/* * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #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] \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; }