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access.cc
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access.cc
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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 {
long Sandbox::sandbox_access(const char *pathname, int mode) {
long long tm;
Debug::syscall(&tm, __NR_access, "Executing handler");
size_t len = strlen(pathname);
struct Request {
struct RequestHeader header;
Access access_req;
char pathname[0];
} __attribute__((packed)) *request;
char data[sizeof(struct Request) + len];
request = reinterpret_cast<struct Request*>(data);
request->access_req.path_length = len;
request->access_req.mode = mode;
memcpy(request->pathname, pathname, len);
long rc = forwardSyscall(__NR_access, &request->header, sizeof(data));
Debug::elapsed(tm, __NR_access);
return rc;
}
bool Sandbox::process_access(const SecureMem::SyscallRequestInfo* info) {
// Read request
SysCalls sys;
Access access_req;
if (read(sys, info->trustedProcessFd, &access_req, sizeof(access_req)) !=
sizeof(access_req)) {
read_parm_failed:
die("Failed to read parameters for access() [process]");
}
int rc = -ENAMETOOLONG;
if (access_req.path_length >= sizeof(info->mem->pathname)) {
char buf[32];
while (access_req.path_length > 0) {
size_t len = access_req.path_length > sizeof(buf) ?
sizeof(buf) : access_req.path_length;
ssize_t i = read(sys, info->trustedProcessFd, buf, len);
if (i <= 0) {
goto read_parm_failed;
}
access_req.path_length -= i;
}
if (write(sys, info->applicationFd, &rc, sizeof(rc)) != sizeof(rc)) {
die("Failed to return data from access() [process]");
}
return false;
}
if (!g_policy.allow_file_namespace) {
// After locking the mutex, we can no longer abandon the system call. So,
// perform checks before clobbering the securely shared memory.
char tmp[access_req.path_length];
if (read(sys, info->trustedProcessFd, tmp, access_req.path_length) !=
(ssize_t)access_req.path_length) {
goto read_parm_failed;
}
Debug::message(("Denying access to \"" +
std::string(tmp, access_req.path_length) + "\"").c_str());
SecureMem::abandonSystemCall(*info, -EACCES);
return false;
}
SecureMem::lockSystemCall(*info);
if (read(sys, info->trustedProcessFd, info->mem->pathname,
access_req.path_length) != (ssize_t)access_req.path_length) {
goto read_parm_failed;
}
info->mem->pathname[access_req.path_length] = '\000';
// TODO(markus): Implement sandboxing policy
Debug::message(("Allowing access to \"" + std::string(info->mem->pathname) +
"\"").c_str());
// Tell trusted thread to access the file.
SecureMem::sendSystemCall(*info, SecureMem::SEND_LOCKED_SYNC,
info->mem->pathname, access_req.mode);
return true;
}
} // namespace