From patchwork Fri Oct 22 19:07:19 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 12578801 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0161CC433EF for ; Fri, 22 Oct 2021 19:07:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DAE6261038 for ; Fri, 22 Oct 2021 19:07:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234326AbhJVTKP (ORCPT ); Fri, 22 Oct 2021 15:10:15 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:37602 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234336AbhJVTJw (ORCPT ); Fri, 22 Oct 2021 15:09:52 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1634929654; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Yf6zWh4iNZNcLivkbyXqcsfhxflYJe6QShRw1LGxKZ0=; b=Agjp7M147+pY4vJmycEZJFRTOyQzmf5lXEp3tpHR70WcAmzHYZkIGnWs95VSephayYW2kW yidmxgVCxX7Cgca6BdOWYLgeVQ6lAeq3+a/DnEKnyF3J2mCr8LG++Kpnh2NS1wTGS9t0JT 9QhDS7ILWR0uz2tokaIR04Af9OmjJjY= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-105-wq9WeYGOOJuatIyF6CSX2g-1; Fri, 22 Oct 2021 15:07:28 -0400 X-MC-Unique: wq9WeYGOOJuatIyF6CSX2g-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4168B801FCE; Fri, 22 Oct 2021 19:07:26 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.19]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5F09F1346F; Fri, 22 Oct 2021 19:07:20 +0000 (UTC) Organization: Red Hat UK Ltd. 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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH v2 36/53] cachefiles: Implement daemon UAPI and cache registration From: David Howells To: linux-cachefs@redhat.com Cc: dhowells@redhat.com, Trond Myklebust , Anna Schumaker , Steve French , Dominique Martinet , Jeff Layton , Matthew Wilcox , Alexander Viro , Omar Sandoval , Linus Torvalds , linux-afs@lists.infradead.org, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs-developer@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Fri, 22 Oct 2021 20:07:19 +0100 Message-ID: <163492963955.1038219.12980947942512814993.stgit@warthog.procyon.org.uk> In-Reply-To: <163492911924.1038219.13107463173777870713.stgit@warthog.procyon.org.uk> References: <163492911924.1038219.13107463173777870713.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org Provide a number of parts of the cachefiles driver. Firstly, the daemon UAPI interface: (1) The miscdev file that is the point of contact with the cachefiled daemon. (2) An open method that will create a cache record. (3) A write method by which the daemon can issue commands, a parser to parse those commands and implementations for most of the commands (the culling management is deferred to a separate patch). (4) A read method by which the state of a cache can be queried. (5) A release method that will cause the cache to be withdrawn from service. (6) A poll method that allows the daemon to check for culling state changes. Secondly, dealing with security and cache registration: (1) Getting the cache cookie from fscache, preventing other caches from trying to set it up for themselves, adding and withdrawing the cache. (2) Looking up/creating the directories that form the structure of the cache. (3) Computing the credentials that will be used for cache access, including security labels. Signed-off-by: David Howells cc: linux-cachefs@redhat.com --- fs/cachefiles/Makefile | 5 fs/cachefiles/bind.c | 296 ++++++++++++++++++++++ fs/cachefiles/daemon.c | 600 +++++++++++++++++++++++++++++++++++++++++++++ fs/cachefiles/interface.c | 42 +++ fs/cachefiles/internal.h | 36 +++ fs/cachefiles/main.c | 13 + fs/cachefiles/security.c | 112 ++++++++ 7 files changed, 1103 insertions(+), 1 deletion(-) create mode 100644 fs/cachefiles/bind.c create mode 100644 fs/cachefiles/interface.c create mode 100644 fs/cachefiles/security.c diff --git a/fs/cachefiles/Makefile b/fs/cachefiles/Makefile index 06a87f78b88c..7017c9113074 100644 --- a/fs/cachefiles/Makefile +++ b/fs/cachefiles/Makefile @@ -4,9 +4,12 @@ # cachefiles-y := \ + bind.o \ daemon.o \ + interface.o \ main.o \ - namei.o + namei.o \ + security.o cachefiles-$(CONFIG_CACHEFILES_ERROR_INJECTION) += error_inject.o diff --git a/fs/cachefiles/bind.c b/fs/cachefiles/bind.c new file mode 100644 index 000000000000..9ca10290064b --- /dev/null +++ b/fs/cachefiles/bind.c @@ -0,0 +1,296 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* Bind and unbind a cache from the filesystem backing it + * + * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "internal.h" + +DECLARE_WAIT_QUEUE_HEAD(cachefiles_clearance_wq); + +static int cachefiles_daemon_add_cache(struct cachefiles_cache *caches); + +/* + * bind a directory as a cache + */ +int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args) +{ + _enter("{%u,%u,%u,%u,%u,%u},%s", + cache->frun_percent, + cache->fcull_percent, + cache->fstop_percent, + cache->brun_percent, + cache->bcull_percent, + cache->bstop_percent, + args); + + /* start by checking things over */ + ASSERT(cache->fstop_percent < cache->fcull_percent && + cache->fcull_percent < cache->frun_percent && + cache->frun_percent < 100); + + ASSERT(cache->bstop_percent < cache->bcull_percent && + cache->bcull_percent < cache->brun_percent && + cache->brun_percent < 100); + + if (*args) { + pr_err("'bind' command doesn't take an argument\n"); + return -EINVAL; + } + + if (!cache->rootdirname) { + pr_err("No cache directory specified\n"); + return -EINVAL; + } + + /* don't permit already bound caches to be re-bound */ + if (test_bit(CACHEFILES_READY, &cache->flags)) { + pr_err("Cache already bound\n"); + return -EBUSY; + } + + return cachefiles_daemon_add_cache(cache); +} + +/* + * add a cache + */ +static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache) +{ + struct fscache_cache *cache_cookie; + struct path path; + struct kstatfs stats; + struct dentry *graveyard, *cachedir, *root; + const struct cred *saved_cred; + int ret; + + _enter(""); + + cache_cookie = fscache_acquire_cache(cache->tag); + if (IS_ERR(cache_cookie)) + return PTR_ERR(cache_cookie); + + if (!fscache_set_cache_state_maybe(cache_cookie, + FSCACHE_CACHE_IS_NOT_PRESENT, + FSCACHE_CACHE_IS_PREPARING)) { + pr_warn("Cache tag in use\n"); + ret = -EBUSY; + goto error_preparing; + } + + /* we want to work under the module's security ID */ + ret = cachefiles_get_security_ID(cache); + if (ret < 0) + goto error_getsec; + + cachefiles_begin_secure(cache, &saved_cred); + + /* look up the directory at the root of the cache */ + ret = kern_path(cache->rootdirname, LOOKUP_DIRECTORY, &path); + if (ret < 0) + goto error_open_root; + + cache->mnt = path.mnt; + root = path.dentry; + + ret = -EINVAL; + if (mnt_user_ns(path.mnt) != &init_user_ns) { + pr_warn("File cache on idmapped mounts not supported"); + goto error_unsupported; + } + + /* check parameters */ + ret = -EOPNOTSUPP; + if (d_is_negative(root) || + !d_backing_inode(root)->i_op->lookup || + !d_backing_inode(root)->i_op->mkdir || + !(d_backing_inode(root)->i_opflags & IOP_XATTR) || + !root->d_sb->s_op->statfs || + !root->d_sb->s_op->sync_fs || + root->d_sb->s_blocksize > PAGE_SIZE) + goto error_unsupported; + + ret = -EROFS; + if (sb_rdonly(root->d_sb)) + goto error_unsupported; + + /* determine the security of the on-disk cache as this governs + * security ID of files we create */ + ret = cachefiles_determine_cache_security(cache, root, &saved_cred); + if (ret < 0) + goto error_unsupported; + + /* get the cache size and blocksize */ + ret = vfs_statfs(&path, &stats); + if (ret < 0) + goto error_unsupported; + + ret = -ERANGE; + if (stats.f_bsize <= 0) + goto error_unsupported; + + ret = -EOPNOTSUPP; + if (stats.f_bsize > PAGE_SIZE) + goto error_unsupported; + + cache->bsize = stats.f_bsize; + cache->bshift = 0; + if (stats.f_bsize < PAGE_SIZE) + cache->bshift = PAGE_SHIFT - ilog2(stats.f_bsize); + + _debug("blksize %u (shift %u)", + cache->bsize, cache->bshift); + + _debug("size %llu, avail %llu", + (unsigned long long) stats.f_blocks, + (unsigned long long) stats.f_bavail); + + /* set up caching limits */ + do_div(stats.f_files, 100); + cache->fstop = stats.f_files * cache->fstop_percent; + cache->fcull = stats.f_files * cache->fcull_percent; + cache->frun = stats.f_files * cache->frun_percent; + + _debug("limits {%llu,%llu,%llu} files", + (unsigned long long) cache->frun, + (unsigned long long) cache->fcull, + (unsigned long long) cache->fstop); + + stats.f_blocks >>= cache->bshift; + do_div(stats.f_blocks, 100); + cache->bstop = stats.f_blocks * cache->bstop_percent; + cache->bcull = stats.f_blocks * cache->bcull_percent; + cache->brun = stats.f_blocks * cache->brun_percent; + + _debug("limits {%llu,%llu,%llu} blocks", + (unsigned long long) cache->brun, + (unsigned long long) cache->bcull, + (unsigned long long) cache->bstop); + + /* get the cache directory and check its type */ + cachedir = cachefiles_get_directory(cache, root, "cache"); + if (IS_ERR(cachedir)) { + ret = PTR_ERR(cachedir); + goto error_unsupported; + } + + cache->store = cachedir; + + /* get the graveyard directory */ + graveyard = cachefiles_get_directory(cache, root, "graveyard"); + if (IS_ERR(graveyard)) { + ret = PTR_ERR(graveyard); + goto error_unsupported; + } + + cache->graveyard = graveyard; + cache->cache = cache_cookie; + + ret = fscache_add_cache(cache_cookie, &cachefiles_cache_ops, cache); + if (ret < 0) + goto error_add_cache; + + /* done */ + set_bit(CACHEFILES_READY, &cache->flags); + dput(root); + + pr_info("File cache on %s registered\n", cache_cookie->name); + + /* check how much space the cache has */ + cachefiles_has_space(cache, 0, 0); + cachefiles_end_secure(cache, saved_cred); + _leave(" = 0 [%px]", cache->cache); + return 0; + +error_add_cache: + dput(cache->graveyard); + cache->graveyard = NULL; +error_unsupported: + dput(cache->store); + cache->store = NULL; + mntput(cache->mnt); + cache->mnt = NULL; + dput(root); +error_open_root: + cachefiles_end_secure(cache, saved_cred); +error_getsec: + fscache_set_cache_state(cache_cookie, FSCACHE_CACHE_IS_NOT_PRESENT); +error_preparing: + fscache_put_cache(cache_cookie, fscache_cache_put_cache); + cache->cache = NULL; + pr_err("Failed to register: %d\n", ret); + return ret; +} + +/* + * Withdraw cache objects. + */ +static void cachefiles_withdraw_cache(struct cachefiles_cache *cache) +{ + struct fscache_cache *fscache = cache->cache; + + pr_info("File cache on %s unregistering\n", fscache->name); + + fscache_withdraw_cache(fscache); + + /* we now have to destroy all the active objects pertaining to this + * cache - which we do by passing them off to thread pool to be + * disposed of */ + // PLACEHOLDER: Withdraw objects + + /* wait for all extant objects to finish their outstanding operations + * and go away */ + _debug("wait for finish %u", atomic_read(&fscache->object_count)); + wait_event(cachefiles_clearance_wq, + atomic_read(&fscache->object_count) == 0); + _debug("cleared"); + + // PLACEHOLDER: Withdraw volume + + /* make sure all outstanding data is written to disk */ + cachefiles_sync_cache(cache); + + _debug("wait for clearance"); + wait_event(cachefiles_clearance_wq, list_empty(&cache->object_list)); + + cache->cache = NULL; + fscache->ops = NULL; + fscache->cache_priv = NULL; + fscache_set_cache_state(fscache, FSCACHE_CACHE_IS_NOT_PRESENT); + fscache_put_cache(fscache, fscache_cache_put_withdraw); +} + +/* + * unbind a cache on fd release + */ +void cachefiles_daemon_unbind(struct cachefiles_cache *cache) +{ + _enter("%px", cache->cache); + + if (test_bit(CACHEFILES_READY, &cache->flags)) + cachefiles_withdraw_cache(cache); + + dput(cache->graveyard); + dput(cache->store); + mntput(cache->mnt); + + kfree(cache->rootdirname); + kfree(cache->secctx); + kfree(cache->tag); + + _leave(""); +} diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c index dca2520a14ee..c23d22a5d4a6 100644 --- a/fs/cachefiles/daemon.c +++ b/fs/cachefiles/daemon.c @@ -21,6 +21,606 @@ #include #include "internal.h" +static int cachefiles_daemon_open(struct inode *, struct file *); +static int cachefiles_daemon_release(struct inode *, struct file *); +static ssize_t cachefiles_daemon_read(struct file *, char __user *, size_t, + loff_t *); +static ssize_t cachefiles_daemon_write(struct file *, const char __user *, + size_t, loff_t *); +static __poll_t cachefiles_daemon_poll(struct file *, + struct poll_table_struct *); +static int cachefiles_daemon_frun(struct cachefiles_cache *, char *); +static int cachefiles_daemon_fcull(struct cachefiles_cache *, char *); +static int cachefiles_daemon_fstop(struct cachefiles_cache *, char *); +static int cachefiles_daemon_brun(struct cachefiles_cache *, char *); +static int cachefiles_daemon_bcull(struct cachefiles_cache *, char *); +static int cachefiles_daemon_bstop(struct cachefiles_cache *, char *); +static int cachefiles_daemon_cull(struct cachefiles_cache *, char *); +static int cachefiles_daemon_debug(struct cachefiles_cache *, char *); +static int cachefiles_daemon_dir(struct cachefiles_cache *, char *); +static int cachefiles_daemon_inuse(struct cachefiles_cache *, char *); +static int cachefiles_daemon_secctx(struct cachefiles_cache *, char *); +static int cachefiles_daemon_tag(struct cachefiles_cache *, char *); + +static unsigned long cachefiles_open; + +const struct file_operations cachefiles_daemon_fops = { + .owner = THIS_MODULE, + .open = cachefiles_daemon_open, + .release = cachefiles_daemon_release, + .read = cachefiles_daemon_read, + .write = cachefiles_daemon_write, + .poll = cachefiles_daemon_poll, + .llseek = noop_llseek, +}; + +struct cachefiles_daemon_cmd { + char name[8]; + int (*handler)(struct cachefiles_cache *cache, char *args); +}; + +static const struct cachefiles_daemon_cmd cachefiles_daemon_cmds[] = { + { "bind", cachefiles_daemon_bind }, + { "brun", cachefiles_daemon_brun }, + { "bcull", cachefiles_daemon_bcull }, + { "bstop", cachefiles_daemon_bstop }, + { "cull", cachefiles_daemon_cull }, + { "debug", cachefiles_daemon_debug }, + { "dir", cachefiles_daemon_dir }, + { "frun", cachefiles_daemon_frun }, + { "fcull", cachefiles_daemon_fcull }, + { "fstop", cachefiles_daemon_fstop }, + { "inuse", cachefiles_daemon_inuse }, + { "secctx", cachefiles_daemon_secctx }, + { "tag", cachefiles_daemon_tag }, + { "", NULL } +}; + + +/* + * do various checks + */ +static int cachefiles_daemon_open(struct inode *inode, struct file *file) +{ + struct cachefiles_cache *cache; + + _enter(""); + + /* only the superuser may do this */ + if (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + /* the cachefiles device may only be open once at a time */ + if (xchg(&cachefiles_open, 1) == 1) + return -EBUSY; + + /* allocate a cache record */ + cache = kzalloc(sizeof(struct cachefiles_cache), GFP_KERNEL); + if (!cache) { + cachefiles_open = 0; + return -ENOMEM; + } + + mutex_init(&cache->daemon_mutex); + init_waitqueue_head(&cache->daemon_pollwq); + INIT_LIST_HEAD(&cache->volumes); + INIT_LIST_HEAD(&cache->object_list); + spin_lock_init(&cache->object_list_lock); + + /* set default caching limits + * - limit at 1% free space and/or free files + * - cull below 5% free space and/or free files + * - cease culling above 7% free space and/or free files + */ + cache->frun_percent = 7; + cache->fcull_percent = 5; + cache->fstop_percent = 1; + cache->brun_percent = 7; + cache->bcull_percent = 5; + cache->bstop_percent = 1; + + file->private_data = cache; + cache->cachefilesd = file; + return 0; +} + +/* + * release a cache + */ +static int cachefiles_daemon_release(struct inode *inode, struct file *file) +{ + struct cachefiles_cache *cache = file->private_data; + + _enter(""); + + ASSERT(cache); + + set_bit(CACHEFILES_DEAD, &cache->flags); + + cachefiles_daemon_unbind(cache); + + /* clean up the control file interface */ + cache->cachefilesd = NULL; + file->private_data = NULL; + cachefiles_open = 0; + + kfree(cache); + + _leave(""); + return 0; +} + +/* + * read the cache state + */ +static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer, + size_t buflen, loff_t *pos) +{ + struct cachefiles_cache *cache = file->private_data; + unsigned long long b_released; + unsigned f_released; + char buffer[256]; + int n; + + //_enter(",,%zu,", buflen); + + if (!test_bit(CACHEFILES_READY, &cache->flags)) + return 0; + + /* check how much space the cache has */ + cachefiles_has_space(cache, 0, 0); + + /* summarise */ + f_released = atomic_xchg(&cache->f_released, 0); + b_released = atomic_long_xchg(&cache->b_released, 0); + clear_bit(CACHEFILES_STATE_CHANGED, &cache->flags); + + n = snprintf(buffer, sizeof(buffer), + "cull=%c" + " frun=%llx" + " fcull=%llx" + " fstop=%llx" + " brun=%llx" + " bcull=%llx" + " bstop=%llx" + " freleased=%x" + " breleased=%llx", + test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '0', + (unsigned long long) cache->frun, + (unsigned long long) cache->fcull, + (unsigned long long) cache->fstop, + (unsigned long long) cache->brun, + (unsigned long long) cache->bcull, + (unsigned long long) cache->bstop, + f_released, + b_released); + + if (n > buflen) + return -EMSGSIZE; + + if (copy_to_user(_buffer, buffer, n) != 0) + return -EFAULT; + + return n; +} + +/* + * command the cache + */ +static ssize_t cachefiles_daemon_write(struct file *file, + const char __user *_data, + size_t datalen, + loff_t *pos) +{ + const struct cachefiles_daemon_cmd *cmd; + struct cachefiles_cache *cache = file->private_data; + ssize_t ret; + char *data, *args, *cp; + + //_enter(",,%zu,", datalen); + + ASSERT(cache); + + if (test_bit(CACHEFILES_DEAD, &cache->flags)) + return -EIO; + + if (datalen > PAGE_SIZE - 1) + return -EOPNOTSUPP; + + /* drag the command string into the kernel so we can parse it */ + data = memdup_user_nul(_data, datalen); + if (IS_ERR(data)) + return PTR_ERR(data); + + ret = -EINVAL; + if (memchr(data, '\0', datalen)) + goto error; + + /* strip any newline */ + cp = memchr(data, '\n', datalen); + if (cp) { + if (cp == data) + goto error; + + *cp = '\0'; + } + + /* parse the command */ + ret = -EOPNOTSUPP; + + for (args = data; *args; args++) + if (isspace(*args)) + break; + if (*args) { + if (args == data) + goto error; + *args = '\0'; + args = skip_spaces(++args); + } + + /* run the appropriate command handler */ + for (cmd = cachefiles_daemon_cmds; cmd->name[0]; cmd++) + if (strcmp(cmd->name, data) == 0) + goto found_command; + +error: + kfree(data); + //_leave(" = %zd", ret); + return ret; + +found_command: + mutex_lock(&cache->daemon_mutex); + + ret = -EIO; + if (!test_bit(CACHEFILES_DEAD, &cache->flags)) + ret = cmd->handler(cache, args); + + mutex_unlock(&cache->daemon_mutex); + + if (ret == 0) + ret = datalen; + goto error; +} + +/* + * poll for culling state + * - use EPOLLOUT to indicate culling state + */ +static __poll_t cachefiles_daemon_poll(struct file *file, + struct poll_table_struct *poll) +{ + struct cachefiles_cache *cache = file->private_data; + __poll_t mask; + + poll_wait(file, &cache->daemon_pollwq, poll); + mask = 0; + + if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags)) + mask |= EPOLLIN; + + if (test_bit(CACHEFILES_CULLING, &cache->flags)) + mask |= EPOLLOUT; + + return mask; +} + +/* + * give a range error for cache space constraints + * - can be tail-called + */ +static int cachefiles_daemon_range_error(struct cachefiles_cache *cache, + char *args) +{ + pr_err("Free space limits must be in range 0%%<=stop%" + */ +static int cachefiles_daemon_frun(struct cachefiles_cache *cache, char *args) +{ + unsigned long frun; + + _enter(",%s", args); + + if (!*args) + return -EINVAL; + + frun = simple_strtoul(args, &args, 10); + if (args[0] != '%' || args[1] != '\0') + return -EINVAL; + + if (frun <= cache->fcull_percent || frun >= 100) + return cachefiles_daemon_range_error(cache, args); + + cache->frun_percent = frun; + return 0; +} + +/* + * set the percentage of files at which to start culling + * - command: "fcull %" + */ +static int cachefiles_daemon_fcull(struct cachefiles_cache *cache, char *args) +{ + unsigned long fcull; + + _enter(",%s", args); + + if (!*args) + return -EINVAL; + + fcull = simple_strtoul(args, &args, 10); + if (args[0] != '%' || args[1] != '\0') + return -EINVAL; + + if (fcull <= cache->fstop_percent || fcull >= cache->frun_percent) + return cachefiles_daemon_range_error(cache, args); + + cache->fcull_percent = fcull; + return 0; +} + +/* + * set the percentage of files at which to stop allocating + * - command: "fstop %" + */ +static int cachefiles_daemon_fstop(struct cachefiles_cache *cache, char *args) +{ + unsigned long fstop; + + _enter(",%s", args); + + if (!*args) + return -EINVAL; + + fstop = simple_strtoul(args, &args, 10); + if (args[0] != '%' || args[1] != '\0') + return -EINVAL; + + if (fstop >= cache->fcull_percent) + return cachefiles_daemon_range_error(cache, args); + + cache->fstop_percent = fstop; + return 0; +} + +/* + * set the percentage of blocks at which to stop culling + * - command: "brun %" + */ +static int cachefiles_daemon_brun(struct cachefiles_cache *cache, char *args) +{ + unsigned long brun; + + _enter(",%s", args); + + if (!*args) + return -EINVAL; + + brun = simple_strtoul(args, &args, 10); + if (args[0] != '%' || args[1] != '\0') + return -EINVAL; + + if (brun <= cache->bcull_percent || brun >= 100) + return cachefiles_daemon_range_error(cache, args); + + cache->brun_percent = brun; + return 0; +} + +/* + * set the percentage of blocks at which to start culling + * - command: "bcull %" + */ +static int cachefiles_daemon_bcull(struct cachefiles_cache *cache, char *args) +{ + unsigned long bcull; + + _enter(",%s", args); + + if (!*args) + return -EINVAL; + + bcull = simple_strtoul(args, &args, 10); + if (args[0] != '%' || args[1] != '\0') + return -EINVAL; + + if (bcull <= cache->bstop_percent || bcull >= cache->brun_percent) + return cachefiles_daemon_range_error(cache, args); + + cache->bcull_percent = bcull; + return 0; +} + +/* + * set the percentage of blocks at which to stop allocating + * - command: "bstop %" + */ +static int cachefiles_daemon_bstop(struct cachefiles_cache *cache, char *args) +{ + unsigned long bstop; + + _enter(",%s", args); + + if (!*args) + return -EINVAL; + + bstop = simple_strtoul(args, &args, 10); + if (args[0] != '%' || args[1] != '\0') + return -EINVAL; + + if (bstop >= cache->bcull_percent) + return cachefiles_daemon_range_error(cache, args); + + cache->bstop_percent = bstop; + return 0; +} + +/* + * set the cache directory + * - command: "dir " + */ +static int cachefiles_daemon_dir(struct cachefiles_cache *cache, char *args) +{ + char *dir; + + _enter(",%s", args); + + if (!*args) { + pr_err("Empty directory specified\n"); + return -EINVAL; + } + + if (cache->rootdirname) { + pr_err("Second cache directory specified\n"); + return -EEXIST; + } + + dir = kstrdup(args, GFP_KERNEL); + if (!dir) + return -ENOMEM; + + cache->rootdirname = dir; + return 0; +} + +/* + * set the cache security context + * - command: "secctx " + */ +static int cachefiles_daemon_secctx(struct cachefiles_cache *cache, char *args) +{ + char *secctx; + + _enter(",%s", args); + + if (!*args) { + pr_err("Empty security context specified\n"); + return -EINVAL; + } + + if (cache->secctx) { + pr_err("Second security context specified\n"); + return -EINVAL; + } + + secctx = kstrdup(args, GFP_KERNEL); + if (!secctx) + return -ENOMEM; + + cache->secctx = secctx; + return 0; +} + +/* + * set the cache tag + * - command: "tag " + */ +static int cachefiles_daemon_tag(struct cachefiles_cache *cache, char *args) +{ + char *tag; + + _enter(",%s", args); + + if (!*args) { + pr_err("Empty tag specified\n"); + return -EINVAL; + } + + if (cache->tag) + return -EEXIST; + + tag = kstrdup(args, GFP_KERNEL); + if (!tag) + return -ENOMEM; + + cache->tag = tag; + return 0; +} + +/* + * request a node in the cache be culled from the current working directory + * - command: "cull " + */ +static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args) +{ + _enter(",%s", args); + + if (strchr(args, '/')) + goto inval; + + if (!test_bit(CACHEFILES_READY, &cache->flags)) { + pr_err("cull applied to unready cache\n"); + return -EIO; + } + + if (test_bit(CACHEFILES_DEAD, &cache->flags)) { + pr_err("cull applied to dead cache\n"); + return -EIO; + } + + return -EOPNOTSUPP; // PLACEHOLDER: Implement culling + +inval: + pr_err("cull command requires dirfd and filename\n"); + return -EINVAL; +} + +/* + * set debugging mode + * - command: "debug " + */ +static int cachefiles_daemon_debug(struct cachefiles_cache *cache, char *args) +{ + unsigned long mask; + + _enter(",%s", args); + + mask = simple_strtoul(args, &args, 0); + if (args[0] != '\0') + goto inval; + + cachefiles_debug = mask; + _leave(" = 0"); + return 0; + +inval: + pr_err("debug command requires mask\n"); + return -EINVAL; +} + +/* + * find out whether an object in the current working directory is in use or not + * - command: "inuse " + */ +static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args) +{ + //_enter(",%s", args); + + if (strchr(args, '/')) + goto inval; + + if (!test_bit(CACHEFILES_READY, &cache->flags)) { + pr_err("inuse applied to unready cache\n"); + return -EIO; + } + + if (test_bit(CACHEFILES_DEAD, &cache->flags)) { + pr_err("inuse applied to dead cache\n"); + return -EIO; + } + + return -EOPNOTSUPP; // PLACEHOLDER: Implement check in use + +inval: + pr_err("inuse command requires dirfd and filename\n"); + return -EINVAL; +} + /* * see if we have space for a number of pages and/or a number of files in the * cache diff --git a/fs/cachefiles/interface.c b/fs/cachefiles/interface.c new file mode 100644 index 000000000000..236d55c13fb1 --- /dev/null +++ b/fs/cachefiles/interface.c @@ -0,0 +1,42 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* FS-Cache interface to CacheFiles + * + * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include +#include +#include +#include +#include +#include +#include "internal.h" + +/* + * sync a cache + */ +void cachefiles_sync_cache(struct cachefiles_cache *cache) +{ + const struct cred *saved_cred; + int ret; + + _enter("%s", cache->cache->name); + + /* make sure all pages pinned by operations on behalf of the netfs are + * written to disc */ + cachefiles_begin_secure(cache, &saved_cred); + down_read(&cache->mnt->mnt_sb->s_umount); + ret = sync_filesystem(cache->mnt->mnt_sb); + up_read(&cache->mnt->mnt_sb->s_umount); + cachefiles_end_secure(cache, saved_cred); + + if (ret == -EIO) + cachefiles_io_error(cache, + "Attempt to sync backing fs superblock returned error %d", + ret); +} + +const struct fscache_cache_ops cachefiles_cache_ops = { + .name = "cachefiles", +}; diff --git a/fs/cachefiles/internal.h b/fs/cachefiles/internal.h index 4e77c3004d98..c472766cdce3 100644 --- a/fs/cachefiles/internal.h +++ b/fs/cachefiles/internal.h @@ -123,9 +123,19 @@ static inline void cachefiles_state_changed(struct cachefiles_cache *cache) wake_up_all(&cache->daemon_pollwq); } +/* + * bind.c + */ +extern wait_queue_head_t cachefiles_clearance_wq; + +extern int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args); +extern void cachefiles_daemon_unbind(struct cachefiles_cache *cache); + /* * daemon.c */ +extern const struct file_operations cachefiles_daemon_fops; + extern int cachefiles_has_space(struct cachefiles_cache *cache, unsigned fnr, unsigned bnr); @@ -168,6 +178,12 @@ static inline int cachefiles_inject_remove_error(void) return cachefiles_error_injection_state & 2 ? -EIO : 0; } +/* + * interface.c + */ +extern const struct fscache_cache_ops cachefiles_cache_ops; +extern void cachefiles_sync_cache(struct cachefiles_cache *cache); + /* * namei.c */ @@ -175,6 +191,26 @@ extern struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache, struct dentry *dir, const char *name); +/* + * security.c + */ +extern int cachefiles_get_security_ID(struct cachefiles_cache *cache); +extern int cachefiles_determine_cache_security(struct cachefiles_cache *cache, + struct dentry *root, + const struct cred **_saved_cred); + +static inline void cachefiles_begin_secure(struct cachefiles_cache *cache, + const struct cred **_saved_cred) +{ + *_saved_cred = override_creds(cache->cache_cred); +} + +static inline void cachefiles_end_secure(struct cachefiles_cache *cache, + const struct cred *saved_cred) +{ + revert_creds(saved_cred); +} + /* * error handling */ diff --git a/fs/cachefiles/main.c b/fs/cachefiles/main.c index 387d42c7185f..22581099236b 100644 --- a/fs/cachefiles/main.c +++ b/fs/cachefiles/main.c @@ -31,6 +31,12 @@ MODULE_DESCRIPTION("Mounted-filesystem based cache"); MODULE_AUTHOR("Red Hat, Inc."); MODULE_LICENSE("GPL"); +static struct miscdevice cachefiles_dev = { + .minor = MISC_DYNAMIC_MINOR, + .name = "cachefiles", + .fops = &cachefiles_daemon_fops, +}; + /* * initialise the fs caching module */ @@ -42,9 +48,15 @@ static int __init cachefiles_init(void) if (ret < 0) goto error_einj; + ret = misc_register(&cachefiles_dev); + if (ret < 0) + goto error_dev; + pr_info("Loaded\n"); return 0; +error_dev: + cachefiles_unregister_error_injection(); error_einj: pr_err("failed to register: %d\n", ret); return ret; @@ -59,6 +71,7 @@ static void __exit cachefiles_exit(void) { pr_info("Unloading\n"); + misc_deregister(&cachefiles_dev); cachefiles_unregister_error_injection(); } diff --git a/fs/cachefiles/security.c b/fs/cachefiles/security.c new file mode 100644 index 000000000000..51daa986aca3 --- /dev/null +++ b/fs/cachefiles/security.c @@ -0,0 +1,112 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* CacheFiles security management + * + * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include +#include +#include "internal.h" + +/* + * determine the security context within which we access the cache from within + * the kernel + */ +int cachefiles_get_security_ID(struct cachefiles_cache *cache) +{ + struct cred *new; + int ret; + + _enter("{%s}", cache->secctx); + + new = prepare_kernel_cred(current); + if (!new) { + ret = -ENOMEM; + goto error; + } + + if (cache->secctx) { + ret = set_security_override_from_ctx(new, cache->secctx); + if (ret < 0) { + put_cred(new); + pr_err("Security denies permission to nominate security context: error %d\n", + ret); + goto error; + } + } + + cache->cache_cred = new; + ret = 0; +error: + _leave(" = %d", ret); + return ret; +} + +/* + * see if mkdir and create can be performed in the root directory + */ +static int cachefiles_check_cache_dir(struct cachefiles_cache *cache, + struct dentry *root) +{ + int ret; + + ret = security_inode_mkdir(d_backing_inode(root), root, 0); + if (ret < 0) { + pr_err("Security denies permission to make dirs: error %d", + ret); + return ret; + } + + ret = security_inode_create(d_backing_inode(root), root, 0); + if (ret < 0) + pr_err("Security denies permission to create files: error %d", + ret); + + return ret; +} + +/* + * check the security details of the on-disk cache + * - must be called with security override in force + * - must return with a security override in force - even in the case of an + * error + */ +int cachefiles_determine_cache_security(struct cachefiles_cache *cache, + struct dentry *root, + const struct cred **_saved_cred) +{ + struct cred *new; + int ret; + + _enter(""); + + /* duplicate the cache creds for COW (the override is currently in + * force, so we can use prepare_creds() to do this) */ + new = prepare_creds(); + if (!new) + return -ENOMEM; + + cachefiles_end_secure(cache, *_saved_cred); + + /* use the cache root dir's security context as the basis with + * which create files */ + ret = set_create_files_as(new, d_backing_inode(root)); + if (ret < 0) { + abort_creds(new); + cachefiles_begin_secure(cache, _saved_cred); + _leave(" = %d [cfa]", ret); + return ret; + } + + put_cred(cache->cache_cred); + cache->cache_cred = new; + + cachefiles_begin_secure(cache, _saved_cred); + ret = cachefiles_check_cache_dir(cache, root); + + if (ret == -EOPNOTSUPP) + ret = 0; + _leave(" = %d", ret); + return ret; +}