chroot() System Call in Linux

NAME

chroot - change root directory

SYNOPSIS

#include <unistd.h> 

int chroot(const char *path); 

DESCRIPTION

chroot() changes the root directory to that specified in path. This directory will be used for pathnames beginning with /. The root directory is inherited by all children of the current process.

Only a privileged process (Linux: one with the CAP_SYS_CHROOT capability) may call chroot(2).This call changes an ingredient in the pathname resolution process and does nothing else.

This call does not change the current working directory, so that after the call ‘.’ can be outside the tree rooted at ‘/’. In particular, the superuser can escape from a ‘chroot jail’ by doing ‘mkdir foo; chroot foo; cd ..’.

This call does not close open file descriptors, and such file descriptors may allow access to files outside the chroot tree.

RETURN VALUE

On success, zero is returned. On error, -1 is returned, and errno is set appropriately.

ERRORS

Depending on the file system, other errors can be returned. The more general errors are listed below:

CONFORMING TO

SVr4, 4.4BSD, SUSv2 (marked LEGACY). This function is not part of POSIX.1-2001.

NOTES

A child process created via fork(2) inherits its parent’s root directory. The root directory is left unchanged by execve(2).

FreeBSD has a stronger jail() system call.

SEE ALSO

• chdir (2)

• path_resolution (2)