@@ -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
new file mode 100644
@@ -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 <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/mount.h>
+#include <linux/statfs.h>
+#include <linux/ctype.h>
+#include <linux/xattr.h>
+#include <trace/events/fscache.h>
+#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("");
+}
@@ -21,6 +21,606 @@
#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 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<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)
+{
+ _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 <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)
+{
+ //_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
new file mode 100644
@@ -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 <linux/slab.h>
+#include <linux/mount.h>
+#include <linux/xattr.h>
+#include <linux/file.h>
+#include <linux/falloc.h>
+#include <trace/events/fscache.h>
+#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",
+};
@@ -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
*/
@@ -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();
}
new file mode 100644
@@ -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 <linux/fs.h>
+#include <linux/cred.h>
+#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;
+}
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 <dhowells@redhat.com> 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