This avoids immediate GLIBC_PRIVATE ABI issues if the size of
struct link_map or struct auditstate changes.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Unconditionally define it to false for static builds.
This avoids the awkward use of weak_extern for _dl_rtld_map
in checks that cannot be possibly true on static builds.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The current DSO dependency sorting tests are for a limited number of
specific cases, including some from particular bug reports.
Add tests that systematically cover all possible DAGs for an
executable and the shared libraries it depends on, directly or
indirectly, up to four objects (an executable and three shared
libraries). (For this kind of DAG - ones with a single source vertex
from which all others are reachable, and an ordering on the edges from
each vertex - there are 57 DAGs on four vertices, 3399 on five
vertices and 1026944 on six vertices; see
https://arxiv.org/pdf/2303.14710 for more details on this enumeration.
I've tested that the 3399 cases with five vertices do all pass if
enabled.)
These tests are replicating the sorting logic from the dynamic linker
(thereby, for example, asserting that it doesn't accidentally change);
I'm not claiming that the logic in the dynamic linker is in some
abstract sense optimal. Note that these tests do illustrate how in
some cases the two sorting algorithms produce different results for a
DAG (I think all the existing tests for such differences are ones
involving cycles, and the motivation for the new algorithm was also to
improve the handling of cycles):
tst-dso-ordering-all4-44: a->[bc];{}->[cba]
output(glibc.rtld.dynamic_sort=1): c>b>a>{}<a<b<c
output(glibc.rtld.dynamic_sort=2): b>c>a>{}<a<c<b
They also illustrate that sometimes the sorting algorithms do not
follow the order in which dependencies are listed in DT_NEEDED even
though there is a valid topological sort that does follow that, which
might be counterintuitive considering that the DT_NEEDED ordering is
followed in the simplest cases:
tst-dso-ordering-all4-56: {}->[abc]
output: c>b>a>{}<a<b<c
shows such a simple case following DT_NEEDED order for destructor
execution (the reverse of it for constructor execution), but
tst-dso-ordering-all4-41: a->[cb];{}->[cba]
output: c>b>a>{}<a<b<c
shows that c and b are in the opposite order to what might be expected
from the simplest case, though there is no dependency requiring such
an opposite order to be used.
(I'm not asserting that either of those things is a problem, simply
observing them as less obvious properties of the sorting algorithms
shown up by these tests.)
Tested for x86_64.
Add explicit instantiation declaration of S<char>::i to silence Clang
error:
tst-unique3.cc:6:18: error: instantiation of variable 'S<char>::i' required here, but no definition is available [-Werror,-Wundefined-var-template]
6 | int t = S<char>::i;
| ^
./tst-unique3.h:5:14: note: forward declaration of template entity is here
5 | static int i;
| ^
tst-unique3.cc:6:18: note: add an explicit instantiation declaration to suppress this warning if 'S<char>::i' is explicitly instantiated in another translation unit
6 | int t = S<char>::i;
| ^
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Since GCC 4.9 doesn't have __builtin_add_overflow:
In file included from tst-stringtable.c:180:0:
stringtable.c: In function ‘stringtable_finalize’:
stringtable.c:185:7: error: implicit declaration of function ‘__builtin_add_overflow’ [-Werror=implicit-function-declaration]
else if (__builtin_add_overflow (previous->offset,
^
return EXIT_UNSUPPORTED for GCC 4.9 or older.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Sam James <sam@gentoo.org>
Since elf/ifuncmain9.c fails at run-time when compiled with GCC 5.4 or
older (PR ipa/81128), return EXIT_UNSUPPORTED for GCC 5.4 or older.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Sam James <sam@gentoo.org>
The postclean-generated setting in elf/Makefile lists
$(objpfx)/dso-sort-tests-2.generated-makefile twice and
$(objpfx)/dso-sort-tests-1.generated-makefile not at all, which looks
like a typo; fix it to list each once.
Tested for x86_64.
Add an additional test of TLS variables, with different alignment,
accessed from different modules. The idea of the alignment test is
similar to tst-tlsalign and the same code is shared for setting up
test variables, but unlike the tst-tlsalign code, there are multiple
threads and variables are accessed from multiple objects to verify
that they get a consistent notion of the address of an object within a
thread. Threads are repeatedly created and shut down to verify proper
initialization in each new thread. The test is also repeated with TLS
descriptors when supported. (However, only initial-exec TLS is
covered in this test.)
Tested for x86_64.
Add tests that the dynamic linker works correctly with symbol names
involving hash collisions, for both choices of hash style (and
--hash-style=both as well). I note that there weren't actually any
previous tests using --hash-style (so tests would only cover the
default linker configuration in that regard). Also test symbol
versions involving hash collisions.
Tested for x86_64.
For a static PIE with non-zero load address, its PT_DYNAMIC segment
entries contain the relocated values for the load address in static PIE.
Since static PIE usually doesn't have PT_PHDR segment, use p_vaddr of
the PT_LOAD segment with offset == 0 as the load address in static PIE
and adjust the entries of PT_DYNAMIC segment in static PIE by properly
setting the l_addr field for static PIE. This fixes BZ #31799.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
The remaining_to_add variable can be 0 if (current_used + count) wraps,
This is caught by GCC 14+ on hppa, which determines from there that
target_seg could be be NULL when remaining_to_add is zero, which in
turns causes a -Wstringop-overflow warning:
In file included from ../include/atomic.h:49,
from dl-find_object.c:20:
In function '_dlfo_update_init_seg',
inlined from '_dl_find_object_update_1' at dl-find_object.c:689:30,
inlined from '_dl_find_object_update' at dl-find_object.c:805:13:
../sysdeps/unix/sysv/linux/hppa/atomic-machine.h:44:4: error: '__atomic_store_4' writing 4 bytes into a region of size 0 overflows the destination [-Werror=stringop-overflow=]
44 | __atomic_store_n ((mem), (val), __ATOMIC_RELAXED); \
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
dl-find_object.c:644:3: note: in expansion of macro 'atomic_store_relaxed'
644 | atomic_store_relaxed (&seg->size, new_seg_size);
| ^~~~~~~~~~~~~~~~~~~~
In function '_dl_find_object_update':
cc1: note: destination object is likely at address zero
In practice, this is not possible as it represent counts of link maps.
Link maps have sizes larger than 1 byte, so the sum of any two link map
counts will always fit within a size_t without wrapping around.
This patch therefore adds a check on remaining_to_add == 0 and tell GCC
that this can not happen using __builtin_unreachable.
Thanks to Andreas Schwab for the investigation.
Closes: BZ #32245
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Tested-by: John David Anglin <dave.anglin@bell.net>
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Linux 6.11 has getrandom() in vDSO. It operates on a thread-local opaque
state allocated with mmap using flags specified by the vDSO.
Multiple states are allocated at once, as many as fit into a page, and
these are held in an array of available states to be doled out to each
thread upon first use, and recycled when a thread terminates. As these
states run low, more are allocated.
To make this procedure async-signal-safe, a simple guard is used in the
LSB of the opaque state address, falling back to the syscall if there's
reentrancy contention.
Also, _Fork() is handled by blocking signals on opaque state allocation
(so _Fork() always sees a consistent state even if it interrupts a
getrandom() call) and by iterating over the thread stack cache on
reclaim_stack. Each opaque state will be in the free states list
(grnd_alloc.states) or allocated to a running thread.
The cancellation is handled by always using GRND_NONBLOCK flags while
calling the vDSO, and falling back to the cancellable syscall if the
kernel returns EAGAIN (would block). Since getrandom is not defined by
POSIX and cancellation is supported as an extension, the cancellation is
handled as 'may occur' instead of 'shall occur' [1], meaning that if
vDSO does not block (the expected behavior) getrandom will not act as a
cancellation entrypoint. It avoids a pthread_testcancel call on the fast
path (different than 'shall occur' functions, like sem_wait()).
It is currently enabled for x86_64, which is available in Linux 6.11,
and aarch64, powerpc32, powerpc64, loongarch64, and s390x, which are
available in Linux 6.12.
Link: https://pubs.opengroup.org/onlinepubs/9799919799/nframe.html [1]
Co-developed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Tested-by: Jason A. Donenfeld <Jason@zx2c4.com> # x86_64
Tested-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> # x86_64, aarch64
Tested-by: Xi Ruoyao <xry111@xry111.site> # x86_64, aarch64, loongarch64
Tested-by: Stefan Liebler <stli@linux.ibm.com> # s390x
The declaration of found_other_class could be jumped
over via the goto just above it, but the code jumped
to uses found_other_class. Move the declaration
up a bit to ensure it's properly declared and initialized.
Before commit ee1ada1bdb
("elf: Rework exception handling in the dynamic loader
[BZ #25486]"), the previous order called the main calloc
to allocate a shadow GOT/PLT array for auditing support.
This happened before libc.so.6 ELF constructors were run, so
a user malloc could run without libc.so.6 having been
initialized fully. One observable effect was that
environ was NULL at this point.
It does not seem to be possible at present to trigger such
an allocation, but it seems more robust to delay switching
to main malloc after ld.so self-relocation is complete.
The elf/tst-rtld-no-malloc-audit test case fails with a
2.34-era glibc that does not have this fix.
Reviewed-by: DJ Delorie <dj@redhat.com>
For a long time, libc.so.6 has dependend on ld.so, which
means that there is a reference to ld.so in all processes,
and rtld_multiple_ref is always true. In fact, if
rtld_multiple_ref were false, some of the ld.so setup code
would not run.
Reviewed-by: DJ Delorie <dj@redhat.com>
In commit c628c22963 (elf: Remove
ldconfig kernel version check), the layout of auxcache entries
changed because the osversion field was removed from
struct aux_cache_file_entry. However, AUX_CACHEMAGIC was not
changed, so existing files are still used, potentially leading
to unintended ldconfig behavior. This commit changes AUX_CACHEMAGIC,
so that the file is regenerated.
Reported-by: DJ Delorie <dj@redhat.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The refactoring did not take the change of variable into account.
Fixes commit 43db5e2c06
("elf: Signal RT_CONSISTENT after relocation processing in dlopen
(bug 31986)").
Previously, a la_activity audit event was generated before
relocation processing completed. This does did not match what
happened during initial startup in elf/rtld.c (towards the end
of dl_main). It also caused various problems if an auditor
tried to open the same shared object again using dlmopen:
If it was the directly loaded object, it had a search scope
associated with it, so the early exit in dl_open_worker_begin
was taken even though the object was unrelocated. This caused
the r_state == RT_CONSISTENT assert to fail. Avoidance of the
assert also depends on reversing the order of r_state update
and auditor event (already implemented in a previous commit).
At the later point, args->map can be NULL due to failure,
so use the assigned namespace ID instead if that is available.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Auditors can call into the dynamic loader again if
LA_ACT_CONSISTENT, and those recursive calls could observe
r_state != RT_CONSISTENT.
We should consider failing dlopen/dlmopen/dlclose if
r_state != RT_CONSISTENT. The dynamic linker is probably not
in a state in which it can handle reentrant calls. This
needs further investigation.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This is conceptually similar to the reported bug, but does not
depend on auditing. The fix is simple: just complete execution
of the constructors. This exposed the fact that the link map
for statically linked executables does not have l_init_called
set, even though constructors have run.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Calling an extern function in a different translation unit before
self-relocation is brittle. The compiler may load the address
at an earlier point in _dl_start, before self-relocation. In
_dl_start_final, the call is behind a compiler barrier, so this
cannot happen.
This case is detected early in the elf/dl-version.c consistency
checks. (These checks could be disabled in the future to allow
the removal of symbol versioning from objects.)
Commit f0b2132b35 ("ld.so: Support moving versioned symbols between
sonames [BZ #24741]) removed another call to _dl_name_match_p. The
_dl_check_caller function no longer exists, and the remaining calls
to _dl_name_match_p happen under the loader lock. This means that
atomic accesses are no longer required for the l_libname list. This
supersedes commit 395be7c218 ("elf: Fix data race in _dl_name_match_p
[BZ #21349]").
Add new testcase elf/tst-startup-errno.c which tests that errno is set
to 0 at first ELF constructor execution and at the start of the
program's main function.
Tested for x86_64
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
The current racy approach is to enable asynchronous cancellation
before making the syscall and restore the previous cancellation
type once the syscall returns, and check if cancellation has happen
during the cancellation entrypoint.
As described in BZ#12683, this approach shows 2 problems:
1. Cancellation can act after the syscall has returned from the
kernel, but before userspace saves the return value. It might
result in a resource leak if the syscall allocated a resource or a
side effect (partial read/write), and there is no way to program
handle it with cancellation handlers.
2. If a signal is handled while the thread is blocked at a cancellable
syscall, the entire signal handler runs with asynchronous
cancellation enabled. This can lead to issues if the signal
handler call functions which are async-signal-safe but not
async-cancel-safe.
For the cancellation to work correctly, there are 5 points at which the
cancellation signal could arrive:
[ ... )[ ... )[ syscall ]( ...
1 2 3 4 5
1. Before initial testcancel, e.g. [*... testcancel)
2. Between testcancel and syscall start, e.g. [testcancel...syscall start)
3. While syscall is blocked and no side effects have yet taken
place, e.g. [ syscall ]
4. Same as 3 but with side-effects having occurred (e.g. a partial
read or write).
5. After syscall end e.g. (syscall end...*]
And libc wants to act on cancellation in cases 1, 2, and 3 but not
in cases 4 or 5. For the 4 and 5 cases, the cancellation will eventually
happen in the next cancellable entrypoint without any further external
event.
The proposed solution for each case is:
1. Do a conditional branch based on whether the thread has received
a cancellation request;
2. It can be caught by the signal handler determining that the saved
program counter (from the ucontext_t) is in some address range
beginning just before the "testcancel" and ending with the
syscall instruction.
3. SIGCANCEL can be caught by the signal handler and determine that
the saved program counter (from the ucontext_t) is in the address
range beginning just before "testcancel" and ending with the first
uninterruptable (via a signal) syscall instruction that enters the
kernel.
4. In this case, except for certain syscalls that ALWAYS fail with
EINTR even for non-interrupting signals, the kernel will reset
the program counter to point at the syscall instruction during
signal handling, so that the syscall is restarted when the signal
handler returns. So, from the signal handler's standpoint, this
looks the same as case 2, and thus it's taken care of.
5. For syscalls with side-effects, the kernel cannot restart the
syscall; when it's interrupted by a signal, the kernel must cause
the syscall to return with whatever partial result is obtained
(e.g. partial read or write).
6. The saved program counter points just after the syscall
instruction, so the signal handler won't act on cancellation.
This is similar to 4. since the program counter is past the syscall
instruction.
So The proposed fixes are:
1. Remove the enable_asynccancel/disable_asynccancel function usage in
cancellable syscall definition and instead make them call a common
symbol that will check if cancellation is enabled (__syscall_cancel
at nptl/cancellation.c), call the arch-specific cancellable
entry-point (__syscall_cancel_arch), and cancel the thread when
required.
2. Provide an arch-specific generic system call wrapper function
that contains global markers. These markers will be used in
SIGCANCEL signal handler to check if the interruption has been
called in a valid syscall and if the syscalls has side-effects.
A reference implementation sysdeps/unix/sysv/linux/syscall_cancel.c
is provided. However, the markers may not be set on correct
expected places depending on how INTERNAL_SYSCALL_NCS is
implemented by the architecture. It is expected that all
architectures add an arch-specific implementation.
3. Rewrite SIGCANCEL asynchronous handler to check for both canceling
type and if current IP from signal handler falls between the global
markers and act accordingly.
4. Adjust libc code to replace LIBC_CANCEL_ASYNC/LIBC_CANCEL_RESET to
use the appropriate cancelable syscalls.
5. Adjust 'lowlevellock-futex.h' arch-specific implementations to
provide cancelable futex calls.
Some architectures require specific support on syscall handling:
* On i386 the syscall cancel bridge needs to use the old int80
instruction because the optimized vDSO symbol the resulting PC value
for an interrupted syscall points to an address outside the expected
markers in __syscall_cancel_arch. It has been discussed in LKML [1]
on how kernel could help userland to accomplish it, but afaik
discussion has stalled.
Also, sysenter should not be used directly by libc since its calling
convention is set by the kernel depending of the underlying x86 chip
(check kernel commit 30bfa7b3488bfb1bb75c9f50a5fcac1832970c60).
* mips o32 is the only kABI that requires 7 argument syscall, and to
avoid add a requirement on all architectures to support it, mips
support is added with extra internal defines.
Checked on aarch64-linux-gnu, arm-linux-gnueabihf, powerpc-linux-gnu,
powerpc64-linux-gnu, powerpc64le-linux-gnu, i686-linux-gnu, and
x86_64-linux-gnu.
[1] https://lkml.org/lkml/2016/3/8/1105
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
With ia64 removal, the function descriptor supports is only used
by HPPA and new architectures do not seem leaning towards this
design.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Macros will automatically use the correct types, without
having to fiddle with internal glibc macros. It's also
impossible to get the types wrong due to aliasing because
support_check_stat_fd and support_check_stat_path do not
depend on the struct stat* types.
The changes reveal some inconsistencies in tests.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The old code used l_init_called as an indicator for whether TLS
initialization was complete. However, it is possible that
TLS for an object is initialized, written to, and then dlopen
for this object is called again, and l_init_called is not true at
this point. Previously, this resulted in TLS being initialized
twice, discarding any interim writes (technically introducing a
use-after-free bug even).
This commit introduces an explicit per-object flag, l_tls_in_slotinfo.
It indicates whether _dl_add_to_slotinfo has been called for this
object. This flag is used to avoid double-initialization of TLS.
In update_tls_slotinfo, the first_static_tls micro-optimization
is removed because preserving the initalization flag for subsequent
use by the second loop for static TLS is a bit complicated, and
another per-object flag does not seem to be worth it. Furthermore,
the l_init_called flag is dropped from the second loop (for static
TLS initialization) because l_need_tls_init on its own prevents
double-initialization.
The remaining l_init_called usage in resize_scopes and update_scopes
is just an optimization due to the use of scope_has_map, so it is
not changed in this commit.
The isupper check ensures that libc.so.6 is TLS is not reverted.
Such a revert happens if l_need_tls_init is not cleared in
_dl_allocate_tls_init for the main_thread case, now that
l_init_called is not checked anymore in update_tls_slotinfo
in elf/dl-open.c.
Reported-by: Jonathon Anderson <janderson@rice.edu>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
AT_HWCAP on some architecture can indeed use all bits.
Checked on x86_64-linux-gnu and powerpc-linux-gnu.
Reviewed-By: Andreas K. Hüttel <dilfridge@gentoo.org>
This avoids a test failure when the system has no /etc/ld.so.cache.
Tested on x86_64-linux-gnu.
Signed-off-by: Xi Ruoyao <xry111@xry111.site>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
ldconfig already ignores files with the -gdb.py suffix, but GDB also
looks for -gdb.gdb and -gdb.scm files. These aren't as widely used, but
libguile at least comes with a -gdb.scm file.
Rename is_gdb_python_file to is_gdb_extension_file, and make it
recognise all three types of GDB extension.
Signed-off-by: Adam Sampson <ats@offog.org>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
is_gdb_python_file is doing a similar test, so it can use this helper
function as well.
Signed-off-by: Adam Sampson <ats@offog.org>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
While working on a patch to add support for the extensible rseq ABI, we
came across an issue where a new 'const' variable would be merged with
the existing '__rseq_size' variable. We tracked this to the use of
'-fmerge-all-constants' which allows the compiler to merge identical
constant variables. This means that all 'const' variables in a compile
unit that are of the same size and are initialized to the same value can
be merged.
In this specific case, on 32 bit systems 'unsigned int' and 'ptrdiff_t'
are both 4 bytes and initialized to 0 which should trigger the merge.
However for reasons we haven't delved into when the attribute 'section
(".data.rel.ro")' is added to the mix, only variables of the same exact
types are merged. As far as we know this behavior is not specified
anywhere and could change with a new compiler version, hence this patch.
Move the definitions of these variables into an assembler file and add
hidden writable aliases for internal use. This has the added bonus of
removing the asm workaround to set the values on rseq registration.
Tested on Debian 12 with GCC 12.2.
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Starting with commit
59974938fe
elf/rtld: Count skipped environment variables for enable_secure
The new testcase elf/tst-tunables-enable_secure-env segfaults on s390 (31bit).
There _start parses the auxiliary vector for some additional checks.
Therefore it skips over the zeros after the environment variables ...
0x7fffac20: 0x7fffbd17 0x7fffbd32 0x7fffbd69 0x00000000
------------------------------------------------^^^last environment variable
... and then it parses the auxiliary vector and stops at AT_NULL.
0x7fffac30: 0x00000000 0x00000021 0x00000000 0x00000000
--------------------------------^^^AT_SYSINFO_EHDR--------------^^^AT_NULL
----------------^^^newp-----------------------------------------^^^oldp
Afterwards it tries to access AT_PHDR which points to somewhere and segfaults.
Due to not incorporating the skip_env variable in the computation of oldp
when shuffling down the auxv in rtld.c, it just copies one entry with AT_NULL
and value 0x00000021 and stops the loop. In reality we have skipped
GLIBC_TUNABLES environment variable (=> skip_env=1). Thus we should copy from
here:
0x7fffac40: 0x00000021 0x7ffff000 0x00000010 0x007fffff
----------------^^^fixed-oldp
This patch fixes the computation of oldp when shuffling down auxiliary vector.
It also adds some checks in the testcase. Those checks also fail on
s390x (64bit) and x86_64 without the fix.
Co-authored-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
It turns out that quite a few applications use bundled mallocs that
have been built to use global-dynamic TLS (instead of the recommended
initial-exec TLS). The previous workaround from
commit afe42e935b ("elf: Avoid some
free (NULL) calls in _dl_update_slotinfo") does not fix all
encountered cases unfortunatelly.
This change avoids the TLS generation update for recursive use
of TLS from a malloc that was called during a TLS update. This
is possible because an interposed malloc has a fixed module ID and
TLS slot. (It cannot be unloaded.) If an initially-loaded module ID
is encountered in __tls_get_addr and the dynamic linker is already
in the middle of a TLS update, use the outdated DTV, thus avoiding
another call into malloc. It's still necessary to update the
DTV to the most recent generation, to get out of the slow path,
which is why the check for recursion is needed.
The bookkeeping is done using a global counter instead of per-thread
flag because TLS access in the dynamic linker is tricky.
All this will go away once the dynamic linker stops using malloc
for TLS, likely as part of a change that pre-allocates all TLS
during pthread_create/dlopen.
Fixes commit d2123d6827 ("elf: Fix slow
tls access after dlopen [BZ #19924]").
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
The conditionals for several mtrace-based tests in catgets, elf, libio,
malloc, misc, nptl, posix, and stdio-common were incorrect leading to
test failures when bootstrapping glibc without perl.
The correct conditional for mtrace-based tests requires three checks:
first checking for run-built-tests, then build-shared, and lastly that
PERL is not equal to "no" (missing perl).
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Remove the definitions of HWCAP_IMPORTANT after removal of
LD_HWCAP_MASK / tunable glibc.cpu.hwcap_mask. There HWCAP_IMPORTANT
was used as default value.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Remove the environment variable LD_HWCAP_MASK and the tunable
glibc.cpu.hwcap_mask as those are not used anymore in common-code
after removal in elf/dl-cache.c:search_cache().
The only remaining user is sparc32 where it is used in
elf_machine_matches_host(). If sparc32 does not need it anymore,
we can get rid of it at all. Otherwise we could also move
LD_HWCAP_MASK / tunable glibc.cpu.hwcap_mask to be sparc32 specific.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Despite of powerpc where the returned integer is stored in tcb,
and the diagnostics output, there is no user anymore.
Thus this patch removes the diagnostics output and
_dl_string_platform for all other platforms.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The legacy hwcaps mechanism was removed with glibc 2.37:
See this commit series:
- d178c67535
x86_64: Remove platform directory library loading test
- 6099908fb8
elf: Remove legacy hwcaps support from the dynamic loader
- b78ff5a25d
elf: Remove legacy hwcaps support from ldconfig
- 4a7094119c
elf: Remove hwcap parameter from add_to_cache signature
- cfbf883db3
elf: Remove hwcap and bits_hwcap fields from struct cache_entry
- 78d9a1620b
Add NEWS entry for legacy hwcaps removal
- ab40f20364
elf: Remove _dl_string_hwcap
- e76369ed63
elf: Simplify output of hwcap subdirectories in ld.so help
According to Florian Weimer, this was an oversight and should also
have been removed.
As ldconfig does not generate ld.so.cache entries with hwcap/platform
bits in the hwcap-field anymore, this patch now skips those entries.
Thus currently only named-hwcap-entries and the default entries are
allowed.
For named-hwcap entries bit 62 is set and also the isa-level bits can
be set.
For the default entries the hwcap-field is 0.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The __stack_prot is used by Linux to make the stack executable if
a modules requires it. It is also marked as RELRO, which requires
to change the segment permission to RW to update it.
Also, there is no need to keep track of the flags: either the stack
will have the default permission of the ABI or should be change to
PROT_READ | PROT_WRITE | PROT_EXEC. The only additional flag,
PROT_GROWSDOWN or PROT_GROWSUP, is Linux only and can be deducted
from _STACK_GROWS_DOWN/_STACK_GROWS_UP.
Also, the check_consistency function was already removed some time
ago.
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Linux 6.9 adds the ELF note type NT_ARM_FPMR. Add this to glibc's
elf.h, along with the previously missed NT_ARM_SSVE, NT_ARM_ZA and
NT_ARM_ZT (added in older kernel versions).
Tested for x86_64.
This has been confirmed to work around some interposed mallocs. Here
is a discussion of the impact test ust/libc-wrapper/test_libc-wrapper
in lttng-tools:
New TLS usage in libgcc_s.so.1, compatibility impact
<https://inbox.sourceware.org/libc-alpha/8734v1ieke.fsf@oldenburg.str.redhat.com/>
Reportedly, this patch also papers over a similar issue when tcmalloc
2.9.1 is not compiled with -ftls-model=initial-exec. Of course the
goal really should be to compile mallocs with the initial-exec TLS
model, but this commit appears to be a useful interim workaround.
Fixes commit d2123d6827 ("elf: Fix slow
tls access after dlopen [BZ #19924]").
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This new note type is defined at https://systemd.io/ELF_DLOPEN_METADATA/
and is used to list shared library dependencies loaded via dlopen().
Distro packagers can use this, via tools like those available at
https://github.com/systemd/package-notes to automatically generate
dependencies when building projects that make use of this
specification.
By defining the note id here we can use it in other projects as a
stable identifier, for example in 'readelf' to pretty-print its
content.
Signed-off-by: Luca Boccassi <bluca@debian.org>
Reviewed-by: Arjun Shankar <arjun@redhat.com>
Page was renamed some time ago, there's a redirect but better
to point to the right one
Signed-off-by: Luca Boccassi <bluca@debian.org>
Reviewed-by: Arjun Shankar <arjun@redhat.com>
There is no _dl_mcount_wrapper prototype in any installed header files.
Fix BZ #31765 by changing _dl_mcount_wrapper to a compat symbol and
obsolete it in glibc 2.40.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Sunil K Pandey <skpgkp2@gmail.com>
This is mostly based on AArch64 and RISC-V implementation.
Add R_LARCH_TLS_DESC32 and R_LARCH_TLS_DESC64 relocations.
For _dl_tlsdesc_dynamic function slow path, temporarily save and restore
all vector registers.
Tunable with environment variables aliases are also ignored if
glibc.rtld.enable_secure is enabled. The tunable parsing is also
optimized a bit, where the loop that checks each environment variable
only checks for the tunables with aliases instead of all tables.
Checked on aarch64-linux-gnu and x86_64-linux-gnu.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
And move it to parse_tunables. It avoids a string comparison for
each tunable.
Checked on aarch64-linux-gnu and x86_64-linux-gnu.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
The 680c597e9c commit made loader reject ill-formatted strings by
first tracking all set tunables and then applying them. However, it does
not take into consideration if the same tunable is set multiple times,
where parse_tunables_string appends the found tunable without checking
if it was already in the list. It leads to a stack-based buffer overflow
if the tunable is specified more than the total number of tunables. For
instance:
GLIBC_TUNABLES=glibc.malloc.check=2:... (repeat over the number of
total support for different tunable).
Instead, use the index of the tunable list to get the expected tunable
entry. Since now the initial list is zero-initialized, the compiler
might emit an extra memset and this requires some minor adjustment
on some ports.
Checked on x86_64-linux-gnu and aarch64-linux-gnu.
Reported-by: Yuto Maeda <maeda@cyberdefense.jp>
Reported-by: Yutaro Shimizu <shimizu@cyberdefense.jp>
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Also compile dl-misc.os with $(rtld-early-cflags) to avoid
Program received signal SIGILL, Illegal instruction.
0x00007ffff7fd36ea in _dl_strtoul (nptr=nptr@entry=0x7fffffffe2c9 "2",
endptr=endptr@entry=0x7fffffffd728) at dl-misc.c:156
156 bool positive = true;
(gdb) bt
#0 0x00007ffff7fd36ea in _dl_strtoul (nptr=nptr@entry=0x7fffffffe2c9 "2",
endptr=endptr@entry=0x7fffffffd728) at dl-misc.c:156
#1 0x00007ffff7fdb1a9 in tunable_initialize (
cur=cur@entry=0x7ffff7ffbc00 <tunable_list+2176>,
strval=strval@entry=0x7fffffffe2c9 "2", len=len@entry=1)
at dl-tunables.c:131
#2 0x00007ffff7fdb3a2 in parse_tunables (valstring=<optimized out>)
at dl-tunables.c:258
#3 0x00007ffff7fdb5d9 in __GI___tunables_init (envp=0x7fffffffdd58)
at dl-tunables.c:288
#4 0x00007ffff7fe44c3 in _dl_sysdep_start (
start_argptr=start_argptr@entry=0x7fffffffdcb0,
dl_main=dl_main@entry=0x7ffff7fe5f80 <dl_main>)
at ../sysdeps/unix/sysv/linux/dl-sysdep.c:110
#5 0x00007ffff7fe5cae in _dl_start_final (arg=0x7fffffffdcb0) at rtld.c:494
#6 _dl_start (arg=0x7fffffffdcb0) at rtld.c:581
#7 0x00007ffff7fe4b38 in _start ()
(gdb)
when setting GLIBC_TUNABLES in glibc compiled with APX.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
On some architectures and depending on the page size, the loader can
also allocate some memory during dependencies loading and it will be
marked as 'loader malloc'. However, if the system page size is
large enough, the initial data page will be enough for all required
allocation and there will be no extra loader mmap. To avoid false
negatives, the test does not check for such pages.
Checked on powerpc64le-linux-gnu with 64k pagesize.
Reviewed-by: Simon Chopin <simon.chopin@canonical.com>
When using the glibc.rtld.enable_secure tunable we need to keep track of
the count of environment variables we skip due to __libc_enable_secure
being set and adjust the auxv section of the stack. This fixes an
assertion when running ld.so directly with glibc.rtld.enable_secure set.
Add a testcase that ensures the assert is not hit.
elf/rtld.c:1324 assert (auxv == sp + 1);
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This reverts commit a1735e0aa8.
The test failure is a real valgrind bug that needs to be fixed before
valgrind is usable with a glibc that has been built with
CC="gcc -march=x86-64-v3". The proposed valgrind patch teaches
valgrind to replace ld.so strcmp with an unoptimized scalar
implementation, thus avoiding any AVX2-related problems.
Valgrind bug: <https://bugs.kde.org/show_bug.cgi?id=485487>
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
None of the existing tests seem to cover the case where
_dl_signal_error is called without an active error handler.
The new elf/tst-rtld-does-not-exist test triggers such a
_dl_signal_error call from _dl_map_object.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
_dl_signal_error may be called with objname == NULL. _dl_exception_create
checks objname == NULL. But fatal_error doesn't. Check objname before
calling fatal_error. This fixes BZ #31596.
Reviewed-by: Sunil K Pandey <skpgkp2@gmail.com>
We would like to avoid statically defining any specific page size on
aarch64-gnu, and instead make sure that everything uses the dynamic
page size, available via vm_page_size and GLRO(dl_pagesize).
There are currently a few places in glibc that require EXEC_PAGESIZE
to be defined. Per Roland's suggestion [0], drop the static
GLRO(dl_pagesize) initializers (for now, only if EXEC_PAGESIZE is not
defined), and don't require EXEC_PAGESIZE definition for libio to
enable mmap usage.
[0]: https://mail.gnu.org/archive/html/bug-hurd/2011-10/msg00035.html
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-ID: <20240323173301.151066-4-bugaevc@gmail.com>
This patch adds a new feature for powerpc. In order to get faster
access to the HWCAP3/HWCAP4 masks, similar to HWCAP/HWCAP2 (i.e. for
implementing __builtin_cpu_supports() in GCC) without the overhead of
reading them from the auxiliary vector, we now reserve space for them
in the TCB.
This is an ABI change for GLIBC 2.39.
Suggested-by: Peter Bergner <bergner@linux.ibm.com>
Reviewed-by: Peter Bergner <bergner@linux.ibm.com>
The aarch64 uses 'trad' for traditional tls and 'desc' for tls
descriptors, but unlike other targets it defaults to 'desc'. The
gnutls2 configure check does not set aarch64 as an ABI that uses
TLS descriptors, which then disable somes stests.
Also rename the internal machinery fron gnu2 to tls descriptors.
Checked on aarch64-linux-gnu.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
ARM _dl_tlsdesc_dynamic slow path has two issues:
* The ip/r12 is defined by AAPCS as a scratch register, and gcc is
used to save the stack pointer before on some function calls. So it
should also be saved/restored as well. It fixes the tst-gnu2-tls2.
* None of the possible VFP registers are saved/restored. ARM has the
additional complexity to have different VFP bank sizes (depending of
VFP support by the chip).
The tst-gnu2-tls2 test is extended to check for VFP registers, although
only for hardfp builds. Different than setcontext, _dl_tlsdesc_dynamic
does not have HWCAP_ARM_IWMMXT (I don't have a way to properly test
it and it is almost a decade since newer hardware was released).
With this patch there is no need to mark tst-gnu2-tls2 as XFAIL.
Checked on arm-linux-gnueabihf.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
Add a tunable for setting __libc_enable_secure to 1. Do not set
__libc_enable_secure to 0 if the tunable is set to 0. Ignore all
tunables if glib.rtld.enable_secure is set. One use-case for this
addition is to enable testing code paths that depend on
__libc_enable_secure being set without the need to use setxid binaries.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
When strcmp-avx2.S is used as the default, elf/tst-valgrind-smoke fails
with
==1272761== Conditional jump or move depends on uninitialised value(s)
==1272761== at 0x4022C98: strcmp (strcmp-avx2.S:462)
==1272761== by 0x400B05B: _dl_name_match_p (dl-misc.c:75)
==1272761== by 0x40085F3: _dl_map_object (dl-load.c:1966)
==1272761== by 0x401AEA4: map_doit (rtld.c:644)
==1272761== by 0x4001488: _dl_catch_exception (dl-catch.c:237)
==1272761== by 0x40015AE: _dl_catch_error (dl-catch.c:256)
==1272761== by 0x401B38F: do_preload (rtld.c:816)
==1272761== by 0x401C116: handle_preload_list (rtld.c:892)
==1272761== by 0x401EDF5: dl_main (rtld.c:1842)
==1272761== by 0x401A79E: _dl_sysdep_start (dl-sysdep.c:140)
==1272761== by 0x401BEEE: _dl_start_final (rtld.c:494)
==1272761== by 0x401BEEE: _dl_start (rtld.c:581)
==1272761== by 0x401AD87: ??? (in */elf/ld.so)
The assembly codes are:
0x0000000004022c80 <+144>: vmovdqu 0x20(%rdi),%ymm0
0x0000000004022c85 <+149>: vpcmpeqb 0x20(%rsi),%ymm0,%ymm1
0x0000000004022c8a <+154>: vpcmpeqb %ymm0,%ymm15,%ymm2
0x0000000004022c8e <+158>: vpandn %ymm1,%ymm2,%ymm1
0x0000000004022c92 <+162>: vpmovmskb %ymm1,%ecx
0x0000000004022c96 <+166>: inc %ecx
=> 0x0000000004022c98 <+168>: jne 0x4022c32 <strcmp+66>
strcmp-avx2.S has 32-byte vector loads of strings which are shorter than
32 bytes:
(gdb) p (char *) ($rdi + 0x20)
$6 = 0x1ffeffea20 "memcheck-amd64-linux.so"
(gdb) p (char *) ($rsi + 0x20)
$7 = 0x4832640 "core-amd64-linux.so"
(gdb) call (int) strlen ((char *) ($rsi + 0x20))
$8 = 19
(gdb) call (int) strlen ((char *) ($rdi + 0x20))
$9 = 23
(gdb)
It triggers the valgrind error. The above code is safe since the loads
don't cross the page boundary. Update tst-valgrind-smoke.sh to accept
an optional suppression file and pass a suppression file to valgrind when
strcmp-avx2.S is the default implementation of strcmp.
Reviewed-by: Sunil K Pandey <skpgkp2@gmail.com>
Compiler generates the following instruction sequence for GNU2 dynamic
TLS access:
leaq tls_var@TLSDESC(%rip), %rax
call *tls_var@TLSCALL(%rax)
or
leal tls_var@TLSDESC(%ebx), %eax
call *tls_var@TLSCALL(%eax)
CALL instruction is transparent to compiler which assumes all registers,
except for EFLAGS and RAX/EAX, are unchanged after CALL. When
_dl_tlsdesc_dynamic is called, it calls __tls_get_addr on the slow
path. __tls_get_addr is a normal function which doesn't preserve any
caller-saved registers. _dl_tlsdesc_dynamic saved and restored integer
caller-saved registers, but didn't preserve any other caller-saved
registers. Add _dl_tlsdesc_dynamic IFUNC functions for FNSAVE, FXSAVE,
XSAVE and XSAVEC to save and restore all caller-saved registers. This
fixes BZ #31372.
Add GLRO(dl_x86_64_runtime_resolve) with GLRO(dl_x86_tlsdesc_dynamic)
to optimize elf_machine_runtime_setup.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
After 78ca44da01
("elf: Relocate libc.so early during startup and dlmopen (bug 31083)")
we start seeing tst-nodeps2 failures when building the testsuite with
--enable-hard-coded-path-in-tests.
When building the testsuite with --enable-hard-coded-path-in-tests
the tst-nodeps2-mod.so is not built with the required DT_RUNPATH
values and the test escapes the test framework and loads the system
libraries and aborts. The fix is to use the existing
$(link-test-modules-rpath-link) variable to set DT_RUNPATH correctly.
No regressions on x86_64.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Add ELF_DYNAMIC_AFTER_RELOC to allow target specific processing after
relocation.
For x86-64, add
#define DT_X86_64_PLT (DT_LOPROC + 0)
#define DT_X86_64_PLTSZ (DT_LOPROC + 1)
#define DT_X86_64_PLTENT (DT_LOPROC + 3)
1. DT_X86_64_PLT: The address of the procedure linkage table.
2. DT_X86_64_PLTSZ: The total size, in bytes, of the procedure linkage
table.
3. DT_X86_64_PLTENT: The size, in bytes, of a procedure linkage table
entry.
With the r_addend field of the R_X86_64_JUMP_SLOT relocation set to the
memory offset of the indirect branch instruction.
Define ELF_DYNAMIC_AFTER_RELOC for x86-64 to rewrite the PLT section
with direct branch after relocation when the lazy binding is disabled.
PLT rewrite is disabled by default since SELinux may disallow modifying
code pages and ld.so can't detect it in all cases. Use
$ export GLIBC_TUNABLES=glibc.cpu.plt_rewrite=1
to enable PLT rewrite with 32-bit direct jump at run-time or
$ export GLIBC_TUNABLES=glibc.cpu.plt_rewrite=2
to enable PLT rewrite with 32-bit direct jump and on APX processors with
64-bit absolute jump at run-time.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
I've updated copyright dates in glibc for 2024. This is the patch for
the changes not generated by scripts/update-copyrights and subsequent
build / regeneration of generated files.
This is a minimal regression test for bug 29039 which only affects
targets with TLSDESC and a reproducer requires that
1) Have modid gaps (closed modules) with old generation.
2) Update a DTV to a newer generation (needs a newer dlopen).
3) But do not update the closed gap entry in that DTV.
4) Reuse the modid gap for a new module (another dlopen).
5) Use dynamic TLSDESC in that new module with old generation (bug).
6) Access TLS via this TLSDESC and the now outdated DTV.
However step (3) in practice rarely happens: during DTV update the
entries for closed modids are initialized to "unallocated" and then
dynamic TLSDESC calls __tls_get_addr independently of its generation.
The only exception to this is DTV setup at thread creation (gaps are
initialized to NULL instead of unallocated) or DTV resize where the
gap entries are outside the previous DTV array (again NULL instead
of unallocated, and this requires loading > DTV_SURPLUS modules).
So the bug can only cause NULL (+ offset) dereference, not use after
free. And the easiest way to get (3) is via thread creation.
Note that step (5) requires that the newly loaded module has larger
TLS than the remaining optional static TLS. And for (6) there cannot
be other TLS access or dlopen in the thread that updates the DTV.
Tested on aarch64-linux-gnu.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
If /tmp is mounted nosuid and make xcheck is run,
then tst-env-setuid fails UNSUPPORTED with "SGID failed: GID and EGID match"
and /var/tmp/tst-sonamemove-runmod1.so.profile is created.
If you then try to rerun the test with a suid mounted test-dir
(the SGID binary is created in test-dir which defaults to /tmp)
with something like that:
make tst-env-setuid-ENV="TMPDIR=..." t=elf/tst-env-setuid test
the test fails as the LD_PROFILE output file is still available
from the previous run.
Thus this patch removes the LD_PROFILE output file in parent
before spawning the SGID binary.
Even if LD_PROFILE is not supported anymore in static binaries,
use a different library and thus output file for tst-env-setuid
and tst-env-setuid-static in order to not interfere if both
tests are run in parallel.
Furthermore the checks in test_child are now more verbose.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The loader now warns for invalid and out-of-range tunable values. The
patch also fixes the parsing of size_t maximum values, where
_dl_strtoul was failing for large values close to SIZE_MAX.
Checked on x86_64-linux-gnu.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
The tunable parsing duplicates the tunable environment variable so it
null-terminates each one since it simplifies the later parsing. It has
the drawback of adding another point of failure (__minimal_malloc
failing), and the memory copy requires tuning the compiler to avoid mem
operations calls.
The parsing now tracks the tunable start and its size. The
dl-tunable-parse.h adds helper functions to help parsing, like a strcmp
that also checks for size and an iterator for suboptions that are
comma-separated (used on hwcap parsing by x86, powerpc, and s390x).
Since the environment variable is allocated on the stack by the kernel,
it is safe to keep the references to the suboptions for later parsing
of string tunables (as done by set_hwcaps by multiple architectures).
Checked on x86_64-linux-gnu, powerpc64le-linux-gnu, and
aarch64-linux-gnu.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
GLRO(dl_lazy) is used to set the parameters for the early
_dl_relocate_object call, so the consider_profiling setting has to
be applied before the call.
Fixes commit 78ca44da01 ("elf: Relocate
libc.so early during startup and dlmopen (bug 31083)").
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
It splits between process_envvars_secure and process_envvars_default,
with the former used to process arguments for __libc_enable_secure.
It does not have any semantic change, just simplify the code so there
is no need to handle __libc_enable_secure on each len switch.
Checked on x86_64-linux-gnu and aarch64-linux-gnu.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
To avoid any environment variable to change setuid binaries
semantics.
Checked on x86_64-linux-gnu.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Florian Weimer
Joseph Myers
H.J. Lu
Alejandro Colomar
Aurelien Jarno
Adhemerval Zanella
DJ Delorie
Aaron Merey
Henrik Lindström
Xi Ruoyao
Adam Sampson
Michael Jeanson
Stefan Liebler
Carlos O'Donell
Luca Boccassi
mengqinggang
Samuel Thibault
Joe Simmons-Talbott
Sergey Bugaev
Manjunath Matti
Andreas Schwab
Paul Eggert
Szabolcs Nagy