Kerbal Space Program

/* Hide Pulseaudio libraries

 * Copyright (C) 2016 kspflo

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * This program 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 General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */

// Build one-liner:

// sudo rm -f hidepulse; gcc -std=gnu99 -O2 -o hidepulse hidepulse.c -ldl && sudo chown root:root hidepulse; sudo chmod u+s hidepulse

#define _GNU_SOURCE

#include <dirent.h>

#include <dlfcn.h>

#include <err.h>

#include <fcntl.h>

#include <sched.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <sys/mount.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <sys/wait.h>

static char *get_libdir(void) {

        Dl_info info;

        void *h, *fn;

        char *p;

        if(!(h = dlopen("libpulse.so", RTLD_LAZY)))

                errx(1, "Failed to resolve libpulse.so");

        if(!(fn = dlsym(h, "pa_stream_new")))

                errx(1, "Failed to resolve symbol pa_stream_new");

        if(!dladdr(fn, &info))

                errx(1, "Failed to retrieve symbol info");

        if((p = strrchr(info.dli_fname, '/')))

                *p = '\0';

        dlclose(h);

        return strdup(info.dli_fname);

}

static void bind_libs(char *sdir, char *ddir) {

        int fd;

        ssize_t len;

        char sbuf[4096], dbuf[4096];

        DIR *dfd;

        struct dirent *dp;

        struct stat stbuf;

        if((dfd = opendir(sdir)) == NULL)

                err(1, "Failed to open source directory '%s'", sdir);

        while((dp = readdir(dfd)) != NULL) {

                snprintf(sbuf, sizeof(sbuf), "%s/%s", sdir, dp->d_name);

                snprintf(dbuf, sizeof(dbuf), "%s/%s", ddir, dp->d_name);

                if(lstat(sbuf, &stbuf) < 0)

                         err(1, "Failed to stat '%s'", sbuf);

                if(S_ISDIR(stbuf.st_mode)) {

                        if(strcmp(dp->d_name, "pulseaudio") == 0) {

                                warnx("Omitting directory '%s'", dp->d_name);

                                continue;

                        }

                        else if(strcmp(dp->d_name, ".") == 0 ||strcmp(dp->d_name, "..") == 0)

                                continue;

                        //printf("mkdir '%s'\n", dbuf);

                        if(mkdir(dbuf, stbuf.st_mode) < 0)

                                err(1, "Failed to create directory mount point '%s'", dbuf);

                }

                else if(S_ISLNK(stbuf.st_mode)) {

                        if(strstr(dp->d_name, "pulse")) {

                                warnx("Omitting symlink '%s'", dp->d_name);

                                continue;

                        }

                        if((len = readlink(sbuf, sbuf, sizeof(sbuf) - 1)) < 0)

                                err(1, "Failed to read symlink '%s'", sbuf);

                        sbuf[len] = '\0';

                        //printf("symlink '%s' -> '%s'\n", dbuf, sbuf);

                        if(symlink(sbuf, dbuf) < 0)

                                err(1, "Failed to create symlink '%s'", dbuf);

                }

                else if(S_ISREG(stbuf.st_mode)) {

                        if(strstr(dp->d_name, "pulse")) {

                                warnx("Omitting file '%s'", dp->d_name);

                                continue;

                        }

                        //printf("creat '%s'\n", dbuf);

                        if((fd = creat(dbuf, stbuf.st_mode)) < 0)

                                err(1, "Failed to create file mount point '%s'", dbuf);

                        close(fd);

                }

                else {

                        warnx("Ignoring file '%s'", dp->d_name);

                        continue;

                }

                mount(sbuf, dbuf, NULL, MS_BIND, NULL);

        }

}

int main(int argc, char **argv) {

        int r;

        uid_t ruid, euid, suid;

        char *libdir, *newlibdir, **args;

        char libdir_template[] = "/tmp/hidepulse.XXXXXX";

        if(argc < 2)

                errx(1, "Usage: %s <program> [<arg1> ... <argN>]", argv[0]);

        libdir = get_libdir();

        if(unshare(CLONE_NEWNS) < 0)

                err(1, "Failed to unshare mount namespace");

        if(mount(NULL, "/", NULL, MS_PRIVATE | MS_REC, NULL) < 0)

                err(1, "Failed to set mount propagation on /");

        newlibdir = mkdtemp(libdir_template);

        if(mount("tmpfs", newlibdir, "tmpfs", 0, NULL) < 0)

                err(1, "Failed to mount new libdir");

        bind_libs(libdir, newlibdir);

        if(mount(newlibdir, newlibdir, NULL, MS_REMOUNT | MS_RDONLY, NULL) < 0)

                err(1, "Failed to re-mount new libdir read-only");

        if(mount(newlibdir, libdir, NULL, MS_MOVE, NULL) < 0)

                err(1, "Failed to move new libdir");

        free(libdir);

        if(rmdir(newlibdir) < 0)

                warn("Failed to remove new libdir");

        if(fork()) {

                wait(NULL);

                return 0;

        }

        getresuid(&ruid, &euid, &suid);

        if(seteuid(ruid) < 0)

                err(1, "Failed to drop privileges");

        args = malloc(sizeof(char *) * argc);

        if(!args)

                err(1, "Failed to allocate argument vector");

        for(int i = 1; i < argc; ++i)

                args[i - 1] = strdup(argv[i]);

        args[argc - 1] = NULL;

        warnx("Executing: '%s'", argv[1]);

        execv(argv[1], args);

        err(1, "Failed to exec '%s'.", argv[1]);

}