The files NEWS, include/link.h, and sysdeps/generic/ldsodefs.h
contribute to the version fingerprint used for detection. The
fingerprint can be further refined using the --with-extra-version-id
configure argument.
_dl_call_libc_early_init is replaced with _dl_lookup_libc_early_init.
The new function is used store a pointer to libc.so's
__libc_early_init function in the libc_map_early_init member of the
ld.so namespace structure. This function pointer can then be called
directly, so the separate invocation function is no longer needed.
The versioned symbol lookup needs the symbol versioning data
structures, so the initialization of libc_map and libc_map_early_init
is now done from _dl_check_map_versions, after this information
becomes available. (_dl_map_object_from_fd does not set this up
in time, so the initialization code had to be moved from there.)
This means that the separate initialization code can be removed from
dl_main because _dl_check_map_versions covers all maps, including
the initial executable loaded by the kernel. The lookup still happens
before relocation and the invocation of IFUNC resolvers, so IFUNC
resolvers are protected from ABI mismatch.
The __libc_early_init function pointer is not protected because
so little code runs between the pointer write and the invocation
(only dynamic linker code and IFUNC resolvers).
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
ELF and GNU hashes can now be computed using the elf_hash and
gnu_hash functions.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
The test is valid for all TLS models, but we want to make a reasonable
effort to test the GNU2 model specifically. For example, aarch64
defaults to GNU2, but does not have -mtls-dialect=gnu2, and the test
was not run there.
Suggested-by: Martin Coufal <mcoufal@redhat.com>
GCC normally does this optimization for us in
strlen_pass::handle_builtin_strcpy but only for optimized
build. To avoid needing to include strcpy.S in the rtld build to
support the debug build, just do the optimization by hand.
The older libc versions are obsolete for over twenty years now.
This patch removes the special flags for libc5 and libc4 and assumes
that all libraries cached are libc6 compatible and use FLAG_ELF_LIBC6.
Checked with a build for all affected architectures.
Co-authored-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Redirect internal assertion failures to __libc_assert_fail, based on
based on __libc_message, which writes directly to STDERR_FILENO
and calls abort. Also disable message translation and reword the
error message slightly (adjusting stdlib/tst-bz20544 accordingly).
As a result of these changes, malloc no longer needs its own
redefinition of __assert_fail.
__libc_assert_fail needs to be stubbed out during rtld dependency
analysis because the rtld rebuilds turn __libc_assert_fail into
__assert_fail, which is unconditionally provided by elf/dl-minimal.c.
This change is not possible for the public assert macro and its
__assert_fail function because POSIX requires that the diagnostic
is written to stderr.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The fix done b2cd93fce6 does not really
work since macro strification does not expand the sizeof nor the
arithmetic operation.
Checked on x86_64-linux-gnu.
NODELETE status is propagated from the referencing object to the
referenced object, not the other way round. The code is correct, only
the log message has the wrong direction.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Using -Werror and -DNDEBUG at the same time will trigger the
following compiler error:
cache.c: In function 'save_cache':
cache.c:758:15: error: unused variable 'old_offset' [-Werror=unused-variable]
758 | off64_t old_offset = lseek64 (fd, extension_offset, SEEK_SET);
| ^~~~~~~~~~
-DNDEBUG disables the assertion, making old_offset unused.
Use __attribute__ ((unused)) to disable this warning.
By adding an internal alias to avoid the GOT indirection.
On some architecture, __libc_single_thread may be accessed through
copy relocations and thus it requires to update also the copies
default copy.
This is done by adding a new internal macro,
libc_hidden_data_{proto,def}, which has an addition argument that
specifies the alias name (instead of default __GI_ one).
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Fangrui Song <maskray@google.com>
If an executable has copy relocations for extern protected data, that
can only work if the library containing the definition is built with
assumptions (a) the compiler emits GOT-generating relocations (b) the
linker produces R_*_GLOB_DAT instead of R_*_RELATIVE. Otherwise the
library uses its own definition directly and the executable accesses a
stale copy. Note: the GOT relocations defeat the purpose of protected
visibility as an optimization, but allow rtld to make the executable and
library use the same copy when copy relocations are present, but it
turns out this never worked perfectly.
ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA has strange semantics when both
a.so and b.so define protected var and the executable copy relocates
var: b.so accesses its own copy even with GLOB_DAT. The behavior change
is from commit 62da1e3b00 (x86) and then
copied to nios2 (ae5eae7cfc) and arc
(0e7d930c4c).
Without ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA, b.so accesses the copy
relocated data like a.so.
There is now a warning for copy relocation on protected symbol since
commit 7374c02b68. It's extremely
unlikely anyone relies on the ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA
behavior, so let's remove it: this removes a check in the symbol lookup
code.
Newer versions of GNU grep (after grep 3.7, not inclusive) will warn on
'egrep' and 'fgrep' invocations.
Convert usages within the tree to their expanded non-aliased counterparts
to avoid irritating warnings during ./configure and the test suite.
Signed-off-by: Sam James <sam@gentoo.org>
Reviewed-by: Fangrui Song <maskray@google.com>
When the first object providing foo defines both foo@v1 and foo@@v2,
dlsym(RTLD_NEXT, "foo") returns foo@v1 while dlsym(RTLD_DEFAULT, "foo")
returns foo@@v2. The issue is that RTLD_DEFAULT uses the
DL_LOOKUP_RETURN_NEWEST flag while RTLD_NEXT doesn't. Fix the RTLD_NEXT
branch to use DL_LOOKUP_RETURN_NEWEST.
Note: the new behavior matches FreeBSD rtld. Future sanitizers will not
need to add versioned interceptors like https://reviews.llvm.org/D96348
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
An __always_inline static function is better to find where exactly a
crash happens, so one can step into the function with GDB.
Reviewed-by: Fangrui Song <maskray@google.com>
Unroll slightly and enforce good instruction scheduling. This improves
performance on out-of-order machines. The unrolling allows for
pipelined multiplies.
As well, as an optional sysdep, reorder the operations and prevent
reassosiation for better scheduling and higher ILP. This commit
only adds the barrier for x86, although it should be either no
change or a win for any architecture.
Unrolling further started to induce slowdowns for sizes [0, 4]
but can help the loop so if larger sizes are the target further
unrolling can be beneficial.
Results for _dl_new_hash
Benchmarked on Tigerlake: 11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz
Time as Geometric Mean of N=30 runs
Geometric of all benchmark New / Old: 0.674
type, length, New Time, Old Time, New Time / Old Time
fixed, 0, 2.865, 2.72, 1.053
fixed, 1, 3.567, 2.489, 1.433
fixed, 2, 2.577, 3.649, 0.706
fixed, 3, 3.644, 5.983, 0.609
fixed, 4, 4.211, 6.833, 0.616
fixed, 5, 4.741, 9.372, 0.506
fixed, 6, 5.415, 9.561, 0.566
fixed, 7, 6.649, 10.789, 0.616
fixed, 8, 8.081, 11.808, 0.684
fixed, 9, 8.427, 12.935, 0.651
fixed, 10, 8.673, 14.134, 0.614
fixed, 11, 10.69, 15.408, 0.694
fixed, 12, 10.789, 16.982, 0.635
fixed, 13, 12.169, 18.411, 0.661
fixed, 14, 12.659, 19.914, 0.636
fixed, 15, 13.526, 21.541, 0.628
fixed, 16, 14.211, 23.088, 0.616
fixed, 32, 29.412, 52.722, 0.558
fixed, 64, 65.41, 142.351, 0.459
fixed, 128, 138.505, 295.625, 0.469
fixed, 256, 291.707, 601.983, 0.485
random, 2, 12.698, 12.849, 0.988
random, 4, 16.065, 15.857, 1.013
random, 8, 19.564, 21.105, 0.927
random, 16, 23.919, 26.823, 0.892
random, 32, 31.987, 39.591, 0.808
random, 64, 49.282, 71.487, 0.689
random, 128, 82.23, 145.364, 0.566
random, 256, 152.209, 298.434, 0.51
Co-authored-by: Alexander Monakov <amonakov@ispras.ru>
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
No change to the code other than moving the function to
dl-new-hash.h. Changed name so its now in the reserved namespace.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
_dl_skip_args is always 0, so the target specific code that modifies
argv after relro protection is applied is no longer used.
After the patch relro protection is applied to _dl_argv consistently
on all targets.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
When an executable is invoked as
./ld.so [ld.so-args] ./exe [exe-args]
then the argv is adujusted in ld.so before calling the entry point of
the executable so ld.so args are not visible to it. On most targets
this requires moving argv, env and auxv on the stack to ensure correct
stack alignment at the entry point. This had several issues:
- The code for this adjustment on the stack is written in asm as part
of the target specific ld.so _start code which is hard to maintain.
- The adjustment is done after _dl_start returns, where it's too late
to update GLRO(dl_auxv), as it is already readonly, so it points to
memory that was clobbered by the adjustment. This is bug 23293.
- _environ is also wrong in ld.so after the adjustment, but it is
likely not used after _dl_start returns so this is not user visible.
- _dl_argv was updated, but for this it was moved out of relro, which
changes security properties across targets unnecessarily.
This patch introduces a generic _dl_start_args_adjust function that
handles the argument adjustments after ld.so processed its own args
and before relro protection is applied.
The same algorithm is used on all targets, _dl_skip_args is now 0, so
existing target specific adjustment code is no longer used. The bug
affects aarch64, alpha, arc, arm, csky, ia64, nios2, s390-32 and sparc,
other targets don't need the change in principle, only for consistency.
The GNU Hurd start code relied on _dl_skip_args after dl_main returned,
now it checks directly if args were adjusted and fixes the Hurd startup
data accordingly.
Follow up patches can remove _dl_skip_args and DL_ARGV_NOT_RELRO.
Tested on aarch64-linux-gnu and cross tested on i686-gnu.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The Linux version used by i686 and m68k provide three overrrides for
generic code:
1. DISTINGUISH_LIB_VERSIONS to print additional information when
libc5 is used by a dependency.
2. EXTRA_LD_ENVVARS to that enabled LD_LIBRARY_VERSION environment
variable.
3. EXTRA_UNSECURE_ENVVARS to add two environment variables related
to aout support.
None are really requires, it has some decades since libc5 or aout
suppported was removed and Linux even remove support for aout files.
The LD_LIBRARY_VERSION is also dead code, dl_correct_cache_id is not
used anywhere.
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
The kernel version check is used to avoid glibc to run on older
kernels where some syscall are not available and fallback code are
not enabled to handle graciously fail. However, it does not prevent
if the kernel does not correctly advertise its version through
vDSO note, uname or procfs.
Also kernel version checks are sometime not desirable by users,
where they want to deploy on different system with different kernel
version knowing the minimum set of syscall is always presented on
such systems.
The kernel version check has been removed along with the
LD_ASSUME_KERNEL environment variable. The minimum kernel used to
built glibc is still provided through NT_GNU_ABI_TAG ELF note and
also printed when libc.so is issued.
Checked on x86_64-linux-gnu.
This implements mmap fallback for a brk failure during TLS
allocation.
scripts/tls-elf-edit.py is updated to support the new patching method.
The script no longer requires that in the input object is of ET_DYN
type.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
When neither DT_HASH nor DT_GNU_HASH is present, the code scans
[DT_SYMTAB, DT_STRTAB). However, there is no guarantee that .dynstr
immediately follows .dynsym (e.g. lld typically places .gnu.version
after .dynsym).
In the absence of a hash table, symbol lookup will always fail
(map->l_nbuckets == 0 in dl-lookup.c) as if the object has no symbol, so
it seems fair for dladdr to do the same.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
__ehdr_start is already used in rltld.c:dl_main, and can serve the
same purpose as _begin. Besides tidying the code, using linker
defined section relative symbols rather than "-defsym _begin=0" better
reflects the intent of _dl_start_final use of _begin, which is to
refer to the load address of ld.so rather than absolute address zero.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
On _dl_map_object the underlying file is not opened in trace mode
(in other cases where the underlying file can't be opened,
_dl_map_object quits with an error). If there any missing libraries
being processed, they will not be considered on final nlist size
passed on _dl_sort_maps later in the function. And it is then used by
_dl_sort_maps_dfs on the stack allocated working maps:
222 /* Array to hold RPO sorting results, before we copy back to maps[]. */
223 struct link_map *rpo[nmaps];
224
225 /* The 'head' position during each DFS iteration. Note that we start at
226 one past the last element due to first-decrement-then-store (see the
227 bottom of above dfs_traversal() routine). */
228 struct link_map **rpo_head = &rpo[nmaps];
However while transversing the 'l_initfini' on dfs_traversal it will
still consider the l_faked maps and thus update rpo more times than the
allocated working 'rpo', overflowing the stack object.
As suggested in bugzilla, one option would be to avoid sorting the maps
for trace mode. However I think ignoring l_faked object does make
sense (there is one less constraint to call the sorting function), it
allows a slight less stack usage for trace, and it is slight simpler
solution.
The tests does trigger the stack overflow, however I tried to make
it more generic to check different scenarios or missing objects.
Checked on x86_64-linux-gnu.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Verify that:
1. A DT_RELR shared library without DT_NEEDED works.
2. A DT_RELR shared library without DT_VERNEED works.
3. A DT_RELR shared library without libc.so on DT_NEEDED works.
With DT_RELR, there may be no relocations in DT_RELA/DT_REL and their
entry values are zero. Don't relocate DT_RELA/DT_REL and update the
combined relocation start address if their entry values are zero.
The EI_ABIVERSION field of the ELF header in executables and shared
libraries can be bumped to indicate the minimum ABI requirement on the
dynamic linker. However, EI_ABIVERSION in executables isn't checked by
the Linux kernel ELF loader nor the existing dynamic linker. Executables
will crash mysteriously if the dynamic linker doesn't support the ABI
features required by the EI_ABIVERSION field. The dynamic linker should
be changed to check EI_ABIVERSION in executables.
Add a glibc version, GLIBC_ABI_DT_RELR, to indicate DT_RELR support so
that the existing dynamic linkers will issue an error on executables with
GLIBC_ABI_DT_RELR dependency. When there is a DT_VERNEED entry with
libc.so on DT_NEEDED, issue an error if there is a DT_RELR entry without
GLIBC_ABI_DT_RELR dependency.
Support __placeholder_only_for_empty_version_map as the placeholder symbol
used only for empty version map to generate GLIBC_ABI_DT_RELR without any
symbols.
PI_STATIC_AND_HIDDEN indicates whether accesses to internal linkage
variables and hidden visibility variables in a shared object (ld.so)
need dynamic relocations (usually R_*_RELATIVE). PI (position
independent) in the macro name is a misnomer: a code sequence using GOT
is typically position-independent as well, but using dynamic relocations
does not meet the requirement.
Not defining PI_STATIC_AND_HIDDEN is legacy and we expect that all new
ports will define PI_STATIC_AND_HIDDEN. Current ports defining
PI_STATIC_AND_HIDDEN are more than the opposite. Change the configure
default.
No functional change.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
When audit modules are loaded, ld.so initialization is not yet
complete, and rtld_active () returns false even though ld.so is
mostly working. Instead, the static dlopen hook is used, but that
does not work at all because this is not a static dlopen situation.
Commit 466c1ea15f ("dlfcn: Rework
static dlopen hooks") moved the hook pointer into _rtld_global_ro,
which means that separate protection is not needed anymore and the
hook pointer can be checked directly.
The guard for disabling libio vtable hardening in _IO_vtable_check
should stay for now.
Fixes commit 8e1472d2c1 ("ld.so:
Examine GLRO to detect inactive loader [BZ #20204]").
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
On non-PI_STATIC_AND_HIDDEN architectures, getting the address of
_rtld_local_ro (for GLRO (dl_final_object)) goes through a GOT entry.
The GOT load may be reordered before self relocation, leading to an
unrelocated/incorrect _rtld_local_ro address.
84e02af1eb tickled GCC powerpc32 to
reorder the GOT load before relative relocations, leading to ld.so
crash. This is similar to the m68k jump table reordering issue fixed by
a8e9b5b807.
Move code after self relocation into _dl_start_final to avoid the
reordering. This fixes powerpc32 and may help other architectures when
ELF_DYNAMIC_RELOCATE is simplified in the future.
This is necessary to place the libio vtables into the RELRO segment.
New tests elf/tst-relro-ldso and elf/tst-relro-libc are added to
verify that this is what actually happens.
The new tests fail on ia64 due to lack of (default) RELRO support
inbutils, so they are XFAILed there.
Hopefully, this will lead to tests that are easier to maintain. The
current approach of parsing readelf -W output using regular expressions
is not necessarily easier than parsing the ELF data directly.
This module is still somewhat incomplete (e.g., coverage of relocation
types and versioning information is missing), but it is sufficient to
perform basic symbol analysis or program header analysis.
The EM_* mapping for architecture-specific constant classes (e.g.,
SttX86_64) is not yet implemented. The classes are defined for the
benefit of elf/tst-glibcelf.py.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
elf_dynamic_do_Rel checks RTLD_BOOTSTRAP in several #ifdef branches.
Create an outside RTLD_BOOTSTRAP branch to simplify reasoning about the
function at the cost of a few duplicate lines.
Since dl_naudit is zero in RTLD_BOOTSTRAP code, the RTLD_BOOTSTRAP
branch can avoid _dl_audit_symbind calls to decrease code size.
Reviewed-by: Adheemrval Zanella <adhemerval.zanella@linaro.org>
After 73fc4e28b9,
__libc_enable_secure_decided is always 0 and a statically linked
executable may overwrite __libc_enable_secure without considering
AT_SECURE.
The __libc_enable_secure has been correctly initialized in _dl_aux_init,
so just remove __libc_enable_secure_decided and __libc_init_secure.
This allows us to remove some startup_get*id functions from
22b79ed7f4.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
The new IBM z16 is added to platform string array.
The macro _DL_PLATFORMS_COUNT is incremented.
_dl_hwcaps_subdir is extended by "z16" if HWCAP_S390_VXRS_PDE2
is set. HWCAP_S390_NNPA is not tested in _dl_hwcaps_subdirs_active
as those instructions may be replaced or removed in future.
tst-glibc-hwcaps.c is extended in order to test z16 via new marker5.
A fatal glibc error is dumped if glibc was build with architecture
level set for z16, but run on an older machine. (See dl-hwcap-check.h)
On 32-bit machines this has no affect. On 64-bit machines
{u}int_fast{16|32} are set as {u}int64_t which is often not
ideal. Particularly x86_64 this change both saves code size and
may save instruction cost.
Full xcheck passes on x86_64.
The count can be zero if an object has already been loaded as
an indirect dependency (so that l_searchlist.r_list in its link
map is still NULL) is promoted to global scope via RTLD_GLOBAL.
Fixes commit 5d28a8962d ("elf: Add _dl_find_object function").
If glibc is configured with --disable-default-pie and build on
s390 with -O3, the tests elf/tst-audit25a and elf/tst-audit25b are
failing as there are additional la_symbind lines for free and malloc.
It turns out that those belong to the executable. In fact those are
the PLT-stubs. Furthermore la_symbind is also called for calloc and
realloc symbols, but those belong to libc.
Those functions are not called at all, but dlsym'ed in
elf/dl-minimal.c:
__rtld_malloc_init_real (struct link_map *main_map)
{
...
void *new_calloc = lookup_malloc_symbol (main_map, "calloc", &version);
void *new_free = lookup_malloc_symbol (main_map, "free", &version);
void *new_malloc = lookup_malloc_symbol (main_map, "malloc", &version);
void *new_realloc = lookup_malloc_symbol (main_map, "realloc", &version);
...
}
Therefore, this commit just ignored symbols with LA_SYMB_DLSYM flag.
Reviewed-by: Adheemrval Zanella <adhemerval.zanella@linaro.org>
If the build itself is run in a container, we may not be able to
fully set up a nested container for test-container testing.
Notably is the mounting of /proc, since it's critical that it
be mounted from within the same PID namespace as its users, and
thus cannot be bind mounted from outside the container like other
mounts.
This patch defaults to using the parent's PID namespace instead of
creating a new one, as this is more likely to be allowed.
If the test needs an isolated PID namespace, it should add the "pidns"
command to its init script.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
And optimize it slightly.
This is commit 8c8510ab27 revised.
In _dl_aux_init in elf/dl-support.c, use an explicit loop
and -fno-tree-loop-distribute-patterns to avoid memset.
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
1. Also generate .d dependency files for $(tests-container) and
$(tests-printers).
2. elf: Add tst-auditmod17.os to extra-test-objs.
3. iconv: Add tst-gconv-init-failure-mod.os to extra-test-objs.
4. malloc: Rename extra-tests-objs to extra-test-objs.
5. linux: Add tst-sysconf-iov_max-uapi.o to extra-test-objs.
6. x86_64: Add tst-x86_64mod-1.o, tst-platformmod-2.o, test-libmvec.o,
test-libmvec-avx.o, test-libmvec-avx2.o and test-libmvec-avx512f.o to
extra-test-objs.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Changes in v2:
1. Update commit log.
commit 163f625cf9
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Tue Dec 21 12:35:47 2021 -0800
elf: Remove excessive p_align check on PT_LOAD segments [BZ #28688]
removed the p_align check against the page size. It caused the loader
error or crash on elf/tst-p_align3 when loading elf/tst-p_alignmod3.so,
which has the invalid p_align in PT_LOAD segments, added by
commit d8d94863ef
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Tue Dec 21 13:42:28 2021 -0800
The loader failure caused by a negative length passed to __mprotect is
random, depending on architecture and toolchain. Update _dl_map_segments
to detect invalid holes. This fixes BZ #28838.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
This reverts commit 8c8510ab27. The
revert is not perfect because the commit included a bug fix for
_dl_sysdep_start with an empty argv, introduced in commit
2d47fa6862 ("Linux: Remove
DL_FIND_ARG_COMPONENTS"), and this bug fix is kept.
The revert is necessary because the reverted commit introduced an
early memset call on aarch64, which leads to crash due to lack of TCB
initialization.
The fix for BZ#22716 replacde LD_TRACE_LOADED_OBJECTS with
LD_TRACE_PRELINKING so mtrace could record executable address
position.
To provide the same information, LD_TRACE_LOADED_OBJECTS is
extended where a value or '2' also prints the executable address
as well. It avoid adding another loader environment variable
to be used solely for mtrace. The vDSO will be printed as
a default library (with '=>' pointing the same name), which is
ok since both mtrace and ldd already handles it.
The mtrace script is changed to also parse the new format. To
correctly support PIE and non-PIE executables, both the default
mtrace address and the one calculated as used (it fixes mtrace
for non-PIE exectuable as for BZ#22716 for PIE).
Checked on x86_64-linux-gnu.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Prelinked binaries and libraries still work, the dynamic tags
DT_GNU_PRELINKED, DT_GNU_LIBLIST, DT_GNU_CONFLICT just ignored
(meaning the process is reallocated as default).
The loader environment variable TRACE_PRELINKING is also removed,
since it used solely on prelink.
Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
And optimize it slightly.
The large switch statement in _dl_sysdep_start can be replaced with
a large array. This reduces source code and binary size. On
i686-linux-gnu:
Before:
text data bss dec hex filename
7791 12 0 7803 1e7b elf/dl-sysdep.os
After:
text data bss dec hex filename
7135 12 0 7147 1beb elf/dl-sysdep.os
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The generic version is the de-facto Linux implementation. It
requires an auxiliary vector, so Hurd does not use it.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
On hppa, a function pointer returned by la_symbind is actually a function
descriptor has the plabel bit set (bit 30). This must be cleared to get
the actual address of the descriptor. If the descriptor has been bound,
the first word of the descriptor is the physical address of theA function,
otherwise, the first word of the descriptor points to a trampoline in the
PLT.
This patch also adds a workaround on tests because on hppa (and it seems
to be the only ABI I have see it), some shared library adds a dynamic PLT
relocation to am empty symbol name:
$ readelf -r elf/tst-audit25mod1.so
[...]
Relocation section '.rela.plt' at offset 0x464 contains 6 entries:
Offset Info Type Sym.Value Sym. Name + Addend
00002008 00000081 R_PARISC_IPLT 508
[...]
It breaks some assumptions on the test, where a symbol with an empty
name ("") is passed on la_symbind.
Checked on x86_64-linux-gnu and hppa-linux-gnu.
Replace tst-audit24bmod2.so with tst-audit24bmod2 to silence:
make[2]: Entering directory '/export/gnu/import/git/gitlab/x86-glibc/elf'
Makefile:2201: warning: overriding recipe for target '/export/build/gnu/tools-build/glibc-gitlab/build-x86_64-linux/elf/tst-audit24bmod2.so'
../Makerules:765: warning: ignoring old recipe for target '/export/build/gnu/tools-build/glibc-gitlab/build-x86_64-linux/elf/tst-audit24bmod2.so'
The rtld audit support show two problems on aarch64:
1. _dl_runtime_resolve does not preserve x8, the indirect result
location register, which might generate wrong result calls
depending of the function signature.
2. The NEON Q registers pushed onto the stack by _dl_runtime_resolve
were twice the size of D registers extracted from the stack frame by
_dl_runtime_profile.
While 2. might result in wrong information passed on the PLT tracing,
1. generates wrong runtime behaviour.
The aarch64 rtld audit support is changed to:
* Both La_aarch64_regs and La_aarch64_retval are expanded to include
both x8 and the full sized NEON V registers, as defined by the
ABI.
* dl_runtime_profile needed to extract registers saved by
_dl_runtime_resolve and put them into the new correctly sized
La_aarch64_regs structure.
* The LAV_CURRENT check is change to only accept new audit modules
to avoid the undefined behavior of not save/restore x8.
* Different than other architectures, audit modules older than
LAV_CURRENT are rejected (both La_aarch64_regs and La_aarch64_retval
changed their layout and there are no requirements to support multiple
audit interface with the inherent aarch64 issues).
* A new field is also reserved on both La_aarch64_regs and
La_aarch64_retval to support variant pcs symbols.
Similar to x86, a new La_aarch64_vector type to represent the NEON
register is added on the La_aarch64_regs (so each type can be accessed
directly).
Since LAV_CURRENT was already bumped to support bind-now, there is
no need to increase it again.
Checked on aarch64-linux-gnu.
Co-authored-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
The audit symbind callback is not called for binaries built with
-Wl,-z,now or when LD_BIND_NOW=1 is used, nor the PLT tracking callbacks
(plt_enter and plt_exit) since this would change the expected
program semantics (where no PLT is expected) and would have performance
implications (such as for BZ#15533).
LAV_CURRENT is also bumped to indicate the audit ABI change (where
la_symbind flags are set by the loader to indicate no possible PLT
trace).
To handle powerpc64 ELFv1 function descriptor, _dl_audit_symbind
requires to know whether bind-now is used so the symbol value is
updated to function text segment instead of the OPD (for lazy binding
this is done by PPC64_LOAD_FUNCPTR on _dl_runtime_resolve).
Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
powerpc64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
For audit modules and dependencies with initial-exec TLS, we can not
set the initial TLS image on default loader initialization because it
would already be set by the audit setup. However, subsequent thread
creation would need to follow the default behaviour.
This patch fixes it by setting l_auditing link_map field not only
for the audit modules, but also for all its dependencies. This is
used on _dl_allocate_tls_init to avoid the static TLS initialization
at load time.
Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
la_activity is not called during application exit, even though
la_objclose is.
Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Add <dl-r_debug.h> to get the adddress of the r_debug structure after
relocation and its offset before relocation from the PT_DYNAMIC segment
to support DT_DEBUG, DT_MIPS_RLD_MAP_REL and DT_MIPS_RLD_MAP.
Co-developed-by: Xi Ruoyao <xry111@mengyan1223.wang>
There was no direct or indirect make dependency on testobj3.so so the
test could fail with
/B/elf/loadfail: failed to load shared object: testobj3.so: cannot open
shared object file: No such file or directory
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
The glibc 2.34 release really should have added a GLIBC_2.34
symbol to the dynamic loader. With it, we could move functions such
as dlopen or pthread_key_create that work on process-global state
into the dynamic loader (once we have fixed a longstanding issue
with static linking). Without the GLIBC_2.34 symbol, yet another
new symbol version would be needed because old glibc will fail to
load binaries due to the missing symbol version in ld.so that newly
linked programs will require.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
This avoid the cross-compiling breakage when the test should not run
($(run-built-tests) equal to no).
Checked on x86_64-linux-gnu and i686-linux-gnu as well with a cross
compile to aarch64-linux-gnu and powerpc64-linux-gnu.
Build tst-p_alignmod3.so with 256 byte page size and verify that it is
rejected with a proper error message.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Add tst-p_alignmod2-edit to edit the copy of tst-p_alignmod-base.so to
set p_align of the first PT_LOAD segment to 1 and verify that the shared
library can be loaded normally.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Add tst-p_alignmod1-edit to edit the copy of tst-p_alignmod-base.so to
reduce p_align of the first PT_LOAD segment by half and verify that the
shared library is mapped with the maximum p_align of all PT_LOAD segments.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
DT_RUNPATH is only used to find the immediate dependencies of the
executable or shared object containing the DT_RUNPATH entry:
1. Define link-test-modules-rpath-link if $(build-hardcoded-path-in-tests)
is yes.
2. Use $(link-test-modules-rpath-link) in build-module-helper so that
test modules can dlopen modules with DT_RUNPATH.
3. Add a test to show why link-test-modules-rpath-link is needed.
This partially fixes BZ #28455.
Check if whether valgrind is available in the test environment.
If not, skip the test. Run smoke tests with valgrind to verify dynamic loader.
First, check if algrind works with the system ld.so in the test
environment. Then run the actual test inside the test environment,
using the just build ld.so and new libraries.
Co-authored-by: Mark Wielaard <mark@klomp.org>
Linker may set p_align of a PT_LOAD segment larger than p_align of the
first PT_LOAD segment to satisfy a section alignment:
Elf file type is DYN (Shared object file)
Entry point 0x0
There are 10 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
LOAD 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000834 0x0000000000000834 R E 0x1000
LOAD 0x0000000000000e00 0x0000000000001e00 0x0000000000001e00
0x0000000000000230 0x0000000000000230 RW 0x1000
LOAD 0x0000000000400000 0x0000000000400000 0x0000000000400000
0x0000000000000004 0x0000000000000008 RW 0x400000
...
Section to Segment mapping:
Segment Sections...
00 .note.gnu.property .note.gnu.build-id .gnu.hash .dynsym .dynstr .gnu.version .gnu.version_r .rela.dyn .rela.plt .init .plt .plt.got .text .fini .rodata .eh_frame_hdr .eh_frame
01 .init_array .fini_array .data.rel.ro .dynamic .got .got.plt
02 .data .bss
We should align the first PT_LOAD segment to the maximum p_align of all
PT_LOAD segments, similar to the kernel commit:
commit ce81bb256a224259ab686742a6284930cbe4f1fa
Author: Chris Kennelly <ckennelly@google.com>
Date: Thu Oct 15 20:12:32 2020 -0700
fs/binfmt_elf: use PT_LOAD p_align values for suitable start address
This fixes BZ #28676.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
And compile it with the early CFLAGS. _dl_setup_hash is called
very early for the ld.so link map, so it should be compiled
differently.
Reviewed-by: Stefan Liebler <stli@linux.ibm.com>
Tested-by: Stefan Liebler <stli@linux.ibm.com>
The usage of internal static symbol for statically linked binaries
does not work correctly for objects built with -D_TIME_BITS=64,
since the internal definition does not provide the expected aliases.
This patch makes it to use the default stat functions instead (which
uses the default 64 time_t alias and types).
Checked on i686-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
l_contiguous was not initialized at all for the main map and
always 0. This commit adds code to check if the LOAD segments
are adjacent to each other, and sets l_contiguous accordingly.
This helps _dl_find_object because it is more efficient if the
main mapping is contiguous.
Note that not all (PIE or non-PIE) binaries are contiguous in this
way because BFD ld creates executables with LOAD holes:
ELF LOAD segments creating holes in the process image on GNU/Linux
https://sourceware.org/pipermail/binutils/2022-January/119082.htmlhttps://sourceware.org/bugzilla/show_bug.cgi?id=28743
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
