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* sudo chown root:root trampoline; sudo chroot +s trampoline
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/mount.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/time.h>
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#include <sys/resource.h>
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#include <limits.h>
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/* conf.h is admin-configured by the setup process.
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* It defines jail_base.
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/* Returns TRUE if the given uid is allowed to execute trampoline.
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* Only root or the web server should be allowed to execute.
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* This is determined by the whitelist allowed_uids in conf.h.
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#ifdef IVLE_AUFS_JAILS
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/* Die more pleasantly if mallocs fail. */
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void *die_if_null(void *ptr)
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perror("not enough memory");
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/* Find the path of the user components of a jail, given a mountpoint. */
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char *jail_src(const char* jailpath)
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srclen = strlen(jail_src_base);
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dstlen = strlen(jail_base);
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src = die_if_null(malloc(strlen(jailpath) + (srclen - dstlen) + 1));
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strcpy(src, jail_src_base);
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strcat(src, jailpath+dstlen);
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/* Check for the validity of a jail in the given path, mounting it if it looks
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* TODO: Updating /etc/mtab would be nice. */
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void mount_if_needed(const char* jailpath)
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/* Check if there is something useful in the jail. If not, it's probably
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jaillib = die_if_null(malloc(strlen(jailpath) + 5));
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sprintf(jaillib, "%s/lib", jailpath);
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if (access(jaillib, F_OK))
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/* No /lib? Mustn't be mounted. Mount it, creating the dir if needed. */
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if (access(jailpath, F_OK))
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if(mkdir(jailpath, 0755))
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syslog(LOG_ERR, "could not create mountpoint %s\n", jailpath);
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perror("could not create jail mountpoint");
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syslog(LOG_NOTICE, "created mountpoint %s\n", jailpath);
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jailsrc = jail_src(jailpath);
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mountdata = die_if_null(malloc(3 + strlen(jailsrc) + 4 + strlen(jail_system) + 3 + 1));
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sprintf(mountdata, "br:%s=rw:%s=ro", jailsrc, jail_system);
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if (mount("none", jailpath, "aufs", 0, mountdata))
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syslog(LOG_ERR, "could not mount %s\n", jailpath);
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perror("could not mount");
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syslog(LOG_INFO, "mounted %s\n", jailpath);
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#endif /* IVLE_AUFS_JAILS */
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/* Unsets any signal mask applied by the parent process */
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int unmask_signals(void)
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sigset = die_if_null(malloc(sizeof(sigset_t)));
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result = sigprocmask(SIG_SETMASK, sigset, NULL);
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printf("%d", result);
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int main(int argc, char* const argv[])
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openlog("trampoline", LOG_CONS | LOG_PID | LOG_NDELAY, LOG_USER);
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#ifdef IVLE_AUFS_JAILS
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mount_if_needed(canonical_jailpath);
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#endif /* IVLE_AUFS_JAILS */
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/* chroot into the jail.
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* Henceforth this process, and its children, cannot see anything above
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* canoncial_jailpath. */
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if (chroot(canonical_jailpath))
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syslog(LOG_ERR, "chroot to %s failed\n", canonical_jailpath);
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perror("could not chroot");
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/* set user resource limits */
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/* Process adress space in memory */
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l.rlim_cur = 192 * 1024 * 1024; /* 192MiB */
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l.rlim_max = 256 * 1024 * 1024; /* 256MiB */
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/* Process size in virtual memory */
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l.rlim_cur = 64 * 1024 * 1024; /* 64Mb */
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l.rlim_max = 72 * 1024 * 1024; /* 64Mb */
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if (setrlimit(RLIMIT_AS, &l))
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perror("could not setrlimit/RLIMIT_AS");
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/* Process data segment in memory
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* Note: This requires a kernel patch to work correctly otherwise it is
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* ineffective (thus you are only limited by RLIMIT_AS)
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l.rlim_cur = 192 * 1024 * 1024; /* 192MiB */
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l.rlim_max = 256 * 1024 * 1024; /* 256MiB */
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if (setrlimit(RLIMIT_DATA, &l))
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perror("could not setrlimit/RLIMIT_DATA");
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l.rlim_cur = 0; /* No core files */
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l.rlim_max = 0; /* No core files */
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if (setrlimit(RLIMIT_CORE, &l))
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perror("could not setrlimit/RLIMIT_CORE");
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l.rlim_cur = 64 * 1024 * 1024; /* 64MiB */
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l.rlim_max = 72 * 1024 * 1024; /* 72MiB */
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if (setrlimit(RLIMIT_FSIZE, &l))
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l.rlim_cur = 64 * 1024 * 1024; /* 64Mb */
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l.rlim_max = 72 * 1024 * 1024; /* 72Mb */
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if (setrlimit(RLIMIT_FSIZE, &l))
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perror("could not setrlimit/RLIMIT_FSIZE");
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/* Remove any signal handler masks so we can send signals to the child */
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perror("could not unmask signals");
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/* If everything was OK daemonize (if required) */
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/* exec (replace this process with the a new instance of the target
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* program). Pass along all the arguments.
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* Note that for script execution, the "program" will be the interpreter,
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* and the first argument will be the script. */
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execv(prog, args);
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/* XXX if (daemon_mode) use syslog? */
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/* nb exec won't return unless there was an error */
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syslog(LOG_ERR, "exec of %s in %s failed", prog, canonical_jailpath);
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perror("could not exec");
added
removed
trampoline/trampoline.c
