Commit Graph

2843 Commits

Author SHA1 Message Date
Javier Pello
4a7094119c elf: Remove hwcap parameter from add_to_cache signature
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>
2022-10-06 07:59:48 -03:00
Javier Pello
b78ff5a25d elf: Remove legacy hwcaps support from ldconfig
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>
2022-10-06 07:59:48 -03:00
Javier Pello
6099908fb8 elf: Remove legacy hwcaps support from the dynamic loader
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>
2022-10-06 07:59:48 -03:00
Adhemerval Zanella Netto
de477abcaa Use '%z' instead of '%Z' on printf functions
The Z modifier is a nonstandard synonymn for z (that predates z
itself) and compiler might issue an warning for in invalid
conversion specifier.

Reviewed-by: Florian Weimer <fweimer@redhat.com>
2022-09-22 08:48:04 -03:00
Florian Weimer
340097d0b5 elf: Extract glibcelf constants from <elf.h>
The need to maintain elf/elf.h and scripts/glibcelf.py in parallel
results in a backporting hazard: they need to be kept in sync to
avoid elf/tst-glibcelf consistency check failures.  glibcelf (unlike
tst-glibcelf) does not use the C implementation to extract constants.
This applies the additional glibcpp syntax checks to <elf.h>.

This  changereplaces the types derived from Python enum types with
custom types _TypedConstant, _IntConstant, and _FlagConstant.  These
types have fewer safeguards, but this also allows incremental
construction and greater flexibility for grouping constants among
the types.  Architectures-specific named constants are now added
as members into their superclasses (but value-based lookup is
still restricted to generic constants only).

Consequently, check_duplicates in elf/tst-glibcelf has been adjusted
to accept differently-named constants of the same value if their
subtypes are distinct.  The ordering check for named constants
has been dropped because they are no longer strictly ordered.

Further test adjustments: Some of the type names are different.
The new types do not support iteration (because it is unclear
whether iteration should cover the all named values (including
architecture-specific constants), or only the generic named values),
so elf/tst-glibcelf now uses by_name explicit (to get all constants).
PF_HP_SBP and PF_PARISC_SBP are now of distinct types (PfHP and
PfPARISC), so they are how both present on the Python side.  EM_NUM
and PT_NUM are filtered (which was an oversight in the old
conversion).

The new version of glibcelf should also be compatible with earlier
Python versions because it no longer depends on the enum module and its
advanced features.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2022-09-22 12:10:41 +02:00
Adhemerval Zanella
fd36873ff9 elf: Use C11 atomics on _dl_mcount
All atomic operation are counters, so relaxed MO should be suffice.

Checked on x86_64-linux-gnu.
Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
2022-09-21 10:57:47 -03:00
Florian Weimer
1df71d32fe elf: Implement force_first handling in _dl_sort_maps_dfs (bug 28937)
The implementation in _dl_close_worker requires that the first
element of l_initfini is always this very map (“We are always the
zeroth entry, and since we don't include ourselves in the
dependency analysis start at 1.”).  Rather than fixing that
assumption, this commit adds an implementation of the force_first
argument to the new dependency sorting algorithm.  This also means
that the directly dlopen'ed shared object is always initialized last,
which is the least surprising behavior in the presence of cycles.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
2022-09-20 11:00:42 +02:00
Sergei Trofimovich
2d7ed98add Makerules: fix MAKEFLAGS assignment for upcoming make-4.4 [BZ# 29564]
make-4.4 will add long flags to MAKEFLAGS variable:

    * WARNING: Backward-incompatibility!
      Previously only simple (one-letter) options were added to the MAKEFLAGS
      variable that was visible while parsing makefiles.  Now, all options
      are available in MAKEFLAGS.

This causes locale builds to fail when long options are used:

    $ make --shuffle
    ...
    make  -C localedata install-locales
    make: invalid shuffle mode: '1662724426r'

The change fixes it by passing eash option via whitespace and dashes.
That way option is appended to both single-word form and whitespace
separated form.

While at it fixed --silent mode detection in $(MAKEFLAGS) by filtering
out --long-options. Otherwise options like --shuffle flag enable silent
mode unintentionally. $(silent-make) variable consolidates the checks.

Resolves: BZ# 29564

CC: Paul Smith <psmith@gnu.org>
CC: Siddhesh Poyarekar <siddhesh@gotplt.org>
Signed-off-by: Sergei Trofimovich <slyich@gmail.com>
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2022-09-13 13:45:32 -04:00
Javier Pello
a23820f605 elf: Fix hwcaps string size overestimation
Commit dad90d5282 added glibc-hwcaps
support for LD_LIBRARY_PATH and, for this, it adjusted the total
string size required in _dl_important_hwcaps. However, in doing so
it inadvertently altered the calculation of the size required for
the power set strings, as the computation of the power set string
size depended on the first value assigned to the total variable,
which is later shifted, resulting in overallocation of string
space. Fix this now by using a different variable to hold the
string size required for glibc-hwcaps.

Signed-off-by: Javier Pello <devel@otheo.eu>
2022-09-08 12:12:35 +02:00
Florian Weimer
dbb75513f5 elf: Rename _dl_sort_maps parameter from skip to force_first
The new implementation will not be able to skip an arbitrary number
of objects.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
2022-09-06 07:38:33 +02:00
Florian Weimer
29eb796119 elf.h: Remove duplicate definition of VER_FLG_WEAK
This did not cause a warning before because the token sequence for
the two definitions was identical.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
2022-09-05 15:02:09 +02:00
Adhemerval Zanella
1e903124ce elf: Restore how vDSO dependency is printed with LD_TRACE_LOADED_OBJECTS (BZ #29539)
The d7703d3176 changed how vDSO like
dependencies are printed, instead of just the name and address it
follows other libraries mode and prints 'name => path'.

Unfortunately, this broke some ldd consumer that uses the output to
filter out the program's dependencies.  For instance CMake
bundleutilities module [1], where GetPrequirite uses the regex to filter
out 'name => path' [2].

This patch restore the previous way to print just the name and the
mapping address.

Checked on x86_64-linux-gnu.

[1] https://github.com/Kitware/CMake/tree/master/Tests/BundleUtilities
[2] https://github.com/Kitware/CMake/blob/master/Modules/GetPrerequisites.cmake#L733

Reviewed-by: Florian Weimer <fweimer@redhat.com>
2022-08-31 09:08:33 -03:00
Florian Weimer
d0e357ff45 elf: Call __libc_early_init for reused namespaces (bug 29528)
libc_map is never reset to NULL, neither during dlclose nor on a
dlopen call which reuses the namespace structure.  As a result, if a
namespace is reused, its libc is not initialized properly.  The most
visible result is a crash in the <ctype.h> functions.

To prevent similar bugs on namespace reuse from surfacing,
unconditionally initialize the chosen namespace to zero using memset.
2022-08-26 21:15:43 +02:00
Florian Weimer
89baed0b93 Revert "Detect ld.so and libc.so version inconsistency during startup"
This reverts commit 6f85dbf102.

Once this change hits the release branches, it will require relinking
of all statically linked applications before static dlopen works
again, for the majority of updates on release branches: The NEWS file
is regularly updated with bug references, so the __libc_early_init
suffix changes, and static dlopen cannot find the function anymore.

While this ABI check is still technically correct (we do require
rebuilding & relinking after glibc updates to keep static dlopen
working), it is too drastic for stable release branches.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
2022-08-25 18:46:43 +02:00
Joseph Myers
025a8cce63 Add NT_LOONGARCH_* from Linux 5.19 to elf.h
Add the new NT_LOONGARCH_* constants from Linux 5.19 to glibc's elf.h.

Tested for x86_64.
2022-08-24 18:19:13 +00:00
Florian Weimer
6f85dbf102 Detect ld.so and libc.so version inconsistency during startup
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>
2022-08-24 17:35:57 +02:00
Florian Weimer
bd13cb19f5 scripts/glibcelf.py: Add hashing support
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>
2022-08-23 19:33:38 +02:00
Florian Weimer
dd2315a866 elf: Run tst-audit-tlsdesc, tst-audit-tlsdesc-dlopen everywhere
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>
2022-08-16 12:00:03 +02:00
Fangrui Song
61d2066c19 elf.h: Add ELFCOMPRESS_ZSTD
From the approved generic ABI proposal
https://groups.google.com/g/generic-abi/c/satyPkuMisk
("Add new ch_type value: ELFCOMPRESS_ZSTD").

Reviewed-by: Florian Weimer <fweimer@redhat.com>
2022-08-10 21:46:09 -07:00
Noah Goldstein
483cfe1a6a elf: Replace strcpy call with memcpy [BZ #29454]
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.
2022-08-09 17:00:03 +08:00
Florian Weimer
6c93af6b45 malloc: Correct the documentation of the top_pad default
DEFAULT_TOP_PAD is defined as 131072 in
sysdeps/generic/malloc-machine.h.
2022-08-04 17:20:48 +02:00
Lucas A. M. Magalhaes
8ee878592c Assume only FLAG_ELF_LIBC6 suport
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>
2022-08-04 09:09:48 -03:00
Florian Weimer
9001cb1102 assert: Do not use stderr in libc-internal assert
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>
2022-08-03 11:43:04 +02:00
Andreas Schwab
521d540562 Don't use unsupported format string in ld.so (bug 29427)
The dynamic loader does not support printf format strings that contain a
literal field width or precision, they have to be specified indirectly.
2022-08-02 10:24:21 +02:00
caiyinyu
2d83247d90 LoongArch: Add relocations and ELF flags to elf.h and scripts/glibcelf.py 2022-07-26 12:35:12 -03:00
Adhemerval Zanella
c353689e49 elf: Fix wrong fscanf usage on tst-pldd
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.
2022-07-15 10:07:55 -03:00
Florian Weimer
2a5b4f7a71 elf: Rename tst-audit26 to tst-audit28
tst-audit26 and tst-audit27 are already used by aarch64.

Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
2022-07-08 14:35:37 +02:00
Florian Weimer
a9f9ee2381 elf: Fix direction of NODELETE log messages during symbol lookup
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>
2022-07-05 14:40:38 +02:00
Florian Weimer
c1ada668a3 elf: Fix -DNDEBUG warning in _dl_start_args_adjust
This is another blocker for building glibc with the default
-Werror setting and -DNDEBUG.
2022-06-28 10:40:16 +02:00
Yang Yanchao
5e89ed42fd elf: Fix compile error with -Werror and -DNDEBUG
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.
2022-06-28 10:28:48 +02:00
Adhemerval Zanella
baf2a265c7 misc: Optimize internal usage of __libc_single_threaded
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>
2022-06-24 17:45:58 -03:00
H.J. Lu
33ead02758 elf: Silence GCC 11/12 false positive warning
Silence GCC 11/12 false positive warning with -mavx512f on dl-load.c:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106008

$ gcc -O2 -fPIC -march=x86-64 -mavx512f -S -Wall ...
dl-load.c: In function ‘_dl_map_object_from_fd.constprop’:
dl-load.c:1158:30: warning: ‘(((char *)loadcmds.113_68 + _933 + 16))[329406144173384849].mapend’ may be used uninitialized [-Wmaybe-uninitialized]
2022-06-17 15:18:10 -07:00
Fangrui Song
de38b2a343 elf: Remove ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA
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.
2022-06-15 11:29:55 -07:00
Andreas Schwab
c2f39be490 elf: add missing newlines in lateglobal test 2022-06-08 15:28:41 +02:00
Joseph Myers
603e5c8ba7 Add PT_AARCH64_MEMTAG_MTE from Linux 5.18 to elf.h
Linux 5.18 defines a new AArch64 ELF segment type
PT_AARCH64_MEMTAG_MTE; add it to elf.h.

Tested with build-many-glibcs.py for aarch64-linux-gnu.
2022-06-06 14:45:34 +00:00
Sam James
7df596a58c grep: egrep -> grep -E, fgrep -> grep -F
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>
2022-06-05 12:09:02 -07:00
Carlos O'Donell
48f4b30780 elf: Add #include <errno.h> for use of E* constants.
In __strerror_r we use errno constants and must include errno.h.

Tested on x86_64 and i686 without regression.
2022-06-02 15:20:36 -04:00
Carlos O'Donell
62c888b337 elf: Add #include <sys/param.h> for MAX usage.
In _dl_audit_pltenter we use MAX and so need to include param.h.

Tested on x86_64 and i686 without regression.
2022-06-02 15:20:36 -04:00
Adhemerval Zanella
81e7fdd7cc elf: Remove _dl_skip_args
Now that no architecture uses it anymore.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2022-05-30 16:33:54 -03:00
Fangrui Song
efa7936e4c dlsym: Make RTLD_NEXT prefer default version definition [BZ #14932]
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>
2022-05-27 12:34:49 -07:00
Fangrui Song
36c1dbaedd elf/dl-reloc.c: Copyright The GNU Toolchain Authors
by following 3.5. Update copyright information
on https://sourceware.org/glibc/wiki/Contribution%20checklist .
The change is advised by Carlos O'Donell.

Note: commit a8b11bd1f8 missed Signed-off-by tag
from Nicholas Guriev <nicholas@guriev.su>.
2022-05-23 19:16:05 -07:00
Nicholas Guriev
a8b11bd1f8 elf: Rewrite long RESOLVE_MAP macro to an always_inline static function
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>
2022-05-23 12:06:44 -07:00
Noah Goldstein
9a421348cd elf: Optimize _dl_new_hash in dl-new-hash.h
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>
2022-05-23 10:38:40 -05:00
Noah Goldstein
6fd435485f elf: Add tests for the dl hash funcs (_dl_new_hash and _dl_elf_hash)
If we want to further optimize the functions tests are needed.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
2022-05-23 10:38:40 -05:00
Noah Goldstein
c4bd509d47 elf: Refactor dl_new_hash so it can be tested / benchmarked
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>
2022-05-23 10:38:40 -05:00
H.J. Lu
2d5ec6692f Enable DT_RELR in glibc shared libraries and PIEs automatically
Enable DT_RELR in glibc shared libraries and position independent
executables (PIE) automatically if linker supports -z pack-relative-relocs.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
2022-05-18 13:04:13 -07:00
Szabolcs Nagy
86147bbeec rtld: Remove DL_ARGV_NOT_RELRO and make _dl_skip_args const
_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>
2022-05-17 10:14:03 +01:00
Szabolcs Nagy
ad43cac44a rtld: Use generic argv adjustment in ld.so [BZ #23293]
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>
2022-05-17 10:14:03 +01:00
Adhemerval Zanella
d2db60d8d8 Remove dl-librecon.h header.
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>
2022-05-16 15:03:49 -03:00
Adhemerval Zanella
c628c22963 elf: Remove ldconfig kernel version check
Now that it was removed on libc.so.
2022-05-16 15:03:49 -03:00