This is currently an opt-in build flag. Once ASLR support is ready and stable
it should changed to opt-out and be enabled by default along with ASLR.
Each application Makefile uses opt-out to ensure that ASLR will be enabled by
default in new directories when the system is compiled with PIE/ASLR. [2]
Mark known build failures as NO_PIE for now.
The only known runtime failure was rtld.
[1] http://www.bsdcan.org/2014/schedule/events/452.en.html
Submitted by: Shawn Webb <lattera@gmail.com>
Discussed between: des@ and Shawn Webb [2]
mode. This allows the binder to be functional in the child after the
fork (assuming no lazy loading of a filter is needed), but other rtld
services which require write lock on rtld_bind_lock cause deadlock, if
called by child.
Change the _rtld_atfork() to lock the bind lock in write mode, making
the rtld fully functional after the fork.
Pre-resolve the symbols which are called by the libthr' fork()
interposer, since dynamic resolution causes deadlock due to the
rtld_bind_lock already owned in the write mode.
Reported and tested by: pho
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
_rtld_debug_postinit(). [1]
- Use __compiler_membar() instead of inline asm in _r_debug_state() and
_r_debug_postinit(). [2]
Pointy hat to: markj [1]
Reported by: attilio [2]
Discussed with: kib
X-MFC-With: r265456
the victim process before its entry point is called, at which point probes
and DOF data are registered with the kernel. The r_debug_state hook cannot
be used for this purpose, as it is called before the program's init routines
are invoked and in particular before DOF data is registered (via drti.o).
Reviewed by: kib
MFC after: 2 weeks
first calls mmap() with the arguments PROT_NONE and MAP_ANON to reserve a
single, contiguous range of virtual addresses for the entire shared library.
Later, rtld calls mmap() with the the shared library's file descriptor
and the argument MAP_FIXED to place the text and data sections within the
reserved range. The rationale for mapping shared libraries in this way is
explained in the commit message for Revision 190885. However, this approach
does have an unintended, negative consequence. Since the first call to
mmap() specifies MAP_ANON and not the shared library's file descriptor, the
kernel has no idea what alignment the vm object backing the file prefers.
As a result, the reserved range's alignment is unlikely to be the same as
the vm object's, and so mapping with superpages becomes impossible. To
address this problem, this revision adds the argument MAP_ALIGNED_SUPER to
the first call to mmap() if the text section is larger than the smallest
superpage size.
To determine if the text section is larger than the smallest superpage
size, rtld must always fetch the page size information. As a result, the
private code for fetching the base page size in rtld's builtin malloc is
redundant. Eliminate it. Requested by: kib
Tested by: zbb (on arm)
Reviewed by: kib (an earlier version)
Discussed with: jhb
Some modules do not align data at least to size of pointer, they uses a
smaller alignment, but our pointer should be aligned to its native
boundary, otherwise on some platforms, hardware alignment checking
will cause bus error.
saving the pointer will overwrite bytes belongs to another memory block
unexpectly, to fix the problem, use (allocated address + sizeof(void *)) as
initial value, and slip to next aligned address, so maximum extra bytes is
sizeof(void *) + align - 1.
Tested by: Andre Albsmeier < mail at ma17 dot ata dot myota dot orgndre >
the max required alignment for the static tls segments, and honor it
when carving the pieces for next module, from the static space. Use
aligned allocator to get properly-aligned dynamic blocks.
Reported by: dt71@gmx.com
Reviewed by: kan
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
On MIPS the .dynamic section is read-only, so the pointer to rtld
information for debuggers cannot be stored there (in DT_DEBUG).
Instead, a special section .rld_map is used.
Sponsored by: DARPA, AFRL
Approved by: re (delphij)
available in 32-bit compatibility mode, unconditional.
Overhaul the man page, which had evolved more by accretion than by design.
Approved by: re (gjb)
MFC after: 3 weeks
PATH_MAX after the token substitution. This is wrong, because
origin_subst_one() performs the substitution on the whole rpath and
similar strings, which contain several pathes separated by colon. As
result, long (but correct) rpath consisting of many path elements is
rejected by the function.
Correct the problem by rewriting the origin_subst_one() to perform two
passes, first pass to calculate the number of substitutions to be
performed, and second pass to generate the resulting string. Second
pass allocates the memory for the result based on the count from the
first pass, without enforcing a limit.
Reported and tested by: pgj
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Normal libraries have base address 0 and are unaffected by this change.
PR: 176216
Submitted by: Damjan Jovanovic <damjan.jov@gmail.com>
Reviewed by: kib
MFC after: 1 week
instead of /libexec/ld-elf.so.1. Below in the Makefile we execute
'chflags noschg ${DESTDIR}/usr/libexec/ld-elf.so.1', which follows
symlink and removes 'schg' flag from system's /libexec/ld-elf.so.1
instead of the one in DESTDIR. It is also more friendly to use
replative paths in symlink in case of jail/chroot environments.
Obtained from: WHEEL Systems
MFC after: 2 weeks
Rtld did not set FD_CLOEXEC on its internal file descriptors; therefore,
such a file descriptor may be passed to a process created by another thread
running in parallel to dlopen() or fdlopen().
No other threads are expected to be running during parsing of the hints
and libmap files but the file descriptors need not be passed to child
processes so add O_CLOEXEC there as well.
This change will break fdlopen() (as used by OpenPAM) on kernels without
F_DUPFD_CLOEXEC (added in July). Note that running new userland on old
kernels is not supported.
Reviewed by: kib
The place where the function is called can be reached if object loading
and relocation fails too, in which case obj pointer will be NULL. Do not
call process_nodelete then, or crash will follow.
Pointy hat to: kan
Trying to up the reference from the load loop risks missing dependencies
that have not been loaded yet.
MFC afer: 1 week
Reported by: nox
Reviewd by: kib
This is not strictly required with the current ABI but will be when we
switch to the ARM EABI. The aapcs requires the stack to be 4 byte aligned
at all times and 8 byte aligned when calling a public subroutine where the
current ABI only requires sp to be a multiple of 4.
by John Marino <draco@marino.st>, with the following (edited) commit
message
Date: Sat, 24 Mar 2012 06:40:50 +0100
Subject: [PATCH 1/1] rtld: Implement DT_RUNPATH and -z nodefaultlib
DT_RUNPATH is incorrectly being considered as an alias of DT_RPATH. The
purpose of DT_RUNPATH is to have two different types of rpath: one that
can be overridden by the environment variable LD_LIBRARY_PATH and one that
can't. With the currently implementation, LD_LIBRARY_PATH will always
trump any embedded rpath or runpath tags.
Current path search order by rtld:
==================================
LD_LIBRARY_PATH
DT_RPATH / DT_RUNPATH (always the same)
ldconfig hints file (default: /var/run/ld-elf.so.hints)
/usr/lib
New path search order by rtld:
==============================
DT_RPATH of the calling object if no DT_RUNPATH
DT_RPATH of the main binary if no DT_RUNPATH and binary isn't calling obj
LD_LIBRARY_PATH
DT_RUNPATH
ldconfig hints file
/usr/lib
The new path search matches how the linux runtime loader works. The other
major added feature is support for linker flag "-z nodefaultlib". When
this flag is passed to the linker, rtld will skip all references to the
standard library search path ("/usr/lib" in this case but it could handle
more color delimited paths) except in DT_RPATH and DT_RUNPATH.
New path search order by rtld with -z nodefaultlib flag set:
============================================================
DT_RPATH of the calling object if no DT_RUNPATH
DT_RPATH of the main binary if no DT_RUNPATH and binary isn't calling obj
LD_LIBRARY_PATH
DT_RUNPATH
ldconfig hints file (skips all references to /usr/lib)
FreeBSD notes:
- we fixed some bugs which were submitted to DragonFly and merged there
as commit 1ff8a2bd3eb6e5587174c6a983303ea3a79e0002;
- we added LD_LIBRARY_PATH_RPATH environment variable to switch to
the previous behaviour of considering DT_RPATH a synonym for DT_RUNPATH;
- the FreeBSD default search path is /lib:/usr/lib and not /usr/lib.
Reviewed by: kan
MFC after: 1 month
MFC note: flip the ld_library_path_rpath default value for stable/9
relocations are performed before the object's initializer is called.
When dlopen()ing an object, relocate the whole DAG rooted in the
object instead of only relocating the object itself and list of newly
loaded dependencies.
Reversed sequence currently can occur if the same object is a
dependency for both filtee and filter, since filtees are loaded
typically during the relocation processing, when some filter
dependencies might be already loaded but not relocated yet.
Reported and tested by: swills
Reviewed by: kan
MFC after: 1 week
object, and eliminate the pread(2) call as well [1]. Mmap the first
page of the object temporaly, and unmap it on error or last use.
Potentially, this leaves one-page gap between succeeding dlopen(3),
but there are other mmap(2) consumers as well.
Fix several cases were the whole mapping of the object leaked on error.
Use MAP_PREFAULT_READ for mmap(2) calls which map real object pages [2].
Insipired by the patch by: Ian Lepore <freebsd damnhippie dyndns org> [1]
Suggested by: alc [2]
MFC after: 2 weeks
object for which digest_dynamic1() was not done yet. Just return
EINVAL and do not try to dereference NULL buckets hash array.
This seems to happen on ia64 for rtld object itself, where the
R_IA_64_FPTR64LSB relocations require symbol lookup. The dynamic
linker itself does not rely on identity of the C-level function
pointers (i.e. function descriptors).
Reported and reviewed by: marcel
MFC after: 8 days
include <file>:
Parse the contents of file before continuing with the current file.
includedir <dir>:
Parse the contents of every file in dir that ends in .conf before continuing
with the current file.
Any file or directory encountered while processing include or includedir
directives will be parsed exactly once, even if it is encountered multiple
times.
Reviewed by: kib, des
Approved by: des (mentor)
MFC after: 1 month
hash elements, and a helper matched_symbol() which match the given hash
entry and request, performing needed type and version checks.
Based on dragonflybsd support for GNU hash by John Marino <draco marino st>
Reviewed by: kan
Tested by: bapt
MFC after: 2 weeks
through the filter loading call chain. This fixes attempts to
write-lock the already locked rtld_bind_lock when filter loading is
initiated by relocation of dlopening dso.
Reported and tested by: Taku YAMAMOTO <taku tackymt homeip net>
MFC after: 1 week
