Don't trust closefrom() on Linux.

glibc's closefrom implementation does not work in a chroot when the kernel
does not have close_range.  It tries to read from /proc/self/fd and when
that fails dies with an assertion of sorts.  Instead, call close_range
ourselves from our compat code and fall back if that fails.  bz#3349,
with william.wilson at canonical.com and fweimer at redhat.com.
This commit is contained in:
Darren Tucker 2021-11-10 12:34:25 +11:00
parent eb1f63195a
commit 10b899a15c
2 changed files with 8 additions and 1 deletions

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@ -839,6 +839,7 @@ main() { if (NSVersionOfRunTimeLibrary("System") >= (60 << 16))
dnl Target SUSv3/POSIX.1-2001 plus BSD specifics.
dnl _DEFAULT_SOURCE is the new name for _BSD_SOURCE
CPPFLAGS="$CPPFLAGS -D_XOPEN_SOURCE=600 -D_BSD_SOURCE -D_DEFAULT_SOURCE"
AC_DEFINE([BROKEN_CLOSEFROM], [1], [broken in chroots on older kernels])
AC_DEFINE([PAM_TTY_KLUDGE], [1],
[Work around problematic Linux PAM modules handling of PAM_TTY])
AC_DEFINE([LOCKED_PASSWD_PREFIX], ["!"],
@ -1820,6 +1821,7 @@ AC_CHECK_FUNCS([ \
cap_rights_limit \
clock \
closefrom \
close_range \
dirfd \
endgrent \
err \

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@ -16,7 +16,7 @@
#include "includes.h"
#ifndef HAVE_CLOSEFROM
#if !defined(HAVE_CLOSEFROM) || defined(BROKEN_CLOSEFROM)
#include <sys/types.h>
#include <sys/param.h>
@ -130,6 +130,11 @@ closefrom(int lowfd)
DIR *dirp;
int len;
#ifdef HAVE_CLOSE_RANGE
if (close_range(lowfd, INT_MAX, 0) == 0)
return;
#endif
/* Check for a /proc/$$/fd directory. */
len = snprintf(fdpath, sizeof(fdpath), "/proc/%ld/fd", (long)getpid());
if (len > 0 && (size_t)len < sizeof(fdpath) && (dirp = opendir(fdpath))) {