From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- ipc/kdbus/fs.c | 508 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 508 insertions(+) create mode 100644 ipc/kdbus/fs.c (limited to 'ipc/kdbus/fs.c') diff --git a/ipc/kdbus/fs.c b/ipc/kdbus/fs.c new file mode 100644 index 000000000..09c480924 --- /dev/null +++ b/ipc/kdbus/fs.c @@ -0,0 +1,508 @@ +/* + * Copyright (C) 2013-2015 Kay Sievers + * Copyright (C) 2013-2015 Greg Kroah-Hartman + * Copyright (C) 2013-2015 Daniel Mack + * Copyright (C) 2013-2015 David Herrmann + * Copyright (C) 2013-2015 Linux Foundation + * + * kdbus is free software; you can redistribute it and/or modify it under + * the terms of the GNU Lesser General Public License as published by the + * Free Software Foundation; either version 2.1 of the License, or (at + * your option) any later version. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "bus.h" +#include "domain.h" +#include "endpoint.h" +#include "fs.h" +#include "handle.h" +#include "node.h" + +#define kdbus_node_from_dentry(_dentry) \ + ((struct kdbus_node *)(_dentry)->d_fsdata) + +static struct inode *fs_inode_get(struct super_block *sb, + struct kdbus_node *node); + +/* + * Directory Management + */ + +static inline unsigned char kdbus_dt_type(struct kdbus_node *node) +{ + switch (node->type) { + case KDBUS_NODE_DOMAIN: + case KDBUS_NODE_BUS: + return DT_DIR; + case KDBUS_NODE_CONTROL: + case KDBUS_NODE_ENDPOINT: + return DT_REG; + } + + return DT_UNKNOWN; +} + +static int fs_dir_fop_iterate(struct file *file, struct dir_context *ctx) +{ + struct dentry *dentry = file->f_path.dentry; + struct kdbus_node *parent = kdbus_node_from_dentry(dentry); + struct kdbus_node *old, *next = file->private_data; + + /* + * kdbusfs directory iterator (modelled after sysfs/kernfs) + * When iterating kdbusfs directories, we iterate all children of the + * parent kdbus_node object. We use ctx->pos to store the hash of the + * child and file->private_data to store a reference to the next node + * object. If ctx->pos is not modified via llseek while you iterate a + * directory, then we use the file->private_data node pointer to + * directly access the next node in the tree. + * However, if you directly seek on the directory, we have to find the + * closest node to that position and cannot use our node pointer. This + * means iterating the rb-tree to find the closest match and start over + * from there. + * Note that hash values are not necessarily unique. Therefore, llseek + * is not guaranteed to seek to the same node that you got when you + * retrieved the position. Seeking to 0, 1, 2 and >=INT_MAX is safe, + * though. We could use the inode-number as position, but this would + * require another rb-tree for fast access. Kernfs and others already + * ignore those conflicts, so we should be fine, too. + */ + + if (!dir_emit_dots(file, ctx)) + return 0; + + /* acquire @next; if deactivated, or seek detected, find next node */ + old = next; + if (next && ctx->pos == next->hash) { + if (kdbus_node_acquire(next)) + kdbus_node_ref(next); + else + next = kdbus_node_next_child(parent, next); + } else { + next = kdbus_node_find_closest(parent, ctx->pos); + } + kdbus_node_unref(old); + + while (next) { + /* emit @next */ + file->private_data = next; + ctx->pos = next->hash; + + kdbus_node_release(next); + + if (!dir_emit(ctx, next->name, strlen(next->name), next->id, + kdbus_dt_type(next))) + return 0; + + /* find next node after @next */ + old = next; + next = kdbus_node_next_child(parent, next); + kdbus_node_unref(old); + } + + file->private_data = NULL; + ctx->pos = INT_MAX; + + return 0; +} + +static loff_t fs_dir_fop_llseek(struct file *file, loff_t offset, int whence) +{ + struct inode *inode = file_inode(file); + loff_t ret; + + /* protect f_off against fop_iterate */ + mutex_lock(&inode->i_mutex); + ret = generic_file_llseek(file, offset, whence); + mutex_unlock(&inode->i_mutex); + + return ret; +} + +static int fs_dir_fop_release(struct inode *inode, struct file *file) +{ + kdbus_node_unref(file->private_data); + return 0; +} + +static const struct file_operations fs_dir_fops = { + .read = generic_read_dir, + .iterate = fs_dir_fop_iterate, + .llseek = fs_dir_fop_llseek, + .release = fs_dir_fop_release, +}; + +static struct dentry *fs_dir_iop_lookup(struct inode *dir, + struct dentry *dentry, + unsigned int flags) +{ + struct dentry *dnew = NULL; + struct kdbus_node *parent; + struct kdbus_node *node; + struct inode *inode; + + parent = kdbus_node_from_dentry(dentry->d_parent); + if (!kdbus_node_acquire(parent)) + return NULL; + + /* returns reference to _acquired_ child node */ + node = kdbus_node_find_child(parent, dentry->d_name.name); + if (node) { + dentry->d_fsdata = node; + inode = fs_inode_get(dir->i_sb, node); + if (IS_ERR(inode)) + dnew = ERR_CAST(inode); + else + dnew = d_splice_alias(inode, dentry); + + kdbus_node_release(node); + } + + kdbus_node_release(parent); + return dnew; +} + +static const struct inode_operations fs_dir_iops = { + .permission = generic_permission, + .lookup = fs_dir_iop_lookup, +}; + +/* + * Inode Management + */ + +static const struct inode_operations fs_inode_iops = { + .permission = generic_permission, +}; + +static struct inode *fs_inode_get(struct super_block *sb, + struct kdbus_node *node) +{ + struct inode *inode; + + inode = iget_locked(sb, node->id); + if (!inode) + return ERR_PTR(-ENOMEM); + if (!(inode->i_state & I_NEW)) + return inode; + + inode->i_private = kdbus_node_ref(node); + inode->i_mapping->a_ops = &empty_aops; + inode->i_mode = node->mode & S_IALLUGO; + inode->i_atime = inode->i_ctime = inode->i_mtime = CURRENT_TIME; + inode->i_uid = node->uid; + inode->i_gid = node->gid; + + switch (node->type) { + case KDBUS_NODE_DOMAIN: + case KDBUS_NODE_BUS: + inode->i_mode |= S_IFDIR; + inode->i_op = &fs_dir_iops; + inode->i_fop = &fs_dir_fops; + set_nlink(inode, 2); + break; + case KDBUS_NODE_CONTROL: + case KDBUS_NODE_ENDPOINT: + inode->i_mode |= S_IFREG; + inode->i_op = &fs_inode_iops; + inode->i_fop = &kdbus_handle_ops; + break; + } + + unlock_new_inode(inode); + + return inode; +} + +/* + * Superblock Management + */ + +static int fs_super_dop_revalidate(struct dentry *dentry, unsigned int flags) +{ + struct kdbus_node *node; + + /* Force lookup on negatives */ + if (!dentry->d_inode) + return 0; + + node = kdbus_node_from_dentry(dentry); + + /* see whether the node has been removed */ + if (!kdbus_node_is_active(node)) + return 0; + + return 1; +} + +static void fs_super_dop_release(struct dentry *dentry) +{ + kdbus_node_unref(dentry->d_fsdata); +} + +static const struct dentry_operations fs_super_dops = { + .d_revalidate = fs_super_dop_revalidate, + .d_release = fs_super_dop_release, +}; + +static void fs_super_sop_evict_inode(struct inode *inode) +{ + struct kdbus_node *node = kdbus_node_from_inode(inode); + + truncate_inode_pages_final(&inode->i_data); + clear_inode(inode); + kdbus_node_unref(node); +} + +static const struct super_operations fs_super_sops = { + .statfs = simple_statfs, + .drop_inode = generic_delete_inode, + .evict_inode = fs_super_sop_evict_inode, +}; + +static int fs_super_fill(struct super_block *sb) +{ + struct kdbus_domain *domain = sb->s_fs_info; + struct inode *inode; + int ret; + + sb->s_blocksize = PAGE_CACHE_SIZE; + sb->s_blocksize_bits = PAGE_CACHE_SHIFT; + sb->s_magic = KDBUS_SUPER_MAGIC; + sb->s_maxbytes = MAX_LFS_FILESIZE; + sb->s_op = &fs_super_sops; + sb->s_time_gran = 1; + + inode = fs_inode_get(sb, &domain->node); + if (IS_ERR(inode)) + return PTR_ERR(inode); + + sb->s_root = d_make_root(inode); + if (!sb->s_root) { + /* d_make_root iput()s the inode on failure */ + return -ENOMEM; + } + + /* sb holds domain reference */ + sb->s_root->d_fsdata = &domain->node; + sb->s_d_op = &fs_super_dops; + + /* sb holds root reference */ + domain->dentry = sb->s_root; + + if (!kdbus_node_activate(&domain->node)) + return -ESHUTDOWN; + + ret = kdbus_domain_populate(domain, KDBUS_MAKE_ACCESS_WORLD); + if (ret < 0) + return ret; + + sb->s_flags |= MS_ACTIVE; + return 0; +} + +static void fs_super_kill(struct super_block *sb) +{ + struct kdbus_domain *domain = sb->s_fs_info; + + if (domain) { + kdbus_node_deactivate(&domain->node); + domain->dentry = NULL; + } + + kill_anon_super(sb); + kdbus_domain_unref(domain); +} + +static int fs_super_set(struct super_block *sb, void *data) +{ + int ret; + + ret = set_anon_super(sb, data); + if (!ret) + sb->s_fs_info = data; + + return ret; +} + +static struct dentry *fs_super_mount(struct file_system_type *fs_type, + int flags, const char *dev_name, + void *data) +{ + struct kdbus_domain *domain; + struct super_block *sb; + int ret; + + domain = kdbus_domain_new(KDBUS_MAKE_ACCESS_WORLD); + if (IS_ERR(domain)) + return ERR_CAST(domain); + + sb = sget(fs_type, NULL, fs_super_set, flags, domain); + if (IS_ERR(sb)) { + kdbus_node_deactivate(&domain->node); + kdbus_domain_unref(domain); + return ERR_CAST(sb); + } + + WARN_ON(sb->s_fs_info != domain); + WARN_ON(sb->s_root); + + ret = fs_super_fill(sb); + if (ret < 0) { + /* calls into ->kill_sb() when done */ + deactivate_locked_super(sb); + return ERR_PTR(ret); + } + + return dget(sb->s_root); +} + +static struct file_system_type fs_type = { + .name = KBUILD_MODNAME "fs", + .owner = THIS_MODULE, + .mount = fs_super_mount, + .kill_sb = fs_super_kill, + .fs_flags = FS_USERNS_MOUNT, +}; + +/** + * kdbus_fs_init() - register kdbus filesystem + * + * This registers a filesystem with the VFS layer. The filesystem is called + * `KBUILD_MODNAME "fs"', which usually resolves to `kdbusfs'. The nameing + * scheme allows to set KBUILD_MODNAME to "kdbus2" and you will get an + * independent filesystem for developers. + * + * Each mount of the kdbusfs filesystem has an kdbus_domain attached. + * Operations on this mount will only affect the attached domain. On each mount + * a new domain is automatically created and used for this mount exclusively. + * If you want to share a domain across multiple mounts, you need to bind-mount + * it. + * + * Mounts of kdbusfs (with a different domain each) are unrelated to each other + * and will never have any effect on any domain but their own. + * + * Return: 0 on success, negative error otherwise. + */ +int kdbus_fs_init(void) +{ + return register_filesystem(&fs_type); +} + +/** + * kdbus_fs_exit() - unregister kdbus filesystem + * + * This does the reverse to kdbus_fs_init(). It unregisters the kdbusfs + * filesystem from VFS and cleans up any allocated resources. + */ +void kdbus_fs_exit(void) +{ + unregister_filesystem(&fs_type); +} + +/* acquire domain of @node, making sure all ancestors are active */ +static struct kdbus_domain *fs_acquire_domain(struct kdbus_node *node) +{ + struct kdbus_domain *domain; + struct kdbus_node *iter; + + /* caller must guarantee that @node is linked */ + for (iter = node; iter->parent; iter = iter->parent) + if (!kdbus_node_is_active(iter->parent)) + return NULL; + + /* root nodes are always domains */ + if (WARN_ON(iter->type != KDBUS_NODE_DOMAIN)) + return NULL; + + domain = kdbus_domain_from_node(iter); + if (!kdbus_node_acquire(&domain->node)) + return NULL; + + return domain; +} + +/** + * kdbus_fs_flush() - flush dcache entries of a node + * @node: Node to flush entries of + * + * This flushes all VFS filesystem cache entries for a node and all its + * children. This should be called whenever a node is destroyed during + * runtime. It will flush the cache entries so the linked objects can be + * deallocated. + * + * This is a no-op if you call it on active nodes (they really should stay in + * cache) or on nodes with deactivated parents (flushing the parent is enough). + * Furthermore, there is no need to call it on nodes whose lifetime is bound to + * their parents'. In those cases, the parent-flush will always also flush the + * children. + */ +void kdbus_fs_flush(struct kdbus_node *node) +{ + struct dentry *dentry, *parent_dentry = NULL; + struct kdbus_domain *domain; + struct qstr name; + + /* active nodes should remain in cache */ + if (!kdbus_node_is_deactivated(node)) + return; + + /* nodes that were never linked were never instantiated */ + if (!node->parent) + return; + + /* acquire domain and verify all ancestors are active */ + domain = fs_acquire_domain(node); + if (!domain) + return; + + switch (node->type) { + case KDBUS_NODE_ENDPOINT: + if (WARN_ON(!node->parent || !node->parent->name)) + goto exit; + + name.name = node->parent->name; + name.len = strlen(node->parent->name); + parent_dentry = d_hash_and_lookup(domain->dentry, &name); + if (IS_ERR_OR_NULL(parent_dentry)) + goto exit; + + /* fallthrough */ + case KDBUS_NODE_BUS: + if (WARN_ON(!node->name)) + goto exit; + + name.name = node->name; + name.len = strlen(node->name); + dentry = d_hash_and_lookup(parent_dentry ? : domain->dentry, + &name); + if (!IS_ERR_OR_NULL(dentry)) { + d_invalidate(dentry); + dput(dentry); + } + + dput(parent_dentry); + break; + + default: + /* all other types are bound to their parent lifetime */ + break; + } + +exit: + kdbus_node_release(&domain->node); +} -- cgit v1.2.3-54-g00ecf