/*
 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sched.h>
#include <signal.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/ptrace.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <asm/unistd.h>
#include "init.h"
#include "kern_constants.h"
#include "os.h"
#include "mem_user.h"
#include "ptrace_user.h"
#include "registers.h"
#include "skas_ptrace.h"

static int ptrace_child(void)
{
        int ret;
        /* Calling os_getpid because some libcs cached getpid incorrectly */
        int pid = os_getpid(), ppid = getppid();
        int sc_result;

        change_sig(SIGWINCH, 0);
        if (ptrace(PTRACE_TRACEME, 0, 0, 0) < 0) {
                perror("ptrace");
                kill(pid, SIGKILL);
        }
        kill(pid, SIGSTOP);

        /*
         * This syscall will be intercepted by the parent. Don't call more than
         * once, please.
         */
        sc_result = os_getpid();

        if (sc_result == pid)
                /* Nothing modified by the parent, we are running normally. */
                ret = 1;
        else if (sc_result == ppid)
                /*
                 * Expected in check_ptrace and check_sysemu when they succeed
                 * in modifying the stack frame
                 */
                ret = 0;
        else
                /* Serious trouble! This could be caused by a bug in host 2.6
                 * SKAS3/2.6 patch before release -V6, together with a bug in
                 * the UML code itself.
                 */
                ret = 2;
        _exit(ret);
}

static void fatal_perror(char *str)
{
        perror(str);
        exit(1);
}

static void fatal(char *fmt, ...)
{
        va_list list;

        va_start(list, fmt);
        vprintf(fmt, list);
        va_end(list);
        fflush(stdout);

        exit(1);
}

static void non_fatal(char *fmt, ...)
{
        va_list list;

        va_start(list, fmt);
        vprintf(fmt, list);
        va_end(list);
        fflush(stdout);
}

static int start_ptraced_child(void)
{
        int pid, n, status;

        pid = fork();
        if (pid == 0)
                ptrace_child();
        else if (pid < 0)
                fatal_perror("start_ptraced_child : fork failed");

        CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
        if (n < 0)
                fatal_perror("check_ptrace : waitpid failed");
        if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
                fatal("check_ptrace : expected SIGSTOP, got status = %d",
                      status);

        return pid;
}

/* When testing for SYSEMU support, if it is one of the broken versions, we
 * must just avoid using sysemu, not panic, but only if SYSEMU features are
 * broken.
 * So only for SYSEMU features we test mustpanic, while normal host features
 * must work anyway!
 */
static int stop_ptraced_child(int pid, int exitcode, int mustexit)
{
        int status, n, ret = 0;

        if (ptrace(PTRACE_CONT, pid, 0, 0) < 0)
                fatal_perror("stop_ptraced_child : ptrace failed");
        CATCH_EINTR(n = waitpid(pid, &status, 0));
        if (!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
                int exit_with = WEXITSTATUS(status);
                if (exit_with == 2)
                        non_fatal("check_ptrace : child exited with status 2. "
                                  "\nDisabling SYSEMU support.\n");
                non_fatal("check_ptrace : child exited with exitcode %d, while "
                          "expecting %d; status 0x%x\n", exit_with,
                          exitcode, status);
                if (mustexit)
                        exit(1);
                ret = -1;
        }

        return ret;
}

/* Changed only during early boot */
int ptrace_faultinfo = 1;
int ptrace_ldt = 1;
int proc_mm = 1;
int skas_needs_stub = 0;

static int __init skas0_cmd_param(char *str, int* add)
{
        ptrace_faultinfo = proc_mm = 0;
        return 0;
}

/* The two __uml_setup would conflict, without this stupid alias. */

static int __init mode_skas0_cmd_param(char *str, int* add)
        __attribute__((alias("skas0_cmd_param")));

__uml_setup("skas0", skas0_cmd_param,
                "skas0\n"
                "    Disables SKAS3 usage, so that SKAS0 is used, unless \n"
                "    you specify mode=tt.\n\n");

__uml_setup("mode=skas0", mode_skas0_cmd_param,
                "mode=skas0\n"
                "    Disables SKAS3 usage, so that SKAS0 is used, unless you \n"
                "    specify mode=tt. Note that this was recently added - on \n"
                "    older kernels you must use simply \"skas0\".\n\n");

/* Changed only during early boot */
static int force_sysemu_disabled = 0;

static int __init nosysemu_cmd_param(char *str, int* add)
{
        force_sysemu_disabled = 1;
        return 0;
}

__uml_setup("nosysemu", nosysemu_cmd_param,
"nosysemu\n"
"    Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
"    SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
"    behaviour of ptrace() and helps reducing host context switch rate.\n"
"    To make it working, you need a kernel patch for your host, too.\n"
"    See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n"
"    information.\n\n");

static void __init check_sysemu(void)
{
        unsigned long regs[MAX_REG_NR];
        int pid, n, status, count=0;

        non_fatal("Checking syscall emulation patch for ptrace...");
        sysemu_supported = 0;
        pid = start_ptraced_child();

        if (ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
                goto fail;

        CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
        if (n < 0)
                fatal_perror("check_sysemu : wait failed");
        if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
                fatal("check_sysemu : expected SIGTRAP, got status = %d",
                      status);

        if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
                fatal_perror("check_sysemu : PTRACE_GETREGS failed");
        if (PT_SYSCALL_NR(regs) != __NR_getpid) {
                non_fatal("check_sysemu got system call number %d, "
                          "expected %d...", PT_SYSCALL_NR(regs), __NR_getpid);
                goto fail;
        }

        n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, os_getpid());
        if (n < 0) {
                non_fatal("check_sysemu : failed to modify system call "
                          "return");
                goto fail;
        }

        if (stop_ptraced_child(pid, 0, 0) < 0)
                goto fail_stopped;

        sysemu_supported = 1;
        non_fatal("OK\n");
        set_using_sysemu(!force_sysemu_disabled);

        non_fatal("Checking advanced syscall emulation patch for ptrace...");
        pid = start_ptraced_child();

        if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
                   (void *) PTRACE_O_TRACESYSGOOD) < 0))
                fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");

        while (1) {
                count++;
                if (ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
                        goto fail;
                CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
                if (n < 0)
                        fatal_perror("check_ptrace : wait failed");

                if (WIFSTOPPED(status) &&
                    (WSTOPSIG(status) == (SIGTRAP|0x80))) {
                        if (!count)
                                fatal("check_ptrace : SYSEMU_SINGLESTEP "
                                      "doesn't singlestep");
                        n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
                                   os_getpid());
                        if (n < 0)
                                fatal_perror("check_sysemu : failed to modify "
                                             "system call return");
                        break;
                }
                else if (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
                        count++;
                else
                        fatal("check_ptrace : expected SIGTRAP or "
                              "(SIGTRAP | 0x80), got status = %d", status);
        }
        if (stop_ptraced_child(pid, 0, 0) < 0)
                goto fail_stopped;

        sysemu_supported = 2;
        non_fatal("OK\n");

        if (!force_sysemu_disabled)
                set_using_sysemu(sysemu_supported);
        return;

fail:
        stop_ptraced_child(pid, 1, 0);
fail_stopped:
        non_fatal("missing\n");
}

static void __init check_ptrace(void)
{
        int pid, syscall, n, status;

        non_fatal("Checking that ptrace can change system call numbers...");
        pid = start_ptraced_child();

        if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
                   (void *) PTRACE_O_TRACESYSGOOD) < 0))
                fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");

        while (1) {
                if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
                        fatal_perror("check_ptrace : ptrace failed");

                CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
                if (n < 0)
                        fatal_perror("check_ptrace : wait failed");

                if (!WIFSTOPPED(status) ||
                   (WSTOPSIG(status) != (SIGTRAP | 0x80)))
                        fatal("check_ptrace : expected (SIGTRAP|0x80), "
                               "got status = %d", status);

                syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
                                 0);
                if (syscall == __NR_getpid) {
                        n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
                                   __NR_getppid);
                        if (n < 0)
                                fatal_perror("check_ptrace : failed to modify "
                                             "system call");
                        break;
                }
        }
        stop_ptraced_child(pid, 0, 1);
        non_fatal("OK\n");
        check_sysemu();
}

extern void check_tmpexec(void);

static void __init check_coredump_limit(void)
{
        struct rlimit lim;
        int err = getrlimit(RLIMIT_CORE, &lim);

        if (err) {
                perror("Getting core dump limit");
                return;
        }

        printf("Core dump limits :\n\tsoft - ");
        if (lim.rlim_cur == RLIM_INFINITY)
                printf("NONE\n");
        else printf("%lu\n", lim.rlim_cur);

        printf("\thard - ");
        if (lim.rlim_max == RLIM_INFINITY)
                printf("NONE\n");
        else printf("%lu\n", lim.rlim_max);
}

void __init os_early_checks(void)
{
        /* Print out the core dump limits early */
        check_coredump_limit();

        check_ptrace();

        /* Need to check this early because mmapping happens before the
         * kernel is running.
         */
        check_tmpexec();
}

static int __init noprocmm_cmd_param(char *str, int* add)
{
        proc_mm = 0;
        return 0;
}

__uml_setup("noprocmm", noprocmm_cmd_param,
"noprocmm\n"
"    Turns off usage of /proc/mm, even if host supports it.\n"
"    To support /proc/mm, the host needs to be patched using\n"
"    the current skas3 patch.\n\n");

static int __init noptracefaultinfo_cmd_param(char *str, int* add)
{
        ptrace_faultinfo = 0;
        return 0;
}

__uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param,
"noptracefaultinfo\n"
"    Turns off usage of PTRACE_FAULTINFO, even if host supports\n"
"    it. To support PTRACE_FAULTINFO, the host needs to be patched\n"
"    using the current skas3 patch.\n\n");

static int __init noptraceldt_cmd_param(char *str, int* add)
{
        ptrace_ldt = 0;
        return 0;
}

__uml_setup("noptraceldt", noptraceldt_cmd_param,
"noptraceldt\n"
"    Turns off usage of PTRACE_LDT, even if host supports it.\n"
"    To support PTRACE_LDT, the host needs to be patched using\n"
"    the current skas3 patch.\n\n");

static inline void check_skas3_ptrace_faultinfo(void)
{
        struct ptrace_faultinfo fi;
        int pid, n;

        non_fatal("  - PTRACE_FAULTINFO...");
        pid = start_ptraced_child();

        n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
        if (n < 0) {
                ptrace_faultinfo = 0;
                if (errno == EIO)
                        non_fatal("not found\n");
                else
                        perror("not found");
        }
        else {
                if (!ptrace_faultinfo)
                        non_fatal("found but disabled on command line\n");
                else
                        non_fatal("found\n");
        }

        init_registers(pid);
        stop_ptraced_child(pid, 1, 1);
}

static inline void check_skas3_ptrace_ldt(void)
{
#ifdef PTRACE_LDT
        int pid, n;
        unsigned char ldtbuf[40];
        struct ptrace_ldt ldt_op = (struct ptrace_ldt) {
                .func = 2, /* read default ldt */
                .ptr = ldtbuf,
                .bytecount = sizeof(ldtbuf)};

        non_fatal("  - PTRACE_LDT...");
        pid = start_ptraced_child();

        n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op);
        if (n < 0) {
                if (errno == EIO)
                        non_fatal("not found\n");
                else {
                        perror("not found");
                }
                ptrace_ldt = 0;
        }
        else {
                if (ptrace_ldt)
                        non_fatal("found\n");
                else
                        non_fatal("found, but use is disabled\n");
        }

        stop_ptraced_child(pid, 1, 1);
#else
        /* PTRACE_LDT might be disabled via cmdline option.
         * We want to override this, else we might use the stub
         * without real need
         */
        ptrace_ldt = 1;
#endif
}

static inline void check_skas3_proc_mm(void)
{
        non_fatal("  - /proc/mm...");
        if (access("/proc/mm", W_OK) < 0) {
                proc_mm = 0;
                perror("not found");
        }
        else if (!proc_mm)
                non_fatal("found but disabled on command line\n");
        else non_fatal("found\n");
}

int can_do_skas(void)
{
        non_fatal("Checking for the skas3 patch in the host:\n");

        check_skas3_proc_mm();
        check_skas3_ptrace_faultinfo();
        check_skas3_ptrace_ldt();

        if (!proc_mm || !ptrace_faultinfo || !ptrace_ldt)
                skas_needs_stub = 1;

        return 1;
}

int __init parse_iomem(char *str, int *add)
{
        struct iomem_region *new;
        struct stat64 buf;
        char *file, *driver;
        int fd, size;

        driver = str;
        file = strchr(str,',');
        if (file == NULL) {
                printf("parse_iomem : failed to parse iomem\n");
                goto out;
        }
        *file = '\0';
        file++;
        fd = open(file, O_RDWR, 0);
        if (fd < 0) {
                perror("parse_iomem - Couldn't open io file");
                goto out;
        }

        if (fstat64(fd, &buf) < 0) {
                perror("parse_iomem - cannot stat_fd file");
                goto out_close;
        }

        new = malloc(sizeof(*new));
        if (new == NULL) {
                perror("Couldn't allocate iomem_region struct");
                goto out_close;
        }

        size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);

        *new = ((struct iomem_region) { .next           = iomem_regions,
                                        .driver         = driver,
                                        .fd             = fd,
                                        .size           = size,
                                        .phys           = 0,
                                        .virt           = 0 });
        iomem_regions = new;
        iomem_size += new->size + UM_KERN_PAGE_SIZE;

        return 0;
 out_close:
        close(fd);
 out:
        return 1;
}