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#include <u.h>
#include <libc.h>
#include <auth.h>
static int debug;
static void
binderr(char *new, char *old, int flag)
{
char dash[4] = { '-' };
if(debug){
if(flag & MCREATE){
dash[2] = 'c';
flag &= ~MCREATE;
}
switch(flag){
case MREPL:
dash[0] = ' ';
if(dash[2] == 'c')
dash[1] = '-';
else
dash[1] = ' ';
break;
case MBEFORE:
dash[1] = 'b';
break;
case MAFTER:
dash[1] = 'a';
break;
}
print("bind %s %s %s\n", dash, new, old);
}
if(bind(new, old, flag) < 0)
sysfatal("bind: %r");
}
static void
resolvenames(char **names, int nname)
{
int i;
char buf[8192];
int fd;
fd = open(".", OREAD|OCEXEC);
if(fd < 0)
sysfatal("could not open .: %r");
fd2path(fd, buf, sizeof buf);
for(i = 0; i < nname; i++){
if(names[i] == nil)
continue;
cleanname(names[i]);
switch(names[i][0]){
case '#':
case '/':
break;
default:
names[i] = cleanname(smprint("%s/%s", buf, names[i]));
}
}
close(fd);
}
static void
sandbox(char **names, int *flags, int nname)
{
char *parts[32];
char rootskel[128];
char src[8192], targ[8192], dir[8192], skel[8192];
char name[8192];
char *newroot;
Dir *d;
int i, j, n;
snprint(rootskel, sizeof rootskel, "#zd/newroot.%d", getpid());
binderr(rootskel, "/", MBEFORE);
newroot = rootskel + strlen("#zd");
for(j = 0; j < nname; j++){
if(names[j] == nil)
continue;
utfecpy(name, &name[sizeof name-1], names[j]);
n = gettokens(name, parts, nelem(parts), "/");
utfecpy(targ, &targ[sizeof targ-1], newroot);
memset(src, 0, sizeof src);
for(i = 0; i < n; i++){
utfecpy(dir, &dir[sizeof dir-1], targ);
snprint(targ, sizeof targ, "%s/%s", targ, parts[i]);
snprint(src, sizeof src, "%s/%s", src, parts[i]);
d = dirstat(targ);
if(d != nil){
free(d);
continue;
}
d = dirstat(src);
if(d == nil)
continue;
if(d->mode & DMDIR)
snprint(skel, sizeof skel, "#zd/%s", parts[i]);
else
snprint(skel, sizeof skel, "#zf/%s", parts[i]);
free(d);
binderr(skel, dir, MBEFORE);
}
binderr(names[j], targ, flags[j]);
}
binderr(newroot, "/", MREPL);
}
void
usage(void)
{
fprint(2, "usage %s: [ -d ] [ -r file ] [ -c dir ] [ -e devs ] cmd args...\n", argv0);
exits("usage");
}
void
main(int argc, char **argv)
{
char *b;
Dir *d;
char devs[1024];
int dfd;
char *parts[256];
int mflags[256];
int nparts;
nparts = 0;
memset(devs, 0, sizeof devs);
ARGBEGIN{
case 'd':
debug = 1;
break;
case 'r':
parts[nparts] = EARGF(usage());
mflags[nparts++] = MREPL;
break;
case 'c':
parts[nparts] = EARGF(usage());
mflags[nparts++] = MCREATE|MREPL;
break;
case 'e':
snprint(devs, sizeof devs, "%s%s", devs, EARGF(usage()));
break;
default:
usage();
break;
}ARGEND
if(argc == 0)
usage();
b = argv[0];
d = dirstat(b);
if(d == nil){
b = smprint("/bin/%s", b);
d = dirstat(b);
if(d == nil)
sysfatal("could not stat %s %r", argv[0]);
}
free(d);
parts[nparts] = b;
mflags[nparts++] = MREPL;
argv[0] = b;
rfork(RFNAMEG|RFENVG);
dfd = open("/dev/drivers", OWRITE|OCEXEC);
if(dfd < 0)
sysfatal("could not /dev/drivers: %r");
resolvenames(parts, nparts);
if(procsetuser("none") < 0)
sysfatal("cant become none: %r");
putenv("user", "none");
sandbox(parts, mflags, nparts);
if(debug)
print("chdev %s\n", devs);
if(devs[0] != '\0'){
if(fprint(dfd, "chdev & %s", devs) <= 0)
sysfatal("could not write chdev: %r");
} else {
if(fprint(dfd, "chdev ~") <= 0)
sysfatal("could not write chdev: %r");
}
close(dfd);
exec(argv[0], argv);
}
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