// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2007 Red Hat.  All rights reserved.
 */

#include <linux/fs.h>
#include <linux/string.h>
#include <linux/xattr.h>
#include <linux/posix_acl_xattr.h>
#include <linux/posix_acl.h>
#include <linux/sched.h>
#include <linux/sched/mm.h>
#include <linux/slab.h>
#include "ctree.h"
#include "xattr.h"
#include "acl.h"
#include "misc.h"

struct posix_acl *btrfs_get_acl(struct inode *inode, int type, bool rcu)
{
        int size;
        const char *name;
        char AUTO_KFREE(value);
        struct posix_acl *acl;

        if (rcu)
                return ERR_PTR(-ECHILD);

        switch (type) {
        case ACL_TYPE_ACCESS:
                name = XATTR_NAME_POSIX_ACL_ACCESS;
                break;
        case ACL_TYPE_DEFAULT:
                name = XATTR_NAME_POSIX_ACL_DEFAULT;
                break;
        default:
                return ERR_PTR(-EINVAL);
        }

        size = btrfs_getxattr(inode, name, NULL, 0);
        if (size > 0) {
                value = kzalloc(size, GFP_KERNEL);
                if (!value)
                        return ERR_PTR(-ENOMEM);
                size = btrfs_getxattr(inode, name, value, size);
        }
        if (size > 0)
                acl = posix_acl_from_xattr(&init_user_ns, value, size);
        else if (size == -ENODATA || size == 0)
                acl = NULL;
        else
                acl = ERR_PTR(size);

        return acl;
}

int __btrfs_set_acl(struct btrfs_trans_handle *trans, struct inode *inode,
                    struct posix_acl *acl, int type)
{
        int ret;
        size_t size = 0;
        const char *name;
        char AUTO_KFREE(value);

        switch (type) {
        case ACL_TYPE_ACCESS:
                name = XATTR_NAME_POSIX_ACL_ACCESS;
                break;
        case ACL_TYPE_DEFAULT:
                if (!S_ISDIR(inode->i_mode))
                        return acl ? -EINVAL : 0;
                name = XATTR_NAME_POSIX_ACL_DEFAULT;
                break;
        default:
                return -EINVAL;
        }

        if (acl) {
                unsigned int nofs_flag;

                /*
                 * We're holding a transaction handle, so use a NOFS memory
                 * allocation context to avoid deadlock if reclaim happens.
                 */
                nofs_flag = memalloc_nofs_save();
                value = posix_acl_to_xattr(&init_user_ns, acl, &size, GFP_KERNEL);
                memalloc_nofs_restore(nofs_flag);
                if (!value)
                        return -ENOMEM;
        }

        if (trans)
                ret = btrfs_setxattr(trans, inode, name, value, size, 0);
        else
                ret = btrfs_setxattr_trans(inode, name, value, size, 0);
        if (ret < 0)
                return ret;

        set_cached_acl(inode, type, acl);
        return 0;
}

int btrfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
                  struct posix_acl *acl, int type)
{
        int ret;
        struct inode *inode = d_inode(dentry);
        umode_t old_mode = inode->i_mode;

        if (type == ACL_TYPE_ACCESS && acl) {
                ret = posix_acl_update_mode(idmap, inode,
                                            &inode->i_mode, &acl);
                if (ret)
                        return ret;
        }
        ret = __btrfs_set_acl(NULL, inode, acl, type);
        if (ret)
                inode->i_mode = old_mode;
        return ret;
}