// 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(""); }