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platform_system_core/sdcard/sdcard.c

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/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/statfs.h>
#include <sys/uio.h>
#include <dirent.h>
#include <limits.h>
#include <ctype.h>
#include <pthread.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/inotify.h>
#include <cutils/fs.h>
#include <cutils/hashmap.h>
#include <cutils/multiuser.h>
#include <private/android_filesystem_config.h>
#include "fuse.h"
/* README
*
* What is this?
*
* sdcard is a program that uses FUSE to emulate FAT-on-sdcard style
* directory permissions (all files are given fixed owner, group, and
* permissions at creation, owner, group, and permissions are not
* changeable, symlinks and hardlinks are not createable, etc.
*
* See usage() for command line options.
*
* It must be run as root, but will drop to requested UID/GID as soon as it
* mounts a filesystem. It will refuse to run if requested UID/GID are zero.
*
* Things I believe to be true:
*
* - ops that return a fuse_entry (LOOKUP, MKNOD, MKDIR, LINK, SYMLINK,
* CREAT) must bump that node's refcount
* - don't forget that FORGET can forget multiple references (req->nlookup)
* - if an op that returns a fuse_entry fails writing the reply to the
* kernel, you must rollback the refcount to reflect the reference the
* kernel did not actually acquire
*
* This daemon can also derive custom filesystem permissions based on directory
* structure when requested. These custom permissions support several features:
*
* - Apps can access their own files in /Android/data/com.example/ without
* requiring any additional GIDs.
* - Separate permissions for protecting directories like Pictures and Music.
* - Multi-user separation on the same physical device.
*
* The derived permissions look like this:
*
* rwxrwx--x root:sdcard_rw /
* rwxrwx--- root:sdcard_pics /Pictures
* rwxrwx--- root:sdcard_av /Music
*
* rwxrwx--x root:sdcard_rw /Android
* rwxrwx--x root:sdcard_rw /Android/data
* rwxrwx--- u0_a12:sdcard_rw /Android/data/com.example
* rwxrwx--x root:sdcard_rw /Android/obb/
* rwxrwx--- u0_a12:sdcard_rw /Android/obb/com.example
*
* rwxrwx--- root:sdcard_all /Android/user
* rwxrwx--x root:sdcard_rw /Android/user/10
* rwxrwx--- u10_a12:sdcard_rw /Android/user/10/Android/data/com.example
*/
#define FUSE_TRACE 0
#if FUSE_TRACE
#define TRACE(x...) fprintf(stderr,x)
#else
#define TRACE(x...) do {} while (0)
#endif
#define ERROR(x...) fprintf(stderr,x)
#define FUSE_UNKNOWN_INO 0xffffffff
/* Maximum number of bytes to write in one request. */
#define MAX_WRITE (256 * 1024)
/* Maximum number of bytes to read in one request. */
#define MAX_READ (128 * 1024)
/* Largest possible request.
* The request size is bounded by the maximum size of a FUSE_WRITE request because it has
* the largest possible data payload. */
#define MAX_REQUEST_SIZE (sizeof(struct fuse_in_header) + sizeof(struct fuse_write_in) + MAX_WRITE)
/* Default number of threads. */
#define DEFAULT_NUM_THREADS 2
/* Pseudo-error constant used to indicate that no fuse status is needed
* or that a reply has already been written. */
#define NO_STATUS 1
/* Path to system-provided mapping of package name to appIds */
static const char* const kPackagesListFile = "/data/system/packages.list";
/* Supplementary groups to execute with */
static const gid_t kGroups[1] = { AID_PACKAGE_INFO };
/* Permission mode for a specific node. Controls how file permissions
* are derived for children nodes. */
typedef enum {
/* Nothing special; this node should just inherit from its parent. */
PERM_INHERIT,
/* This node is one level above a normal root; used for legacy layouts
* which use the first level to represent user_id. */
PERM_LEGACY_PRE_ROOT,
/* This node is "/" */
PERM_ROOT,
/* This node is "/Android" */
PERM_ANDROID,
/* This node is "/Android/data" */
PERM_ANDROID_DATA,
/* This node is "/Android/obb" */
PERM_ANDROID_OBB,
/* This node is "/Android/user" */
PERM_ANDROID_USER,
} perm_t;
/* Permissions structure to derive */
typedef enum {
DERIVE_NONE,
DERIVE_LEGACY,
DERIVE_UNIFIED,
} derive_t;
struct handle {
int fd;
};
struct dirhandle {
DIR *d;
};
struct node {
__u32 refcount;
__u64 nid;
__u64 gen;
/* State derived based on current position in hierarchy. */
perm_t perm;
userid_t userid;
uid_t uid;
gid_t gid;
mode_t mode;
struct node *next; /* per-dir sibling list */
struct node *child; /* first contained file by this dir */
struct node *parent; /* containing directory */
size_t namelen;
char *name;
/* If non-null, this is the real name of the file in the underlying storage.
* This may differ from the field "name" only by case.
* strlen(actual_name) will always equal strlen(name), so it is safe to use
* namelen for both fields.
*/
char *actual_name;
/* If non-null, an exact underlying path that should be grafted into this
* position. Used to support things like OBB. */
char* graft_path;
size_t graft_pathlen;
};
static int str_hash(void *key) {
return hashmapHash(key, strlen(key));
}
/** Test if two string keys are equal ignoring case */
static bool str_icase_equals(void *keyA, void *keyB) {
return strcasecmp(keyA, keyB) == 0;
}
static int int_hash(void *key) {
return (int) (uintptr_t) key;
}
static bool int_equals(void *keyA, void *keyB) {
return keyA == keyB;
}
/* Global data structure shared by all fuse handlers. */
struct fuse {
pthread_mutex_t lock;
__u64 next_generation;
int fd;
derive_t derive;
bool split_perms;
gid_t write_gid;
struct node root;
char obbpath[PATH_MAX];
Hashmap* package_to_appid;
Hashmap* appid_with_rw;
};
/* Private data used by a single fuse handler. */
struct fuse_handler {
struct fuse* fuse;
int token;
/* To save memory, we never use the contents of the request buffer and the read
* buffer at the same time. This allows us to share the underlying storage. */
union {
__u8 request_buffer[MAX_REQUEST_SIZE];
__u8 read_buffer[MAX_READ];
};
};
static inline void *id_to_ptr(__u64 nid)
{
return (void *) (uintptr_t) nid;
}
static inline __u64 ptr_to_id(void *ptr)
{
return (__u64) (uintptr_t) ptr;
}
static void acquire_node_locked(struct node* node)
{
node->refcount++;
TRACE("ACQUIRE %p (%s) rc=%d\n", node, node->name, node->refcount);
}
static void remove_node_from_parent_locked(struct node* node);
static void release_node_locked(struct node* node)
{
TRACE("RELEASE %p (%s) rc=%d\n", node, node->name, node->refcount);
if (node->refcount > 0) {
node->refcount--;
if (!node->refcount) {
TRACE("DESTROY %p (%s)\n", node, node->name);
remove_node_from_parent_locked(node);
/* TODO: remove debugging - poison memory */
memset(node->name, 0xef, node->namelen);
free(node->name);
free(node->actual_name);
memset(node, 0xfc, sizeof(*node));
free(node);
}
} else {
ERROR("Zero refcnt %p\n", node);
}
}
static void add_node_to_parent_locked(struct node *node, struct node *parent) {
node->parent = parent;
node->next = parent->child;
parent->child = node;
acquire_node_locked(parent);
}
static void remove_node_from_parent_locked(struct node* node)
{
if (node->parent) {
if (node->parent->child == node) {
node->parent->child = node->parent->child->next;
} else {
struct node *node2;
node2 = node->parent->child;
while (node2->next != node)
node2 = node2->next;
node2->next = node->next;
}
release_node_locked(node->parent);
node->parent = NULL;
node->next = NULL;
}
}
/* Gets the absolute path to a node into the provided buffer.
*
* Populates 'buf' with the path and returns the length of the path on success,
* or returns -1 if the path is too long for the provided buffer.
*/
static ssize_t get_node_path_locked(struct node* node, char* buf, size_t bufsize) {
const char* name;
size_t namelen;
if (node->graft_path) {
name = node->graft_path;
namelen = node->graft_pathlen;
} else if (node->actual_name) {
name = node->actual_name;
namelen = node->namelen;
} else {
name = node->name;
namelen = node->namelen;
}
if (bufsize < namelen + 1) {
return -1;
}
ssize_t pathlen = 0;
if (node->parent && node->graft_path == NULL) {
pathlen = get_node_path_locked(node->parent, buf, bufsize - namelen - 2);
if (pathlen < 0) {
return -1;
}
buf[pathlen++] = '/';
}
memcpy(buf + pathlen, name, namelen + 1); /* include trailing \0 */
return pathlen + namelen;
}
/* Finds the absolute path of a file within a given directory.
* Performs a case-insensitive search for the file and sets the buffer to the path
* of the first matching file. If 'search' is zero or if no match is found, sets
* the buffer to the path that the file would have, assuming the name were case-sensitive.
*
* Populates 'buf' with the path and returns the actual name (within 'buf') on success,
* or returns NULL if the path is too long for the provided buffer.
*/
static char* find_file_within(const char* path, const char* name,
char* buf, size_t bufsize, int search)
{
size_t pathlen = strlen(path);
size_t namelen = strlen(name);
size_t childlen = pathlen + namelen + 1;
char* actual;
if (bufsize <= childlen) {
return NULL;
}
memcpy(buf, path, pathlen);
buf[pathlen] = '/';
actual = buf + pathlen + 1;
memcpy(actual, name, namelen + 1);
if (search && access(buf, F_OK)) {
struct dirent* entry;
DIR* dir = opendir(path);
if (!dir) {
ERROR("opendir %s failed: %s\n", path, strerror(errno));
return actual;
}
while ((entry = readdir(dir))) {
if (!strcasecmp(entry->d_name, name)) {
/* we have a match - replace the name, don't need to copy the null again */
memcpy(actual, entry->d_name, namelen);
break;
}
}
closedir(dir);
}
return actual;
}
static void attr_from_stat(struct fuse_attr *attr, const struct stat *s, const struct node* node)
{
attr->ino = node->nid;
attr->size = s->st_size;
attr->blocks = s->st_blocks;
attr->atime = s->st_atime;
attr->mtime = s->st_mtime;
attr->ctime = s->st_ctime;
attr->atimensec = s->st_atime_nsec;
attr->mtimensec = s->st_mtime_nsec;
attr->ctimensec = s->st_ctime_nsec;
attr->mode = s->st_mode;
attr->nlink = s->st_nlink;
attr->uid = node->uid;
attr->gid = node->gid;
/* Filter requested mode based on underlying file, and
* pass through file type. */
int owner_mode = s->st_mode & 0700;
int filtered_mode = node->mode & (owner_mode | (owner_mode >> 3) | (owner_mode >> 6));
attr->mode = (attr->mode & S_IFMT) | filtered_mode;
}
static int touch(char* path, mode_t mode) {
int fd = open(path, O_RDWR | O_CREAT | O_EXCL | O_NOFOLLOW, mode);
if (fd == -1) {
if (errno == EEXIST) {
return 0;
} else {
ERROR("Failed to open(%s): %s\n", path, strerror(errno));
return -1;
}
}
close(fd);
return 0;
}
static void derive_permissions_locked(struct fuse* fuse, struct node *parent,
struct node *node) {
appid_t appid;
/* By default, each node inherits from its parent */
node->perm = PERM_INHERIT;
node->userid = parent->userid;
node->uid = parent->uid;
node->gid = parent->gid;
node->mode = parent->mode;
if (fuse->derive == DERIVE_NONE) {
return;
}
/* Derive custom permissions based on parent and current node */
switch (parent->perm) {
case PERM_INHERIT:
/* Already inherited above */
break;
case PERM_LEGACY_PRE_ROOT:
/* Legacy internal layout places users at top level */
node->perm = PERM_ROOT;
node->userid = strtoul(node->name, NULL, 10);
break;
case PERM_ROOT:
/* Assume masked off by default. */
node->mode = 0770;
if (!strcasecmp(node->name, "Android")) {
/* App-specific directories inside; let anyone traverse */
node->perm = PERM_ANDROID;
node->mode = 0771;
} else if (fuse->split_perms) {
if (!strcasecmp(node->name, "DCIM")
|| !strcasecmp(node->name, "Pictures")) {
node->gid = AID_SDCARD_PICS;
} else if (!strcasecmp(node->name, "Alarms")
|| !strcasecmp(node->name, "Movies")
|| !strcasecmp(node->name, "Music")
|| !strcasecmp(node->name, "Notifications")
|| !strcasecmp(node->name, "Podcasts")
|| !strcasecmp(node->name, "Ringtones")) {
node->gid = AID_SDCARD_AV;
}
}
break;
case PERM_ANDROID:
if (!strcasecmp(node->name, "data")) {
/* App-specific directories inside; let anyone traverse */
node->perm = PERM_ANDROID_DATA;
node->mode = 0771;
} else if (!strcasecmp(node->name, "obb")) {
/* App-specific directories inside; let anyone traverse */
node->perm = PERM_ANDROID_OBB;
node->mode = 0771;
/* Single OBB directory is always shared */
node->graft_path = fuse->obbpath;
node->graft_pathlen = strlen(fuse->obbpath);
} else if (!strcasecmp(node->name, "user")) {
/* User directories must only be accessible to system, protected
* by sdcard_all. Zygote will bind mount the appropriate user-
* specific path. */
node->perm = PERM_ANDROID_USER;
node->gid = AID_SDCARD_ALL;
node->mode = 0770;
}
break;
case PERM_ANDROID_DATA:
case PERM_ANDROID_OBB:
appid = (appid_t) (uintptr_t) hashmapGet(fuse->package_to_appid, node->name);
if (appid != 0) {
node->uid = multiuser_get_uid(parent->userid, appid);
}
node->mode = 0770;
break;
case PERM_ANDROID_USER:
/* Root of a secondary user */
node->perm = PERM_ROOT;
node->userid = strtoul(node->name, NULL, 10);
node->gid = AID_SDCARD_R;
node->mode = 0771;
break;
}
}
/* Return if the calling UID holds sdcard_rw. */
static bool get_caller_has_rw_locked(struct fuse* fuse, const struct fuse_in_header *hdr) {
/* No additional permissions enforcement */
if (fuse->derive == DERIVE_NONE) {
return true;
}
appid_t appid = multiuser_get_app_id(hdr->uid);
return hashmapContainsKey(fuse->appid_with_rw, (void*) (uintptr_t) appid);
}
/* Kernel has already enforced everything we returned through
* derive_permissions_locked(), so this is used to lock down access
* even further, such as enforcing that apps hold sdcard_rw. */
static bool check_caller_access_to_name(struct fuse* fuse,
const struct fuse_in_header *hdr, const struct node* parent_node,
const char* name, int mode, bool has_rw) {
/* Always block security-sensitive files at root */
if (parent_node && parent_node->perm == PERM_ROOT) {
if (!strcasecmp(name, "autorun.inf")
|| !strcasecmp(name, ".android_secure")
|| !strcasecmp(name, "android_secure")) {
return false;
}
}
/* No additional permissions enforcement */
if (fuse->derive == DERIVE_NONE) {
return true;
}
/* Root always has access; access for any other UIDs should always
* be controlled through packages.list. */
if (hdr->uid == 0) {
return true;
}
/* If asking to write, verify that caller either owns the
* parent or holds sdcard_rw. */
if (mode & W_OK) {
if (parent_node && hdr->uid == parent_node->uid) {
return true;
}
return has_rw;
}
/* No extra permissions to enforce */
return true;
}
static bool check_caller_access_to_node(struct fuse* fuse,
const struct fuse_in_header *hdr, const struct node* node, int mode, bool has_rw) {
return check_caller_access_to_name(fuse, hdr, node->parent, node->name, mode, has_rw);
}
struct node *create_node_locked(struct fuse* fuse,
struct node *parent, const char *name, const char* actual_name)
{
struct node *node;
size_t namelen = strlen(name);
node = calloc(1, sizeof(struct node));
if (!node) {
return NULL;
}
node->name = malloc(namelen + 1);
if (!node->name) {
free(node);
return NULL;
}
memcpy(node->name, name, namelen + 1);
if (strcmp(name, actual_name)) {
node->actual_name = malloc(namelen + 1);
if (!node->actual_name) {
free(node->name);
free(node);
return NULL;
}
memcpy(node->actual_name, actual_name, namelen + 1);
}
node->namelen = namelen;
node->nid = ptr_to_id(node);
node->gen = fuse->next_generation++;
derive_permissions_locked(fuse, parent, node);
acquire_node_locked(node);
add_node_to_parent_locked(node, parent);
return node;
}
static int rename_node_locked(struct node *node, const char *name,
const char* actual_name)
{
size_t namelen = strlen(name);
int need_actual_name = strcmp(name, actual_name);
/* make the storage bigger without actually changing the name
* in case an error occurs part way */
if (namelen > node->namelen) {
char* new_name = realloc(node->name, namelen + 1);
if (!new_name) {
return -ENOMEM;
}
node->name = new_name;
if (need_actual_name && node->actual_name) {
char* new_actual_name = realloc(node->actual_name, namelen + 1);
if (!new_actual_name) {
return -ENOMEM;
}
node->actual_name = new_actual_name;
}
}
/* update the name, taking care to allocate storage before overwriting the old name */
if (need_actual_name) {
if (!node->actual_name) {
node->actual_name = malloc(namelen + 1);
if (!node->actual_name) {
return -ENOMEM;
}
}
memcpy(node->actual_name, actual_name, namelen + 1);
} else {
free(node->actual_name);
node->actual_name = NULL;
}
memcpy(node->name, name, namelen + 1);
node->namelen = namelen;
return 0;
}
static struct node *lookup_node_by_id_locked(struct fuse *fuse, __u64 nid)
{
if (nid == FUSE_ROOT_ID) {
return &fuse->root;
} else {
return id_to_ptr(nid);
}
}
static struct node* lookup_node_and_path_by_id_locked(struct fuse* fuse, __u64 nid,
char* buf, size_t bufsize)
{
struct node* node = lookup_node_by_id_locked(fuse, nid);
if (node && get_node_path_locked(node, buf, bufsize) < 0) {
node = NULL;
}
return node;
}
static struct node *lookup_child_by_name_locked(struct node *node, const char *name)
{
for (node = node->child; node; node = node->next) {
/* use exact string comparison, nodes that differ by case
* must be considered distinct even if they refer to the same
* underlying file as otherwise operations such as "mv x x"
* will not work because the source and target nodes are the same. */
if (!strcmp(name, node->name)) {
return node;
}
}
return 0;
}
static struct node* acquire_or_create_child_locked(
struct fuse* fuse, struct node* parent,
const char* name, const char* actual_name)
{
struct node* child = lookup_child_by_name_locked(parent, name);
if (child) {
acquire_node_locked(child);
} else {
child = create_node_locked(fuse, parent, name, actual_name);
}
return child;
}
static void fuse_init(struct fuse *fuse, int fd, const char *source_path,
gid_t write_gid, derive_t derive, bool split_perms) {
pthread_mutex_init(&fuse->lock, NULL);
fuse->fd = fd;
fuse->next_generation = 0;
fuse->derive = derive;
fuse->split_perms = split_perms;
fuse->write_gid = write_gid;
memset(&fuse->root, 0, sizeof(fuse->root));
fuse->root.nid = FUSE_ROOT_ID; /* 1 */
fuse->root.refcount = 2;
fuse->root.namelen = strlen(source_path);
fuse->root.name = strdup(source_path);
fuse->root.userid = 0;
fuse->root.uid = AID_ROOT;
/* Set up root node for various modes of operation */
switch (derive) {
case DERIVE_NONE:
/* Traditional behavior that treats entire device as being accessible
* to sdcard_rw, and no permissions are derived. */
fuse->root.perm = PERM_ROOT;
fuse->root.mode = 0775;
fuse->root.gid = AID_SDCARD_RW;
break;
case DERIVE_LEGACY:
/* Legacy behavior used to support internal multiuser layout which
* places user_id at the top directory level, with the actual roots
* just below that. Shared OBB path is also at top level. */
fuse->root.perm = PERM_LEGACY_PRE_ROOT;
fuse->root.mode = 0771;
fuse->root.gid = AID_SDCARD_R;
fuse->package_to_appid = hashmapCreate(256, str_hash, str_icase_equals);
fuse->appid_with_rw = hashmapCreate(128, int_hash, int_equals);
snprintf(fuse->obbpath, sizeof(fuse->obbpath), "%s/obb", source_path);
fs_prepare_dir(fuse->obbpath, 0775, getuid(), getgid());
break;
case DERIVE_UNIFIED:
/* Unified multiuser layout which places secondary user_id under
* /Android/user and shared OBB path under /Android/obb. */
fuse->root.perm = PERM_ROOT;
fuse->root.mode = 0771;
fuse->root.gid = AID_SDCARD_R;
fuse->package_to_appid = hashmapCreate(256, str_hash, str_icase_equals);
fuse->appid_with_rw = hashmapCreate(128, int_hash, int_equals);
snprintf(fuse->obbpath, sizeof(fuse->obbpath), "%s/Android/obb", source_path);
break;
}
}
static void fuse_status(struct fuse *fuse, __u64 unique, int err)
{
struct fuse_out_header hdr;
hdr.len = sizeof(hdr);
hdr.error = err;
hdr.unique = unique;
write(fuse->fd, &hdr, sizeof(hdr));
}
static void fuse_reply(struct fuse *fuse, __u64 unique, void *data, int len)
{
struct fuse_out_header hdr;
struct iovec vec[2];
int res;
hdr.len = len + sizeof(hdr);
hdr.error = 0;
hdr.unique = unique;
vec[0].iov_base = &hdr;
vec[0].iov_len = sizeof(hdr);
vec[1].iov_base = data;
vec[1].iov_len = len;
res = writev(fuse->fd, vec, 2);
if (res < 0) {
ERROR("*** REPLY FAILED *** %d\n", errno);
}
}
static int fuse_reply_entry(struct fuse* fuse, __u64 unique,
struct node* parent, const char* name, const char* actual_name,
const char* path)
{
struct node* node;
struct fuse_entry_out out;
struct stat s;
if (lstat(path, &s) < 0) {
return -errno;
}
pthread_mutex_lock(&fuse->lock);
node = acquire_or_create_child_locked(fuse, parent, name, actual_name);
if (!node) {
pthread_mutex_unlock(&fuse->lock);
return -ENOMEM;
}
memset(&out, 0, sizeof(out));
attr_from_stat(&out.attr, &s, node);
out.attr_valid = 10;
out.entry_valid = 10;
out.nodeid = node->nid;
out.generation = node->gen;
pthread_mutex_unlock(&fuse->lock);
fuse_reply(fuse, unique, &out, sizeof(out));
return NO_STATUS;
}
static int fuse_reply_attr(struct fuse* fuse, __u64 unique, const struct node* node,
const char* path)
{
struct fuse_attr_out out;
struct stat s;
if (lstat(path, &s) < 0) {
return -errno;
}
memset(&out, 0, sizeof(out));
attr_from_stat(&out.attr, &s, node);
out.attr_valid = 10;
fuse_reply(fuse, unique, &out, sizeof(out));
return NO_STATUS;
}
static int handle_lookup(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header *hdr, const char* name)
{
struct node* parent_node;
char parent_path[PATH_MAX];
char child_path[PATH_MAX];
const char* actual_name;
pthread_mutex_lock(&fuse->lock);
parent_node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid,
parent_path, sizeof(parent_path));
TRACE("[%d] LOOKUP %s @ %llx (%s)\n", handler->token, name, hdr->nodeid,
parent_node ? parent_node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!parent_node || !(actual_name = find_file_within(parent_path, name,
child_path, sizeof(child_path), 1))) {
return -ENOENT;
}
if (!check_caller_access_to_name(fuse, hdr, parent_node, name, R_OK, false)) {
return -EACCES;
}
return fuse_reply_entry(fuse, hdr->unique, parent_node, name, actual_name, child_path);
}
static int handle_forget(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header *hdr, const struct fuse_forget_in *req)
{
struct node* node;
pthread_mutex_lock(&fuse->lock);
node = lookup_node_by_id_locked(fuse, hdr->nodeid);
TRACE("[%d] FORGET #%lld @ %llx (%s)\n", handler->token, req->nlookup,
hdr->nodeid, node ? node->name : "?");
if (node) {
__u64 n = req->nlookup;
while (n--) {
release_node_locked(node);
}
}
pthread_mutex_unlock(&fuse->lock);
return NO_STATUS; /* no reply */
}
static int handle_getattr(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header *hdr, const struct fuse_getattr_in *req)
{
struct node* node;
char path[PATH_MAX];
pthread_mutex_lock(&fuse->lock);
node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid, path, sizeof(path));
TRACE("[%d] GETATTR flags=%x fh=%llx @ %llx (%s)\n", handler->token,
req->getattr_flags, req->fh, hdr->nodeid, node ? node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!node) {
return -ENOENT;
}
if (!check_caller_access_to_node(fuse, hdr, node, R_OK, false)) {
return -EACCES;
}
return fuse_reply_attr(fuse, hdr->unique, node, path);
}
static int handle_setattr(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header *hdr, const struct fuse_setattr_in *req)
{
bool has_rw;
struct node* node;
char path[PATH_MAX];
struct timespec times[2];
pthread_mutex_lock(&fuse->lock);
has_rw = get_caller_has_rw_locked(fuse, hdr);
node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid, path, sizeof(path));
TRACE("[%d] SETATTR fh=%llx valid=%x @ %llx (%s)\n", handler->token,
req->fh, req->valid, hdr->nodeid, node ? node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!node) {
return -ENOENT;
}
if (!check_caller_access_to_node(fuse, hdr, node, W_OK, has_rw)) {
return -EACCES;
}
/* XXX: incomplete implementation on purpose.
* chmod/chown should NEVER be implemented.*/
if ((req->valid & FATTR_SIZE) && truncate(path, req->size) < 0) {
return -errno;
}
/* Handle changing atime and mtime. If FATTR_ATIME_and FATTR_ATIME_NOW
* are both set, then set it to the current time. Else, set it to the
* time specified in the request. Same goes for mtime. Use utimensat(2)
* as it allows ATIME and MTIME to be changed independently, and has
* nanosecond resolution which fuse also has.
*/
if (req->valid & (FATTR_ATIME | FATTR_MTIME)) {
times[0].tv_nsec = UTIME_OMIT;
times[1].tv_nsec = UTIME_OMIT;
if (req->valid & FATTR_ATIME) {
if (req->valid & FATTR_ATIME_NOW) {
times[0].tv_nsec = UTIME_NOW;
} else {
times[0].tv_sec = req->atime;
times[0].tv_nsec = req->atimensec;
}
}
if (req->valid & FATTR_MTIME) {
if (req->valid & FATTR_MTIME_NOW) {
times[1].tv_nsec = UTIME_NOW;
} else {
times[1].tv_sec = req->mtime;
times[1].tv_nsec = req->mtimensec;
}
}
TRACE("[%d] Calling utimensat on %s with atime %ld, mtime=%ld\n",
handler->token, path, times[0].tv_sec, times[1].tv_sec);
if (utimensat(-1, path, times, 0) < 0) {
return -errno;
}
}
return fuse_reply_attr(fuse, hdr->unique, node, path);
}
static int handle_mknod(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_mknod_in* req, const char* name)
{
bool has_rw;
struct node* parent_node;
char parent_path[PATH_MAX];
char child_path[PATH_MAX];
const char* actual_name;
pthread_mutex_lock(&fuse->lock);
has_rw = get_caller_has_rw_locked(fuse, hdr);
parent_node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid,
parent_path, sizeof(parent_path));
TRACE("[%d] MKNOD %s 0%o @ %llx (%s)\n", handler->token,
name, req->mode, hdr->nodeid, parent_node ? parent_node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!parent_node || !(actual_name = find_file_within(parent_path, name,
child_path, sizeof(child_path), 1))) {
return -ENOENT;
}
if (!check_caller_access_to_name(fuse, hdr, parent_node, name, W_OK, has_rw)) {
return -EACCES;
}
__u32 mode = (req->mode & (~0777)) | 0664;
if (mknod(child_path, mode, req->rdev) < 0) {
return -errno;
}
return fuse_reply_entry(fuse, hdr->unique, parent_node, name, actual_name, child_path);
}
static int handle_mkdir(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_mkdir_in* req, const char* name)
{
bool has_rw;
struct node* parent_node;
char parent_path[PATH_MAX];
char child_path[PATH_MAX];
const char* actual_name;
pthread_mutex_lock(&fuse->lock);
has_rw = get_caller_has_rw_locked(fuse, hdr);
parent_node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid,
parent_path, sizeof(parent_path));
TRACE("[%d] MKDIR %s 0%o @ %llx (%s)\n", handler->token,
name, req->mode, hdr->nodeid, parent_node ? parent_node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!parent_node || !(actual_name = find_file_within(parent_path, name,
child_path, sizeof(child_path), 1))) {
return -ENOENT;
}
if (!check_caller_access_to_name(fuse, hdr, parent_node, name, W_OK, has_rw)) {
return -EACCES;
}
__u32 mode = (req->mode & (~0777)) | 0775;
if (mkdir(child_path, mode) < 0) {
return -errno;
}
/* When creating /Android/data and /Android/obb, mark them as .nomedia */
if (parent_node->perm == PERM_ANDROID && !strcasecmp(name, "data")) {
char nomedia[PATH_MAX];
snprintf(nomedia, PATH_MAX, "%s/.nomedia", child_path);
if (touch(nomedia, 0664) != 0) {
ERROR("Failed to touch(%s): %s\n", nomedia, strerror(errno));
return -ENOENT;
}
}
if (parent_node->perm == PERM_ANDROID && !strcasecmp(name, "obb")) {
char nomedia[PATH_MAX];
snprintf(nomedia, PATH_MAX, "%s/.nomedia", fuse->obbpath);
if (touch(nomedia, 0664) != 0) {
ERROR("Failed to touch(%s): %s\n", nomedia, strerror(errno));
return -ENOENT;
}
}
return fuse_reply_entry(fuse, hdr->unique, parent_node, name, actual_name, child_path);
}
static int handle_unlink(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const char* name)
{
bool has_rw;
struct node* parent_node;
char parent_path[PATH_MAX];
char child_path[PATH_MAX];
pthread_mutex_lock(&fuse->lock);
has_rw = get_caller_has_rw_locked(fuse, hdr);
parent_node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid,
parent_path, sizeof(parent_path));
TRACE("[%d] UNLINK %s @ %llx (%s)\n", handler->token,
name, hdr->nodeid, parent_node ? parent_node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!parent_node || !find_file_within(parent_path, name,
child_path, sizeof(child_path), 1)) {
return -ENOENT;
}
if (!check_caller_access_to_name(fuse, hdr, parent_node, name, W_OK, has_rw)) {
return -EACCES;
}
if (unlink(child_path) < 0) {
return -errno;
}
return 0;
}
static int handle_rmdir(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const char* name)
{
bool has_rw;
struct node* parent_node;
char parent_path[PATH_MAX];
char child_path[PATH_MAX];
pthread_mutex_lock(&fuse->lock);
has_rw = get_caller_has_rw_locked(fuse, hdr);
parent_node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid,
parent_path, sizeof(parent_path));
TRACE("[%d] RMDIR %s @ %llx (%s)\n", handler->token,
name, hdr->nodeid, parent_node ? parent_node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!parent_node || !find_file_within(parent_path, name,
child_path, sizeof(child_path), 1)) {
return -ENOENT;
}
if (!check_caller_access_to_name(fuse, hdr, parent_node, name, W_OK, has_rw)) {
return -EACCES;
}
if (rmdir(child_path) < 0) {
return -errno;
}
return 0;
}
static int handle_rename(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_rename_in* req,
const char* old_name, const char* new_name)
{
bool has_rw;
struct node* old_parent_node;
struct node* new_parent_node;
struct node* child_node;
char old_parent_path[PATH_MAX];
char new_parent_path[PATH_MAX];
char old_child_path[PATH_MAX];
char new_child_path[PATH_MAX];
const char* new_actual_name;
int res;
pthread_mutex_lock(&fuse->lock);
has_rw = get_caller_has_rw_locked(fuse, hdr);
old_parent_node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid,
old_parent_path, sizeof(old_parent_path));
new_parent_node = lookup_node_and_path_by_id_locked(fuse, req->newdir,
new_parent_path, sizeof(new_parent_path));
TRACE("[%d] RENAME %s->%s @ %llx (%s) -> %llx (%s)\n", handler->token,
old_name, new_name,
hdr->nodeid, old_parent_node ? old_parent_node->name : "?",
req->newdir, new_parent_node ? new_parent_node->name : "?");
if (!old_parent_node || !new_parent_node) {
res = -ENOENT;
goto lookup_error;
}
if (!check_caller_access_to_name(fuse, hdr, old_parent_node, old_name, W_OK, has_rw)) {
res = -EACCES;
goto lookup_error;
}
if (!check_caller_access_to_name(fuse, hdr, new_parent_node, new_name, W_OK, has_rw)) {
res = -EACCES;
goto lookup_error;
}
child_node = lookup_child_by_name_locked(old_parent_node, old_name);
if (!child_node || get_node_path_locked(child_node,
old_child_path, sizeof(old_child_path)) < 0) {
res = -ENOENT;
goto lookup_error;
}
acquire_node_locked(child_node);
pthread_mutex_unlock(&fuse->lock);
/* Special case for renaming a file where destination is same path
* differing only by case. In this case we don't want to look for a case
* insensitive match. This allows commands like "mv foo FOO" to work as expected.
*/
int search = old_parent_node != new_parent_node
|| strcasecmp(old_name, new_name);
if (!(new_actual_name = find_file_within(new_parent_path, new_name,
new_child_path, sizeof(new_child_path), search))) {
res = -ENOENT;
goto io_error;
}
TRACE("[%d] RENAME %s->%s\n", handler->token, old_child_path, new_child_path);
res = rename(old_child_path, new_child_path);
if (res < 0) {
res = -errno;
goto io_error;
}
pthread_mutex_lock(&fuse->lock);
res = rename_node_locked(child_node, new_name, new_actual_name);
if (!res) {
remove_node_from_parent_locked(child_node);
add_node_to_parent_locked(child_node, new_parent_node);
}
goto done;
io_error:
pthread_mutex_lock(&fuse->lock);
done:
release_node_locked(child_node);
lookup_error:
pthread_mutex_unlock(&fuse->lock);
return res;
}
static int open_flags_to_access_mode(int open_flags) {
if ((open_flags & O_ACCMODE) == O_RDONLY) {
return R_OK;
} else if ((open_flags & O_ACCMODE) == O_WRONLY) {
return W_OK;
} else {
/* Probably O_RDRW, but treat as default to be safe */
return R_OK | W_OK;
}
}
static int handle_open(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_open_in* req)
{
bool has_rw;
struct node* node;
char path[PATH_MAX];
struct fuse_open_out out;
struct handle *h;
pthread_mutex_lock(&fuse->lock);
has_rw = get_caller_has_rw_locked(fuse, hdr);
node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid, path, sizeof(path));
TRACE("[%d] OPEN 0%o @ %llx (%s)\n", handler->token,
req->flags, hdr->nodeid, node ? node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!node) {
return -ENOENT;
}
if (!check_caller_access_to_node(fuse, hdr, node,
open_flags_to_access_mode(req->flags), has_rw)) {
return -EACCES;
}
h = malloc(sizeof(*h));
if (!h) {
return -ENOMEM;
}
TRACE("[%d] OPEN %s\n", handler->token, path);
h->fd = open(path, req->flags);
if (h->fd < 0) {
free(h);
return -errno;
}
out.fh = ptr_to_id(h);
out.open_flags = 0;
out.padding = 0;
fuse_reply(fuse, hdr->unique, &out, sizeof(out));
return NO_STATUS;
}
static int handle_read(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_read_in* req)
{
struct handle *h = id_to_ptr(req->fh);
__u64 unique = hdr->unique;
__u32 size = req->size;
__u64 offset = req->offset;
int res;
/* Don't access any other fields of hdr or req beyond this point, the read buffer
* overlaps the request buffer and will clobber data in the request. This
* saves us 128KB per request handler thread at the cost of this scary comment. */
TRACE("[%d] READ %p(%d) %u@%llu\n", handler->token,
h, h->fd, size, offset);
if (size > sizeof(handler->read_buffer)) {
return -EINVAL;
}
res = pread64(h->fd, handler->read_buffer, size, offset);
if (res < 0) {
return -errno;
}
fuse_reply(fuse, unique, handler->read_buffer, res);
return NO_STATUS;
}
static int handle_write(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_write_in* req,
const void* buffer)
{
struct fuse_write_out out;
struct handle *h = id_to_ptr(req->fh);
int res;
TRACE("[%d] WRITE %p(%d) %u@%llu\n", handler->token,
h, h->fd, req->size, req->offset);
res = pwrite64(h->fd, buffer, req->size, req->offset);
if (res < 0) {
return -errno;
}
out.size = res;
fuse_reply(fuse, hdr->unique, &out, sizeof(out));
return NO_STATUS;
}
static int handle_statfs(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr)
{
char path[PATH_MAX];
struct statfs stat;
struct fuse_statfs_out out;
int res;
pthread_mutex_lock(&fuse->lock);
TRACE("[%d] STATFS\n", handler->token);
res = get_node_path_locked(&fuse->root, path, sizeof(path));
pthread_mutex_unlock(&fuse->lock);
if (res < 0) {
return -ENOENT;
}
if (statfs(fuse->root.name, &stat) < 0) {
return -errno;
}
memset(&out, 0, sizeof(out));
out.st.blocks = stat.f_blocks;
out.st.bfree = stat.f_bfree;
out.st.bavail = stat.f_bavail;
out.st.files = stat.f_files;
out.st.ffree = stat.f_ffree;
out.st.bsize = stat.f_bsize;
out.st.namelen = stat.f_namelen;
out.st.frsize = stat.f_frsize;
fuse_reply(fuse, hdr->unique, &out, sizeof(out));
return NO_STATUS;
}
static int handle_release(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_release_in* req)
{
struct handle *h = id_to_ptr(req->fh);
TRACE("[%d] RELEASE %p(%d)\n", handler->token, h, h->fd);
close(h->fd);
free(h);
return 0;
}
static int handle_fsync(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_fsync_in* req)
{
int is_data_sync = req->fsync_flags & 1;
struct handle *h = id_to_ptr(req->fh);
int res;
TRACE("[%d] FSYNC %p(%d) is_data_sync=%d\n", handler->token,
h, h->fd, is_data_sync);
res = is_data_sync ? fdatasync(h->fd) : fsync(h->fd);
if (res < 0) {
return -errno;
}
return 0;
}
static int handle_flush(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr)
{
TRACE("[%d] FLUSH\n", handler->token);
return 0;
}
static int handle_opendir(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_open_in* req)
{
struct node* node;
char path[PATH_MAX];
struct fuse_open_out out;
struct dirhandle *h;
pthread_mutex_lock(&fuse->lock);
node = lookup_node_and_path_by_id_locked(fuse, hdr->nodeid, path, sizeof(path));
TRACE("[%d] OPENDIR @ %llx (%s)\n", handler->token,
hdr->nodeid, node ? node->name : "?");
pthread_mutex_unlock(&fuse->lock);
if (!node) {
return -ENOENT;
}
if (!check_caller_access_to_node(fuse, hdr, node, R_OK, false)) {
return -EACCES;
}
h = malloc(sizeof(*h));
if (!h) {
return -ENOMEM;
}
TRACE("[%d] OPENDIR %s\n", handler->token, path);
h->d = opendir(path);
if (!h->d) {
free(h);
return -errno;
}
out.fh = ptr_to_id(h);
out.open_flags = 0;
out.padding = 0;
fuse_reply(fuse, hdr->unique, &out, sizeof(out));
return NO_STATUS;
}
static int handle_readdir(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_read_in* req)
{
char buffer[8192];
struct fuse_dirent *fde = (struct fuse_dirent*) buffer;
struct dirent *de;
struct dirhandle *h = id_to_ptr(req->fh);
TRACE("[%d] READDIR %p\n", handler->token, h);
if (req->offset == 0) {
/* rewinddir() might have been called above us, so rewind here too */
TRACE("[%d] calling rewinddir()\n", handler->token);
rewinddir(h->d);
}
de = readdir(h->d);
if (!de) {
return 0;
}
fde->ino = FUSE_UNKNOWN_INO;
/* increment the offset so we can detect when rewinddir() seeks back to the beginning */
fde->off = req->offset + 1;
fde->type = de->d_type;
fde->namelen = strlen(de->d_name);
memcpy(fde->name, de->d_name, fde->namelen + 1);
fuse_reply(fuse, hdr->unique, fde,
FUSE_DIRENT_ALIGN(sizeof(struct fuse_dirent) + fde->namelen));
return NO_STATUS;
}
static int handle_releasedir(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_release_in* req)
{
struct dirhandle *h = id_to_ptr(req->fh);
TRACE("[%d] RELEASEDIR %p\n", handler->token, h);
closedir(h->d);
free(h);
return 0;
}
static int handle_init(struct fuse* fuse, struct fuse_handler* handler,
const struct fuse_in_header* hdr, const struct fuse_init_in* req)
{
struct fuse_init_out out;
TRACE("[%d] INIT ver=%d.%d maxread=%d flags=%x\n",
handler->token, req->major, req->minor, req->max_readahead, req->flags);
out.major = FUSE_KERNEL_VERSION;
out.minor = FUSE_KERNEL_MINOR_VERSION;
out.max_readahead = req->max_readahead;
out.flags = FUSE_ATOMIC_O_TRUNC | FUSE_BIG_WRITES;
out.max_background = 32;
out.congestion_threshold = 32;
out.max_write = MAX_WRITE;
fuse_reply(fuse, hdr->unique, &out, sizeof(out));
return NO_STATUS;
}
static int handle_fuse_request(struct fuse *fuse, struct fuse_handler* handler,
const struct fuse_in_header *hdr, const void *data, size_t data_len)
{
switch (hdr->opcode) {
case FUSE_LOOKUP: { /* bytez[] -> entry_out */
const char* name = data;
return handle_lookup(fuse, handler, hdr, name);
}
case FUSE_FORGET: {
const struct fuse_forget_in *req = data;
return handle_forget(fuse, handler, hdr, req);
}
case FUSE_GETATTR: { /* getattr_in -> attr_out */
const struct fuse_getattr_in *req = data;
return handle_getattr(fuse, handler, hdr, req);
}
case FUSE_SETATTR: { /* setattr_in -> attr_out */
const struct fuse_setattr_in *req = data;
return handle_setattr(fuse, handler, hdr, req);
}
// case FUSE_READLINK:
// case FUSE_SYMLINK:
case FUSE_MKNOD: { /* mknod_in, bytez[] -> entry_out */
const struct fuse_mknod_in *req = data;
const char *name = ((const char*) data) + sizeof(*req);
return handle_mknod(fuse, handler, hdr, req, name);
}
case FUSE_MKDIR: { /* mkdir_in, bytez[] -> entry_out */
const struct fuse_mkdir_in *req = data;
const char *name = ((const char*) data) + sizeof(*req);
return handle_mkdir(fuse, handler, hdr, req, name);
}
case FUSE_UNLINK: { /* bytez[] -> */
const char* name = data;
return handle_unlink(fuse, handler, hdr, name);
}
case FUSE_RMDIR: { /* bytez[] -> */
const char* name = data;
return handle_rmdir(fuse, handler, hdr, name);
}
case FUSE_RENAME: { /* rename_in, oldname, newname -> */
const struct fuse_rename_in *req = data;
const char *old_name = ((const char*) data) + sizeof(*req);
const char *new_name = old_name + strlen(old_name) + 1;
return handle_rename(fuse, handler, hdr, req, old_name, new_name);
}
// case FUSE_LINK:
case FUSE_OPEN: { /* open_in -> open_out */
const struct fuse_open_in *req = data;
return handle_open(fuse, handler, hdr, req);
}
case FUSE_READ: { /* read_in -> byte[] */
const struct fuse_read_in *req = data;
return handle_read(fuse, handler, hdr, req);
}
case FUSE_WRITE: { /* write_in, byte[write_in.size] -> write_out */
const struct fuse_write_in *req = data;
const void* buffer = (const __u8*)data + sizeof(*req);
return handle_write(fuse, handler, hdr, req, buffer);
}
case FUSE_STATFS: { /* getattr_in -> attr_out */
return handle_statfs(fuse, handler, hdr);
}
case FUSE_RELEASE: { /* release_in -> */
const struct fuse_release_in *req = data;
return handle_release(fuse, handler, hdr, req);
}
case FUSE_FSYNC: {
const struct fuse_fsync_in *req = data;
return handle_fsync(fuse, handler, hdr, req);
}
// case FUSE_SETXATTR:
// case FUSE_GETXATTR:
// case FUSE_LISTXATTR:
// case FUSE_REMOVEXATTR:
case FUSE_FLUSH: {
return handle_flush(fuse, handler, hdr);
}
case FUSE_OPENDIR: { /* open_in -> open_out */
const struct fuse_open_in *req = data;
return handle_opendir(fuse, handler, hdr, req);
}
case FUSE_READDIR: {
const struct fuse_read_in *req = data;
return handle_readdir(fuse, handler, hdr, req);
}
case FUSE_RELEASEDIR: { /* release_in -> */
const struct fuse_release_in *req = data;
return handle_releasedir(fuse, handler, hdr, req);
}
// case FUSE_FSYNCDIR:
case FUSE_INIT: { /* init_in -> init_out */
const struct fuse_init_in *req = data;
return handle_init(fuse, handler, hdr, req);
}
default: {
TRACE("[%d] NOTIMPL op=%d uniq=%llx nid=%llx\n",
handler->token, hdr->opcode, hdr->unique, hdr->nodeid);
return -ENOSYS;
}
}
}
static void handle_fuse_requests(struct fuse_handler* handler)
{
struct fuse* fuse = handler->fuse;
for (;;) {
ssize_t len = read(fuse->fd,
handler->request_buffer, sizeof(handler->request_buffer));
if (len < 0) {
if (errno != EINTR) {
ERROR("[%d] handle_fuse_requests: errno=%d\n", handler->token, errno);
}
continue;
}
if ((size_t)len < sizeof(struct fuse_in_header)) {
ERROR("[%d] request too short: len=%zu\n", handler->token, (size_t)len);
continue;
}
const struct fuse_in_header *hdr = (void*)handler->request_buffer;
if (hdr->len != (size_t)len) {
ERROR("[%d] malformed header: len=%zu, hdr->len=%u\n",
handler->token, (size_t)len, hdr->len);
continue;
}
const void *data = handler->request_buffer + sizeof(struct fuse_in_header);
size_t data_len = len - sizeof(struct fuse_in_header);
__u64 unique = hdr->unique;
int res = handle_fuse_request(fuse, handler, hdr, data, data_len);
/* We do not access the request again after this point because the underlying
* buffer storage may have been reused while processing the request. */
if (res != NO_STATUS) {
if (res) {
TRACE("[%d] ERROR %d\n", handler->token, res);
}
fuse_status(fuse, unique, res);
}
}
}
static void* start_handler(void* data)
{
struct fuse_handler* handler = data;
handle_fuse_requests(handler);
return NULL;
}
static bool remove_str_to_int(void *key, void *value, void *context) {
Hashmap* map = context;
hashmapRemove(map, key);
free(key);
return true;
}
static bool remove_int_to_null(void *key, void *value, void *context) {
Hashmap* map = context;
hashmapRemove(map, key);
return true;
}
static int read_package_list(struct fuse *fuse) {
pthread_mutex_lock(&fuse->lock);
hashmapForEach(fuse->package_to_appid, remove_str_to_int, fuse->package_to_appid);
hashmapForEach(fuse->appid_with_rw, remove_int_to_null, fuse->appid_with_rw);
FILE* file = fopen(kPackagesListFile, "r");
if (!file) {
ERROR("failed to open package list: %s\n", strerror(errno));
pthread_mutex_unlock(&fuse->lock);
return -1;
}
char buf[512];
while (fgets(buf, sizeof(buf), file) != NULL) {
char package_name[512];
int appid;
char gids[512];
if (sscanf(buf, "%s %d %*d %*s %*s %s", package_name, &appid, gids) == 3) {
char* package_name_dup = strdup(package_name);
hashmapPut(fuse->package_to_appid, package_name_dup, (void*) (uintptr_t) appid);
char* token = strtok(gids, ",");
while (token != NULL) {
if (strtoul(token, NULL, 10) == fuse->write_gid) {
hashmapPut(fuse->appid_with_rw, (void*) (uintptr_t) appid, (void*) (uintptr_t) 1);
break;
}
token = strtok(NULL, ",");
}
}
}
TRACE("read_package_list: found %d packages, %d with write_gid\n",
hashmapSize(fuse->package_to_appid),
hashmapSize(fuse->appid_with_rw));
fclose(file);
pthread_mutex_unlock(&fuse->lock);
return 0;
}
static void watch_package_list(struct fuse* fuse) {
struct inotify_event *event;
char event_buf[512];
int nfd = inotify_init();
if (nfd < 0) {
ERROR("inotify_init failed: %s\n", strerror(errno));
return;
}
bool active = false;
while (1) {
if (!active) {
int res = inotify_add_watch(nfd, kPackagesListFile, IN_DELETE_SELF);
if (res == -1) {
if (errno == ENOENT || errno == EACCES) {
/* Framework may not have created yet, sleep and retry */
ERROR("missing packages.list; retrying\n");
sleep(3);
continue;
} else {
ERROR("inotify_add_watch failed: %s\n", strerror(errno));
return;
}
}
/* Watch above will tell us about any future changes, so
* read the current state. */
if (read_package_list(fuse) == -1) {
ERROR("read_package_list failed: %s\n", strerror(errno));
return;
}
active = true;
}
int event_pos = 0;
int res = read(nfd, event_buf, sizeof(event_buf));
if (res < (int) sizeof(*event)) {
if (errno == EINTR)
continue;
ERROR("failed to read inotify event: %s\n", strerror(errno));
return;
}
while (res >= (int) sizeof(*event)) {
int event_size;
event = (struct inotify_event *) (event_buf + event_pos);
TRACE("inotify event: %08x\n", event->mask);
if ((event->mask & IN_IGNORED) == IN_IGNORED) {
/* Previously watched file was deleted, probably due to move
* that swapped in new data; re-arm the watch and read. */
active = false;
}
event_size = sizeof(*event) + event->len;
res -= event_size;
event_pos += event_size;
}
}
}
static int ignite_fuse(struct fuse* fuse, int num_threads)
{
struct fuse_handler* handlers;
int i;
handlers = malloc(num_threads * sizeof(struct fuse_handler));
if (!handlers) {
ERROR("cannot allocate storage for threads\n");
return -ENOMEM;
}
for (i = 0; i < num_threads; i++) {
handlers[i].fuse = fuse;
handlers[i].token = i;
}
/* When deriving permissions, this thread is used to process inotify events,
* otherwise it becomes one of the FUSE handlers. */
i = (fuse->derive == DERIVE_NONE) ? 1 : 0;
for (; i < num_threads; i++) {
pthread_t thread;
int res = pthread_create(&thread, NULL, start_handler, &handlers[i]);
if (res) {
ERROR("failed to start thread #%d, error=%d\n", i, res);
goto quit;
}
}
if (fuse->derive == DERIVE_NONE) {
handle_fuse_requests(&handlers[0]);
} else {
watch_package_list(fuse);
}
ERROR("terminated prematurely\n");
/* don't bother killing all of the other threads or freeing anything,
* should never get here anyhow */
quit:
exit(1);
}
static int usage()
{
ERROR("usage: sdcard [OPTIONS] <source_path> <dest_path>\n"
" -u: specify UID to run as\n"
" -g: specify GID to run as\n"
" -w: specify GID required to write (default sdcard_rw, requires -d or -l)\n"
" -t: specify number of threads to use (default %d)\n"
" -d: derive file permissions based on path\n"
" -l: derive file permissions based on legacy internal layout\n"
" -s: split derived permissions for pics, av\n"
"\n", DEFAULT_NUM_THREADS);
return 1;
}
static int run(const char* source_path, const char* dest_path, uid_t uid,
gid_t gid, gid_t write_gid, int num_threads, derive_t derive,
bool split_perms) {
int fd;
char opts[256];
int res;
struct fuse fuse;
/* cleanup from previous instance, if necessary */
umount2(dest_path, 2);
fd = open("/dev/fuse", O_RDWR);
if (fd < 0){
ERROR("cannot open fuse device: %s\n", strerror(errno));
return -1;
}
snprintf(opts, sizeof(opts),
"fd=%i,rootmode=40000,default_permissions,allow_other,user_id=%d,group_id=%d",
fd, uid, gid);
res = mount("/dev/fuse", dest_path, "fuse", MS_NOSUID | MS_NODEV, opts);
if (res < 0) {
ERROR("cannot mount fuse filesystem: %s\n", strerror(errno));
goto error;
}
res = setgroups(sizeof(kGroups) / sizeof(kGroups[0]), kGroups);
if (res < 0) {
ERROR("cannot setgroups: %s\n", strerror(errno));
goto error;
}
res = setgid(gid);
if (res < 0) {
ERROR("cannot setgid: %s\n", strerror(errno));
goto error;
}
res = setuid(uid);
if (res < 0) {
ERROR("cannot setuid: %s\n", strerror(errno));
goto error;
}
fuse_init(&fuse, fd, source_path, write_gid, derive, split_perms);
umask(0);
res = ignite_fuse(&fuse, num_threads);
/* we do not attempt to umount the file system here because we are no longer
* running as the root user */
error:
close(fd);
return res;
}
int main(int argc, char **argv)
{
int res;
const char *source_path = NULL;
const char *dest_path = NULL;
uid_t uid = 0;
gid_t gid = 0;
gid_t write_gid = AID_SDCARD_RW;
int num_threads = DEFAULT_NUM_THREADS;
derive_t derive = DERIVE_NONE;
bool split_perms = false;
int i;
struct rlimit rlim;
int opt;
while ((opt = getopt(argc, argv, "u:g:w:t:dls")) != -1) {
switch (opt) {
case 'u':
uid = strtoul(optarg, NULL, 10);
break;
case 'g':
gid = strtoul(optarg, NULL, 10);
break;
case 'w':
write_gid = strtoul(optarg, NULL, 10);
break;
case 't':
num_threads = strtoul(optarg, NULL, 10);
break;
case 'd':
derive = DERIVE_UNIFIED;
break;
case 'l':
derive = DERIVE_LEGACY;
break;
case 's':
split_perms = true;
break;
case '?':
default:
return usage();
}
}
for (i = optind; i < argc; i++) {
char* arg = argv[i];
if (!source_path) {
source_path = arg;
} else if (!dest_path) {
dest_path = arg;
} else if (!uid) {
uid = strtoul(arg, NULL, 10);
} else if (!gid) {
gid = strtoul(arg, NULL, 10);
} else {
ERROR("too many arguments\n");
return usage();
}
}
if (!source_path) {
ERROR("no source path specified\n");
return usage();
}
if (!dest_path) {
ERROR("no dest path specified\n");
return usage();
}
if (!uid || !gid) {
ERROR("uid and gid must be nonzero\n");
return usage();
}
if (num_threads < 1) {
ERROR("number of threads must be at least 1\n");
return usage();
}
if (split_perms && derive == DERIVE_NONE) {
ERROR("cannot split permissions without deriving\n");
return usage();
}
rlim.rlim_cur = 8192;
rlim.rlim_max = 8192;
if (setrlimit(RLIMIT_NOFILE, &rlim)) {
ERROR("Error setting RLIMIT_NOFILE, errno = %d\n", errno);
}
res = run(source_path, dest_path, uid, gid, write_gid, num_threads, derive, split_perms);
return res < 0 ? 1 : 0;
}
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