similar to the same token in glibc.
Requested and reviewed by: bapt
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D37329
to ignore lack of execute permission on the binary. The check is a
bad security theatre anyway.
Reviewed by: arichardson, imp
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D32464
The current lookup prefers a strong definition to a STB_WEAK definition
(similar to glibc pre-2.2 behavior) which does not conform to the ELF
specification.
The non-compliant behavior provoked https://reviews.llvm.org/D4418
which was intended to fix -shared-libasan but introduced
new problems (and caused some sanitizer tests (e.g.
test/asan/TestCases/interception_failure_test.cpp) to fail): sanitizer
interceptors are STB_GLOBAL instead of STB_WEAK, so defining a second
STB_GLOBAL interceptor can lead to a multiple definition linker error.
For example, in a -fsanitize={address,memory,...} build, libc functions
like malloc/free/strtol/... cannot be provided by user object files.
See
https://docs.freebsd.org/cgi/getmsg.cgi?fetch=16483939+0+archive/2014/freebsd-current/20140716.freebsd-current
for discussions.
This patch implements the ELF-compliant behavior when LD_DYNAMIC_WEAK is
set. STB_WEAK wrestling in symbol lookups in `Search the dynamic linker
itself` are untouched.
Reviewed by: kib
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D26352
dl_iterate_phdr() dlpi_tls_data should provide the TLS module segment
address, and not the TLS init segment address as it does now.
Reported by: emacsray@gmail.com
PR: 254774
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
The new PRELOAD_FDS variable accepts a list of file descriptors
that should be loaded into the process.
This may be used to optimize a loading process - in the case when
we already have a file descriptor to the library; we don't have
to look into multiple PATH to find it.
It may also be used in capability mode to load a single additional
library without the need to open a directory that contains it.
The last use of this functionality t may be a race-free method
of loading libraries.
Reviewed by: kib, markj
Differential Revision: https://reviews.freebsd.org/D29334
- whitespace at end of input line
- skipping paragraph macro: Pp at the end of Sh
- new sentence, new line
- consider using OS macro: Fx
- AUTHORS section without An macro
- skipping paragraph macro: Pp before Ss
It is wrong to relate on __FreeBSD_version, either from
include/param.h, kernel, or libc, to check for rtld features.
Rtld might be from newer world than the running userspace.
Add special private symbols exported by rtld itself, to indicate the
changes in runtime behavior, and features that cannot be otherwise
detected or deduced at runtime.
Note that the symbols are not exported from libc, so they intentionally
cannot be linked against, and exported from the private namespace from rtld.
Consumers are required to use dlsym(3). For instance, for
_rtld_version_laddr_offset, user should do
ptr = dlsym(RTLD_DEFAULT, "_rtld_version_laddr_offset")
or even
ptr = dlvsym(RTLD_DEFAULT, "_rtld_version_laddr_offset",
"FBSDprivate_1.0");
Non-null ptr means that the change is present.
Also add _rtld_version__FreeBSD_version indicator to report the
headers version used at time of the rtld build.
Reviewed by: jhb
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D24982
Reviewed by: emaste, jonathan (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D10826
When I originally documented the LD_LIBRARY_PATH_FDS environment variable,
I used `.Ev` rather than `.It Ev` to introduce it; this led to the
documentation being embedded in the previous paragraph (LD_LIBRARY_PATH).
From the manpage:
When set to a nonempty string, prevents modifications of the PLT slots
when doing bindings. As result, each call of the PLT-resolved
function is resolved. In combination with debug output, this provides
complete account of all bind actions at runtime.
Same feature exists on Linux and Solaris.
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
This variable allows the loading of shared libraries via directory descriptors
rather than via library paths. If LD_LIBRARY_PATH_FDS=3:4:12, the directories
represented by file descriptors 3, 4 and 12 will searched for shared libraries
before the normal path-based mechanisms are used. This allows us to execute
unprivileged binaries from within a Capsicum sandbox even if they require
shared libraries.
Approved by: rwatson (mentor)
Reviewed by: kib
MFC after: 3 weeks
Sponsored by: DARPA/AFRL
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
filters are implemented.
Filtees are loaded on demand, unless LD_LOADFLTR environment variable
is set or -z loadfltr was specified during the linking. This forces
rtld to upgrade read-locked rtld_bind_lock to write lock when it
encounters an object with filter during symbol lookup.
Consolidate common arguments of the symbol lookup functions in the
SymLook structure. Track the state of the rtld locks in the
RtldLockState structure. Pass local RtldLockState through the rtld
symbol lookup calls to allow lock upgrades.
Reviewed by: kan
Tested by: Mykola Dzham <i levsha me>, nwhitehorn (powerpc)
the rtld hints file. This environment variable would be unset if the
process is considered as tainted with setuid/setgid. This feature gives
a convenient way of using a custom set of shared library that is not
located in the default location and switch back.
Feature requested by: iXsystems
Original patch by: John Hixson
MFC after: 2 weeks
Another handy libmap patch. Lets you do stuff like this:
LD_LIBMAP="libpthread.so.1=libthr.so.1" mythreadedapp
If you already have a program-specific override in libmap.conf, note
that you must use a program-specific override in LD_LIBMAP:
LD_LIBMAP="[mythreadedapp],libpthread.so.1=libthr.so.1" mythreadedapp
PR: bin/74471
Submitted by: Dan Nelson <dnelson AT allantgroup.com>
MFC after: 2 weeks
Setting the LD_DUMP_REL_PRE or LD_DUMP_REL_POST environment variables
cause rtld-elf to output a table of all relocations.
This is useful for debugging.
This is an optional feature, disabled by default.
This will be useful to people testing the various POSIX threading
libraries under -CURRENT but can easily serve other needs.
