diff options
Diffstat (limited to 'fs/cachefiles/daemon.c')
| -rw-r--r-- | fs/cachefiles/daemon.c | 814 |
1 files changed, 814 insertions, 0 deletions
diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c new file mode 100644 index 0000000000..aa4efcabb5 --- /dev/null +++ b/fs/cachefiles/daemon.c @@ -0,0 +1,814 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* Daemon interface + * + * Copyright (C) 2007, 2021 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include <linux/module.h> +#include <linux/init.h> +#include <linux/sched.h> +#include <linux/completion.h> +#include <linux/slab.h> +#include <linux/fs.h> +#include <linux/file.h> +#include <linux/namei.h> +#include <linux/poll.h> +#include <linux/mount.h> +#include <linux/statfs.h> +#include <linux/ctype.h> +#include <linux/string.h> +#include <linux/fs_struct.h> +#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 int cachefiles_daemon_bind(struct cachefiles_cache *, char *); +static void cachefiles_daemon_unbind(struct cachefiles_cache *); + +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 }, +#ifdef CONFIG_CACHEFILES_ONDEMAND + { "copen", cachefiles_ondemand_copen }, +#endif + { "", NULL } +}; + + +/* + * Prepare a cache for caching. + */ +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); + refcount_set(&cache->unbind_pincount, 1); + xa_init_flags(&cache->reqs, XA_FLAGS_ALLOC); + xa_init_flags(&cache->ondemand_ids, XA_FLAGS_ALLOC1); + + /* 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; +} + +static void cachefiles_flush_reqs(struct cachefiles_cache *cache) +{ + struct xarray *xa = &cache->reqs; + struct cachefiles_req *req; + unsigned long index; + + /* + * Make sure the following two operations won't be reordered. + * 1) set CACHEFILES_DEAD bit + * 2) flush requests in the xarray + * Otherwise the request may be enqueued after xarray has been + * flushed, leaving the orphan request never being completed. + * + * CPU 1 CPU 2 + * ===== ===== + * flush requests in the xarray + * test CACHEFILES_DEAD bit + * enqueue the request + * set CACHEFILES_DEAD bit + */ + smp_mb(); + + xa_lock(xa); + xa_for_each(xa, index, req) { + req->error = -EIO; + complete(&req->done); + } + xa_unlock(xa); + + xa_destroy(&cache->reqs); + xa_destroy(&cache->ondemand_ids); +} + +void cachefiles_put_unbind_pincount(struct cachefiles_cache *cache) +{ + if (refcount_dec_and_test(&cache->unbind_pincount)) { + cachefiles_daemon_unbind(cache); + cachefiles_open = 0; + kfree(cache); + } +} + +void cachefiles_get_unbind_pincount(struct cachefiles_cache *cache) +{ + refcount_inc(&cache->unbind_pincount); +} + +/* + * 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); + + if (cachefiles_in_ondemand_mode(cache)) + cachefiles_flush_reqs(cache); + + /* clean up the control file interface */ + cache->cachefilesd = NULL; + file->private_data = NULL; + + cachefiles_put_unbind_pincount(cache); + + _leave(""); + return 0; +} + +static ssize_t cachefiles_do_daemon_read(struct cachefiles_cache *cache, + char __user *_buffer, size_t buflen) +{ + unsigned long long b_released; + unsigned f_released; + char buffer[256]; + int n; + + /* check how much space the cache has */ + cachefiles_has_space(cache, 0, 0, cachefiles_has_space_check); + + /* 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; +} + +/* + * 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; + + //_enter(",,%zu,", buflen); + + if (!test_bit(CACHEFILES_READY, &cache->flags)) + return 0; + + if (cachefiles_in_ondemand_mode(cache)) + return cachefiles_ondemand_daemon_read(cache, _buffer, buflen); + else + return cachefiles_do_daemon_read(cache, _buffer, buflen); +} + +/* + * Take a command from cachefilesd, parse it and act on it. + */ +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 (cachefiles_in_ondemand_mode(cache)) { + if (!xa_empty(&cache->reqs)) + mask |= EPOLLIN; + } else { + 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<cull<run<100%%\n"); + + return -EINVAL; +} + +/* + * Set the percentage of files at which to stop culling + * - command: "frun <N>%" + */ +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 <N>%" + */ +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 <N>%" + */ +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 <N>%" + */ +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 <N>%" + */ +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 <N>%" + */ +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 <name>" + */ +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 <ctx>" + */ +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 <name>" + */ +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 <name>" + */ +static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args) +{ + struct path path; + const struct cred *saved_cred; + int ret; + + _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; + } + + get_fs_pwd(current->fs, &path); + + if (!d_can_lookup(path.dentry)) + goto notdir; + + cachefiles_begin_secure(cache, &saved_cred); + ret = cachefiles_cull(cache, path.dentry, args); + cachefiles_end_secure(cache, saved_cred); + + path_put(&path); + _leave(" = %d", ret); + return ret; + +notdir: + path_put(&path); + pr_err("cull command requires dirfd to be a directory\n"); + return -ENOTDIR; + +inval: + pr_err("cull command requires dirfd and filename\n"); + return -EINVAL; +} + +/* + * Set debugging mode + * - command: "debug <mask>" + */ +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 <name>" + */ +static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args) +{ + struct path path; + const struct cred *saved_cred; + int ret; + + //_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; + } + + get_fs_pwd(current->fs, &path); + + if (!d_can_lookup(path.dentry)) + goto notdir; + + cachefiles_begin_secure(cache, &saved_cred); + ret = cachefiles_check_in_use(cache, path.dentry, args); + cachefiles_end_secure(cache, saved_cred); + + path_put(&path); + //_leave(" = %d", ret); + return ret; + +notdir: + path_put(&path); + pr_err("inuse command requires dirfd to be a directory\n"); + return -ENOTDIR; + +inval: + pr_err("inuse command requires dirfd and filename\n"); + return -EINVAL; +} + +/* + * Bind a directory as a cache + */ +static 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); + + if (cache->fstop_percent >= cache->fcull_percent || + cache->fcull_percent >= cache->frun_percent || + cache->frun_percent >= 100) + return -ERANGE; + + if (cache->bstop_percent >= cache->bcull_percent || + cache->bcull_percent >= cache->brun_percent || + cache->brun_percent >= 100) + return -ERANGE; + + 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; + } + + if (IS_ENABLED(CONFIG_CACHEFILES_ONDEMAND)) { + if (!strcmp(args, "ondemand")) { + set_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags); + } else if (*args) { + pr_err("Invalid argument to the 'bind' command\n"); + return -EINVAL; + } + } else if (*args) { + pr_err("'bind' command doesn't take an argument\n"); + return -EINVAL; + } + + /* Make sure we have copies of the tag string */ + if (!cache->tag) { + /* + * The tag string is released by the fops->release() + * function, so we don't release it on error here + */ + cache->tag = kstrdup("CacheFiles", GFP_KERNEL); + if (!cache->tag) + return -ENOMEM; + } + + return cachefiles_add_cache(cache); +} + +/* + * Unbind a cache. + */ +static void cachefiles_daemon_unbind(struct cachefiles_cache *cache) +{ + _enter(""); + + if (test_bit(CACHEFILES_READY, &cache->flags)) + cachefiles_withdraw_cache(cache); + + cachefiles_put_directory(cache->graveyard); + cachefiles_put_directory(cache->store); + mntput(cache->mnt); + + kfree(cache->rootdirname); + kfree(cache->secctx); + kfree(cache->tag); + + _leave(""); +} |