path: root/arch/um/os-Linux/skas/process.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2021 Benjamin Berg <benjamin@sipsolutions.net>
 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
 * Copyright (C) 2002- 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 */

#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <sched.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <mem_user.h>
#include <sys/mman.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <asm/unistd.h>
#include <as-layout.h>
#include <init.h>
#include <kern_util.h>
#include <mem.h>
#include <os.h>
#include <ptrace_user.h>
#include <registers.h>
#include <skas.h>
#include <sysdep/stub.h>
#include <sysdep/mcontext.h>
#include <linux/futex.h>
#include <linux/threads.h>
#include <timetravel.h>
#include <asm-generic/rwonce.h>
#include "../internal.h"

int is_skas_winch(int pid, int fd, void *data)
{
	return pid == getpgrp();
}

static const char *ptrace_reg_name(int idx)
{
#define R(n) case HOST_##n: return #n

	switch (idx) {
#ifdef __x86_64__
	R(BX);
	R(CX);
	R(DI);
	R(SI);
	R(DX);
	R(BP);
	R(AX);
	R(R8);
	R(R9);
	R(R10);
	R(R11);
	R(R12);
	R(R13);
	R(R14);
	R(R15);
	R(ORIG_AX);
	R(CS);
	R(SS);
	R(EFLAGS);
#elif defined(__i386__)
	R(IP);
	R(SP);
	R(EFLAGS);
	R(AX);
	R(BX);
	R(CX);
	R(DX);
	R(SI);
	R(DI);
	R(BP);
	R(CS);
	R(SS);
	R(DS);
	R(FS);
	R(ES);
	R(GS);
	R(ORIG_AX);
#endif
	}
	return "";
}

static int ptrace_dump_regs(int pid)
{
	unsigned long regs[MAX_REG_NR];
	int i;

	if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
		return -errno;

	printk(UM_KERN_ERR "Stub registers -\n");
	for (i = 0; i < ARRAY_SIZE(regs); i++) {
		const char *regname = ptrace_reg_name(i);

		printk(UM_KERN_ERR "\t%s\t(%2d): %lx\n", regname, i, regs[i]);
	}

	return 0;
}

/*
 * Signals that are OK to receive in the stub - we'll just continue it.
 * SIGWINCH will happen when UML is inside a detached screen.
 */
#define STUB_SIG_MASK ((1 << SIGALRM) | (1 << SIGWINCH))

/* Signals that the stub will finish with - anything else is an error */
#define STUB_DONE_MASK (1 << SIGTRAP)

void wait_stub_done(int pid)
{
	int n, status, err;

	while (1) {
		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
		if ((n < 0) || !WIFSTOPPED(status))
			goto bad_wait;

		if (((1 << WSTOPSIG(status)) & STUB_SIG_MASK) == 0)
			break;

		err = ptrace(PTRACE_CONT, pid, 0, 0);
		if (err) {
			printk(UM_KERN_ERR "%s : continue failed, errno = %d\n",
			       __func__, errno);
			fatal_sigsegv();
		}
	}

	if (((1 << WSTOPSIG(status)) & STUB_DONE_MASK) != 0)
		return;

bad_wait:
	err = ptrace_dump_regs(pid);
	if (err)
		printk(UM_KERN_ERR "Failed to get registers from stub, errno = %d\n",
		       -err);
	printk(UM_KERN_ERR "%s : failed to wait for SIGTRAP, pid = %d, n = %d, errno = %d, status = 0x%x\n",
	       __func__, pid, n, errno, status);
	fatal_sigsegv();
}

void wait_stub_done_seccomp(struct mm_id *mm_idp, int running, int wait_sigsys)
{
	struct stub_data *data = (void *)mm_idp->stack;
	int ret;

	do {
		const char byte = 0;
		struct iovec iov = {
			.iov_base = (void *)&byte,
			.iov_len = sizeof(byte),
		};
		union {
			char data[CMSG_SPACE(sizeof(mm_idp->syscall_fd_map))];
			struct cmsghdr align;
		} ctrl;
		struct msghdr msgh = {
			.msg_iov = &iov,
			.msg_iovlen = 1,
		};

		if (!running) {
			if (mm_idp->syscall_fd_num) {
				unsigned int fds_size =
					sizeof(int) * mm_idp->syscall_fd_num;
				struct cmsghdr *cmsg;

				msgh.msg_control = ctrl.data;
				msgh.msg_controllen = CMSG_SPACE(fds_size);
				cmsg = CMSG_FIRSTHDR(&am