mirror of
https://github.com/google/sandboxed-api.git
synced 2024-03-22 13:11:30 +08:00
120 lines
3.7 KiB
C++
120 lines
3.7 KiB
C++
// Copyright 2019 Google LLC
|
|
//
|
|
// 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
|
|
//
|
|
// https://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 "sandboxed_api/embed_file.h"
|
|
|
|
#include <fcntl.h>
|
|
#include <sys/stat.h>
|
|
#include <sys/syscall.h>
|
|
#include <sys/types.h>
|
|
#include <unistd.h>
|
|
|
|
#include "sandboxed_api/file_toc.h"
|
|
#include "absl/strings/str_cat.h"
|
|
#include "absl/synchronization/mutex.h"
|
|
#include "sandboxed_api/sandbox2/util.h"
|
|
#include "sandboxed_api/util/fileops.h"
|
|
#include "sandboxed_api/util/raw_logging.h"
|
|
|
|
namespace sapi {
|
|
|
|
EmbedFile* EmbedFile::instance() {
|
|
static auto* embed_file_instance = new EmbedFile();
|
|
return embed_file_instance;
|
|
}
|
|
|
|
int EmbedFile::CreateFdForFileToc(const FileToc* toc) {
|
|
// Create a memfd/temp file and write contents of the SAPI library to it.
|
|
int fd = -1;
|
|
if (!sandbox2::util::CreateMemFd(&fd, toc->name)) {
|
|
SAPI_RAW_LOG(ERROR, "Couldn't create a temporary file for TOC name '%s'",
|
|
toc->name);
|
|
return -1;
|
|
}
|
|
file_util::fileops::FDCloser embed_fd(fd);
|
|
|
|
if (!file_util::fileops::WriteToFD(embed_fd.get(), toc->data, toc->size)) {
|
|
SAPI_RAW_PLOG(ERROR, "Couldn't write SAPI embed file '%s' to memfd file",
|
|
toc->name);
|
|
return -1;
|
|
}
|
|
|
|
// Make the underlying file non-writeable.
|
|
if (fchmod(embed_fd.get(),
|
|
S_IRUSR | S_IXUSR | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH) == -1) {
|
|
SAPI_RAW_PLOG(ERROR, "Could't make FD=%d RX-only", embed_fd.get());
|
|
return -1;
|
|
}
|
|
|
|
// Ideally, we'd seal the file here using fcntl(). However, in rare cases,
|
|
// adding the file seals F_SEAL_SEAL | F_SEAL_SHRINK | F_SEAL_GROW |
|
|
// F_SEAL_WRITE results in EBUSY errors.
|
|
// This is likely because of an interaction of SEAL_WRITE with pending writes
|
|
// to the mapped memory region (see memfd_wait_for_pins() in Linux'
|
|
// mm/memfd.c). Since fsync() is a no-op on memfds, it doesn't help to
|
|
// ameliorate the problem.
|
|
|
|
// Instead of working around problems with CRIU we reopen the file as
|
|
// read-only.
|
|
fd = open(absl::StrCat("/proc/", getpid(), "/fd/", embed_fd.get()).c_str(),
|
|
O_RDONLY | O_CLOEXEC);
|
|
if (fd == -1) {
|
|
SAPI_RAW_PLOG(ERROR, "Couldn't reopen '%d' read-only through /proc",
|
|
embed_fd.get());
|
|
return -1;
|
|
}
|
|
return fd;
|
|
}
|
|
|
|
int EmbedFile::GetFdForFileToc(const FileToc* toc) {
|
|
// Access to file_tocs_ must be guarded.
|
|
absl::MutexLock lock{&file_tocs_mutex_};
|
|
|
|
// If a file-descriptor for this toc already exists, just return it.
|
|
auto entry = file_tocs_.find(toc);
|
|
if (entry != file_tocs_.end()) {
|
|
SAPI_RAW_VLOG(3,
|
|
"Returning pre-existing embed file entry for '%s', fd: %d "
|
|
"(orig name: '%s')",
|
|
toc->name, entry->second, entry->first->name);
|
|
return entry->second;
|
|
}
|
|
|
|
int embed_fd = CreateFdForFileToc(toc);
|
|
if (embed_fd == -1) {
|
|
SAPI_RAW_LOG(ERROR, "Cannot create a file for FileTOC: '%s'", toc->name);
|
|
return -1;
|
|
}
|
|
|
|
SAPI_RAW_VLOG(1, "Created new embed file entry for '%s' with fd: %d",
|
|
toc->name, embed_fd);
|
|
|
|
file_tocs_[toc] = embed_fd;
|
|
return embed_fd;
|
|
}
|
|
|
|
int EmbedFile::GetDupFdForFileToc(const FileToc* toc) {
|
|
int fd = GetFdForFileToc(toc);
|
|
if (fd == -1) {
|
|
return -1;
|
|
}
|
|
fd = dup(fd);
|
|
if (fd == -1) {
|
|
SAPI_RAW_PLOG(ERROR, "dup failed");
|
|
}
|
|
return fd;
|
|
}
|
|
|
|
} // namespace sapi
|