya->ae_tag != entryb->ae_tag ||
                    entrya->ae_id != entryb->ae_id ||
                    entrya->ae_perm != entryb->ae_perm ||
                    entrya->ae_entry_type != entryb->ae_entry_type ||
                    entrya->ae_flags != entryb->ae_flags)
                        return (0);
        }

        return (1);
}

/*
 * This routine is used to determine whether to remove extended attribute
 * that stores ACL contents.
 */
int
acl_nfs4_is_trivial(const struct acl *aclp, int file_owner_id)
{
        int trivial;
        mode_t tmpmode = 0;
        struct acl *tmpaclp;

        if (aclp->acl_cnt > 6)
                return (0);

        /*
         * Compute the mode from the ACL, then compute new ACL from that mode.
         * If the ACLs are identical, then the ACL is trivial.
         *
         * XXX: I guess there is a faster way to do this.  However, even
         *      this slow implementation significantly speeds things up
         *      for files that don't have non-trivial ACLs - it's critical
         *      for performance to not use EA when they are not needed.
         *
         * First try the PSARC/2010/029 semantics.
         */
        tmpaclp = acl_alloc(KM_SLEEP);
        __acl_nfs4_sync_mode_from_acl(&tmpmode, aclp);
        acl_nfs4_trivial_from_mode(tmpaclp, tmpmode);
        trivial = _acls_are_equal(aclp, tmpaclp);
        if (trivial) {
                acl_free(tmpaclp);
                return (trivial);
        }

        /*
         * Check if it's a draft-ietf-nfsv4-minorversion1-03.txt trivial ACL.
         */
        acl_free(tmpaclp);

        return (trivial);
}

int
acl_nfs4_check(const struct acl *aclp, int is_directory)
{
        size_t i;
        const struct acl_entry *ae;

        /*
         * The spec doesn't seem to say anything about ACL validity.
         * It seems there is not much to do here.  There is even no need
         * to count "owner@" or "everyone@" (ACL_USER_OBJ and ACL_EVERYONE)
         * entries, as there can be several of them and that's perfectly
         * valid.  There can be none of them too.  Really.
         */

        if (aclp->acl_cnt > ACL_MAX_ENTRIES || aclp->acl_cnt <= 0)
                return SET_ERROR(EINVAL);

        for (i = 0; i < aclp->acl_cnt; i++) {
                ae = &(aclp->acl_entry[i]);

                switch (ae->ae_tag) {
                case ACL_USER_OBJ:
                case ACL_GROUP_OBJ:
                case ACL_EVERYONE:
                        if (ae->ae_id != ACL_UNDEFINED_ID)
                                return SET_ERROR(EINVAL);
                        break;

                case ACL_USER:
                case ACL_GROUP:
                        if (ae->ae_id == ACL_UNDEFINED_ID)
                                return SET_ERROR(EINVAL);
                        break;

                default:
                        return SET_ERROR(EINVAL);
                }

                if ((ae->ae_perm | ACL_NFS4_PERM_BITS) != ACL_NFS4_PERM_BITS)
                        return SET_ERROR(EINVAL);

                /*
                 * Disallow ACL_ENTRY_TYPE_AUDIT and ACL_ENTRY_TYPE_ALARM for now.
                 */
                if (ae->ae_entry_type != ACL_ENTRY_TYPE_ALLOW &&
                    ae->ae_entry_type != ACL_ENTRY_TYPE_DENY)
                        return SET_ERROR(EINVAL);

                if ((ae->ae_flags | ACL_FLAGS_BITS) != ACL_FLAGS_BITS)
                        return SET_ERROR(EINVAL);

                /* Disallow unimplemented flags. */
                if (ae->ae_flags & (ACL_ENTRY_SUCCESSFUL_ACCESS |
                    ACL_ENTRY_FAILED_ACCESS))
                        return SET_ERROR(EINVAL);

                /* Disallow flags not allowed for ordinary files. */
                if (!is_directory) {
                        if (ae->ae_flags & (ACL_ENTRY_FILE_INHERIT |
                            ACL_ENTRY_DIRECTORY_INHERIT |
                            ACL_ENTRY_NO_PROPAGATE_INHERIT | ACL_ENTRY_INHERIT_ONLY))
                                return SET_ERROR(EINVAL);
                }
        }

        return 0;
}
#endif