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// Copyright (c) 2010 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "debug.h"
#include "sandbox_impl.h"
namespace playground {
int Sandbox::sandbox_open(const char *pathname, int flags, mode_t mode) {
Debug::syscall(__NR_open, "Executing handler");
size_t len = strlen(pathname);
struct Request {
int sysnum;
long long cookie;
Open open_req;
char pathname[0];
} __attribute__((packed)) *request;
char data[sizeof(struct Request) + len];
request = reinterpret_cast<struct Request*>(data);
request->sysnum = __NR_open;
request->cookie = cookie();
request->open_req.path_length = len;
request->open_req.flags = flags;
request->open_req.mode = mode;
memcpy(request->pathname, pathname, len);
long rc;
SysCalls sys;
if (write(sys, processFdPub(), request, sizeof(data)) != (int)sizeof(data) ||
read(sys, threadFdPub(), &rc, sizeof(rc)) != sizeof(rc)) {
die("Failed to forward open() request [sandbox]");
}
return static_cast<int>(rc);
}
bool Sandbox::process_open(int parentMapsFd, int sandboxFd, int threadFdPub,
int threadFd, SecureMem::Args* mem) {
// Read request
SysCalls sys;
Open open_req;
if (read(sys, sandboxFd, &open_req, sizeof(open_req)) != sizeof(open_req)) {
read_parm_failed:
die("Failed to read parameters for open() [process]");
}
int rc = -ENAMETOOLONG;
if (open_req.path_length >= sizeof(mem->pathname)) {
char buf[32];
while (open_req.path_length > 0) {
size_t len = open_req.path_length > sizeof(buf) ?
sizeof(buf) : open_req.path_length;
ssize_t i = read(sys, sandboxFd, buf, len);
if (i <= 0) {
goto read_parm_failed;
}
open_req.path_length -= i;
}
if (write(sys, threadFd, &rc, sizeof(rc)) != sizeof(rc)) {
die("Failed to return data from open() [process]");
}
return false;
}
if ((open_req.flags & O_ACCMODE) != O_RDONLY) {
// After locking the mutex, we can no longer abandon the system call. So,
// perform checks before clobbering the securely shared memory.
char tmp[open_req.path_length];
if (read(sys, sandboxFd, tmp, open_req.path_length) !=
(ssize_t)open_req.path_length) {
goto read_parm_failed;
}
Debug::message(("Denying access to \"" + std::string(tmp) + "\"").c_str());
SecureMem::abandonSystemCall(threadFd, -EACCES);
return false;
}
SecureMem::lockSystemCall(parentMapsFd, mem);
if (read(sys, sandboxFd, mem->pathname, open_req.path_length) !=
(ssize_t)open_req.path_length) {
goto read_parm_failed;
}
mem->pathname[open_req.path_length] = '\000';
// TODO(markus): Implement sandboxing policy. For now, we allow read
// access to everything. That's probably not correct.
Debug::message(("Allowing access to \"" + std::string(mem->pathname) +
"\"").c_str());
// Tell trusted thread to open the file.
SecureMem::sendSystemCall(threadFdPub, true, parentMapsFd, mem, __NR_open,
mem->pathname - (char*)mem + (char*)mem->self,
open_req.flags, open_req.mode);
return true;
}
} // namespace
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