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-rw-r--r--tools/safeexec.c523
1 files changed, 523 insertions, 0 deletions
diff --git a/tools/safeexec.c b/tools/safeexec.c
new file mode 100644
index 0000000..33f16b7
--- /dev/null
+++ b/tools/safeexec.c
@@ -0,0 +1,523 @@
+/*
+ safeexec
+ Executar um comando num ambiente protegido
+ pbv, 1999-2000
+ alterado por cassio@ime.usp.br 2003-2011
+
+ THIS PROGRAM HAS TO BE INSTALLED WITH SETUID ROOT TO HAVE ALL FUNCTIONS WORKING
+ $ gcc -Wall -o safeexec safeexec.c
+ $ chown root.root safeexec
+ $ chmod 4555 safeexec
+*/
+#include <stdlib.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <glob.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <sys/resource.h>
+#include <signal.h>
+#include <time.h>
+
+#include <string.h>
+#include <errno.h>
+
+/* tempo de erro entre o sinal e o estouro no caso de time-limit */
+#define EPSILON 0.01
+
+#define KBYTE 1024
+#define MBYTE (KBYTE*KBYTE)
+
+pid_t child_pid; /* pid of the child process */
+
+double cpu_timeoutdouble = 5.0;
+struct rlimit cpu_timeout = {5,5}; /* max cpu time (seconds) */
+struct rlimit max_nofile = {64,64}; /* max number of open files */
+struct rlimit max_fsize = {128*MBYTE,128*MBYTE}; /* max filesize */
+
+struct rlimit max_data = {128*MBYTE, 128*MBYTE}; /* max data segment size */
+struct rlimit max_core = {0, 0}; /* max core file size */
+struct rlimit max_rss = {128*MBYTE, 128*MBYTE}; /* max resident set size */
+
+struct rlimit max_processes = {64,64}; /* max number of processes */
+
+
+int real_timeout = 30; /* max real time (seconds) */
+
+int dochroot = 0, st=1;
+int nruns = 1;
+int allproc;
+int killallproc;
+int bequiet;
+int checknchild;
+int user, group;
+const char vers[] = "1.5.1";
+
+#define BUFFSIZE 256
+char curdir[BUFFSIZE], rootdir[BUFFSIZE], saida[BUFFSIZE], entrada[BUFFSIZE], erro[BUFFSIZE];
+
+struct Proc {
+ int uid, pid, ppid, gid, group;
+ unsigned long utime, stime;
+ long cutime, cstime;
+ unsigned long starttime;
+ unsigned long vsize;
+ long rss;
+ long resident, share, text, lib, data;
+};
+
+unsigned int getprocs(pid_t ppid, pid_t ppid2, int userid, int groupid, int *nchild, struct Proc **Pr);
+
+void exitandkill(int ret) {
+ if(killallproc) {
+ if(!bequiet)
+ fprintf(stderr,"safeexec: killing all recent processes from this user/group to avoid possible malicious code... use -K if you don't want this\n");
+ struct Proc *P;
+ unsigned n;
+ int nchild, i;
+ if((n = getprocs(child_pid,getpid(),user,group,&nchild,&P)) > 0) {
+ for(i = 0; i < n; i++) {
+ if(!bequiet)
+ fprintf(stderr,"safeexec: killing processes pid=%d\n", P[i].pid);
+ kill(P[i].pid,9); /* kill children and all processes with userid/groupid that started after us if instructed to do so */
+ }
+ }
+ }
+ switch(ret) {
+ case 8: fprintf(stderr,"safeexec: security threat because strange processes\n"); break;
+ case 7: fprintf(stderr,"safeexec: memory limit exceeded\n"); break;
+ case 5: fprintf(stderr,"safeexec: parameter problem\n"); break;
+ case 6:
+ case 4: fprintf(stderr,"safeexec: ERROR! internal error\n"); break;
+ case 3: fprintf(stderr,"safeexec: time limit exceeded\n"); break;
+ case 2: fprintf(stderr,"safeexec: runtime error\n"); break;
+ case 9: fprintf(stderr,"safeexec: runtime error\n"); break;
+ }
+ exit(ret);
+}
+
+unsigned int getprocs(pid_t ppid, pid_t ppid2, int userid, int groupid, int *nchild, struct Proc **Pr) {
+ const int SIZE=10000;
+ char a[SIZE], b[SIZE];
+ unsigned long pidtime=0;
+ glob_t globbuf;
+ unsigned int i, j, k, ki, oldi, n;
+ FILE *tn;
+ struct stat sstat;
+ struct Proc *P, Ptmp;
+
+ glob("/proc/[0-9]*", GLOB_NOSORT, NULL, &globbuf);
+
+ P = calloc(globbuf.gl_pathc, sizeof(struct Proc));
+ if (P == NULL) {
+ if(!bequiet) fprintf(stderr,"safeexec: problem with malloc");
+ exitandkill(4);
+ }
+ *Pr = P;
+
+ for (i = j = 0; i < globbuf.gl_pathc; i++) {
+ snprintf(a, sizeof(a)-1, "%s%s",
+ globbuf.gl_pathv[globbuf.gl_pathc - i - 1], "/stat");
+ snprintf(b, sizeof(b)-1, "%s%s",
+ globbuf.gl_pathv[globbuf.gl_pathc - i - 1], "/statm");
+#ifdef DEBUG
+ fprintf(stderr,"[opening %s and %s]\n", a,b);
+#endif
+ tn = fopen(b, "r");
+ if (tn == NULL) continue; /* process vanished since glob() */
+ n = fread(b, 1, SIZE, tn);
+ fclose(tn);
+ tn = fopen(a, "r");
+ if (tn == NULL) continue; /* process vanished since glob() */
+ n = fread(a, 1, SIZE, tn);
+ fstat(fileno(tn), &sstat);
+ P[j].uid = sstat.st_uid;
+ P[j].gid = sstat.st_gid;
+ fclose(tn);
+
+ sscanf(a, "%d %*s %*s %d %d %*s %*s %*s %*s %*s %*s %*s %*s %lu %lu %ld %ld %*s %*s %*s %*s %lu %lu %ld",
+ &P[j].pid,&P[j].ppid,&P[j].group,&P[j].utime,&P[j].stime,&P[j].cutime,&P[j].cstime,&P[j].starttime,&P[j].vsize,&P[j].rss);
+ sscanf(b, "%*s %ld %ld %ld %ld %ld",
+ &P[j].resident,&P[j].share,&P[j].text,&P[j].lib,&P[j].data);
+ if(P[j].pid == ppid2) pidtime = P[j].starttime;
+#ifdef DEBUG
+ fprintf(stderr,"[check %d,%d,%d,%ld]", P[j].pid, P[j].ppid, P[j].gid, P[j].rss);
+#endif
+ j++;
+ }
+
+ i = 0;
+ oldi = 1;
+ *nchild = 0;
+ while(i != oldi) {
+ oldi = i;
+ for(k = i; k < j; ++k) {
+ if(P[k].pid != ppid) {
+ for(ki = 0; ki < i; ++ki)
+ if(P[k].ppid == P[ki].pid) {
+ break;
+ }
+ if(ki >= i) {
+ continue;
+ }
+ }
+ Ptmp = P[i];
+ P[i] = P[k];
+ P[k] = Ptmp;
+ ++i;
+ }
+ }
+ *nchild = i;
+ while(i < j) {
+ if(P[i].uid != userid || P[i].gid != groupid || P[i].starttime < pidtime || P[i].pid==ppid2) {
+ P[i] = P[--j];
+ } else {
+ if(!bequiet)
+ fprintf(stderr,"safeexec: process %d has user %d, group %d, time %lu, which is suspicious\n",P[i].pid,userid,groupid,P[i].starttime);
+ i++;
+ }
+ }
+ globfree(&globbuf);
+ return i;
+}
+
+int testsystem(pid_t p, pid_t pp, int userid, int groupid, double memlim, double rsslim) {
+ struct rusage uso;
+ getrusage(RUSAGE_CHILDREN, &uso);
+ double mem1=0., mem2=0.;
+ struct Proc *P;
+ unsigned n, i;
+ int ret = 1, nchild;
+ n = getprocs(p,pp,userid,groupid,&nchild,&P);
+ if(checknchild) {
+ if(nchild != n) {
+ if(!bequiet) {
+ fprintf(stderr,"\nsafeexec: %d children of this user/group, but list has %d processes (who are the others?).\n",nchild,n);
+ fprintf(stderr,"safeexec: detached children found! Aborting because of possible malicious code... use -a if you don't want this\n");
+ }
+ exitandkill(8);
+ }
+ }
+ if(n > 0) {
+ for(i = 0; i < n; i++) {
+#ifdef DEBUG
+ fprintf(stderr,"\ndata+stack:%ld, rss:%ld, exe:%ld\n", P[i].data,P[i].rss,P[i].lib+P[i].text+P[i].share);
+#endif
+ mem2 += (P[i].lib+P[i].text+P[i].share+P[i].data)*getpagesize(); // in pages
+ mem1 += P[i].rss*getpagesize();
+ }
+#ifdef DEBUG
+ fprintf(stderr,"\nTOTAL rss:%lf, data+stack+exe:%lf\n", mem1, mem2);
+#endif
+ if(mem2 > memlim || mem1 > rsslim) {
+ if(!bequiet)
+ fprintf(stderr,"\nsafeexec: memory limit exceeded\n");
+ exitandkill(7);
+ }
+ if(nchild == 0) ret = 2;
+ } else {
+ mem1 = ((uso.ru_maxrss+uso.ru_ixrss+uso.ru_idrss+uso.ru_isrss));
+// fprintf(stderr,"WARNING: controlling only waited-for children! Security issues here if code is not trustful...\n");
+ if(mem1 > memlim) {
+ if(!bequiet)
+ fprintf(stderr,"\nsafeexec: memory limit exceeded of %lfMB\n",memlim/1048576.);
+ exitandkill(7);
+ }
+ ret = 0;
+ }
+ free(P);
+ return ret;
+}
+
+char timekill=0;
+
+/* alarm handler */
+void handle_alarm(int sig) {
+ static int iter=0;
+#ifdef DEBUG
+ fprintf(stderr,"parent alarmed\n");
+#endif
+ testsystem(child_pid,getpid(),allproc?user:-1,allproc?group:-1,max_data.rlim_max,max_rss.rlim_max);
+ if(++iter >= real_timeout) {
+ if(!bequiet)
+ fprintf(stderr, "safeexec: timed-out (realtime) after %d seconds\n", real_timeout);
+ fflush(stderr);
+ timekill=1;
+ kill(child_pid,9); /* kill child */
+ exitandkill(3);
+ }
+ alarm(1); /* set alarm and wait for child execution */
+}
+
+
+void usage(int argc, char **argv) {
+ fprintf(stderr, "safeexec version %s\nusage: %s [ options ] cmd [ arg1 arg2 ... ]\n", vers, argv[0]);
+ fprintf(stderr, "available options are:\n");
+ fprintf(stderr, "\t-c <max core file size> (default: %d)\n",
+ (int) max_core.rlim_max);
+ fprintf(stderr, "\t-f <max file size> (default: %d kbytes)\n",
+ (int) (max_fsize.rlim_max/1024.));
+ fprintf(stderr, "\t-F <max number of files> (default: %d)\n",
+ (int) max_nofile.rlim_max);
+ fprintf(stderr, "\t-d <max process memory> (default: %d kbytes)\n",
+ (int) (max_data.rlim_max/1024.));
+ fprintf(stderr, "\t-m <max process resident memory> (default: %d kbytes)\n",
+ (int) (max_rss.rlim_max/1024.));
+ fprintf(stderr, "\t-u <max number of child procs> (default: %d)\n",
+ (int) max_processes.rlim_max);
+ fprintf(stderr, "\t-t <max cpu time> (default: %d secs)\n",
+ (int) cpu_timeout.rlim_max);
+ fprintf(stderr, "\t-T <max real time> (default: %d secs)\n",
+ (int) real_timeout);
+ fprintf(stderr, "\t-C <actual directory> (default: cwd)\n");
+ fprintf(stderr, "\t-R <root directory> (default: none)\n");
+ fprintf(stderr, "\t-n <chroot it?> (default: %d)\n", dochroot);
+ fprintf(stderr, "\t-r <number of runs?> (default: %d)\n", nruns);
+ fprintf(stderr, "\t-i <standard input file> (default: not defined)\n");
+ fprintf(stderr, "\t-o <standard output file> (default: not defined)\n");
+ fprintf(stderr, "\t-e <standard error file> (default: not defined)\n");
+ fprintf(stderr, "\t-U <user id> (default: %d)\n", user);
+ fprintf(stderr, "\t-G <group id> (default: %d)\n", group);
+ fprintf(stderr, "\t-p <show spent time?> (default: %d)\n", st);
+ fprintf(stderr, "\t-a disable checking all processes (look only to the non-detached children) (default %s)\n", allproc?"enabled":"disabled");
+ fprintf(stderr, "\t-s disable checking existence of detached children (default %s)\n", checknchild?"enabled":"disabled");
+ fprintf(stderr, "\t-K disable killing all processes with user/group id after us (default %s)\n", killallproc?"enabled":"disabled");
+ fprintf(stderr, "\t-q be quiet (default %s)\n", bequiet?"enabled":"disabled");
+/*******
+Note that currently Linux does not support strong memory usage limits, so we have
+to enforce it by checking the amount of memory periodically
+********/
+}
+
+int main(int argc, char **argv) {
+ int status, opt, ret=0;
+ time_t ini;
+ int currun = 0;
+ struct stat sstat;
+ double dt;
+ setvbuf(stderr, NULL, _IONBF, 0);
+ entrada[0] = saida[0] = erro[0] = rootdir[0] = curdir[0] = 0;
+ user = group = -1;
+ allproc = 1;
+ checknchild=1;
+ killallproc=1;
+ bequiet=0;
+
+ if(argc>1 && !strcmp("--help", argv[1])) {
+ usage(argc,argv);
+ exit(5);
+ }
+
+ /* parse command-line options */
+ getcwd(curdir, BUFFSIZE); /* default: use cwd as rootdir */
+ while( (opt=getopt(argc,argv,"qKar:c:d:m:f:F:t:T:u:n:i:o:e:C:R:G:U:p:s")) != -1 ) {
+ switch(opt) {
+ case 'q': bequiet=1;
+ break;
+ case 'a': allproc=0;
+ break;
+ case 'K': killallproc=0;
+ break;
+ case 's':
+ checknchild=0;
+ break;
+ case 'c': max_core.rlim_max = max_core.rlim_cur = atoi(optarg);
+ break;
+ case 'f': max_fsize.rlim_max = max_fsize.rlim_cur = KBYTE*atoi(optarg);
+ break;
+ case 'F': max_nofile.rlim_max = max_nofile.rlim_cur = atoi(optarg);
+ break;
+ case 'd': max_data.rlim_max = max_data.rlim_cur = KBYTE*atoi(optarg);
+ break;
+ case 'm': max_rss.rlim_max = max_rss.rlim_cur = KBYTE*atoi(optarg);
+ break;
+ case 't': cpu_timeout.rlim_max = cpu_timeout.rlim_cur = 1 + ((int) atof(optarg));
+ cpu_timeoutdouble = atof(optarg);
+ break;
+ case 'T': real_timeout = atoi(optarg);
+ break;
+ case 'u': max_processes.rlim_max = max_processes.rlim_cur = atoi(optarg);
+ break;
+ case 'U': user = atoi(optarg);
+ break;
+ case 'r': nruns = atoi(optarg);
+ break;
+ case 'G': group = atoi(optarg);
+ break;
+ case 'R': strncpy(rootdir, optarg, 255); /* root directory */
+ rootdir[255]=0;
+ break;
+ case 'C': strncpy(curdir, optarg, 255); /* root directory */
+ curdir[255]=0;
+ break;
+ case 'i': strncpy(entrada, optarg, 255);
+ entrada[255]=0;
+ break;
+ case 'o': strncpy(saida, optarg, 255);
+ saida[255]=0;
+ break;
+ case 'e': strncpy(erro, optarg, 255);
+ erro[255]=0;
+ break;
+ case 'n': dochroot = atoi(optarg);
+ break;
+ case 'p': st = atoi(optarg);
+ break;
+ case '?': usage(argc,argv);
+ exit(5);
+ }
+ }
+
+ if(optind >= argc) { /* no more arguments */
+ usage(argc,argv);
+ exit(5);
+ }
+
+ if(dochroot && chroot(rootdir)) {
+ fprintf(stderr,"ERROR %s\n",strerror(errno));
+ fprintf(stderr,"%s: unable to chroot to directory %s\n",
+ argv[0], rootdir);
+ exit(4);
+ }
+ /* change the root directory (ZP: and working dir, in not root)*/
+ if(curdir[0] && chdir(curdir)) {
+ fprintf(stderr,"ERROR %s\n",strerror(errno));
+ fprintf(stderr,"%s: unable to change directory to %s\n",
+ argv[0], curdir);
+ exit(4);
+ }
+
+ stat(".", &sstat);
+ if(user == -1) {
+ user = (int) sstat.st_uid;
+ if(!bequiet) {
+ fprintf(stderr, "Security note: if the sub-code is not trustful, it shall be run with a different user from the one running safeexec.\
+Use -U and -G for that, but you might need to have root privilegies.\n");
+ }
+ }
+ if(group == -1)
+ group = (int) sstat.st_gid;
+ if(user == 0 || group == 0) {
+ fprintf(stderr, "ERROR: safeexec shall not be instructed to run the sub-code as root\n");
+ exit(4);
+ }
+
+ time(&ini);
+ dt = 0.;
+// int iter=0;
+ doagain:
+ if((child_pid=fork())) {
+ struct rusage uso;
+ /* ------------------- parent process ----------------------------- */
+ if(currun == 0) {
+ setrlimit(RLIMIT_CORE, &max_core);
+ }
+ currun++;
+ if(!bequiet)
+ fprintf(stderr,"safeexec: starting the job. Parent controller has pid %d, child is %d...\n",getpid(),child_pid);
+ alarm(1); /* set alarm and wait for child execution */
+ signal(SIGALRM, handle_alarm);
+ while(waitpid(child_pid, &status, 0) != child_pid) ;
+ if(timekill) exitandkill(3);
+
+ testsystem(child_pid,getpid(),allproc?user:-1,allproc?group:-1,max_data.rlim_max,max_rss.rlim_max);
+
+ getrusage(RUSAGE_CHILDREN, &uso);
+ dt = uso.ru_utime.tv_sec+(double)uso.ru_utime.tv_usec/1000000.0+
+ uso.ru_stime.tv_sec+(double)uso.ru_stime.tv_usec/1000000.0;
+// printf("user runnning time: %.4lf\n",uso.ru_utime.tv_sec+(double)uso.ru_utime.tv_usec/1000000.0);
+// printf("system runnning time: %.4lf\n",uso.ru_stime.tv_sec+(double)uso.ru_stime.tv_usec/1000000.0);
+// printf("total runnning time: %.4lf\n",dt);
+
+ if (dt >= cpu_timeoutdouble) {
+// printf ("utsec=%d utusec=%d stsec=%d stusec=%d\n", uso.ru_utime.tv_sec, uso.ru_utime.tv_usec, uso.ru_stime.tv_sec, uso.ru_stime.tv_usec);
+ if(!bequiet)
+ fprintf(stderr, "safeexec: timed-out (cputime) after %.2lf seconds\n", cpu_timeoutdouble);
+ fflush(stderr);
+// fprintf(stdout, "timed-out (cputime) after %d seconds\n", cpu_timeoutint);
+// fflush(stdout);
+ exitandkill(3);
+ }
+
+ // check if child got an uncaught signal error & reproduce it in parent
+ if(WIFSIGNALED(status)) {
+ fprintf (stderr, "safeexec: RUN-TIME SIGNAL REPORTED BY THE PROGRAM %s: %d\n", argv[optind], WTERMSIG(status));
+ fflush(stderr);
+// raise(WTERMSIG(status));
+ exitandkill(2);
+ }
+
+ if(WIFEXITED(status)) {
+ if(WEXITSTATUS(status)) {
+ ret = WEXITSTATUS(status)+10;
+ if(!bequiet)
+ fprintf (stderr, "safeexec: PROGRAM EXITED WITH NONZERO CODE %s: %d\n",
+ argv[optind], ret-10);
+ } else ret = 0;
+ } else {
+ fprintf (stderr, "safeexec: PROGRAM TERMINATED ABNORMALLY %s\n",
+ argv[optind]);
+ exitandkill(9);
+ }
+
+ if(currun < nruns) goto doagain;
+
+ // otherwise just report the exit code:
+ if (st) fprintf (stderr, "safeexec: TOTAL TIME RUNNING %s: %u sec (%lf sec)\n", argv[optind], (unsigned int) (time(NULL)-ini), dt);
+ exitandkill(ret);
+ } else {
+ /* ------------------- child process ------------------------------ */
+#ifdef DEBUG
+ fprintf(stderr,"child started\n");
+#endif
+ /* change the group id to 'nobody' */
+ if(setgid(group)<0) {
+ fprintf(stderr,"ERROR %s\n",strerror(errno));
+ fprintf(stderr, "%s: unable to change gid to %d\n", argv[0], group);
+ exit(4);
+ }
+ /* change the user id to 'nobody' */
+ if(setuid(user)<0) {
+ fprintf(stderr,"ERROR %s\n",strerror(errno));
+ fprintf(stderr, "%s: unable to change uid to %d\n", argv[0], user);
+ exit(4);
+ }
+
+ if(currun==nruns-1) {
+ if (saida[0]) freopen(saida, "w", stdout);
+ if (erro[0]) freopen(erro, "w", stderr);
+ } else {
+ freopen("/dev/null", "w", stdout);
+ freopen("/dev/null", "w", stderr);
+ }
+ if (entrada[0]) freopen(entrada, "r", stdin);
+
+ /* attempt to change the hard limits */
+ /*******Note that currently Linux does not support memory usage limits********/
+
+ cpu_timeout.rlim_max+=1; cpu_timeout.rlim_cur+=1;
+
+ if( setrlimit(RLIMIT_CPU, &cpu_timeout) ||
+ setrlimit(RLIMIT_DATA, &max_data) ||
+ setrlimit(RLIMIT_STACK, &max_data) ||
+ setrlimit(RLIMIT_CORE, &max_core) ||
+ setrlimit(RLIMIT_RSS, &max_rss) ||
+ setrlimit(RLIMIT_FSIZE, &max_fsize) ||
+ setrlimit(RLIMIT_NOFILE, &max_nofile) ||
+ setrlimit(RLIMIT_NPROC, &max_processes) ) {
+ fprintf(stderr,"ERROR %s\n",strerror(errno));
+ fprintf(stderr, "%s: can't set hard limits\n", argv[0]);
+ exit(6);
+ }
+
+ /* attempt to exec the child process */
+ if(execv(argv[optind],&argv[optind]) < 0) {
+ fprintf(stderr,"ERROR %s\n",strerror(errno));
+ fprintf(stderr, "%s: unable to exec %s\n", argv[0], argv[optind]);
+ exit(6);
+ }
+ }
+ return 0;
+}
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