chroot doesn't work (with anything)

sydney-troz · 02-26-2007, 07:33 AM

I know there are lots of posts in every Linux forum about getting apache to work with a chroot jail, but my problem is slightly more general: I can't get anything to work with chroot: not even bash.

I followed a howto (http://www.linux.com/article.pl?sid=04/05/24/1450203) for setting up apache, which didn't work, but when I tried copying bash's shared libs and running it in the jail, it didn't work either. This all led me to believe that there was a more fundamental problem here than just apache.

I followed the above page to the letter, so any help would be greatly appreciated.

Thanks,
Syd

unSpawn · 02-26-2007, 10:48 AM

Are there any errors in any of the logs? The HOWTO also says:

Quote:

If something has gone wrong, you should try running your chrooted httpd with strace. The command # strace chroot /chroot/httpd /usr/sbin/httpd 2> httpd.strace redirects the output of strace to a file named httpd.strace which should give you an idea where the problem lies.

. You tried that too?

nx5000 · 02-26-2007, 11:34 AM

Try
strace -f -o /tmp/chroot chroot /chroot /bin/bash

You're not using prelink by any chance? I had some problems with this combined with chroot

sydney-troz · 02-28-2007, 08:23 AM

Here's the strace output for strace chroot /usr/sbin/httpd:

Quote:

execve("/usr/sbin/chroot", ["/usr/sbin/chroot", "/chroot/httpd", "/usr/sbin/httpd"], [/* 28 vars */]) = 0
brk(0) = 0x605000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2aaaaaaab000
uname({sys="Linux", node="localhost.localdomain", ...}) = 0
access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=165946, ...}) = 0
mmap(NULL, 165946, PROT_READ, MAP_PRIVATE, 3, 0) = 0x2aaaaaaac000
close(3) = 0
open("/lib64/libc.so.6", O_RDONLY) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0@\333\301"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1678472, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2aaaaaad5000
mmap(0x32f2c00000, 3461304, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x32f2c00000
mprotect(0x32f2d44000, 2097152, PROT_NONE) = 0
mmap(0x32f2f44000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x144000) = 0x32f2f44000
mmap(0x32f2f49000, 16568, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x32f2f49000
close(3) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x2aaaaaad6000
arch_prctl(ARCH_SET_FS, 0x2aaaaaad6260) = 0
mprotect(0x32f2f44000, 16384, PROT_READ) = 0
mprotect(0x32f1e19000, 4096, PROT_READ) = 0
munmap(0x2aaaaaaac000, 165946) = 0
brk(0) = 0x605000
brk(0x626000) = 0x626000
open("/usr/lib/locale/locale-archive", O_RDONLY) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=55561888, ...}) = 0
mmap(NULL, 55561888, PROT_READ, MAP_PRIVATE, 3, 0) = 0x2aaaaaad7000
close(3) = 0
chroot("/chroot/httpd") = 0
chdir("/") = 0
execve("/usr/sbin/httpd", ["/usr/sbin/httpd"], [/* 28 vars */]) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/locale.alias", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.UTF-8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.utf8/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/coreutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
write(2, "/usr/sbin/chroot: ", 18/usr/sbin/chroot: ) = 18
write(2, "cannot run command `/usr/sbin/ht"..., 36cannot run command `/usr/sbin/httpd') = 36
open("/usr/share/locale/en_US.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US.utf8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.UTF-8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.utf8/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
write(2, ": No such file or directory", 27: No such file or directory) = 27
write(2, "\n", 1
) = 1
close(1) = 0
exit_group(127) = ?
Process 3598 detached

nx5000 · 02-28-2007, 08:28 AM

Quote:

chroot("/chroot/httpd") = 0
chdir("/") = 0
execve("/usr/sbin/httpd", ["/usr/sbin/httpd"], [/* 28 vars */]) = -1 ENOENT (No such file or directory)

/chroot/httpd/usr/sbin/httpd exist?

sydney-troz · 03-05-2007, 06:16 PM

Yes it does.

Sorry it took me so long to reply

nx5000 · 03-07-2007, 07:43 AM

If you are sure about this, then I have a problem to understand what strace says.

From the tutorial, you have done this steps, don't you?
|
|
v

# cp /lib/libsafe* /chroot/httpd/lib/
# cp /lib/libm* /chroot/httpd/lib/
# cp /lib/libcrypt* /chroot/httpd/lib/
# cp /lib/libdb* /chroot/httpd/lib/
# cp /usr/lib/libexpat* /chroot/httpd/usr/lib/
# cp /lib/libdl* /chroot/httpd/lib/
# cp /lib/libc* /chroot/httpd/lib/
# cp /lib/ld-* /chroot/httpd/lib/

Hum.. no real idea otherwise.

There's a tool called makejail I think. Never used it but it is supposed to automate this, give it a try maybe.