/* Copyright (C) 2014 Stony Brook University
This file is part of Graphene Library OS.
Graphene Library OS is free software: you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public License
as published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.
Graphene Library OS is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see . */
/*
* db_process.c
*
* This source file contains functions to create a child process and terminate
* the running process. Child does not inherit any objects or memory from its
* parent pricess. A Parent process may not modify the execution of its
* children. It can wait for a child to exit using its handle. Also, parent and
* child may communicate through I/O streams provided by the parent to the child
* at creation.
*/
#include
#include
#include "sgx_internal.h"
#include "sgx_tls.h"
#include "sgx_enclave.h"
#include
#include
#include
#define PAL_LOADER RUNTIME_FILE("pal-Linux-SGX")
struct proc_args {
PAL_SEC_STR exec_name;
unsigned int instance_id;
unsigned int parent_process_id;
int stream_fd;
int cargo_fd;
PAL_SEC_STR pipe_prefix;
};
/*
* vfork() shares stack between child and parent. Any stack modifications in
* child are reflected in parent's stack. Compiler may unwittingly modify
* child's stack for its own purposes and thus corrupt parent's stack
* (e.g., GCC re-uses the same stack area for local vars with non-overlapping
* lifetimes).
* Introduce noinline function with stack area used only by child.
* Make this function non-local to keep function signature.
* NOTE: more tricks may be needed to prevent unexpected optimization for
* future compiler.
*/
static int __attribute_noinline
vfork_exec(int child_stream, int parent_stream, int parent_cargo, const char** argv) {
int ret = ARCH_VFORK();
if (ret)
return ret;
/* child: close parent's FDs, rewire child stream to init FD, and execve */
INLINE_SYSCALL(close, 1, parent_stream);
INLINE_SYSCALL(close, 1, parent_cargo);
ret = INLINE_SYSCALL(dup2, 2, child_stream, PROC_INIT_FD);
if (!IS_ERR(ret)) {
extern char** environ;
ret = INLINE_SYSCALL(execve, 3, PAL_LOADER, argv, environ);
/* shouldn't get to here */
SGX_DBG(DBG_E, "unexpected failure of new process\n");
}
__asm__ volatile ("hlt");
return 0;
}
int sgx_create_process(const char* uri, int nargs, const char** args, int* stream_fd, int* cargo_fd) {
int ret, rete, child;
int fds[4] = { -1, -1, -1, -1 };
if (!uri || !strstartswith_static(uri, URI_PREFIX_FILE))
return -EINVAL;
int socktype = SOCK_STREAM;
if (IS_ERR((ret = INLINE_SYSCALL(socketpair, 4, AF_UNIX, socktype, 0, &fds[0]))) ||
IS_ERR((ret = INLINE_SYSCALL(socketpair, 4, AF_UNIX, socktype, 0, &fds[2]))))
goto out;
const char ** argv = __alloca(sizeof(const char *) * (nargs + 2));
argv[0] = PAL_LOADER;
memcpy(argv + 1, args, sizeof(const char *) * nargs);
argv[nargs + 1] = NULL;
/* Child's signal handler may mess with parent's memory during vfork(),
* so block signals
*/
ret = block_async_signals(true);
if (ret < 0) {
ret = -ret;
goto out;
}
ret = vfork_exec(/*child_stream=*/fds[0], /*parent_stream=*/fds[1], /*parent_cargo=*/fds[3], argv);
if (IS_ERR(ret))
goto out;
/* parent continues here */
child = ret;
/* children unblock async signals by sgx_signal_setup() */
ret = block_async_signals(false);
if (ret < 0) {
ret = -ret;
goto out;
}
INLINE_SYSCALL(close, 1, fds[0]); /* child stream */
INLINE_SYSCALL(close, 1, fds[2]); /* child cargo */
struct pal_sec * pal_sec = &pal_enclave.pal_sec;
struct proc_args proc_args;
memcpy(proc_args.exec_name, uri, sizeof(PAL_SEC_STR));
proc_args.instance_id = pal_sec->instance_id;
proc_args.parent_process_id = pal_sec->pid;
proc_args.stream_fd = fds[0];
proc_args.cargo_fd = fds[2];
memcpy(proc_args.pipe_prefix, pal_sec->pipe_prefix, sizeof(PAL_SEC_STR));
ret = INLINE_SYSCALL(write, 3, fds[1], &proc_args, sizeof(struct proc_args));
if (IS_ERR(ret) || (size_t)ret < sizeof(struct proc_args)) {
ret = -EPERM;
goto out;
}
ret = INLINE_SYSCALL(read, 3, fds[1], &rete, sizeof(int));
if (IS_ERR(ret) || (size_t)ret < sizeof(int)) {
ret = -EPERM;
goto out;
}
if (IS_ERR(rete)) {
ret = rete;
goto out;
}
INLINE_SYSCALL(fcntl, 3, fds[1], F_SETFD, FD_CLOEXEC);
INLINE_SYSCALL(fcntl, 3, fds[3], F_SETFD, FD_CLOEXEC);
if (stream_fd)
*stream_fd = fds[1];
if (cargo_fd)
*cargo_fd = fds[3];
ret = child;
out:
if (IS_ERR(ret)) {
for (int i = 0; i < 4; i++)
if (fds[i] >= 0)
INLINE_SYSCALL(close, 1, fds[i]);
}
return ret;
}
int sgx_init_child_process (struct pal_sec * pal_sec)
{
struct proc_args proc_args;
int ret = INLINE_SYSCALL(read, 3, PROC_INIT_FD, &proc_args, sizeof(struct proc_args));
if (IS_ERR(ret)) {
if (ERRNO(ret) == EBADF)
return 0;
return ret;
}
int child_status = 0;
ret = INLINE_SYSCALL(write, 3, PROC_INIT_FD, &child_status, sizeof(int));
if (IS_ERR(ret))
return ret;
memcpy(pal_sec->exec_name, proc_args.exec_name, sizeof(PAL_SEC_STR));
pal_sec->instance_id = proc_args.instance_id;
pal_sec->ppid = proc_args.parent_process_id;
pal_sec->stream_fd = proc_args.stream_fd;
pal_sec->cargo_fd = proc_args.cargo_fd;
memcpy(pal_sec->pipe_prefix, proc_args.pipe_prefix, sizeof(PAL_SEC_STR));
return 1;
}