Currently, DT_TEXTREL is incompatible with IFUNC. When DT_TEXTREL or
DF_TEXTREL is seen, the dynamic linker calls __mprotect on the segments
with PROT_READ|PROT_WRITE before applying dynamic relocations. It leads
to segfault when performing IFUNC resolution (which requires PROT_EXEC
as well for the IFUNC resolver).
This patch makes it call __mprotect with extra PROT_WRITE bit, which
will keep the PROT_EXEC bit if exists, and thus fixes the segfault.
FreeBSD rtld libexec/rtld-elf/rtld.c (reloc_textrel_prot) does the same.
Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
sparc64-linux-gnu, sparcv9-linux-gnu, and armv8-linux-gnueabihf.
Adam J. Richte <adam_richter2004@yahoo.com>
Adhemerval Zanella <adhemerval.zanella@linaro.org>
Fangrui Song <maskray@google.com>
[BZ #20480]
* config.h.in (CAN_TEXTREL_IFUNC): New define.
* configure.ac: Add check if linker supports textrel relocation with
ifunc.
* elf/dl-reloc.c (_dl_relocate_object): Use all required flags on
DT_TEXTREL segments, not only PROT_READ and PROT_WRITE.
* elf/Makefile (ifunc-pie-tests): Add tst-ifunc-textrel.
(CFLAGS-tst-ifunc-textrel.c): New rule.
* elf/tst-ifunc-textrel.c: New file.
posix/wordexp-test.c used libc-internal.h for PTR_ALIGN_DOWN; similar
to what was done with libc-diag.h, I have split the definitions of
cast_to_integer, ALIGN_UP, ALIGN_DOWN, PTR_ALIGN_UP, and PTR_ALIGN_DOWN
to a new header, libc-pointer-arith.h.
It then occurred to me that the remaining declarations in libc-internal.h
are mostly to do with early initialization, and probably most of the
files including it, even in the core code, don't need it anymore. Indeed,
only 19 files actually need what remains of libc-internal.h. 23 others
need libc-diag.h instead, and 12 need libc-pointer-arith.h instead.
No file needs more than one of them, and 16 don't need any of them!
So, with this patch, libc-internal.h stops including libc-diag.h as
well as losing the pointer arithmetic macros, and all including files
are adjusted.
* include/libc-pointer-arith.h: New file. Define
cast_to_integer, ALIGN_UP, ALIGN_DOWN, PTR_ALIGN_UP, and
PTR_ALIGN_DOWN here.
* include/libc-internal.h: Definitions of above macros
moved from here. Don't include libc-diag.h anymore either.
* posix/wordexp-test.c: Include stdint.h and libc-pointer-arith.h.
Don't include libc-internal.h.
* debug/pcprofile.c, elf/dl-tunables.c, elf/soinit.c, io/openat.c
* io/openat64.c, misc/ptrace.c, nptl/pthread_clock_gettime.c
* nptl/pthread_clock_settime.c, nptl/pthread_cond_common.c
* string/strcoll_l.c, sysdeps/nacl/brk.c
* sysdeps/unix/clock_settime.c
* sysdeps/unix/sysv/linux/i386/get_clockfreq.c
* sysdeps/unix/sysv/linux/ia64/get_clockfreq.c
* sysdeps/unix/sysv/linux/powerpc/get_clockfreq.c
* sysdeps/unix/sysv/linux/sparc/sparc64/get_clockfreq.c:
Don't include libc-internal.h.
* elf/get-dynamic-info.h, iconv/loop.c
* iconvdata/iso-2022-cn-ext.c, locale/weight.h, locale/weightwc.h
* misc/reboot.c, nis/nis_table.c, nptl_db/thread_dbP.h
* nscd/connections.c, resolv/res_send.c, soft-fp/fmadf4.c
* soft-fp/fmasf4.c, soft-fp/fmatf4.c, stdio-common/vfscanf.c
* sysdeps/ieee754/dbl-64/e_lgamma_r.c
* sysdeps/ieee754/dbl-64/k_rem_pio2.c
* sysdeps/ieee754/flt-32/e_lgammaf_r.c
* sysdeps/ieee754/flt-32/k_rem_pio2f.c
* sysdeps/ieee754/ldbl-128/k_tanl.c
* sysdeps/ieee754/ldbl-128ibm/k_tanl.c
* sysdeps/ieee754/ldbl-96/e_lgammal_r.c
* sysdeps/ieee754/ldbl-96/k_tanl.c, sysdeps/nptl/futex-internal.h:
Include libc-diag.h instead of libc-internal.h.
* elf/dl-load.c, elf/dl-reloc.c, locale/programs/locarchive.c
* nptl/nptl-init.c, string/strcspn.c, string/strspn.c
* malloc/malloc.c, sysdeps/i386/nptl/tls.h
* sysdeps/nacl/dl-map-segments.h, sysdeps/x86_64/atomic-machine.h
* sysdeps/unix/sysv/linux/spawni.c
* sysdeps/x86_64/nptl/tls.h:
Include libc-pointer-arith.h instead of libc-internal.h.
* elf/get-dynamic-info.h, sysdeps/nacl/dl-map-segments.h
* sysdeps/x86_64/atomic-machine.h:
Add multiple include guard.
In _dl_nothread_init_static_tls() and init_one_static_tls() we must not
touch the DTV of other threads since we do not have ownership of them.
The DTV need not be initialized at this point anyway since only LD/GD
accesses will use them. If LD/GD accesses occur they will take care to
initialize their own thread's DTV.
Concurrency comments were removed from the patch since they need to be
reworked along with a full description of DTV ownership and when it is
or is not safe to modify these structures.
Alexandre Oliva's original patch and discussion:
https://sourceware.org/ml/libc-alpha/2016-09/msg00512.html
An earlier fix for TLS dropped early initialization of DTV entries for
modules using static TLS, leaving it for __tls_get_addr to set them
up. That worked on platforms that require the GD access model to be
relaxed to LE in the main executable, but it caused a regression on
platforms that allow GD in the main executable, particularly in
statically-linked programs: they use a custom __tls_get_addr that does
not update the DTV, which fails when the DTV early initialization is
not performed.
In static programs, __libc_setup_tls performs the DTV initialization
for the main thread, but the DTV of other threads is set up in
_dl_allocate_tls_init, so that's the fix that matters.
Restoring the initialization in the remaining functions modified by
this patch was just for uniformity. It's not clear that it is ever
needed: even on platforms that allow GD in the main executable, the
dynamically-linked version of __tls_get_addr would set up the DTV
entries, even for static TLS modules, while updating the DTV counter.
for ChangeLog
[BZ #19826]
* elf/dl-tls.c (_dl_allocate_tls_init): Restore DTV early
initialization of static TLS entries.
* elf/dl-reloc.c (_dl_nothread_init_static_tls): Likewise.
* nptl/allocatestack.c (init_one_static_tls): Likewise.
In a reference to PR ld/19908 make ld.so respect symbol export classes
aka visibility and treat STV_HIDDEN and STV_INTERNAL symbols as local,
preventing such symbols from preempting exported symbols.
According to the ELF gABI[1] neither STV_HIDDEN nor STV_INTERNAL symbols
are supposed to be present in linked binaries:
"A hidden symbol contained in a relocatable object must be either
removed or converted to STB_LOCAL binding by the link-editor when the
relocatable object is included in an executable file or shared object."
"An internal symbol contained in a relocatable object must be either
removed or converted to STB_LOCAL binding by the link-editor when the
relocatable object is included in an executable file or shared object."
however some GNU binutils versions produce such symbols in some cases.
PR ld/19908 is one and we also have this note in scripts/abilist.awk:
so clearly there is linked code out there which contains such symbols
which is prone to symbol table misinterpretation, and it'll be more
productive if we handle this gracefully, under the Robustness Principle:
"be liberal in what you accept, and conservative in what you produce",
especially as this is a simple (STV_HIDDEN|STV_INTERNAL) => STB_LOCAL
mapping.
References:
[1] "System V Application Binary Interface - DRAFT - 24 April 2001",
The Santa Cruz Operation, Inc., "Symbol Table",
<http://www.sco.com/developers/gabi/2001-04-24/ch4.symtab.html>
* sysdeps/generic/ldsodefs.h
(dl_symbol_visibility_binds_local_p): New inline function.
* elf/dl-addr.c (determine_info): Treat hidden and internal
symbols as local.
* elf/dl-lookup.c (do_lookup_x): Likewise.
* elf/dl-reloc.c (RESOLVE_MAP): Likewise.
A shared object doesn't need PLT if there are no PLT relocations. It
shouldn't be an error if DT_PLTRELSZ is missing.
[BZ #18410]
* elf/dl-reloc.c (_dl_relocate_object): Don't issue an error
for missing DT_PLTRELSZ.
for ChangeLog
[BZ #17090]
[BZ #17620]
[BZ #17621]
[BZ #17628]
* NEWS: Update.
* elf/dl-tls.c (_dl_update_slotinfo): Clean up outdated DTV
entries with Static TLS too. Skip entries past the end of the
allocated DTV, from Alan Modra.
(tls_get_addr_tail): Update to glibc_likely/unlikely. Move
Static TLS DTV entry set up from...
(_dl_allocate_tls_init): ... here (fix modid assertion), ...
* elf/dl-reloc.c (_dl_nothread_init_static_tls): ... here...
* nptl/allocatestack.c (init_one_static_tls): ... and here...
* elf/dlopen.c (dl_open_worker): Drop l_tls_modid upper bound
for Static TLS.
* elf/tlsdeschtab.h (map_generation): Return size_t. Check
that the slot we find is associated with the given map before
using its generation count.
* nptl_db/db_info.c: Include ldsodefs.h.
(rtld_global, dtv_slotinfo_list, dtv_slotinfo): New typedefs.
* nptl_db/structs.def (DB_RTLD_VARIABLE): New macro.
(DB_MAIN_VARIABLE, DB_RTLD_GLOBAL_FIELD): Likewise.
(link_map::l_tls_offset): New struct field.
(dtv_t::counter): Likewise.
(rtld_global): New struct.
(_rtld_global): New rtld variable.
(dl_tls_dtv_slotinfo_list): New rtld global field.
(dtv_slotinfo_list): New struct.
(dtv_slotinfo): Likewise.
* nptl_db/td_symbol_list.c: Drop gnu/lib-names.h include.
(td_lookup): Rename to...
(td_mod_lookup): ... this. Use new mod parameter instead of
LIBPTHREAD_SO.
* nptl_db/td_thr_tlsbase.c: Include link.h.
(dtv_slotinfo_list, dtv_slotinfo): New functions.
(td_thr_tlsbase): Check DTV generation. Compute Static TLS
addresses even if the DTV is out of date or missing them.
* nptl_db/fetch-value.c (_td_locate_field): Do not refuse to
index zero-length arrays.
* nptl_db/thread_dbP.h: Include gnu/lib-names.h.
(td_lookup): Make it a macro implemented in terms of...
(td_mod_lookup): ... this declaration.
* nptl_db/db-symbols.awk (DB_RTLD_VARIABLE): Override.
(DB_MAIN_VARIABLE): Likewise.
We are replacing all of the bespoke alignment code with
ALIGN_UP, ALIGN_DOWN, PTR_ALIGN_UP, and PTR_ALIGN_DOWN.
This cleans up malloc/malloc.c, malloc/arena.c, and
elf/dl-reloc.c. It also makes all the code consistently
use pagesize, and powerof2 as required.
Code size is reduced with the removal of precomputed
pagemask, and use of pagesize instead. No measurable
difference in performance.
No regressions on x86_64.
During auditing or profiling modes the dynamic loader
builds a cache of the relocated PLT entries in order
to reuse them when called again through the same PLT
entry. This way the PLT entry is never completed and
the call into the resolver always results in profiling
or auditing code running.
The problem is that the PLT relocation cache size
is not computed correctly. The size of the cache
should be "Size of a relocation result structure"
x "Number of PLT-related relocations". Instead the
code erroneously computes "Size of a relocation
result" x "Number of bytes worth of PLT-related
relocations". I can only assume this was a mistake
in the understanding of the value of DT_PLTRELSZ
which is the number of bytes of PLT-related relocs.
We do have a DT_RELACOUNT entry, which is a count
for dynamic relative relocs, but we have no
DT_PLTRELCOUNT and thus we need to compute it.
This patch corrects the computation of the size of the
relocation table used by the glibc profiling code.
For more details see:
https://sourceware.org/ml/libc-alpha/2014-09/msg00513.html
[BZ #17411]
* elf/dl-reloc.c (_dl_relocate_object): Allocate correct amount for
l_reloc_result.
Resolves: #15465
The program name may be unavailable if the user application tampers
with argc and argv[]. Some parts of the dynamic linker caters for
this while others don't, so this patch consolidates the check and
fallback into a single macro and updates all users.
* elf/dl-load.c (_dl_map_object_from_fd): Only call audit hooks
if we are not loading a new audit library.
* elf/dl-reloc (_dl_relocate_object): Third parameter is now a bitmask.
Only use profiling trampoline for auditing if we are not relocating
an audit library.
* elf/dl-open.c (dl_open_worker): Adjust _dl_relocate_object call.
* elf/rtld.c: Likewise.
* sysdeps/generic/ldsodefs.h: Adjust _dl_relocate_object prototype.
* elf/dl-close.c (_dl_close): Check for it.
* elf/dl-reloc.c (CHECK_STATIC_TLS): Likewise.
(_dl_allocate_static_tls): Likewise.
* elf/dl-tls.c (_dl_allocate_tls_init): Likewise.
(__tls_get_addr): Protect from race conditions in setting l_tls_offset
to it.
* elf/tst-tls16.c: New file.
* elf/tst-tlsmod16a.c: New file.
* elf/tst-tlsmod16b.c: New file.
* elf/Makefile: Add rules to build and run tst-tls16.
* elf/dl-reloc.c (_dl_nothread_init_static_tls): Assert that dtv
array index is within bounds.
* elf/dl-load.c: Do not allow PT_TLS in modules loaded in statically
linked code.
* sysdeps/generic/dl-tls.c [!SHARED]: Don't build _dl_next_tls_modid.
* elf/Makefile: Remove rules to build and run tst-tls9-static.
2004-03-06 Ulrich Drepper <drepper@redhat.com>
* elf/dl-lookup.c: We don't need for specialized lookup functions.
Combining the functionality does not slow down relocation processing,
it might even speed it up a little.
* sysdeps/generic/ldsodefs.h: Adjust prototypes for lookup function.
Add only one function pointer to rtlf_global_ro.
* elf/do-lookup.h: Replace #ifs with ifs.
* elf/dl-libc.c: Adjust _dl_lookup_* callers.
* elf/dl-reloc.c: Likewise.
* elf/dl-runtime.c: Likewise.
* elf/dl-sym.c: Likewise.
* elf/rtld.c: Likewise. Adjust _rtld_global_ro initialization.
* sysdeps/generic/ldsodefs.h (__rtld_local_attribute__,
__rtld_global_attribute__): Undef after use.
(_rtld_local_ro): Define __rtld_local_attribute__ with just hidden
if available.
* sysdeps/alpha/Subdirs: New file.
* sysdeps/alpha/soft-fp/Makefile: New file.
* sysdeps/alpha/soft-fp/Versions: New file.
* sysdeps/alpha/soft-fp/local-soft-fp.h: New file.
* sysdeps/alpha/soft-fp/ots_add.c: New file.
* sysdeps/alpha/soft-fp/ots_cmp.c: new file.
* sysdeps/alpha/soft-fp/ots_cmpe.c: New file.
* sysdeps/alpha/soft-fp/ots_cvtqux.c: New file.
* sysdeps/alpha/soft-fp/ots_cvtqx.c: New file.
* sysdeps/alpha/soft-fp/ots_cvttx.c: New file.
* sysdeps/alpha/soft-fp/ots_cvtxq.c: New file.
* sysdeps/alpha/soft-fp/ots_cvtxt.c: New file.
* sysdeps/alpha/soft-fp/ots_div.c: New file.
* sysdeps/alpha/soft-fp/ots_mul.c: New file.
* sysdeps/alpha/soft-fp/ots_nintxq.c: New file.
* sysdeps/alpha/soft-fp/ots_sub.c: New file.
2004-01-13 Ulrich Drepper <drepper@redhat.com>
* Makeconfig: Define relro-LDFLAGS if have-z-relro==yes. Add it to
LDFLAGS.so and LDFLAGS-rtld.
(+link): Add relro-LDFLAGS.
* Makeconfig (shlib.lds): Place __libc_subfreeres, __libc_atexit, and
__libc_thread_subfreeres sections after .jcr section.
* config.make.in: Add have-z-relro.
* configure.in: Add check for -z relro option.
* include/link.h (struct link_map): Add relro_addr and relro_size
members.
* elf/dl-load.c (_dl_map_object_from_fd): Recognize PT_GNU_RELRO.
* elf/dl-reloc.c (_dl_relocate_object): At the end, make relro
part of loaded segments read-only.
* elf/elf.h: Define PT_GNU_RELRO.
* elf/rtld.c (_dl_start): Recognize PT_GNU_RELRO of ld.so.
(dl_main): Recognize PT_GNU_RELRO of the application. Call
_dl_debug_initialize and initialize l_info[DT_DEBUG] before
relocations.
2003-10-01 Thorsten Kukuk <kukuk@suse.de>
* elf/dl-reloc.c (_dl_allocate_static_tls): Move definition of
variables only used if TLS_DTV_AT_TP is defined into the #if branch.
2003-09-27 Wolfram Gloger <wg@malloc.de>
* malloc/malloc.c: Include <malloc-machine.h> earlier instead of
"thread-m.h", so that default parameters can be overridden in a
system-specific malloc-machine.h. Remove extra ; from extern "C"
closing brace.
* sysdeps/generic/malloc-machine.h: New file.
* sysdeps/mach/hurd/malloc-machine.h: New file.
* malloc/thread-m.h: Removed.
* malloc/Makefile: Remove CFLAGS-malloc.c parameter addition, it
is in sysdeps/generic/malloc-machine.h now.
* elf/dl-reloc.c (_dl_allocate_static_tls): Move definition of
variables only used if TLS_TCB_AT_TP is defined into the #if
branch.
2003-07-24 Ulrich Drepper <drepper@redhat.com>
* include/link.h (struct link_map): Add l_tls_firstbyte_offset field.
* sysdeps/generic/dl-tls.c [TLS_TCB_AT_TP] (_dl_determine_tlsoffset):
Fix calculation of offsets to take misalignment of first byte in
file into account.
* elf/dl-load.c (_dl_map_object_from_fd): Initialize
l_tls_firstbyte_offset field.
* elf/rtld.c (_dl_start_final, _dl_start, dl_main): Likewise.
* elf/dl-reloc.c (_dl_allocate_static_tls): Change return type to int.
Take l_tls_firstbyte_offset information into account.
(CHECK_STATIS_TLS): _dl_allocate_static_tls can fail now.
* sysdeps/generic/ldsodefs.h: Adjust _dl_allocate_static_tls prototype.
* elf/Makefile: Add rules to build and run tst-tls14.
* elf/tst-tls14.c: New file.
* elf/tst-tlsmod14a.c: New file.
* elf/tst-tlsmod14b.c: New file.
