one. Search global objects, together with main object and
dependencies, for the requested symbol.
Move the common code from symlook_default() into new helper
symlook_global(), and use it both in symlook_global() and
get_program_var_addr().
Supply lock state to get_program_var_addr().
Reviewed by: kan
Tested by: Mykola Dzham <i levsha me>
by kernel, and parse PT_GNU_STACK phdr from linked and loaded dsos.
If the loaded dso requires executable stack, as specified by PF_X bit
of p_flags of PT_GNU_STACK phdr, but current stack protection does not
permit execution, the __pthread_map_stacks_exec symbol is looked up
and called. It should be implemented in libc or threading library and
change the protection mode of all thread stacks to be executable.
Provide a private interface _rtld_get_stack_prot() to export the stack
access mode as calculated by rtld.
Reviewed by: kan
3DNow, MMX and floating point instructions in rtld-elf.
Otherwise, _rtld_bind() (and whatever it calls) could possibly clobber
function arguments that are passed in SSE/3DNow/MMX/FP registers,
usually floating point values. This can happen, for example, when clang
generates SSE code for memset() or memcpy() calls.
One symptom of this is sshd dying early on amd64 with "PRNG not seeded",
which is ultimately caused by libcrypto.so.6 calling RAND_add() with a
double parameter. That parameter is passed via %xmm0, which gets wiped
out by an SSE memset() in _rtld_bind().
Reviewed by: kib, kan
C function, the caller's stack frame must have room to store all of the
arguments to that function. While here, fix stack frame alignment issues.
Without this change, the compiler will save r3 and r4 into the caller's
stack frame before calling setjmp() in _rtld_bind(). These would then
overwrite arguments to the newly-bound function, causing eventual failures.
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)
dlclose() call may unload the object of the outer call prematurely
because objects are unreferenced before _fini() calls.
Fix this by unreferencing objects after calling objlist_call_fini() in
dlclose(). Therefore objlist_call_fini() now calls the fini function if
the reference count of an object is 1. In addition we must restart the
list_fini traversal after every _fini() call because another dlclose()
call might have modified the reference counts.
Add an XXX comment to objlist_call_fini() about possible race with
dlopen().
PR: 133246, 149464
Reviewed by: kan, kib
loaded as a dependency and marked -z nodlopen, object' DAG is already
initialized by load_needed_objects(). Due to this, the init_dag() call
from dlopen() does not increment refcount for the object [1].
Change init_dag() to not increment DAG refcount. Require explicit calls
to ref_dag() to increment, and assert that ref_dag() and unref_dag()
are called for root that has dag initialized. To fix the noted issue,
unconditionally call both init_dag() and ref_dag() in dlopen() for the
case when the object was already loaded, making it similar to the case
of newly loaded object.
Noted by: jh [1]
Reviewed by: jh, kan
MFC after: 6 days
dependency, then the dso never has its DAG initialized. Empty DAG
makes ref_dag() call in dlopen() a nop, and the dso refcount is off
by one.
Initialize the DAG on the first dlopen() call, using a boolean flag
to prevent double initialization.
From the PR (edited):
Assume we have a library liba.so, containing a function a(), and a
library libb.so, containing function b(). liba.so needs functionality
from libb.so, so liba.so links in libb.so.
An application doesn't know about the relation between these libraries,
but needs to call a() and b(). It dlopen()s liba.so and obtains a
pointer to a(), then it dlopen()s libb.so and obtains a pointer to b().
As soon as the application doesn't need a() anymore, it dlclose()s liba.so.
Expected result: the pointer to b() is still valid and can be called
Actual result: the pointer to b() has become invalid, even though the
application did not dlclose() the handle to libb.so. On calling b(), the
application crashes with a segmentation fault.
PR: misc/151861
Based on patch by: jh
Reviewed by: kan
Tested by: Arjan van Leeuwen <freebsd-maintainer opera com>
MFC after: 1 week
With r169630 I disabled symbol versioning because it broke rtld. With
r211706 rtld got broken for ia64 & powerpc64. It was fixed for powerpc64
with r212497. In between, r211749 removed the exports table because the
version script handled the exports. But wait, symbol versioning was
disabled on ia64.
With exports controlled by the version script and symbol versioning
disabled, all symbols are exported and too many symbols bind to the
definition in rtld. Let's just say that waird things happen.
So, enable symbol versioning on ia64 and apply a work-around for the
SIGSEGV that triggered r169630 to begin with: when rtld relocates
itself, it comes across r_debug_state and for some reason can't find the
definition. This causes a failure, relocation aborts and null pointers
galore. The work-around is to ignore the missing definition when rtld
is relocating itself and keep going.
Maybe with the next binutils this will all go away. Maybe not, in
which case I still need to figure out why r_debug_state cannot be found.
BTW: r_debug_state is in the symbol map -- I don't think any other rtld
symbols that rtld references are in the symbol map...
where long PLT calls in multi-threaded environments could end up with
incorrect jmptab values. The second is that, after the addition of extended
PLT support, I forgot to update the PLT icache synchronization code to cover
the extended PLT instead of just the basic PLT.
MFC after: 10 days
atexit and __cxa_atexit handlers that are either installed by unloaded
dso, or points to the functions provided by the dso.
Use _rtld_addr_phdr to locate segment information from the address of
private variable belonging to the dso, supplied by crtstuff.c. Provide
utility function __elf_phdr_match_addr to do the match of address against
dso executable segment.
Call back into libthr from __cxa_finalize using weak
__pthread_cxa_finalize symbol to remove any atfork handler which
function points into unloaded object.
The rtld needs private __pthread_cxa_finalize symbol to not require
resolution of the weak undefined symbol at initialization time. This
cannot work, since rtld is relocated before sym_zero is set up.
Idea by: kan
Reviewed by: kan (previous version)
MFC after: 3 weeks
Use local version of getpagesize(), rtld_getpagesize() in private allocator.
Override the __getosreldate() previously fetched from libc_pic.a with
local version that uses aux value if present. Note that __getosreldate()
is used by rtld indirectly, by mmap(2) libc wrapper.
To be able to utilize aux, split digest_dynamic() for use by init_rtld()
into two parts, where the first one does not call malloc(), and the
second part uses it. init_rtld() is able to initialize global variables
before digest_dynamic2() calls. In particular, pagesize and osreldate are
set up from the aux values.
Now, rtld avoids (two) sysctl calls in startup.
Tested by: marius (sparc64)
MFC after: 1 month
r211130 in favor of this more general fix.
This fixes a compilation error for mips 64-bit little endian build.
libexec/rtld-elf/mips/reloc.c:196: warning: right shift count >= width of type
Suggested by: stefanf, jchandra, bde
libexec/rtld-elf/mips/reloc.c:196: warning: right shift count >= width of type
When the expression '(r_info) >> 32' was passed to bswap32() it was promptly
changed to '(uint32_t)(r_info) >> 32' which is not what we intended.
and symbol map are required to support various consequences of the dot
symbol scheme:
- Symbols beginning with a dot are reserved, so start private symbols with
an underscore.
- In order to set RTLD breakpoints, gdb must be able to locate the text
entry point, not the data section function descriptor, so add
.r_debug_state to the symbol map on powerpc64.
Obtained from: projects/ppc64
fix for it.
The bug occurs when using the --as-needed flag to ld in the presence of
synthetic linker-generated symbols that reference symbols defined in
linked-to shared libraries with versioned symbols. When the only symbols
used from a library fall into this category, ld will drop the DT_NEEDED
entry for it, but retain the versioning information. This bug is best
fixed/hacked around in binutils, not in rtld.
Discussed with: kan
because calling mmap() etc. may use GOT which is not set up
yet. Use calloc() instead of mmap() in cases where this
was the case before (sparc64, powerpc, arm).
Submitted by: Dimitry Andric (dimitry andric com)
Reviewed by: kan
Approved by: ed (mentor)
o Use obj->tlsinitsize to determine whether there's initialized data.
o If obj->tlssize > obj->tlsinitsize, then bzero uninitialized data.
o Don't exclude variant I from the work-around in free_tls_offset().
Just like bin/ and sbin/, I think setting WARNS to the highest value
possible will make it more attractive for people to fix warnings.
- The WARNS variable is set in the Makefile in the directory of the
application itself, making it more likely that it will be removed out
of curiosity to see what happens.
- New applications will most likely build with WARNS=6 out of the box,
because the author would more likely fix the warnings during
development than lower WARNS.
Unfortunately almost all apps in libexec require a lowered value of
WARNS.
adjustment for all virtual addresses encoded into the ELF structures of
it. PIE binary could and should be loaded at non-zero mapbase.
For sym_zero pseudosymbol used as a return value from find_symdef()
for undefined weak symbols, st_value also should be adjusted, since
_rtld_bind corrects symbol values by relocbase.
Discussed with: bz
Reviewed by: kan
Tested by: bz (i386, amd64), bsam (linux)
MFC after: some time
ELF header from the front of the file. As all other I/O on the binary
is done using mmap(), this avoids the need for seek privileges on the
file descriptor during run-time linking.
MFC after: 1 month
Sponsored by: Google
is not equal to its memory size.
This eliminates unneeded clearing of the text segment that often
happens due to text end not being page-aligned.
For instance,
$ readelf -l /lib/libedit.so.6
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
LOAD 0x000000 0x00000000 0x00000000 0x139e1 0x139e1 R E 0x1000
LOAD 0x014000 0x00014000 0x00014000 0x00f04 0x00f14 RW 0x1000
DYNAMIC 0x014cc4 0x00014cc4 0x00014cc4 0x000d0 0x000d0 RW 0x4
$ procstat -v $$ (for /bin/sh)
68585 0x28097000 0x280aa000 r-x 6 0 21 14 CN vn /lib/libedit.so.6
68585 0x280aa000 0x280ab000 r-x 1 0 1 0 CN vn /lib/libedit.so.6 <==
68585 0x280ab000 0x280ac000 rwx 1 0 1 0 CN vn /lib/libedit.so.6
Note the splitted map entry marked by '<=='.
Reviewed by: kan
Approved by: re (kensmith)
MFC after: 1 month
compiled with stack protector.
Use libssp_nonshared library to pull __stack_chk_fail_local symbol into
each library that needs it instead of pulling it from libc. GCC
generates local calls to this function which result in absolute
relocations put into position-independent code segment, making dynamic
loader do extra work every time given shared library is being relocated
and making affected text pages non-shareable.
Reviewed by: kib
Approved by: re (kib)
Use libssp_nonshared library to pull __stack_chk_fail_local symbol into
each library that needs it instead of pulling it from libc. GCC generates
local calls to this function which result in absolute relocations put into
position-independent code segment, making dynamic loader do extra work everys
time given shared library is being relocated and making affected text pages
non-shareable.
Reviewed by: kib
Approved by: re (kensmith)
altered through their .init code. This might happen if init
vector calls dlopen on its own and that dlopen causes some not
yet initialized object to be initialized earlier as part of that
dlopened DAG.
Do not reset module reference counts to zero on final fini vector
run when process is exiting. Just add an additional parameter to
force fini vector invocation regardless of current reference count
value if object was not destructed yet. This allows dlclose called
from fini vector to proceed normally instead of failing with handle
validation error.
Reviewed by: kib
Reported by: venki kaps
dlsym seaches using this handle are expected to look for symbol
definitions in all objects loaded at the program start time along
with all objects currently in RTLD_GLOBAL scope.
Discussed with: kib
Reported by: Maho NAKATA
MFC after: 2 weeks
for the mapping by the object' file with the protection and mode of
the first loadable segment over the whole region. Then, it maps other
segments at the appropriate addresses inside the region.
On amd64, due to default alignment of the segments being 1Gb, the
subsequent segment mappings leave the holes in the region, that usually
contain mapping of the object' file past eof. Such mappings prevent
wiring of the address space, because the pages cannot be faulted in.
Change the way the mapping of the ELF objects is constructed, by first
mapping PROT_NONE anonymous memory over the whole range, and then
mapping the segments of the object over it. Take advantage of this new
order and allocate .bss by changing the protection of the range instead
of remapping.
Note that we cannot simply keep the holes between segments, because
other mappings may be made there. Among other issues, when the dso is
unloaded, rtld unmaps the whole region, deleting unrelated mappings.
The kernel ELF image activator does put the holes between segments, but
this is not critical for now because kernel loads only executable image
and interpreter, both cannot be unloaded. This will be fixed later, if
needed.
Reported and tested by: Hans Ottevanger <fbsdhackers beasties demon nl>
Suggested and reviewed by: kan, alc
dlfunc() called dlsym() to do the work, and dlsym() determines the dso
that originating the call by the return address. Due to this, dlfunc()
operated as if the caller is always the libc.
To fix this, move the dlfunc() to rtld, where it can call the internal
implementation of dlsym, and still correctly fetch return address.
Provide usual weak stub for the symbol from libc for static binaries.
dlfunc is put to FBSD_1.0 symver namespace in the ld.so export to
override dlfunc@FBSD_1.0 weak symbol, exported by libc.
Reported, analyzed and tested by: Tijl Coosemans <tijl ulyssis org>
PR: standards/133339
Reviewed by: kan
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
soneeded pathes. The $ORIGIN, $OSNAME, $OSREL and $PLATFORM tokens
are supported. Enabling the substitution requires DF_ORIGIN flag in
DT_FLAGS or DF_1_ORIGIN if DF_FLAGS_1, that may be set with -z origin
gnu ld flag. Translation is unconditionally disabled for setuid/setgid
processes.
The $ORIGIN translation relies on the AT_EXECPATH auxinfo supplied
by kernel.
Requested by: maho
Tested by: maho, pho
Reviewed by: kan
does not use any external symbols, thus avoiding possible recursion into
rtld to resolve symbols, when called.
Reviewed by: kan, davidxu
Tested by: rink
MFC after: 1 month
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)
derivitive of NetBSD's mips_reloc.c, so pull in the copyright notice
from there.
Also, a minor tweak to load/store pointers. Other changes from NetBSD
likely would be useful too...
Obtained from: NetBSD
from working.
From p4 filelog of the upstream file in p4
//depot/projects/mips2-jnpr/src/libexec/rtld-elf/mips/reloc.c
... #6 change 140737 edit on 2008/04/27 by gonzo@gonzo_jeeves (text+ko)
o Looks like handler for R_MIPS_REL32 brought by CS 137942
is broken for tradmips. Code from NetBSD's
libexec/ld.elf_so/arch/mips/mips_reloc.c works just fine.
... #3 change 137942 edit on 2008/03/17 by rrs@rrs-mips2-jnpr (text+ko)
Any relocation symbol lookup if its 0. It looks like
this is the way the compiler indicates you need to
look in another shared library. When we hit these
as we relocate a object we will do the symbol
lookups and setup the relocation table with the
right value.
Submitted by: rrs@, gonzo@
bit flag, otherwise if a thread acquired a lock, another thread
or the current thread itself can no longer acquire another lock
because thread_mask_set() return whole flag word, this results
bit leaking in the word and misbehavior in later locking and
unlocking.
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
- It is opt-out for now so as to give it maximum testing, but it may be
turned opt-in for stable branches depending on the consensus. You
can turn it off with WITHOUT_SSP.
- WITHOUT_SSP was previously used to disable the build of GNU libssp.
It is harmless to steal the knob as SSP symbols have been provided
by libc for a long time, GNU libssp should not have been much used.
- SSP is disabled in a few corners such as system bootstrap programs
(sys/boot), process bootstrap code (rtld, csu) and SSP symbols themselves.
- It should be safe to use -fstack-protector-all to build world, however
libc will be automatically downgraded to -fstack-protector because it
breaks rtld otherwise.
- This option is unavailable on ia64.
Enable GCC stack protection (aka Propolice) for kernel:
- It is opt-out for now so as to give it maximum testing.
- Do not compile your kernel with -fstack-protector-all, it won't work.
Submitted by: Jeremie Le Hen <jeremie@le-hen.org>
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.
sparc64, use ANSI function headers and specifically indicate the lack of
arguments with 'void'. Otherwise, warnings are generated at WARNS=3 for
libkse, leading to a compile failure with -Werror.
in the way we implement handling of relocations.
As for the kernel part this fixes the loading of lots of modules,
which failed to load due to unresolvable symbols when built after
the GCC 4.2.0 import. This wasn't due to a change in GCC itself
though but one of several changes in configuration done along the
import. Specfically, HAVE_AS_REGISTER_PSEUDO_OP, which causes GCC
to denote global registers used for scratch purposes and in turn
GAS uses R_SPARC_OLO10 relocations for, is now defined.
While at it replace some more ELF_R_TYPE which should have been
ELF64_R_TYPE_ID but didn't cause problems so far.
- Sync a sanity check between kernel and rtld(1) and change it to be
maintenance free regarding the type used for the lookup table.
- Sprinkle const on lookup tables.
- Use __FBSDID.
Reported and tested by: yongari
MFC after: 5 days
itself. It needs mmap(2), which now needs getosreldate(3) and
which in turn uses a global variable to cache the result. This
cannot be done before linking is done.
See also: ../sparc64/reloc.c:1.15
Approved by: re (kensmith)
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
symbol lookup failures that later result in null-pointer
dereferences. This needs looking into, but since we're
close to release it's possible that it's not resolved before
that time.
Warning, after symbol versioning is enabled, going back is not easy
(use WITHOUT_SYMVER at your own risk).
Change the default thread library to libthr.
There most likely still needs to be a version bump for at least the
thread libraries. If necessary, this will happen later.
to override weak symbols exported by libc, so by definition these two
are using the same symbol version names.
Reflect the reality by referring to libc's Versions.def directly.
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
* Add posix_memalign().
* Move calloc() from calloc.c to malloc.c. Add a calloc() implementation in
rtld-elf in order to make the loader happy (even though calloc() isn't
used in rtld-elf).
* Add _malloc_prefork() and _malloc_postfork(), and use them instead of
directly manipulating __malloc_lock.
Approved by: phk, markm (mentor)
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
Like on libthr, there is an i386_set_gsbase() stub implementation here
to avoid libc.so.5 issues. This should likely be a weak symbol and I
expect this will be fixed soon.
Approved by: re
loads and stores (resp.) The ldq_u and stq_u instruction mask off the
lower 3 bits of the final address before loading from or storing to
the address, so as to avoid unaligned loads and stores. They do not
themselves allow loads from or stores to unaligned addresses. Replace
the macro definitions by a packed struct dereference.
Submitted by: Richard Henderson (rth at twiddle dot net)
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
