And make always supported. The configure option was added on glibc 2.25
and some features require it (such as hwcap mask, huge pages support, and
lock elisition tuning). It also simplifies the build permutations.
Changes from v1:
* Remove glibc.rtld.dynamic_sort changes, it is orthogonal and needs
more discussion.
* Cleanup more code.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Now that there is no need to use a special linker script to hardening
internal data structures, remove the --with-default-link configure
option and associated definitions.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Instead of using a special ELF section along with a linker script
directive to put the IO vtables within the RELRO section, the libio
vtables are all moved to an array marked as data.relro (so linker
will place in the RELRO segment without the need of extra directives).
To avoid static linking namespace issues and including all vtable
referenced objects, all required function pointers are set to weak alias.
Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
They are both used by __libc_freeres to free all library malloc
allocated resources to help tooling like mtrace or valgrind with
memory leak tracking.
The current scheme uses assembly markers and linker script entries
to consolidate the free routine function pointers in the RELRO segment
and to be freed buffers in BSS.
This patch changes it to use specific free functions for
libc_freeres_ptrs buffers and call the function pointer array directly
with call_function_static_weak.
It allows the removal of both the internal macros and the linker
script sections.
Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
After commit ed3ce71f5c ("elf: Move la_activity (LA_ACT_ADD) after
_dl_add_to_namespace_list() (BZ #28062)") it is no longer necessary to
reset the debugger state in the error case, since the debugger
notification only happens after no more errors can occur.
It was possible to run this test individually and have it fail because
it can't find testobj1.so. This patch adds that dependency, to prevent
such issues.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Some toolchains, such as that used on Gentoo Hardened, set -z now out of
the box. This trips up a couple of tests.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
When mcount overflows, no gmon.out file is generated, but no message is printed
to the user, leaving the user with no idea why, and thinking maybe there is
some bug - which is how BZ 27576 ended up being logged. Print a message to
stderr in this case so the user knows what is going on.
As a comment in sys/gmon.h acknowledges, the hardcoded MAXARCS value is too
small for some large applications, including the test case in that BZ. Rather
than increase it, add tunables to enable MINARCS and MAXARCS to be overridden
at runtime (glibc.gmon.minarcs and glibc.gmon.maxarcs). So if a user gets the
mcount overflow error, they can try increasing maxarcs (they might need to
increase minarcs too if the heuristic is wrong in their case.)
Note setting minarcs/maxarcs too large can cause monstartup to fail with an
out of memory error. If you set them large enough, it can cause an integer
overflow in calculating the buffer size. I haven't done anything to defend
against that - it would not generally be a security vulnerability, since these
tunables will be ignored in suid/sgid programs (due to the SXID_ERASE default),
and if you can set GLIBC_TUNABLES in the environment of a process, you can take
it over anyway (LD_PRELOAD, LD_LIBRARY_PATH, etc). I thought about modifying
the code of monstartup to defend against integer overflows, but doing so is
complicated, and I realise the existing code is susceptible to them even prior
to this change (e.g. try passing a pathologically large highpc argument to
monstartup), so I decided just to leave that possibility in-place.
Add a test case which demonstrates mcount overflow and the tunables.
Document the new tunables in the manual.
Signed-off-by: Simon Kissane <skissane@gmail.com>
Reviewed-by: DJ Delorie <dj@redhat.com>
While cleaning up old libc version support, the deprecated libc4 code was
accidentally kept in `implicit_soname`, instead of the libc6 code.
This causes additional symlinks to be created by `ldconfig` for libraries
without a soname, e.g. a library `libsomething.123.456.789` without a soname
will create a `libsomething.123` -> `libsomething.123.456.789` symlink.
As the libc6 version of the `implicit_soname` code is a trivial `xstrdup`,
just inline it and remove `implicit_soname` altogether.
Some further simplification looks possible (e.g. the call to `create_links`
looks like a no-op if `soname == NULL`, other than the verbose printfs), but
logic is kept as-is for now.
Fixes: BZ #30125
Fixes: 8ee878592c ("Assume only FLAG_ELF_LIBC6 suport")
Signed-off-by: Joan Bruguera <joanbrugueram@gmail.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The test is sufficient to detect the ldconfig bug fixed in
commit 9fe6f63638 ("elf: Fix 64 time_t
support for installed statically binaries").
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Almost all uses of rawmemchr find the end of a string. Since most targets use
a generic implementation, replacing it with strchr is better since that is
optimized by compilers into strlen (s) + s. Also fix the generic rawmemchr
implementation to use a cast to unsigned char in the if statement.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The 73fc4e28b9 refactor did not add the GL(dl_phdr) and
GL(dl_phnum) for static build, relying on the __ehdr_start symbol,
which is always added by the static linker, to get the correct values.
This is problematic in some ways:
- The segment may see its in-memory size differ from its in-file
size (or the binary may have holes). The Linux has fixed is to
provide concise values for both AT_PHDR and AT_PHNUM (commit
0da1d5002745c - "fs/binfmt_elf: Fix AT_PHDR for unusual ELF files")
- Some archs (alpha for instance) the hidden weak reference is not
correctly pulled by the static linker and __ehdr_start address
end up being 0, which makes GL(dl_phdr) and GL(dl_phnum) have both
invalid values (and triggering a segfault later on libc.so while
accessing TLS variables).
The safer fix is to just restore the previous behavior to setup
GL(dl_phdr) and GL(dl_phnum) for static based on kernel auxv. The
__ehdr_start fallback can also be simplified by not assuming weak
linkage (as for PIE).
The libc-static.c auxv init logic is moved to dl-support.c, since
the later is build without SHARED and then GLRO macro is defined
to access the variables directly.
The _dl_phdr is also assumed to be always non NULL, since an invalid
NULL values does not trigger TLS initialization (which is used in
various libc systems).
Checked on aarch64-linux-gnu, x86_64-linux-gnu, and i686-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
I've updated copyright dates in glibc for 2023. This is the patch for
the changes not generated by scripts/update-copyrights and subsequent
build / regeneration of generated files.
Always null-terminate the buffer and set E2BIG if the buffer is too
small. This fixes bug 27857.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
vfprintf is entangled with vfwprintf (of course), __printf_fp,
__printf_fphex, __vstrfmon_l_internal, and the strfrom family of
functions. The latter use the internal snprintf functionality,
so vsnprintf is converted as well.
The simples conversion is __printf_fphex, followed by
__vstrfmon_l_internal and __printf_fp, and finally
__vfprintf_internal and __vfwprintf_internal. __vsnprintf_internal
and strfrom* are mostly consuming the new interfaces, so they
are comparatively simple.
__printf_fp is a public symbol, so the FILE *-based interface
had to preserved.
The __printf_fp rewrite does not change the actual binary-to-decimal
conversion algorithm, and digits are still not emitted directly to
the target buffer. However, the staging buffer now uses bytes
instead of wide characters, and one buffer copy is eliminated.
The changes are at least performance-neutral in my testing.
Floating point printing and snprintf improved measurably, so that
this Lua script
for i=1,5000000 do
print(i, i * math.pi)
end
runs about 5% faster for me. To preserve fprintf performance for
a simple "%d" format, this commit has some logic changes under
LABEL (unsigned_number) to avoid additional function calls. There
are certainly some very easy performance improvements here: binary,
octal and hexadecimal formatting can easily avoid the temporary work
buffer (the number of digits can be computed ahead-of-time using one
of the __builtin_clz* built-ins). Decimal formatting can use a
specialized version of _itoa_word for base 10.
The existing (inconsistent) width handling between strfmon and printf
is preserved here. __print_fp_buffer_1 would have to use
__translated_number_width to achieve ISO conformance for printf.
Test expectations in libio/tst-vtables-common.c are adjusted because
the internal staging buffer merges all virtual function calls into
one.
In general, stack buffer usage is greatly reduced, particularly for
unbuffered input streams. __printf_fp can still use a large buffer
in binary128 mode for %g, though.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
These buffers will eventually be used instead of FILE * objects
to implement printf functions. The multibyte buffer is struct
__printf_buffer, the wide buffer is struct __wprintf_buffer.
To enable writing type-generic code, the header files
printf_buffer-char.h and printf_buffer-wchar_t.h define the
Xprintf macro differently, enabling Xprintf (buffer) to stand
for __printf_buffer and __wprintf_buffer as appropriate. For
common cases, macros like Xprintf_buffer are provided as a more
syntactically convenient shortcut.
Buffer-specific flush callbacks are implemented with a switch
statement instead of a function pointer, to avoid hardening issues
similar to those of libio vtables. struct __printf_buffer_as_file
is needed to support custom printf specifiers because the public
interface for that requires passing a FILE *, which is why there
is a trapdoor back from these buffers to FILE * streams.
Since the immediate user of these interfaces knows when processing
has finished, there is no flush callback for the end of processing,
only a flush callback for the intermediate buffer flush.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Current scheme only consideres the first argument for both --required
and --optional, where the idea is to append a new item.
Checked on x86_64-linux-gnu.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
The static linker might impose any order or internal function
position, so change the test to check if the audit prints the
symbol only once in any order.
Check the return value of malloc based on the function header comment of
_dl_make_tlsdesc_dynamic(). If the return value fails, NULL is returned.
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
This makes it more likely that the compiler can compute the strlen
argument in _startup_fatal at compile time, which is required to
avoid a dependency on strlen this early during process startup.
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
The old exception handling implementation used function interposition
to replace the dynamic loader implementation (no TLS support) with the
libc implementation (TLS support). This results in problems if the
link order between the dynamic loader and libc is reversed (bug 25486).
The new implementation moves the entire implementation of the
exception handling functions back into the dynamic loader, using
THREAD_GETMEM and THREAD_SETMEM for thread-local data support.
These depends on Hurd support for these macros, added in commit
b65a82e4e7 ("hurd: Add THREAD_GET/SETMEM/_NC").
One small obstacle is that the exception handling facilities are used
before the TCB has been set up, so a check is needed if the TCB is
available. If not, a regular global variable is used to store the
exception handling information.
Also rename dl-error.c to dl-catch.c, to avoid confusion with the
dlerror function.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
The maximum number of directives is already limited by the maximum
value of iovec, and current padding usage on _dl_map_object_from_fd
specifies a value of 16 (2 times sizeof (void *)) in hexa, which is
less than the INT_STRLEN_BOUND(void *) (20 for LP64).
This works if pointers are larger than 8 bytes, for instance 16.
In this case the maximum padding would be 32 and the IFMTSIZE would
be 40.
The resulting code does use a slightly larger static stack, the
output of -fstack-usage (for x86_64):
* master:
dl-printf.c:35:1:_dl_debug_vdprintf 1344 dynamic
* patch:
dl-printf.c:36:1:_dl_debug_vdprintf 2416 static
However, there is an improvement in code generation:
* master
text data bss dec hex filename
3309 0 0 3309 ced elf/dl-printf.os
* patch
text data bss dec hex filename
3151 0 0 3151 c4f elf/dl-printf.os
Checked on x86_64-linux-gnu.
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
When --enable-hardcoded-path-in-tests is used only with DT_RUNPATH,
elf/tst-relr3 and elf/tst-relr4 failed to run. Their dependency
libraries, tst-relr-mod3a.so and tst-relr-mod4a.so, are failed to
load since DT_RUNPATH on executable doesn't apply to them. Build
tst-relr-mod3a.so and tst-relr-mod4a.so with $(LDFLAGS-rpath-ORIGIN)
to add DT_RUNPATH for their dependency libraries.
Reviewed-by: Fangrui Song <maskray@google.com>
By default glibc only allocates enough static TLS for 4 link namespaces
including the initial one. So only use 3 dlmopens in the test.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
The alloca size did not consider the optional width parameter for
padding which could cause buffer underflow. The width is currently used
e.g. by _dl_map_object_from_fd which passes 2 * sizeof(void *) which
can be larger than the alloca buffer size on targets where
sizeof(void *) >= 2 * sizeof(unsigned long).
Even if large width is not used on existing targets it is better to fix
the formatting code to avoid surprises.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
This consolidates the destructor invocations from _dl_fini and
dlclose. Remove the micro-optimization that avoids
calling _dl_call_fini if they are no destructors (as dlclose is quite
expensive anyway). The debug log message is now printed
unconditionally.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This allows the rest of dynamic loader to check whether the TCB
has been set up (and THREAD_GETMEM and THREAD_SETMEM will work).
Reviewed-by: Siddhesh Poyarekar <siddhesh@gotplt.org>
The data in the _ns_debug member must be preserved, otherwise
_dl_debug_initialize enters an infinite loop. To be conservative,
only clear the libc_map member for now, to fix bug 29528.
Fixes commit d0e357ff45
("elf: Call __libc_early_init for reused namespaces (bug 29528)"),
by reverting most of it.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
Besides the option being gcc specific, this approach is still fragile
and not future proof since we do not know if this will be the only
optimization option gcc will add that transforms loops to memset
(or any libcall).
This patch adds a new header, dl-symbol-redir-ifunc.h, that can b
used to redirect the compiler generated libcalls to port the generic
memset implementation if required.
Checked on x86_64-linux-gnu and aarch64-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
The print_hwcap_1 machinery was useful for the legacy hwcaps
subdirectories, but it is not worth the trouble now that they
are gone.
Signed-off-by: Javier Pello <devel@otheo.eu>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
They were set to 0 on initialisation and never changed later after
last commit.
Signed-off-by: Javier Pello <devel@otheo.eu>
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Last commit made it so that the value passed for that parameter was
always 0 at its only call site.
Signed-off-by: Javier Pello <devel@otheo.eu>
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Remove support for the legacy hwcaps subdirectories from ldconfig.
Signed-off-by: Javier Pello <devel@otheo.eu>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Remove support for the legacy hwcaps subdirectories from the dynamic
loader.
Signed-off-by: Javier Pello <devel@otheo.eu>
Reviewed-by: Florian Weimer <fweimer@redhat.com>
