Threading library calls _pre before the fork, allowing the rtld to
lock itself to ensure that other threads of the process are out of
dynamic linker. _post releases the locks.
This allows the rtld to have consistent state in the child. Although
child may legitimately call only async-safe functions, the call may
need plt relocation resolution, and this requires working rtld.
Reported and debugging help by: rink
Reviewed by: kan, davidxu
MFC after: 1 month (anyway, not before 7.1 is out)
contexts as rtld's malloc is not thread safe and is only supposed to be
called with exclusive bind lock already held.
The originating PR submitted a patch on top of different pre-requisite
workaroud for unsafe dlopen calls, and the patch was midief slighlty to apply
to stock sources for the purpose of this commit. Running rtld malloc from
unlocked contexts is a bug on its own.
PR: 126950
Submited by: Oleg Dolgov
programs.
From the PR description:
The gcc runtime's _Unwind_Find_FDE function, invoked during exception
handling's stack unwinding, is not safe to execute from within multiple
threads. FreeBSD' s dl_iterate_phdr() however permits multiple threads
to pass through it though. The result is surprisingly reliable infinite
looping of one or more threads if they just happen to be unwinding at
the same time.
Introduce the new lock that is write locked around the dl_iterate_pdr,
thus providing required exclusion for the stack unwinders.
PR: threads/123062
Submitted by: Andy Newman <an at atrn org>
Reviewed by: kan
MFC after: 2 weeks
This code came from the merged mips2 and Juniper mips repositories.
Warner Losh, Randall Seager, Oleksandr Tymoshenko and Olivier Houchard
worked to merge, debug and integrate this code. This code may also
contain code derived from NetBSD.
potentially dangerous environment variables all together. It should be
noted that the run-time linker will not honnor these environment variables
if the process is tainted currently. However, once a child of the tainted
process calls setuid(2), it's status as being tainted (as defined by
issetugid(2)) will be removed. This could be problematic because
subsequent activations of the run-time linker could honnor these
dangerous variables.
This is more of an anti foot-shot mechanism, there is nothing I am
aware of in base that does this, however there may be third party
utilities which do, and there is no real negative impact of clearing
these environment variables.
Discussed on: secteam
Reviewed by: cperciva
PR: kern/109836
MFC after: 2 weeks
main object list, its versioning information needs to be examined
separately.
This hopefully fixes problems that people running with SYMVER_ENABLED
are experiencing.
activate the traces, set the LD_UTRACE (or LD_32_UTRACE) environment
variable. This also includes code in kdump(8) to parse the traces.
Reviewed by: kan, jdp
MFC after: 2 weeks
dso that are actually loading. If dso a.so depends on b.so, then dlsym
with handle from dlopen("b.so") will fail unconditionally.
Correct implementation shall use the Obj_Entry.needed list to walk
dependencies DAG.
Test provided by: jkim
Tested (prev. version) by: jkim, Nicolas Blais <nb_root at videotron ca>, h.blanke at chello nl
Pointy hat to: kib
Approved by: kan (mentor)
given as dso handle, but also in the implicit dependencies of that dso.
Also, const-ify the read-only parameter objlist of symlook_list.
Reported by: "Simon 'corecode' Schubert" <corecode at fs ei tum de>
Approved by: kan (mentor)
X-MFC-After: 6.2
oldest versioned symbol available. Do not accept hidden symbols for
all other versions.
Use "<obj->path>: <error message>" for all error messages in new
functions to make them more consistent.
to be compatible with symbol versioning support as implemented by
GNU libc and documented by http://people.redhat.com/~drepper/symbol-versioning
and LSB 3.0.
Implement dlvsym() function to allow lookups for a specific version of
a given symbol.
means:
o Remove Elf64_Quarter,
o Redefine Elf64_Half to be 16-bit,
o Redefine Elf64_Word to be 32-bit,
o Add Elf64_Xword and Elf64_Sxword for 64-bit entities,
o Use Elf_Size in MI code to abstract the difference between
Elf32_Word and Elf64_Word.
o Add Elf_Ssize as the signed counterpart of Elf_Size.
MFC after: 2 weeks
we included the length of the path in the returned size but not the length
of the associated Dl_serpath structure. Without this fix, programs
attempting to allocate a structure to hold the search path information
would allocate too small of a buffer and rtld would overrun the buffer
while filling it via a subsequent RTLD_DI_SERINFO request.
Submitted by: "William K. Josephson" wkj at morphisms dot net
Reviewed by: jdp
MFC after: 2 weeks
are initialised to zero. When freeing TLS, don't attempt to free DTV
slots which were not used.
Pointed out by: Joerg Sonnenberger
X-MFC-After: After the branch, probably
LD_LIBMAP_DISABLE, LD_LIBRARY_PATH) are used, then make sure the
libraries being loaded aren't on a noexec-mounted filesystem.
This is a compromise position: I'm assuming that nobody will be silly
enough to set the noexec mount flag on part of the default library
path, in order to avoid adding extra overhead into the common case
(where those environment variables aren't used).
Discussed with: csjp, secteam
MFC after: 1 week
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
(and that is for now being worked around by a binutils patch).
The rtld code tested &_DYNAMIC against 0 to see whether rtld itself
was built as PIC or not. While the sparc64 MD code did not rely
on the preset value of the GOT slot for _DYNAMIC any more due
to previous binutils changes, it still used to not be 0, so
that this check did work. The new binutils do however initialize
this slot with 0. As a consequence, rtld would not properly initialize
itself and crash.
Fix that by introducing a new macro, RTLD_IS_DYNAMIC, to take the role
of this test. For sparc64, it is implemented using the rtld_dynamic()
code that was already there. If an architecture does not provide its
own implementation, we default to the old check.
While being there, mark _DYNAMIC as a weak symbol in the sparc64
rtld_start.S. This is needed in the LDSCRIPT case, which is however
not currently supported for want of an actual ldscript.
Sanity checked with md5 on alpha, amd64, i386 and ia64.
that this provokes. "Wherever possible" means "In the kernel OR NOT
C++" (implying C).
There are places where (void *) pointers are not valid, such as for
function pointers, but in the special case of (void *)0, agreement
settles on it being OK.
Most of the fixes were NULL where an integer zero was needed; many
of the fixes were NULL where ascii <nul> ('\0') was needed, and a
few were just "other".
Tested on: i386 sparc64
(libmap available) and 1 for failure. Assign this return to the
global 'libmap_disable' variable in rtld.c.
This totally prevents any libmap functions from being called after
lm_init() if no config file is present.
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.
implementation in case default one provided by rtld is
not suitable.
Consolidate various identical MD lock implementation into
a single file using appropriate machine/atomic.h.
Approved by: re (scottl)
