// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2008, Christoph Hellwig
 * All Rights Reserved.
 */
#include "xfs_platform.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_da_format.h"
#include "xfs_da_btree.h"
#include "xfs_attr.h"
#include "xfs_trace.h"
#include "xfs_error.h"
#include "xfs_acl.h"
#include "xfs_trans.h"
#include "xfs_xattr.h"

#include <linux/posix_acl_xattr.h>

/*
 * Locking scheme:
 *  - all ACL updates are protected by inode->i_mutex, which is taken before
 *    calling into this file.
 */

STATIC struct posix_acl *
xfs_acl_from_disk(
        struct xfs_mount        *mp,
        const struct xfs_acl    *aclp,
        int                     len,
        int                     max_entries)
{
        struct posix_acl_entry *acl_e;
        struct posix_acl *acl;
        const struct xfs_acl_entry *ace;
        unsigned int count, i;

        if (len < sizeof(*aclp)) {
                XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, aclp,
                                len);
                return ERR_PTR(-EFSCORRUPTED);
        }

        count = be32_to_cpu(aclp->acl_cnt);
        if (count > max_entries || XFS_ACL_SIZE(count) != len) {
                XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp, aclp,
                                len);
                return ERR_PTR(-EFSCORRUPTED);
        }

        acl = posix_acl_alloc(count, GFP_KERNEL);
        if (!acl)
                return ERR_PTR(-ENOMEM);

        for (i = 0; i < count; i++) {
                acl_e = &acl->a_entries[i];
                ace = &aclp->acl_entry[i];

                /*
                 * The tag is 32 bits on disk and 16 bits in core.
                 *
                 * Because every access to it goes through the core
                 * format first this is not a problem.
                 */
                acl_e->e_tag = be32_to_cpu(ace->ae_tag);
                acl_e->e_perm = be16_to_cpu(ace->ae_perm);

                switch (acl_e->e_tag) {
                case ACL_USER:
                        acl_e->e_uid = make_kuid(&init_user_ns,
                                                 be32_to_cpu(ace->ae_id));
                        break;
                case ACL_GROUP:
                        acl_e->e_gid = make_kgid(&init_user_ns,
                                                 be32_to_cpu(ace->ae_id));
                        break;
                case ACL_USER_OBJ:
                case ACL_GROUP_OBJ:
                case ACL_MASK:
                case ACL_OTHER:
                        break;
                default:
                        goto fail;
                }
        }
        return acl;

fail:
        posix_acl_release(acl);
        return ERR_PTR(-EINVAL);
}

STATIC void
xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
{
        const struct posix_acl_entry *acl_e;
        struct xfs_acl_entry *ace;
        int i;

        aclp->acl_cnt = cpu_to_be32(acl->a_count);
        for (i = 0; i < acl->a_count; i++) {
                ace = &aclp->acl_entry[i];
                acl_e = &acl->a_entries[i];

                ace->ae_tag = cpu_to_be32(acl_e->e_tag);
                switch (acl_e->e_tag) {
                case ACL_USER:
                        ace->ae_id = cpu_to_be32(
                                        from_kuid(&init_user_ns, acl_e->e_uid));
                        break;
                case ACL_GROUP:
                        ace->ae_id = cpu_to_be32(
                                        from_kgid(&init_user_ns, acl_e->e_gid));
                        break;
                default:
                        ace->ae_id = cpu_to_be32(ACL_UNDEFINED_ID);
                        break;
                }

                ace->ae_perm = cpu_to_be16(acl_e->e_perm);
        }
}

struct posix_acl *
xfs_get_acl(struct inode *inode, int type, bool rcu)
{
        struct xfs_inode        *ip = XFS_I(inode);
        struct xfs_mount        *mp = ip->i_mount;
        struct posix_acl        *acl = NULL;
        struct xfs_da_args      args = {
                .dp             = ip,
                .attr_filter    = XFS_ATTR_ROOT,
                .valuelen       = XFS_ACL_MAX_SIZE(mp),
        };
        int                     error;

        if (rcu)
                return ERR_PTR(-ECHILD);

        trace_xfs_get_acl(ip);

        switch (type) {
        case ACL_TYPE_ACCESS:
                args.name = SGI_ACL_FILE;
                break;
        case ACL_TYPE_DEFAULT:
                args.name = SGI_ACL_DEFAULT;
                break;
        default:
                BUG();
        }
        args.namelen = strlen(args.name);

        /*
         * If the attribute doesn't exist make sure we have a negative cache
         * entry, for any other error assume it is transient.
         */
        error = xfs_attr_get(&args);
        if (!error) {
                acl = xfs_acl_from_disk(mp, args.value, args.valuelen,
                                        XFS_ACL_MAX_ENTRIES(mp));
        } else if (error != -ENOATTR) {
                acl = ERR_PTR(error);
        }

        kvfree(args.value);
        return acl;
}

int
__xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
{
        struct xfs_inode        *ip = XFS_I(inode);
        struct xfs_da_args      args = {
                .dp             = ip,
                .attr_filter    = XFS_ATTR_ROOT,
        };
        int                     error;

        switch (type) {
        case ACL_TYPE_ACCESS:
                args.name = SGI_ACL_FILE;
                break;
        case ACL_TYPE_DEFAULT:
                if (!S_ISDIR(inode->i_mode))
                        return acl ? -EACCES : 0;
                args.name = SGI_ACL_DEFAULT;
                break;
        default:
                return -EINVAL;
        }
        args.namelen = strlen(args.name);

        if (acl) {
                args.valuelen = XFS_ACL_SIZE(acl->a_count);
                args.value = kvzalloc(args.valuelen, GFP_KERNEL);
                if (!args.value)
                        return -ENOMEM;
                xfs_acl_to_disk(args.value, acl);
                error = xfs_attr_change(&args, XFS_ATTRUPDATE_UPSERT);
                kvfree(args.value);
        } else {
                error = xfs_attr_change(&args, XFS_ATTRUPDATE_REMOVE);
                /*
                 * If the attribute didn't exist to start with that's fine.
                 */
                if (error == -ENOATTR)
                        error = 0;
        }

        if (!error)
                set_cached_acl(inode, type, acl);
        return error;
}

static int
xfs_acl_set_mode(
        struct inode            *inode,
        umode_t                 mode)
{
        struct xfs_inode        *ip = XFS_I(inode);
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_trans        *tp;
        int                     error;

        error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
        if (error)
                return error;

        xfs_ilock(ip, XFS_ILOCK_EXCL);
        xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
        inode->i_mode = mode;
        inode_set_ctime_current(inode);
        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);

        if (xfs_has_wsync(mp))
                xfs_trans_set_sync(tp);
        return xfs_trans_commit(tp);
}

int
xfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
            struct posix_acl *acl, int type)
{
        umode_t mode;
        bool set_mode = false;
        int error = 0;
        struct inode *inode = d_inode(dentry);

        if (!acl)
                goto set_acl;

        error = -E2BIG;
        if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
                return error;

        if (type == ACL_TYPE_ACCESS) {
                error = posix_acl_update_mode(idmap, inode, &mode, &acl);
                if (error)
                        return error;
                set_mode = true;
        }

 set_acl:
        /*
         * We set the mode after successfully updating the ACL xattr because the
         * xattr update can fail at ENOSPC and we don't want to change the mode
         * if the ACL update hasn't been applied.
         */
        error =  __xfs_set_acl(inode, acl, type);
        if (!error && set_mode && mode != inode->i_mode)
                error = xfs_acl_set_mode(inode, mode);
        return error;
}

/*
 * Invalidate any cached ACLs if the user has bypassed the ACL interface.
 * We don't validate the content whatsoever so it is caller responsibility to
 * provide data in valid format and ensure i_mode is consistent.
 */
void
xfs_forget_acl(
        struct inode            *inode,
        const char              *name)
{
        if (!strcmp(name, SGI_ACL_FILE))
                forget_cached_acl(inode, ACL_TYPE_ACCESS);
        else if (!strcmp(name, SGI_ACL_DEFAULT))
                forget_cached_acl(inode, ACL_TYPE_DEFAULT);
}