cachepc-qemu

Fork of AMDESE/qemu with changes for cachepc side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-qemu
Log | Files | Refs | Submodules | LICENSE | sfeed.txt

os-posix.c (8428B)

      1/*
      2 * os-posix.c
      3 *
      4 * Copyright (c) 2003-2008 Fabrice Bellard
      5 * Copyright (c) 2010 Red Hat, Inc.
      6 *
      7 * Permission is hereby granted, free of charge, to any person obtaining a copy
      8 * of this software and associated documentation files (the "Software"), to deal
      9 * in the Software without restriction, including without limitation the rights
     10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     11 * copies of the Software, and to permit persons to whom the Software is
     12 * furnished to do so, subject to the following conditions:
     13 *
     14 * The above copyright notice and this permission notice shall be included in
     15 * all copies or substantial portions of the Software.
     16 *
     17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
     20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
     23 * THE SOFTWARE.
     24 */
     25
     26#include "qemu/osdep.h"
     27#include <sys/wait.h>
     28#include <pwd.h>
     29#include <grp.h>
     30#include <libgen.h>
     31
     32#include "qemu-common.h"
     33/* Needed early for CONFIG_BSD etc. */
     34#include "net/slirp.h"
     35#include "qemu/qemu-options.h"
     36#include "qemu/error-report.h"
     37#include "qemu/log.h"
     38#include "sysemu/runstate.h"
     39#include "qemu/cutils.h"
     40
     41#ifdef CONFIG_LINUX
     42#include <sys/prctl.h>
     43#endif
     44
     45/*
     46 * Must set all three of these at once.
     47 * Legal combinations are              unset   by name   by uid
     48 */
     49static struct passwd *user_pwd;    /*   NULL   non-NULL   NULL   */
     50static uid_t user_uid = (uid_t)-1; /*   -1      -1        >=0    */
     51static gid_t user_gid = (gid_t)-1; /*   -1      -1        >=0    */
     52
     53static const char *chroot_dir;
     54static int daemonize;
     55static int daemon_pipe;
     56
     57void os_setup_early_signal_handling(void)
     58{
     59    struct sigaction act;
     60    sigfillset(&act.sa_mask);
     61    act.sa_flags = 0;
     62    act.sa_handler = SIG_IGN;
     63    sigaction(SIGPIPE, &act, NULL);
     64}
     65
     66static void termsig_handler(int signal, siginfo_t *info, void *c)
     67{
     68    qemu_system_killed(info->si_signo, info->si_pid);
     69}
     70
     71void os_setup_signal_handling(void)
     72{
     73    struct sigaction act;
     74
     75    memset(&act, 0, sizeof(act));
     76    act.sa_sigaction = termsig_handler;
     77    act.sa_flags = SA_SIGINFO;
     78    sigaction(SIGINT,  &act, NULL);
     79    sigaction(SIGHUP,  &act, NULL);
     80    sigaction(SIGTERM, &act, NULL);
     81}
     82
     83void os_set_proc_name(const char *s)
     84{
     85#if defined(PR_SET_NAME)
     86    char name[16];
     87    if (!s)
     88        return;
     89    pstrcpy(name, sizeof(name), s);
     90    /* Could rewrite argv[0] too, but that's a bit more complicated.
     91       This simple way is enough for `top'. */
     92    if (prctl(PR_SET_NAME, name)) {
     93        error_report("unable to change process name: %s", strerror(errno));
     94        exit(1);
     95    }
     96#else
     97    error_report("Change of process name not supported by your OS");
     98    exit(1);
     99#endif
    100}
    101
    102
    103static bool os_parse_runas_uid_gid(const char *optarg)
    104{
    105    unsigned long lv;
    106    const char *ep;
    107    uid_t got_uid;
    108    gid_t got_gid;
    109    int rc;
    110
    111    rc = qemu_strtoul(optarg, &ep, 0, &lv);
    112    got_uid = lv; /* overflow here is ID in C99 */
    113    if (rc || *ep != ':' || got_uid != lv || got_uid == (uid_t)-1) {
    114        return false;
    115    }
    116
    117    rc = qemu_strtoul(ep + 1, 0, 0, &lv);
    118    got_gid = lv; /* overflow here is ID in C99 */
    119    if (rc || got_gid != lv || got_gid == (gid_t)-1) {
    120        return false;
    121    }
    122
    123    user_pwd = NULL;
    124    user_uid = got_uid;
    125    user_gid = got_gid;
    126    return true;
    127}
    128
    129/*
    130 * Parse OS specific command line options.
    131 * return 0 if option handled, -1 otherwise
    132 */
    133int os_parse_cmd_args(int index, const char *optarg)
    134{
    135    switch (index) {
    136    case QEMU_OPTION_runas:
    137        user_pwd = getpwnam(optarg);
    138        if (user_pwd) {
    139            user_uid = -1;
    140            user_gid = -1;
    141        } else if (!os_parse_runas_uid_gid(optarg)) {
    142            error_report("User \"%s\" doesn't exist"
    143                         " (and is not <uid>:<gid>)",
    144                         optarg);
    145            exit(1);
    146        }
    147        break;
    148    case QEMU_OPTION_chroot:
    149        chroot_dir = optarg;
    150        break;
    151    case QEMU_OPTION_daemonize:
    152        daemonize = 1;
    153        break;
    154#if defined(CONFIG_LINUX)
    155    case QEMU_OPTION_enablefips:
    156        warn_report("-enable-fips is deprecated, please build QEMU with "
    157                    "the `libgcrypt` library as the cryptography provider "
    158                    "to enable FIPS compliance");
    159        fips_set_state(true);
    160        break;
    161#endif
    162    default:
    163        return -1;
    164    }
    165
    166    return 0;
    167}
    168
    169static void change_process_uid(void)
    170{
    171    assert((user_uid == (uid_t)-1) || user_pwd == NULL);
    172    assert((user_uid == (uid_t)-1) ==
    173           (user_gid == (gid_t)-1));
    174
    175    if (user_pwd || user_uid != (uid_t)-1) {
    176        gid_t intended_gid = user_pwd ? user_pwd->pw_gid : user_gid;
    177        uid_t intended_uid = user_pwd ? user_pwd->pw_uid : user_uid;
    178        if (setgid(intended_gid) < 0) {
    179            error_report("Failed to setgid(%d)", intended_gid);
    180            exit(1);
    181        }
    182        if (user_pwd) {
    183            if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) {
    184                error_report("Failed to initgroups(\"%s\", %d)",
    185                        user_pwd->pw_name, user_pwd->pw_gid);
    186                exit(1);
    187            }
    188        } else {
    189            if (setgroups(1, &user_gid) < 0) {
    190                error_report("Failed to setgroups(1, [%d])",
    191                        user_gid);
    192                exit(1);
    193            }
    194        }
    195        if (setuid(intended_uid) < 0) {
    196            error_report("Failed to setuid(%d)", intended_uid);
    197            exit(1);
    198        }
    199        if (setuid(0) != -1) {
    200            error_report("Dropping privileges failed");
    201            exit(1);
    202        }
    203    }
    204}
    205
    206static void change_root(void)
    207{
    208    if (chroot_dir) {
    209        if (chroot(chroot_dir) < 0) {
    210            error_report("chroot failed");
    211            exit(1);
    212        }
    213        if (chdir("/")) {
    214            error_report("not able to chdir to /: %s", strerror(errno));
    215            exit(1);
    216        }
    217    }
    218
    219}
    220
    221void os_daemonize(void)
    222{
    223    if (daemonize) {
    224        pid_t pid;
    225        int fds[2];
    226
    227        if (pipe(fds) == -1) {
    228            exit(1);
    229        }
    230
    231        pid = fork();
    232        if (pid > 0) {
    233            uint8_t status;
    234            ssize_t len;
    235
    236            close(fds[1]);
    237
    238            do {
    239                len = read(fds[0], &status, 1);
    240            } while (len < 0 && errno == EINTR);
    241
    242            /* only exit successfully if our child actually wrote
    243             * a one-byte zero to our pipe, upon successful init */
    244            exit(len == 1 && status == 0 ? 0 : 1);
    245
    246        } else if (pid < 0) {
    247            exit(1);
    248        }
    249
    250        close(fds[0]);
    251        daemon_pipe = fds[1];
    252        qemu_set_cloexec(daemon_pipe);
    253
    254        setsid();
    255
    256        pid = fork();
    257        if (pid > 0) {
    258            exit(0);
    259        } else if (pid < 0) {
    260            exit(1);
    261        }
    262        umask(027);
    263
    264        signal(SIGTSTP, SIG_IGN);
    265        signal(SIGTTOU, SIG_IGN);
    266        signal(SIGTTIN, SIG_IGN);
    267    }
    268}
    269
    270void os_setup_post(void)
    271{
    272    int fd = 0;
    273
    274    if (daemonize) {
    275        if (chdir("/")) {
    276            error_report("not able to chdir to /: %s", strerror(errno));
    277            exit(1);
    278        }
    279        TFR(fd = qemu_open_old("/dev/null", O_RDWR));
    280        if (fd == -1) {
    281            exit(1);
    282        }
    283    }
    284
    285    change_root();
    286    change_process_uid();
    287
    288    if (daemonize) {
    289        uint8_t status = 0;
    290        ssize_t len;
    291
    292        dup2(fd, 0);
    293        dup2(fd, 1);
    294        /* In case -D is given do not redirect stderr to /dev/null */
    295        if (!qemu_logfile) {
    296            dup2(fd, 2);
    297        }
    298
    299        close(fd);
    300
    301        do {        
    302            len = write(daemon_pipe, &status, 1);
    303        } while (len < 0 && errno == EINTR);
    304        if (len != 1) {
    305            exit(1);
    306        }
    307    }
    308}
    309
    310void os_set_line_buffering(void)
    311{
    312    setvbuf(stdout, NULL, _IOLBF, 0);
    313}
    314
    315bool is_daemonized(void)
    316{
    317    return daemonize;
    318}
    319
    320int os_mlock(void)
    321{
    322#ifdef HAVE_MLOCKALL
    323    int ret = 0;
    324
    325    ret = mlockall(MCL_CURRENT | MCL_FUTURE);
    326    if (ret < 0) {
    327        error_report("mlockall: %s", strerror(errno));
    328    }
    329
    330    return ret;
    331#else
    332    return -ENOSYS;
    333#endif
    334}