diff options
Diffstat (limited to 'fuse_sideload.c')
| -rw-r--r-- | fuse_sideload.c | 527 |
1 files changed, 0 insertions, 527 deletions
diff --git a/fuse_sideload.c b/fuse_sideload.c deleted file mode 100644 index 48e6cc53a..000000000 --- a/fuse_sideload.c +++ /dev/null @@ -1,527 +0,0 @@ -/* - * Copyright (C) 2014 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. - */ - -// This module creates a special filesystem containing two files. -// -// "/sideload/package.zip" appears to be a normal file, but reading -// from it causes data to be fetched from the adb host. We can use -// this to sideload packages over an adb connection without having to -// store the entire package in RAM on the device. -// -// Because we may not trust the adb host, this filesystem maintains -// the following invariant: each read of a given position returns the -// same data as the first read at that position. That is, once a -// section of the file is read, future reads of that section return -// the same data. (Otherwise, a malicious adb host process could -// return one set of bits when the package is read for signature -// verification, and then different bits for when the package is -// accessed by the installer.) If the adb host returns something -// different than it did on the first read, the reader of the file -// will see their read fail with EINVAL. -// -// The other file, "/sideload/exit", is used to control the subprocess -// that creates this filesystem. Calling stat() on the exit file -// causes the filesystem to be unmounted and the adb process on the -// device shut down. -// -// Note that only the minimal set of file operations needed for these -// two files is implemented. In particular, you can't opendir() or -// readdir() on the "/sideload" directory; ls on it won't work. - -#include <ctype.h> -#include <dirent.h> -#include <errno.h> -#include <fcntl.h> -#include <limits.h> -#include <linux/fuse.h> -#include <pthread.h> -#include <stdio.h> -#include <stdlib.h> -#include <string.h> -#include <sys/inotify.h> -#include <sys/mount.h> -#include <sys/param.h> -#include <sys/resource.h> -#include <sys/stat.h> -#include <sys/statfs.h> -#include <sys/time.h> -#include <sys/uio.h> -#include <unistd.h> - -#include "mincrypt/sha256.h" -#include "fuse_sideload.h" - -#define PACKAGE_FILE_ID (FUSE_ROOT_ID+1) -#define EXIT_FLAG_ID (FUSE_ROOT_ID+2) - -#define NO_STATUS 1 -#define NO_STATUS_EXIT 2 - -struct fuse_data { - int ffd; // file descriptor for the fuse socket - - struct provider_vtab* vtab; - void* cookie; - - uint64_t file_size; // bytes - - uint32_t block_size; // block size that the adb host is using to send the file to us - uint32_t file_blocks; // file size in block_size blocks - - uid_t uid; - gid_t gid; - - uint32_t curr_block; // cache the block most recently read from the host - uint8_t* block_data; - - uint8_t* extra_block; // another block of storage for reads that - // span two blocks - - uint8_t* hashes; // SHA-256 hash of each block (all zeros - // if block hasn't been read yet) -}; - -static void fuse_reply(struct fuse_data* fd, __u64 unique, const void *data, size_t 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 = /* const_cast */(void*)(data); - vec[1].iov_len = len; - - res = writev(fd->ffd, vec, 2); - if (res < 0) { - printf("*** REPLY FAILED *** %s\n", strerror(errno)); - } -} - -static int handle_init(void* data, struct fuse_data* fd, const struct fuse_in_header* hdr) { - const struct fuse_init_in* req = data; - struct fuse_init_out out; - size_t fuse_struct_size; - - - /* Kernel 2.6.16 is the first stable kernel with struct fuse_init_out - * defined (fuse version 7.6). The structure is the same from 7.6 through - * 7.22. Beginning with 7.23, the structure increased in size and added - * new parameters. - */ - if (req->major != FUSE_KERNEL_VERSION || req->minor < 6) { - printf("Fuse kernel version mismatch: Kernel version %d.%d, Expected at least %d.6", - req->major, req->minor, FUSE_KERNEL_VERSION); - return -1; - } - - out.minor = MIN(req->minor, FUSE_KERNEL_MINOR_VERSION); - fuse_struct_size = sizeof(out); -#if defined(FUSE_COMPAT_22_INIT_OUT_SIZE) - /* FUSE_KERNEL_VERSION >= 23. */ - - /* If the kernel only works on minor revs older than or equal to 22, - * then use the older structure size since this code only uses the 7.22 - * version of the structure. */ - if (req->minor <= 22) { - fuse_struct_size = FUSE_COMPAT_22_INIT_OUT_SIZE; - } -#endif - - out.major = FUSE_KERNEL_VERSION; - out.max_readahead = req->max_readahead; - out.flags = 0; - out.max_background = 32; - out.congestion_threshold = 32; - out.max_write = 4096; - fuse_reply(fd, hdr->unique, &out, fuse_struct_size); - - return NO_STATUS; -} - -static void fill_attr(struct fuse_attr* attr, struct fuse_data* fd, - uint64_t nodeid, uint64_t size, uint32_t mode) { - memset(attr, 0, sizeof(*attr)); - attr->nlink = 1; - attr->uid = fd->uid; - attr->gid = fd->gid; - attr->blksize = 4096; - - attr->ino = nodeid; - attr->size = size; - attr->blocks = (size == 0) ? 0 : (((size-1) / attr->blksize) + 1); - attr->mode = mode; -} - -static int handle_getattr(void* data, struct fuse_data* fd, const struct fuse_in_header* hdr) { - const struct fuse_getattr_in* req = data; - struct fuse_attr_out out; - memset(&out, 0, sizeof(out)); - out.attr_valid = 10; - - if (hdr->nodeid == FUSE_ROOT_ID) { - fill_attr(&(out.attr), fd, hdr->nodeid, 4096, S_IFDIR | 0555); - } else if (hdr->nodeid == PACKAGE_FILE_ID) { - fill_attr(&(out.attr), fd, PACKAGE_FILE_ID, fd->file_size, S_IFREG | 0444); - } else if (hdr->nodeid == EXIT_FLAG_ID) { - fill_attr(&(out.attr), fd, EXIT_FLAG_ID, 0, S_IFREG | 0); - } else { - return -ENOENT; - } - - fuse_reply(fd, hdr->unique, &out, sizeof(out)); - return (hdr->nodeid == EXIT_FLAG_ID) ? NO_STATUS_EXIT : NO_STATUS; -} - -static int handle_lookup(void* data, struct fuse_data* fd, - const struct fuse_in_header* hdr) { - struct fuse_entry_out out; - memset(&out, 0, sizeof(out)); - out.entry_valid = 10; - out.attr_valid = 10; - - if (strncmp(FUSE_SIDELOAD_HOST_FILENAME, data, - sizeof(FUSE_SIDELOAD_HOST_FILENAME)) == 0) { - out.nodeid = PACKAGE_FILE_ID; - out.generation = PACKAGE_FILE_ID; - fill_attr(&(out.attr), fd, PACKAGE_FILE_ID, fd->file_size, S_IFREG | 0444); - } else if (strncmp(FUSE_SIDELOAD_HOST_EXIT_FLAG, data, - sizeof(FUSE_SIDELOAD_HOST_EXIT_FLAG)) == 0) { - out.nodeid = EXIT_FLAG_ID; - out.generation = EXIT_FLAG_ID; - fill_attr(&(out.attr), fd, EXIT_FLAG_ID, 0, S_IFREG | 0); - } else { - return -ENOENT; - } - - fuse_reply(fd, hdr->unique, &out, sizeof(out)); - return (out.nodeid == EXIT_FLAG_ID) ? NO_STATUS_EXIT : NO_STATUS; -} - -static int handle_open(void* data, struct fuse_data* fd, const struct fuse_in_header* hdr) { - const struct fuse_open_in* req = data; - - if (hdr->nodeid == EXIT_FLAG_ID) return -EPERM; - if (hdr->nodeid != PACKAGE_FILE_ID) return -ENOENT; - - struct fuse_open_out out; - memset(&out, 0, sizeof(out)); - out.fh = 10; // an arbitrary number; we always use the same handle - fuse_reply(fd, hdr->unique, &out, sizeof(out)); - return NO_STATUS; -} - -static int handle_flush(void* data, struct fuse_data* fd, const struct fuse_in_header* hdr) { - return 0; -} - -static int handle_release(void* data, struct fuse_data* fd, const struct fuse_in_header* hdr) { - return 0; -} - -// Fetch a block from the host into fd->curr_block and fd->block_data. -// Returns 0 on successful fetch, negative otherwise. -static int fetch_block(struct fuse_data* fd, uint32_t block) { - if (block == fd->curr_block) { - return 0; - } - - if (block >= fd->file_blocks) { - memset(fd->block_data, 0, fd->block_size); - fd->curr_block = block; - return 0; - } - - size_t fetch_size = fd->block_size; - if (block * fd->block_size + fetch_size > fd->file_size) { - // If we're reading the last (partial) block of the file, - // expect a shorter response from the host, and pad the rest - // of the block with zeroes. - fetch_size = fd->file_size - (block * fd->block_size); - memset(fd->block_data + fetch_size, 0, fd->block_size - fetch_size); - } - - int result = fd->vtab->read_block(fd->cookie, block, fd->block_data, fetch_size); - if (result < 0) return result; - - fd->curr_block = block; - - // Verify the hash of the block we just got from the host. - // - // - If the hash of the just-received data matches the stored hash - // for the block, accept it. - // - If the stored hash is all zeroes, store the new hash and - // accept the block (this is the first time we've read this - // block). - // - Otherwise, return -EINVAL for the read. - - uint8_t hash[SHA256_DIGEST_SIZE]; - SHA256_hash(fd->block_data, fd->block_size, hash); - uint8_t* blockhash = fd->hashes + block * SHA256_DIGEST_SIZE; - if (memcmp(hash, blockhash, SHA256_DIGEST_SIZE) == 0) { - return 0; - } - - int i; - for (i = 0; i < SHA256_DIGEST_SIZE; ++i) { - if (blockhash[i] != 0) { - fd->curr_block = -1; - return -EIO; - } - } - - memcpy(blockhash, hash, SHA256_DIGEST_SIZE); - return 0; -} - -static int handle_read(void* data, struct fuse_data* fd, const struct fuse_in_header* hdr) { - const struct fuse_read_in* req = data; - struct fuse_out_header outhdr; - struct iovec vec[3]; - int vec_used; - int result; - - if (hdr->nodeid != PACKAGE_FILE_ID) return -ENOENT; - - uint64_t offset = req->offset; - uint32_t size = req->size; - - // The docs on the fuse kernel interface are vague about what to - // do when a read request extends past the end of the file. We - // can return a short read -- the return structure does include a - // length field -- but in testing that caused the program using - // the file to segfault. (I speculate that this is due to the - // reading program accessing it via mmap; maybe mmap dislikes when - // you return something short of a whole page?) To fix this we - // zero-pad reads that extend past the end of the file so we're - // always returning exactly as many bytes as were requested. - // (Users of the mapped file have to know its real length anyway.) - - outhdr.len = sizeof(outhdr) + size; - outhdr.error = 0; - outhdr.unique = hdr->unique; - vec[0].iov_base = &outhdr; - vec[0].iov_len = sizeof(outhdr); - - uint32_t block = offset / fd->block_size; - result = fetch_block(fd, block); - if (result != 0) return result; - - // Two cases: - // - // - the read request is entirely within this block. In this - // case we can reply immediately. - // - // - the read request goes over into the next block. Note that - // since we mount the filesystem with max_read=block_size, a - // read can never span more than two blocks. In this case we - // copy the block to extra_block and issue a fetch for the - // following block. - - uint32_t block_offset = offset - (block * fd->block_size); - - if (size + block_offset <= fd->block_size) { - // First case: the read fits entirely in the first block. - - vec[1].iov_base = fd->block_data + block_offset; - vec[1].iov_len = size; - vec_used = 2; - } else { - // Second case: the read spills over into the next block. - - memcpy(fd->extra_block, fd->block_data + block_offset, - fd->block_size - block_offset); - vec[1].iov_base = fd->extra_block; - vec[1].iov_len = fd->block_size - block_offset; - - result = fetch_block(fd, block+1); - if (result != 0) return result; - vec[2].iov_base = fd->block_data; - vec[2].iov_len = size - vec[1].iov_len; - vec_used = 3; - } - - if (writev(fd->ffd, vec, vec_used) < 0) { - printf("*** READ REPLY FAILED: %s ***\n", strerror(errno)); - } - return NO_STATUS; -} - -int run_fuse_sideload(struct provider_vtab* vtab, void* cookie, - uint64_t file_size, uint32_t block_size) -{ - int result; - - // If something's already mounted on our mountpoint, try to remove - // it. (Mostly in case of a previous abnormal exit.) - umount2(FUSE_SIDELOAD_HOST_MOUNTPOINT, MNT_FORCE); - - if (block_size < 1024) { - fprintf(stderr, "block size (%u) is too small\n", block_size); - return -1; - } - if (block_size > (1<<22)) { // 4 MiB - fprintf(stderr, "block size (%u) is too large\n", block_size); - return -1; - } - - struct fuse_data fd; - memset(&fd, 0, sizeof(fd)); - fd.vtab = vtab; - fd.cookie = cookie; - fd.file_size = file_size; - fd.block_size = block_size; - fd.file_blocks = (file_size == 0) ? 0 : (((file_size-1) / block_size) + 1); - - if (fd.file_blocks > (1<<18)) { - fprintf(stderr, "file has too many blocks (%u)\n", fd.file_blocks); - result = -1; - goto done; - } - - fd.hashes = (uint8_t*)calloc(fd.file_blocks, SHA256_DIGEST_SIZE); - if (fd.hashes == NULL) { - fprintf(stderr, "failed to allocate %d bites for hashes\n", - fd.file_blocks * SHA256_DIGEST_SIZE); - result = -1; - goto done; - } - - fd.uid = getuid(); - fd.gid = getgid(); - - fd.curr_block = -1; - fd.block_data = (uint8_t*)malloc(block_size); - if (fd.block_data == NULL) { - fprintf(stderr, "failed to allocate %d bites for block_data\n", block_size); - result = -1; - goto done; - } - fd.extra_block = (uint8_t*)malloc(block_size); - if (fd.extra_block == NULL) { - fprintf(stderr, "failed to allocate %d bites for extra_block\n", block_size); - result = -1; - goto done; - } - - fd.ffd = open("/dev/fuse", O_RDWR); - if (fd.ffd < 0) { - perror("open /dev/fuse"); - result = -1; - goto done; - } - - char opts[256]; - snprintf(opts, sizeof(opts), - ("fd=%d,user_id=%d,group_id=%d,max_read=%u," - "allow_other,rootmode=040000"), - fd.ffd, fd.uid, fd.gid, block_size); - - result = mount("/dev/fuse", FUSE_SIDELOAD_HOST_MOUNTPOINT, - "fuse", MS_NOSUID | MS_NODEV | MS_RDONLY | MS_NOEXEC, opts); - if (result < 0) { - perror("mount"); - goto done; - } - uint8_t request_buffer[sizeof(struct fuse_in_header) + PATH_MAX*8]; - for (;;) { - ssize_t len = TEMP_FAILURE_RETRY(read(fd.ffd, request_buffer, sizeof(request_buffer))); - if (len == -1) { - perror("read request"); - if (errno == ENODEV) { - result = -1; - break; - } - continue; - } - - if ((size_t)len < sizeof(struct fuse_in_header)) { - fprintf(stderr, "request too short: len=%zu\n", (size_t)len); - continue; - } - - struct fuse_in_header* hdr = (struct fuse_in_header*) request_buffer; - void* data = request_buffer + sizeof(struct fuse_in_header); - - result = -ENOSYS; - - switch (hdr->opcode) { - case FUSE_INIT: - result = handle_init(data, &fd, hdr); - break; - - case FUSE_LOOKUP: - result = handle_lookup(data, &fd, hdr); - break; - - case FUSE_GETATTR: - result = handle_getattr(data, &fd, hdr); - break; - - case FUSE_OPEN: - result = handle_open(data, &fd, hdr); - break; - - case FUSE_READ: - result = handle_read(data, &fd, hdr); - break; - - case FUSE_FLUSH: - result = handle_flush(data, &fd, hdr); - break; - - case FUSE_RELEASE: - result = handle_release(data, &fd, hdr); - break; - - default: - fprintf(stderr, "unknown fuse request opcode %d\n", hdr->opcode); - break; - } - - if (result == NO_STATUS_EXIT) { - result = 0; - break; - } - - if (result != NO_STATUS) { - struct fuse_out_header outhdr; - outhdr.len = sizeof(outhdr); - outhdr.error = result; - outhdr.unique = hdr->unique; - TEMP_FAILURE_RETRY(write(fd.ffd, &outhdr, sizeof(outhdr))); - } - } - - done: - fd.vtab->close(fd.cookie); - - result = umount2(FUSE_SIDELOAD_HOST_MOUNTPOINT, MNT_DETACH); - if (result < 0) { - printf("fuse_sideload umount failed: %s\n", strerror(errno)); - } - - if (fd.ffd) close(fd.ffd); - free(fd.hashes); - free(fd.block_data); - free(fd.extra_block); - - return result; -} |