root/fs/ceph/acl.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * linux/fs/ceph/acl.c
 *
 * Copyright (C) 2013 Guangliang Zhao, <lucienchao@gmail.com>
 */

#include <linux/ceph/ceph_debug.h>
#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/slab.h>

#include "super.h"
#include "mds_client.h"

static inline void ceph_set_cached_acl(struct inode *inode,
                                        int type, struct posix_acl *acl)
{
        struct ceph_inode_info *ci = ceph_inode(inode);

        spin_lock(&ci->i_ceph_lock);
        if (__ceph_caps_issued_mask_metric(ci, CEPH_CAP_XATTR_SHARED, 0))
                set_cached_acl(inode, type, acl);
        else
                forget_cached_acl(inode, type);
        spin_unlock(&ci->i_ceph_lock);
}

struct posix_acl *ceph_get_acl(struct inode *inode, int type, bool rcu)
{
        struct ceph_client *cl = ceph_inode_to_client(inode);
        int size;
        unsigned int retry_cnt = 0;
        const char *name;
        char *value = NULL;
        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:
                BUG();
        }

retry:
        size = __ceph_getxattr(inode, name, "", 0);
        if (size > 0) {
                value = kzalloc(size, GFP_NOFS);
                if (!value)
                        return ERR_PTR(-ENOMEM);
                size = __ceph_getxattr(inode, name, value, size);
        }

        if (size == -ERANGE && retry_cnt < 10) {
                retry_cnt++;
                kfree(value);
                value = NULL;
                goto retry;
        }

        if (size > 0) {
                acl = posix_acl_from_xattr(&init_user_ns, value, size);
        } else if (size == -ENODATA || size == 0) {
                acl = NULL;
        } else {
                pr_err_ratelimited_client(cl, "%llx.%llx failed, err=%d\n",
                                          ceph_vinop(inode), size);
                acl = ERR_PTR(-EIO);
        }

        kfree(value);

        if (!IS_ERR(acl))
                ceph_set_cached_acl(inode, type, acl);

        return acl;
}

int ceph_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
                 struct posix_acl *acl, int type)
{
        int ret = 0;
        size_t size = 0;
        const char *name = NULL;
        char *value = NULL;
        struct iattr newattrs;
        struct inode *inode = d_inode(dentry);
        struct timespec64 old_ctime = inode_get_ctime(inode);
        umode_t new_mode = inode->i_mode, old_mode = inode->i_mode;

        if (ceph_snap(inode) != CEPH_NOSNAP) {
                ret = -EROFS;
                goto out;
        }

        switch (type) {
        case ACL_TYPE_ACCESS:
                name = XATTR_NAME_POSIX_ACL_ACCESS;
                if (acl) {
                        ret = posix_acl_update_mode(idmap, inode,
                                                    &new_mode, &acl);
                        if (ret)
                                goto out;
                }
                break;
        case ACL_TYPE_DEFAULT:
                if (!S_ISDIR(inode->i_mode)) {
                        ret = acl ? -EINVAL : 0;
                        goto out;
                }
                name = XATTR_NAME_POSIX_ACL_DEFAULT;
                break;
        default:
                ret = -EINVAL;
                goto out;
        }

        if (acl) {
                value = posix_acl_to_xattr(&init_user_ns, acl, &size, GFP_NOFS);
                if (!value) {
                        ret = -ENOMEM;
                        goto out;
                }
        }

        if (new_mode != old_mode) {
                newattrs.ia_ctime = current_time(inode);
                newattrs.ia_mode = new_mode;
                newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
                ret = __ceph_setattr(idmap, inode, &newattrs, NULL);
                if (ret)
                        goto out_free;
        }

        ret = __ceph_setxattr(inode, name, value, size, 0);
        if (ret) {
                if (new_mode != old_mode) {
                        newattrs.ia_ctime = old_ctime;
                        newattrs.ia_mode = old_mode;
                        newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
                        __ceph_setattr(idmap, inode, &newattrs, NULL);
                }
                goto out_free;
        }

        ceph_set_cached_acl(inode, type, acl);

out_free:
        kfree(value);
out:
        return ret;
}

int ceph_pre_init_acls(struct inode *dir, umode_t *mode,
                       struct ceph_acl_sec_ctx *as_ctx)
{
        struct posix_acl *acl, *default_acl;
        size_t val_size1 = 0, val_size2 = 0;
        struct ceph_pagelist *pagelist = NULL;
        void *tmp_buf1 = NULL, *tmp_buf2 = NULL;
        int err;

        err = posix_acl_create(dir, mode, &default_acl, &acl);
        if (err)
                return err;

        if (acl) {
                err = posix_acl_equiv_mode(acl, mode);
                if (err < 0)
                        goto out_err;
                if (err == 0) {
                        posix_acl_release(acl);
                        acl = NULL;
                }
        }

        if (!default_acl && !acl)
                return 0;

        err = -ENOMEM;
        pagelist = ceph_pagelist_alloc(GFP_KERNEL);
        if (!pagelist)
                goto out_err;

        err = ceph_pagelist_reserve(pagelist, PAGE_SIZE);
        if (err)
                goto out_err;

        ceph_pagelist_encode_32(pagelist, acl && default_acl ? 2 : 1);

        if (acl) {
                size_t len = strlen(XATTR_NAME_POSIX_ACL_ACCESS);

                err = -ENOMEM;
                tmp_buf1 = posix_acl_to_xattr(&init_user_ns, acl,
                                              &val_size1, GFP_KERNEL);
                if (!tmp_buf1)
                        goto out_err;
                err = ceph_pagelist_reserve(pagelist, len + val_size1 + 8);
                if (err)
                        goto out_err;
                ceph_pagelist_encode_string(pagelist, XATTR_NAME_POSIX_ACL_ACCESS,
                                            len);
                ceph_pagelist_encode_32(pagelist, val_size1);
                ceph_pagelist_append(pagelist, tmp_buf1, val_size1);
        }
        if (default_acl) {
                size_t len = strlen(XATTR_NAME_POSIX_ACL_DEFAULT);

                err = -ENOMEM;
                tmp_buf2 = posix_acl_to_xattr(&init_user_ns, default_acl,
                                              &val_size2, GFP_KERNEL);
                if (!tmp_buf2)
                        goto out_err;
                err = ceph_pagelist_reserve(pagelist, len + val_size2 + 8);
                if (err)
                        goto out_err;
                ceph_pagelist_encode_string(pagelist,
                                          XATTR_NAME_POSIX_ACL_DEFAULT, len);
                ceph_pagelist_encode_32(pagelist, val_size2);
                ceph_pagelist_append(pagelist, tmp_buf2, val_size2);
        }

        kfree(tmp_buf1);
        kfree(tmp_buf2);

        as_ctx->acl = acl;
        as_ctx->default_acl = default_acl;
        as_ctx->pagelist = pagelist;
        return 0;

out_err:
        posix_acl_release(acl);
        posix_acl_release(default_acl);
        kfree(tmp_buf1);
        kfree(tmp_buf2);
        if (pagelist)
                ceph_pagelist_release(pagelist);
        return err;
}

void ceph_init_inode_acls(struct inode *inode, struct ceph_acl_sec_ctx *as_ctx)
{
        if (!inode)
                return;
        ceph_set_cached_acl(inode, ACL_TYPE_ACCESS, as_ctx->acl);
        ceph_set_cached_acl(inode, ACL_TYPE_DEFAULT, as_ctx->default_acl);
}