Without CET, a jump into a newly loaded object through an overwritten
link map often does not crash, it just executes some random code.
CET detects this in some cases because the function pointer does not
point to the start of a function in the replacement shared object,
so there is no ENDBR instruction.
The new test uses a small shared object and the existing dangling
link map to trigger the bug.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
We should clear GL(dl_initfirst) when freeing its link_map memory.
Tested on Fedora 31/x86-64 with CET.
Reviewed-by: Florian Weimer <fweimer@redhat.com>
This new test was introduced with recent commit
591236f1a3.
If run on 32bit, it fails while renaming tst-ldconfig-ld-mod.so as there is no
/usr/lib64 directory. This patch is constructing the file name with help of
support_libdir_prefix.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Test ldconfig after /etc/ld.so.conf update and verify a running process
observes changes to /etc/ld.so.cache.
The test uses the test-in-container framework.
Reviewed-by: Arjun Shankar <arjun@redhat.com>
This patch moves the vDSO setup from libc to loader code, just after
the vDSO link_map setup. For static case the initialization
is moved to _dl_non_dynamic_init instead.
Instead of using the mangled pointer, the vDSO data is set as
attribute_relro (on _rtld_global_ro for shared or _dl_vdso_* for
static). It is read-only even with partial relro.
It fixes BZ#24967 now that the vDSO pointer is setup earlier than
malloc interposition is called.
Also, vDSO calls should not be a problem for static dlopen as
indicated by BZ#20802. The vDSO pointer would be zero-initialized
and the syscall will be issued instead.
Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
arm-linux-gnueabihf, powerpc64le-linux-gnu, powerpc64-linux-gnu,
powerpc-linux-gnu, s390x-linux-gnu, sparc64-linux-gnu, and
sparcv9-linux-gnu. I also run some tests on mips.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
The code is similar to the one at elf/dl-reloc.c, where it checks for
the l_relro_size from the link_map (obtained from PT_GNU_RELRO header
from program headers) and calls_dl_protected_relro.
For testing I will use the ones proposed by Florian's patch
'elf: Add tests for working RELRO protection' [1].
Checked on x86_64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu,
aarch64-linux-gnu, s390x-linux-gnu, and sparc64-linux-gnu. I also
check with --enable-static pie on x86_64-linux-gnu, i686-linux-gnu,
and aarch64-linux-gnu which seems the only architectures where
static PIE is actually working (as per 9d7a3741c9, on
arm-linux-gnueabihf, powerpc64{le}-linux-gnu, and s390x-linux-gnu
I am seeing runtime issues not related to my patch).
[1] https://sourceware.org/ml/libc-alpha/2019-10/msg00059.html
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
I've updated copyright dates in glibc for 2020. This is the patch for
the changes not generated by scripts/update-copyrights and subsequent
build / regeneration of generated files. As well as the usual annual
updates, mainly dates in --version output (minus libc.texinfo which
previously had to be handled manually but is now successfully updated
by update-copyrights), there is a fix to
sysdeps/unix/sysv/linux/powerpc/bits/termios-c_lflag.h where a typo in
the copyright notice meant it failed to be updated automatically.
Please remember to include 2020 in the dates for any new files added
in future (which means updating any existing uncommitted patches you
have that add new files to use the new copyright dates in them).
Previously, ld.so was invoked only with the elf subdirectory on the
library search path. Since the soname link for libc.so only exists in
the top-level build directory, this leaked the system libc into the
test.
Blocking signals causes issues with certain anti-malware solutions
which rely on an unblocked SIGSYS signal for system calls they
intercept.
This reverts commit a2e8aa0d9e
("Block signals during the initial part of dlopen") and adds
comments related to async signal safety to active_nodelete and
its caller.
Note that this does not make lazy binding async-signal-safe with regards
to dlopen. It merely avoids introducing new async-signal-safety hazards
as part of the NODELETE changes.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Commit a2e8aa0d9e ("Block signals during
the initial part of dlopen") was deemed necessary because of
read-modify-write operations like the one in add_dependency in
elf/dl-lookup.c. In the old code, we check for any kind of NODELETE
status and bail out:
/* Redo the NODELETE check, as when dl_load_lock wasn't held
yet this could have changed. */
if (map->l_nodelete != link_map_nodelete_inactive)
goto out;
And then set pending status (during relocation):
if (flags & DL_LOOKUP_FOR_RELOCATE)
map->l_nodelete = link_map_nodelete_pending;
else
map->l_nodelete = link_map_nodelete_active;
If a signal arrives during relocation and the signal handler, through
lazy binding, adds a global scope dependency on the same map, it will
set map->l_nodelete to link_map_nodelete_active. This will be
overwritten with link_map_nodelete_pending by the dlopen relocation
code.
To avoid such problems in relation to the l_nodelete member, this
commit introduces two flags for active NODELETE status (irrevocable)
and pending NODELETE status (revocable until activate_nodelete is
invoked). As a result, NODELETE processing in dlopen does not
introduce further reasons why lazy binding from signal handlers
is unsafe during dlopen, and a subsequent commit can remove signal
blocking from dlopen.
This does not address pre-existing issues (unrelated to the NODELETE
changes) which make lazy binding in a signal handler during dlopen
unsafe, such as the use of malloc in both cases.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
The assumption behind the assert in activate_nodelete was wrong:
Inconsistency detected by ld.so: dl-open.c: 459: activate_nodelete:
Assertion `!imap->l_init_called || imap->l_type != lt_loaded' failed! (edit)
It can happen that an already-loaded object that is in the local
scope is promoted to NODELETE status, via binding to a unique
symbol.
Similarly, it is possible that such NODELETE promotion occurs to
an already-loaded object from the global scope. This is why the
loop in activate_nodelete has to cover all objects in the namespace
of the new object.
In do_lookup_unique, it could happen that the NODELETE status of
an already-loaded object was overwritten with a pending NODELETE
status. As a result, if dlopen fails, this could cause a loss of
the NODELETE status of the affected object, eventually resulting
in an incorrect unload.
Fixes commit f63b73814f ("Remove all
loaded objects if dlopen fails, ignoring NODELETE [BZ #20839]").
Since commit a3cc4f48e9 ("Remove
--as-needed configure test."), --as-needed support is no longer
optional.
The macros are not much shorter and do not provide documentary
value, either, so this commit removes them.
This commit adds missing skip_ifunc checks to aarch64, arm, i386,
sparc, and x86_64. A new test case ensures that IRELATIVE IFUNC
resolvers do not run in various diagnostic modes of the dynamic
loader.
Reviewed-By: Szabolcs Nagy <szabolcs.nagy@arm.com>
This reverts the non-test change from commit d0093c5cef
("Call _dl_open_check after relocation [BZ #24259]"), given that
the underlying bug has been fixed properly in commit 61b74477fa7f63
("Remove all loaded objects if dlopen fails, ignoring NODELETE
[BZ #20839]").
Tested on x86-64-linux-gnu, with and without --enable-cet.
Change-Id: I995a6cfb89f25d2b0cf5e606428c2a93eb48fc33
Lazy binding in a signal handler that interrupts a dlopen sees
intermediate dynamic linker state. This has likely been always
unsafe, but with the new pending NODELETE state, this is clearly
incorrect. Other threads are excluded via the loader lock, but the
current thread is not. Blocking signals until right before ELF
constructors run is the safe thing to do.
Change-Id: Iad079080ebe7442c13313ba11dc2797953faef35
This introduces a “pending NODELETE” state in the link map, which is
flipped to the persistent NODELETE state late in dlopen, via
activate_nodelete. During initial relocation, symbol binding
records pending NODELETE state only. dlclose ignores pending NODELETE
state. Taken together, this results that a partially completed dlopen
is rolled back completely because new NODELETE mappings are unloaded.
Tested on x86_64-linux-gnu and i386-linux-gnu.
Change-Id: Ib2a3d86af6f92d75baca65431d74783ee0dbc292
This change splits the scope and TLS slotinfo updates in dlopen into
two parts: one to resize the data structures, and one to actually apply
the update. The call to add_to_global_resize in dl_open_worker is moved
before the demarcation point at which no further memory allocations are
allowed.
_dl_add_to_slotinfo is adjusted to make the list update optional. There
is some optimization possibility here because we could grow the slotinfo
list of arrays in a single call, one the largest TLS modid is known.
This commit does not fix the fatal meory allocation failure in
_dl_update_slotinfo. Ideally, this error during dlopen should be
recoverable.
The update order of scopes and TLS data structures is retained, although
it appears to be more correct to fully initialize TLS first, and then
expose symbols in the newly loaded objects via the scope update.
Tested on x86_64-linux-gnu.
Change-Id: I240c58387dabda3ca1bcab48b02115175fa83d6c
The call to add_to_global in dl_open_worker happens after running ELF
constructors for new objects. At this point, proper recovery from
malloc failure would be quite complicated: We would have to run the
ELF destructors and close all opened objects, something that we
currently do not do.
Instead, this change splits add_to_global into two phases,
add_to_global_resize (which can raise an exception, called before ELF
constructors run), and add_to_global_update (which cannot, called
after ELF constructors). A complication arises due to recursive
dlopen: After the inner dlopen consumes some space, the pre-allocation
in the outer dlopen may no longer be sufficient. A new member in the
namespace structure, _ns_global_scope_pending_adds keeps track of the
maximum number of objects that need to be added to the global scope.
This enables the inner add_to_global_resize call to take into account
the needs of an outer dlopen.
Most code in the dynamic linker assumes that the number of global
scope entries fits into an unsigned int (matching the r_nlist member
of struct r_scop_elem). Therefore, change the type of
_ns_global_scope_alloc to unsigned int (from size_t), and add overflow
checks.
Change-Id: Ie08e2f318510d5a6a4bcb1c315f46791b5b77524
If a lazy binding failure happens during the execution of an ELF
constructor or destructor, the dynamic loader catches the error
and reports it using the dlerror mechanism. This is undesirable
because there could be other constructors and destructors that
need processing (which are skipped), and the process is in an
inconsistent state at this point. Therefore, we have to issue
a fatal dynamic loader error error and terminate the process.
Note that the _dl_catch_exception in _dl_open is just an inner catch,
to roll back some state locally. If called from dlopen, there is
still an outer catch, which is why calling _dl_init via call_dl_init
and a no-exception is required and cannot be avoiding by moving the
_dl_init call directly into _dl_open.
_dl_fini does not need changes because it does not install an error
handler, so errors are already fatal there.
Change-Id: I6b1addfe2e30f50a1781595f046f44173db9491a
Obtaining the link map is potentially very slow because it requires
iterating over all loaded objects in the current implementation. If
the caller supplied an explicit handle (i.e., not one of the RTLD_*
constants), the dlsym implementation does not need the identity of the
caller (except in the special case of auditing), so this change
avoids computing it in that case.
Even in the minimal case (dlsym called from a main program linked with
-dl), this shows a small speedup, perhaps around five percent. The
performance improvement can be arbitrarily large in principle (if
_dl_find_dso_for_object has to iterate over many link maps).
Change-Id: Ide5d9e2cc7ac25a0ffae8fb4c26def0c898efa29
In GCC 10, the default at -O2 is now -ftree-loop-distribute-patterns.
This optimization causes GCC to "helpfully" convert the hand-written
loop in _dl_start into a call to memset, which is not available that
early in program startup. Similar problems in other places in GLIBC
have been addressed by explicitly building with
-fno-tree-loop-distribute-patterns, but this one may have been
overlooked previously because it only affects targets where
HAVE_BUILTIN_MEMSET is not defined.
This patch fixes a bug observed on nios2-linux-gnu target that caused
all programs to segv on startup.
This will allow changes in dependency processing during non-lazy
binding, for more precise processing of NODELETE objects: During
initial relocation in dlopen, the fate of NODELETE objects is still
unclear, so objects which are depended upon by NODELETE objects
cannot immediately be marked as NODELETE.
Change-Id: Ic7b94a3f7c4719a00ca8e6018088567824da0658
In some cases, it is necessary to introduce noexcept regions
where raised dynamic loader exceptions (e.g., from lazy binding)
are fatal, despite being nested in a code region with an active
exception handler. This change enhances _dl_catch_exception with
to provide such a capability. The existing function is reused,
so that it is not necessary to introduce yet another function with
a similar purpose.
Change-Id: Iec1bf642ff95a349fdde8040e9baf851ac7b8904
To improve GCC 10 compatibility, it is necessary to remove the l_audit
zero-length array from the end of struct link_map. In preparation of
that, this commit introduces an accessor function for the audit state,
so that it is possible to change the representation of the audit state
without adjusting the code that accesses it.
Tested on x86_64-linux-gnu. Built on i686-gnu.
Change-Id: Id815673c29950fc011ae5301d7cde12624f658df
Only one of the currently defined flags is incompatible with versioned
symbol lookups, so it makes sense to check for that flag and not its
complement.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Gabriel F. T. Gomes <gabrielftg@linux.ibm.com>
Change-Id: I3384349cef90cfd91862ebc34a4053f0c0a99404
From the beginning, elf/tst-dlopen-aout has exercised two different
bugs: (a) failure to report errors for a dlopen of the executable
itself in some cases (bug 24900) and (b) incorrect rollback of the
TLS modid allocation in case of a dlopen failure (bug 16634).
This commit replaces the test with elf/tst-dlopen-self for (a) and
elf/tst-dlopen-tlsmodid for (b). The latter tests use the
elf/tst-dlopen-self binaries (or iconv) with dlopen, so they are
no longer self-dlopen tests.
Tested on x86_64-linux-gnu and i686-linux-gnu, with a toolchain that
does not default to PIE.
Commit a42faf59d6 ("Fix BZ #16634.")
attempted to fix a TLS modid consistency issue by adding additional
checks to the open_verify function. However, this is fragile
because open_verify cannot reliably predict whether
_dl_map_object_from_fd will later fail in the more complex cases
(such as memory allocation failures). Therefore, this commit
assigns the TLS modid as late as possible. At that point, the link
map pointer will eventually be passed to _dl_close, which will undo
the TLS modid assignment.
Reviewed-by: Gabriel F. T. Gomes <gabrielftg@linux.ibm.com>
If the loader is invoked explicitly and loads the main executable,
it stores the file ID of the main executable in l_file_id. This
information is not available if the main excutable is loaded by the
kernel, so this is another case where the two cases differ.
This enhances commit 23d2e5faf0
("elf: Self-dlopen failure with explict loader invocation
[BZ #24900]").
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Gabriel F. T. Gomes <gabrielftg@linux.ibm.com>
The testcase forks a child process and runs pldd with PID of
this child. On systems where /proc/sys/kernel/yama/ptrace_scope
differs from zero, pldd will fail with
/usr/bin/pldd: cannot attach to process 3: Operation not permitted
This patch checks if ptrace_scope exists, is zero "classic ptrace permissions"
or one "restricted ptrace". If ptrace_scope exists and has a higher
restriction, then the test is marked as UNSUPPORTED.
The case "restricted ptrace" is handled by rearranging the processes involved
during the test. Now we have the following process tree:
-parent: do_test (performs output checks)
--subprocess 1: pldd_process (becomes pldd via execve)
---subprocess 2: target_process (ptraced via pldd)
ChangeLog:
* elf/tst-pldd.c (do_test): Add UNSUPPORTED check.
Rearrange subprocesses.
(pldd_process): New function.
* support/Makefile (libsupport-routines): Add support_ptrace.
* support/xptrace.h: New file.
* support/support_ptrace.c: Likewise.
This patch is a reimplementation of [1], which was submitted back in
2015. Copyright issue has been sorted [2] last year. It proposed a new
section (.gnu.xhash) and related dynamic tag (GT_GNU_XHASH). The new
section would be virtually identical to the existing .gnu.hash except
for the translation table (xlat) which would contain correct MIPS
.dynsym indexes corresponding to the hashvals in chains. This is because
MIPS ABI imposes a different ordering of the dynsyms than the one
expected by the .gnu.hash section. Another addition would be a leading
word at the beggining of the section, which would contain the number of
entries in the translation table.
In this patch, the new section name and dynamic tag are changed to
reflect the fact that the section should be treated as MIPS specific
(.MIPS.xhash and DT_MIPS_XHASH).
This patch addresses the alignment issue reported in [3] which is caused
by the leading word of the .MIPS.xhash section. Leading word is now
removed in the corresponding binutils patch, and the number of entries
in the translation table is computed using DT_MIPS_SYMTABNO dynamic tag.
Since the MIPS specific dl-lookup.c file was removed following the
initial patch submission, I opted for the definition of three new macros
in the generic ldsodefs.h. ELF_MACHINE_GNU_HASH_ADDRIDX defines the
index of the dynamic tag in the l_info array. ELF_MACHINE_HASH_SYMIDX is
used to calculate the index of a symbol in GNU hash. On MIPS, it is
defined to look up the symbol index in the translation table.
ELF_MACHINE_XHASH_SETUP is defined for MIPS only. It initializes the
.MIPS.xhash pointer in the link_map_machine struct.
The other major change is bumping the highest EI_ABIVERSION value for
MIPS to suggest that the dynamic linker now supports GNU hash.
The patch was tested by running the glibc testsuite for the three MIPS
ABIs (o32, n32 and n64) and for x86_64-linux-gnu.
[1] https://sourceware.org/ml/binutils/2015-10/msg00057.html
[2] https://sourceware.org/ml/binutils/2018-03/msg00025.html
[3] https://sourceware.org/ml/binutils/2016-01/msg00006.html
* elf/dl-addr.c (determine_info): Calculate the symbol index
using the newly defined ELF_MACHINE_HASH_SYMIDX macro.
* elf/dl-lookup.c (do_lookup_x): Ditto.
(_dl_setup_hash): Initialize MIPS xhash translation table.
* elf/elf.h (SHT_MIPS_XHASH): New define.
(DT_MIPS_XHASH): New define.
* sysdeps/generic/ldsodefs.h (ELF_MACHINE_GNU_HASH_ADDRIDX): New
define.
(ELF_MACHINE_HASH_SYMIDX): Ditto.
(ELF_MACHINE_XHASH_SETUP): Ditto.
* sysdeps/mips/ldsodefs.h (ELF_MACHINE_GNU_HASH_ADDRIDX): New
define.
(ELF_MACHINE_HASH_SYMIDX): Ditto.
(ELF_MACHINE_XHASH_SETUP): Ditto.
* sysdeps/mips/linkmap.h (struct link_map_machine): New member.
* sysdeps/unix/sysv/linux/mips/ldsodefs.h: Increment valid ABI
version.
* sysdeps/unix/sysv/linux/mips/libc-abis: New ABI version.
In case of an explicit loader invocation, ld.so essentially performs
a dlopen call to load the main executable. Since the pathname of
the executable is known at this point, it gets stored in the link
map. In regular mode, the pathname is not known and "" is used
instead.
As a result, if a program calls dlopen on the pathname of the main
program, the dlopen call succeeds and returns a handle for the main
map. This results in an unnecessary difference between glibc
testing (without --enable-hardcoded-path-in-tests) and production
usage.
This commit discards the names when building the link map in
_dl_new_object for the main executable, but it still determines
the origin at this point in case of an explict loader invocation.
The reason is that the specified pathname has to be used; the kernel
has a different notion of the main executable.
dlopen can no longer open PIE binaries, so it is not necessary
to link the executable as non-PIE to trigger a dlopen failure.
If we hard-code the path to the real executable, we can run the test
with and without hard-coded paths because the dlopen path will not
be recognized as the main program in both cases. (With an explict
loader invocation, the loader currently adds argv[0] to l_libname
for the main map and the dlopen call suceeds as a result; it does
not do that in standard mode.)
This change should be fully backwards-compatible because the old
code aborted the load if a soname mismatch was encountered
(instead of searching further for a matching symbol). This means
that no different symbols are found.
The soname check was explicitly disabled for the skip_map != NULL
case. However, this only happens with dl(v)sym and RTLD_NEXT,
and those lookups do not come with a verneed entry that could be used
for the check.
The error check was already explicitly disabled for the skip_map !=
NULL case, that is, when dl(v)sym was called with RTLD_NEXT. But
_dl_vsym always sets filename in the struct r_found_version argument
to NULL, so the check was not active anyway. This means that
symbol lookup results for the skip_map != NULL case do not change,
either.
STO_AARCH64_VARIANT_PCS is a non-visibility st_other flag for marking
symbols that reference functions that may follow a variant PCS with
different register usage convention from the base PCS.
DT_AARCH64_VARIANT_PCS is a dynamic tag that marks ELF modules that
have R_*_JUMP_SLOT relocations for symbols marked with
STO_AARCH64_VARIANT_PCS (i.e. have variant PCS calls via a PLT).
* elf/elf.h (STO_AARCH64_VARIANT_PCS): Define.
(DT_AARCH64_VARIANT_PCS): Define.
This test corrupts /var/cache/ldconfig/aux-cache and executes ldconfig
to check it will not segfault using the corrupted aux_cache. The test
uses the test-in-container framework. Verified no regressions on
x86_64.
This patch adds the new NT_ARM_PACA_KEYS and NT_ARM_PACG_KEYS from
Linux 5.1 to glibc's elf.h.
Tested for x86_64.
* elf/elf.h (NT_ARM_PACA_KEYS): New macro.
(NT_ARM_PACG_KEYS): Likewise.
Use a new libsupport support_bindir_prefix instead of a hardcoded
/usr/bin to create the pldd path on container directory.
Checked on x86_64-linux-gnu with default and non-default --prefix and
--bindir paths, as well with --enable-hardcoded-path-in-tests.
[BZ #24544]
* elf/tst-pldd.c (do_test): Use support_bindir_prefix instead of
pre-defined value.
Reviewed-by: DJ Delorie <dj@redhat.com>
The elf/tst-pldd (added by 1a4c27355e to fix BZ#18035) test does
not expect the hardcoded paths that are output by pldd when the test
is built with --enable-hardcoded-path-in-tests. Instead of showing
the ABI installed library names for loader and libc (such as
ld-linux-x86-64.so.2 and libc.so.6 for x86_64), pldd shows the default
built ld.so and libc.so.
It makes the tests fail with an invalid expected loader/libc name.
This patch fixes the elf-pldd test by adding the canonical ld.so and
libc.so names in the expected list of possible outputs when parsing
the result output from pldd. The test now handles both default
build and --enable-hardcoded-path-in-tests option.
Checked on x86_64-linux-gnu (built with and without
--enable-hardcoded-path-in-tests) and i686-linux-gnu.
* elf/tst-pldd.c (in_str_list): New function.
(do_test): Add default names for ld and libc as one option.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
The audit module itself can be linked with BIND_NOW; it does not
affect its functionality.
This should complete the leftovers from commit
2d6ab5df3b ("Document and fix
--enable-bind-now [BZ #21015]").
Since 9182aa6799 (Fix vDSO l_name for GDB's, BZ#387) the initial link_map
for executable itself and loader will have both l_name and l_libname->name
holding the same value due:
elf/dl-object.c
95 new->l_name = *realname ? realname : (char *) newname->name + libname_len - 1;
Since newname->name points to new->l_libname->name.
This leads to pldd to an infinite call at:
elf/pldd-xx.c
203 again:
204 while (1)
205 {
206 ssize_t n = pread64 (memfd, tmpbuf.data, tmpbuf.length, name_offset);
228 /* Try the l_libname element. */
229 struct E(libname_list) ln;
230 if (pread64 (memfd, &ln, sizeof (ln), m.l_libname) == sizeof (ln))
231 {
232 name_offset = ln.name;
233 goto again;
234 }
Since the value at ln.name (l_libname->name) will be the same as previously
read. The straightforward fix is just avoid the check and read the new list
entry.
I checked also against binaries issues with old loaders with fix for BZ#387,
and pldd could dump the shared objects.
Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, and
powerpc64le-linux-gnu.
[BZ #18035]
* elf/Makefile (tests-container): Add tst-pldd.
* elf/pldd-xx.c: Use _Static_assert in of pldd_assert.
(E(find_maps)): Avoid use alloca, use default read file operations
instead of explicit LFS names, and fix infinite loop.
* elf/pldd.c: Explicit set _FILE_OFFSET_BITS, cleanup headers.
(get_process_info): Use _Static_assert instead of assert, use default
directory operations instead of explicit LFS names, and free some
leadek pointers.
* elf/tst-pldd.c: New file.
This patch refactor how hp-timing is used on loader code for statistics
report. The HP_TIMING_AVAIL and HP_SMALL_TIMING_AVAIL are removed and
HP_TIMING_INLINE is used instead to check for hp-timing avaliability.
For alpha, which only defines HP_SMALL_TIMING_AVAIL, the HP_TIMING_INLINE
is set iff for IS_IN(rtld).
Checked on aarch64-linux-gnu, x86_64-linux-gnu, and i686-linux-gnu. I also
checked the builds for all afected ABIs.
* benchtests/bench-timing.h: Replace HP_TIMING_AVAIL with
HP_TIMING_INLINE.
* nptl/descr.h: Likewise.
* elf/rtld.c (RLTD_TIMING_DECLARE, RTLD_TIMING_NOW, RTLD_TIMING_DIFF,
RTLD_TIMING_ACCUM_NT, RTLD_TIMING_SET): Define.
(dl_start_final_info, _dl_start_final, dl_main, print_statistics):
Abstract hp-timing usage with RTLD_* macros.
* sysdeps/alpha/hp-timing.h (HP_TIMING_INLINE): Define iff IS_IN(rtld).
(HP_TIMING_AVAIL, HP_SMALL_TIMING_AVAIL): Remove.
* sysdeps/generic/hp-timing.h (HP_TIMING_AVAIL, HP_SMALL_TIMING_AVAIL,
HP_TIMING_NONAVAIL): Likewise.
* sysdeps/ia64/hp-timing.h (HP_TIMING_AVAIL, HP_SMALL_TIMING_AVAIL):
Likewise.
* sysdeps/powerpc/powerpc32/power4/hp-timing.h (HP_TIMING_AVAIL,
HP_SMALL_TIMING_AVAIL): Likewise.
* sysdeps/powerpc/powerpc64/hp-timing.h (HP_TIMING_AVAIL,
HP_SMALL_TIMING_AVAIL): Likewise.
* sysdeps/sparc/sparc32/sparcv9/hp-timing.h (HP_TIMING_AVAIL,
HP_SMALL_TIMING_AVAIL): Likewise.
* sysdeps/sparc/sparc64/hp-timing.h (HP_TIMING_AVAIL,
HP_SMALL_TIMING_AVAIL): Likewise.
* sysdeps/x86/hp-timing.h (HP_TIMING_AVAIL, HP_SMALL_TIMING_AVAIL):
Likewise.
* sysdeps/generic/hp-timing-common.h: Update comment with
HP_TIMING_AVAIL removal.
This patch removes CLOCK_THREAD_CPUTIME_ID and CLOCK_PROCESS_CPUTIME_ID support
from clock_gettime and clock_settime generic implementation. For Linux, kernel
already provides supports through the syscall and Hurd HTL lacks
__pthread_clock_gettime and __pthread_clock_settime internal implementation.
As described in clock_gettime man-page [1] on 'Historical note for SMP
system', implementing CLOCK_{THREAD,PROCESS}_CPUTIME_ID with timer registers
is error-prone and susceptible to timing and accurary issues that the libc
can not deal without kernel support.
This allows removes unused code which, however, still incur in some runtime
overhead in thread creation (the struct pthread cpuclock_offset
initialization).
If hurd eventually wants to support them it should either either implement as
a kernel facility (or something related due its architecture) or in system
specific implementation.
Checked on aarch64-linux-gnu, x86_64-linux-gnu, and i686-linux-gnu. I also
checked on a i686-gnu build.
* nptl/Makefile (libpthread-routines): Remove pthread_clock_gettime and
pthread_clock_settime.
* nptl/pthreadP.h (__find_thread_by_id): Remove prototype.
* elf/dl-support.c [!HP_TIMING_NOAVAIL] (_dl_cpuclock_offset): Remove.
(_dl_non_dynamic_init): Remove _dl_cpuclock_offset setting.
* elf/rtld.c (_dl_start_final): Likewise.
* nptl/allocatestack.c (__find_thread_by_id): Remove function.
* sysdeps/generic/ldsodefs.h [!HP_TIMING_NOAVAIL] (_dl_cpuclock_offset):
Remove.
* sysdeps/mach/hurd/dl-sysdep.c [!HP_TIMING_NOAVAIL]
(_dl_cpuclock_offset): Remove.
* nptl/descr.h (struct pthread): Rename cpuclock_offset to
cpuclock_offset_ununsed.
* nptl/nptl-init.c (__pthread_initialize_minimal_internal): Remove
cpuclock_offset set.
* nptl/pthread_create.c (START_THREAD_DEFN): Likewise.
* sysdeps/nptl/fork.c (__libc_fork): Likewise.
* nptl/pthread_clock_gettime.c: Remove file.
* nptl/pthread_clock_settime.c: Likewise.
* sysdeps/unix/clock_gettime.c (hp_timing_gettime): Remove function.
[HP_TIMING_AVAIL] (realtime_gettime): Remove CLOCK_THREAD_CPUTIME_ID
and CLOCK_PROCESS_CPUTIME_ID support.
* sysdeps/unix/clock_settime.c (hp_timing_gettime): Likewise.
[HP_TIMING_AVAIL] (realtime_gettime): Likewise.
* sysdeps/posix/clock_getres.c (hp_timing_getres): Likewise.
[HP_TIMING_AVAIL] (__clock_getres): Likewise.
* sysdeps/unix/clock_nanosleep.c (CPUCLOCK_P, INVALID_CLOCK_P):
Likewise.
(__clock_nanosleep): Remove CPUCLOCK_P and INVALID_CLOCK_P usage.
[1] http://man7.org/linux/man-pages/man2/clock_gettime.2.html
Starting with commit 1616d034b6
the output was corrupted on some platforms as _dl_procinfo
was called for every auxv entry and on some architectures like s390
all entries were represented as "AT_HWCAP".
This patch is removing the condition and let _dl_procinfo decide if
an entry is printed in a platform specific or generic way.
This patch also adjusts all _dl_procinfo implementations which assumed
that they are only called for AT_HWCAP or AT_HWCAP2. They are now just
returning a non-zero-value for entries which are not handled platform
specifc.
ChangeLog:
* elf/dl-sysdep.c (_dl_show_auxv): Remove condition and always
call _dl_procinfo.
* sysdeps/unix/sysv/linux/s390/dl-procinfo.h (_dl_procinfo):
Ignore types other than AT_HWCAP.
* sysdeps/sparc/dl-procinfo.h (_dl_procinfo): Likewise.
* sysdeps/unix/sysv/linux/i386/dl-procinfo.h (_dl_procinfo):
Likewise.
* sysdeps/powerpc/dl-procinfo.h (_dl_procinfo): Adjust comment
in the case of falling back to generic output mechanism.
* sysdeps/unix/sysv/linux/arm/dl-procinfo.h (_dl_procinfo):
Likewise.
This patch adds some defines relate to machine flag and section information,
which is used by elfutils elflint check. A C-SKY typo is also fixed with
this patch.
* elf/elf.h (EF_CSKY_ABIMASK, EF_CSKY_OTHER, EF_CSKY_PROCESSOR)
(EF_CSKY_ABIV1, EF_CSKY_ABIV2, SHT_CSKY_ATTRIBUTES): New defines.
It is possible that the link editor injects an allocated ABI tag note
before the artificial, allocated large note in the test. Note parsing
in open_verify stops when the first ABI tag note is encountered, so if
the ABI tag note comes first, the problematic code is not actually
exercised.
Also tweak the artificial note so that it is a syntactically valid
4-byte aligned note, in case the link editor tries to parse notes and
process them.
Improves the testing part of commit 0065aaaaae.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
The existing tests all use global symbols (but with different
visibility). Local symbols could be treated differently by the
compiler and linker (as was the case on POWER ELFv2, causing
bug 23937), and we did not have test coverage for this.
Tested on x86-64 and POWER ELFv2 little-endian, with and without
--disable-multi-arch. On POWER, the test cases elf/ifuncmain9,
elf/ifuncmain9pic, elf/ifuncmain9pie reproduce bug 23937 with older
binutils.
We should run IFUNC tests with --disable-multi-arch if the toolchain
supports IFUNCs. For correctness, --disable-multi-arch must not
remove IFUNC support from the loader.
Tested on x86-64, x32 and i686 with and without --disable-multi-arch.
* configure.ac (have-ifunc): New LIBC_CONFIG_VAR.
* configure: Regenerated.
* elf/Makefile: Run IFUNC tests if binutils supports IFUNC.
Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
The clone.S patch fixes 2 elfutils testsuite unwind failures, where the
backtrace gets stuck repeating __thread_start until we hit the backtrace
limit. This was confirmed by building and installing a patched glibc and
then building elfutils and running its testsuite.
Unfortunately, the testcase isn't working as expected and I don't know why.
The testcase passes even when my clone.S patch is not installed. The testcase
looks logically similarly to the elfutils testcases that are failing. Maybe
there is a subtle difference in how the glibc unwinding works versus the
elfutils unwinding? I don't have good gdb pthread support yet, so I haven't
found a way to debug this. Anyways, I don't know if the testcase is useful or
not. If the testcase isn't useful then maybe the clone.S patch is OK without
a testcase?
Jim
[BZ #24040]
* elf/Makefile (CFLAGS-tst-unwind-main.c): Add -DUSE_PTHREADS=0.
* elf/tst-unwind-main.c: If USE_PTHEADS, include pthread.h and error.h
(func): New.
(main): If USE_PTHREADS, call pthread_create to run func. Otherwise
call func directly.
* nptl/Makefile (tests): Add tst-unwind-thread.
(CFLAGS-tst-unwind-thread.c): Define.
* nptl/tst-unwind-thread.c: New file.
* sysdeps/unix/sysv/linux/riscv/clone.S (__thread_start): Mark ra
as undefined.
This change moves the audit module loading and early notification into
separate functions out of dl_main.
It restores the bug fix from commit
8e889c5da3 ("elf: Fix LD_AUDIT for
modules with invalid version (BZ#24122)") which was reverted in commit
83e6b59625 ("[elf] Revert 8e889c5da3
(BZ#24122)").
The actual bug fix is the separate error message for the case when
la_version returns zero. The dynamic linker error message (which is
NULL in this case) is no longer used. Based on the intended use of
version zero (ignore this module due to explicit request), the message
is only printed if debugging is enabled.
This patch adds fall-through comments in some cases where -Wextra
produces implicit-fallthrough warnings.
The patch is non-exhaustive. Apart from architecture-specific code
for non-x86_64 architectures, it does not change sunrpc/xdr.c (legacy
code, probably should have such changes, but left to be dealt with
separately), or places that already had comments about the
fall-through but not matching the form expected by
-Wimplicit-fallthrough=3 (the default level with -Wextra; my
inclination is to adjust those comments to match rather than
downgrading to -Wimplicit-fallthrough=1 to allow any comment), or one
place where I thought the implicit fallthrough was not correct and so
should be handled separately as a bug fix. I think the key thing to
consider in review of this patch is whether the fall-through is indeed
intended and correct in each place where such a comment is added.
Tested for x86_64.
* elf/dl-exception.c (_dl_exception_create_format): Add
fall-through comments.
* elf/ldconfig.c (parse_conf_include): Likewise.
* elf/rtld.c (print_statistics): Likewise.
* locale/programs/charmap.c (parse_charmap): Likewise.
* misc/mntent_r.c (__getmntent_r): Likewise.
* posix/wordexp.c (parse_arith): Likewise.
(parse_backtick): Likewise.
* resolv/ns_ttl.c (ns_parse_ttl): Likewise.
* sysdeps/x86/cpu-features.c (init_cpu_features): Likewise.
* sysdeps/x86_64/dl-machine.h (elf_machine_rela): Likewise.
One group of warnings seen with -Wextra is warnings for static or
inline not at the start of a declaration (-Wold-style-declaration).
This patch fixes various such cases for inline, ensuring it comes at
the start of the declaration (after any static). A common case of the
fix is "static inline <type> __always_inline"; the definition of
__always_inline starts with __inline, so the natural change is to
"static __always_inline <type>". Other cases of the warning may be
harder to fix (one pattern is a function definition that gets
rewritten to be static by an including file, "#define funcname static
wrapped_funcname" or similar), but it seems worth fixing these cases
with inline anyway.
Tested for x86_64.
* elf/dl-load.h (_dl_postprocess_loadcmd): Use __always_inline
before return type, without separate inline.
* elf/dl-tunables.c (maybe_enable_malloc_check): Likewise.
* elf/dl-tunables.h (tunable_is_name): Likewise.
* malloc/malloc.c (do_set_trim_threshold): Likewise.
(do_set_top_pad): Likewise.
(do_set_mmap_threshold): Likewise.
(do_set_mmaps_max): Likewise.
(do_set_mallopt_check): Likewise.
(do_set_perturb_byte): Likewise.
(do_set_arena_test): Likewise.
(do_set_arena_max): Likewise.
(do_set_tcache_max): Likewise.
(do_set_tcache_count): Likewise.
(do_set_tcache_unsorted_limit): Likewise.
* nis/nis_subr.c (count_dots): Likewise.
* nptl/allocatestack.c (advise_stack_range): Likewise.
* sysdeps/ieee754/dbl-64/s_sin.c (do_cos): Likewise.
(do_sin): Likewise.
(reduce_sincos): Likewise.
(do_sincos): Likewise.
* sysdeps/unix/sysv/linux/x86/elision-conf.c
(do_set_elision_enable): Likewise.
(TUNABLE_CALLBACK_FNDECL): Likewise.
Add support for AT_L1I_CACHESIZE, AT_L1I_CACHEGEOMETRY,
AT_L1D_CACHESIZE, AT_L1D_CACHEGEOMETRY, AT_L2_CACHESIZE,
AT_L2_CACHEGEOMETRY, AT_L3_CACHESIZE and AT_L3_CACHEGEOMETRY when
LD_SHOW_AUXV=1.
AT_L*_CACHESIZE is printed as decimal and represent the number of
bytes of the cache.
AT_L*_CACHEGEOMETRY is treated in order to specify the cache line size
and its associativity.
Example output from a POWER8:
AT_L1I_CACHESIZE: 32768
AT_L1I_CACHEGEOMETRY: 128B line size, 8-way set associative
AT_L1D_CACHESIZE: 65536
AT_L1D_CACHEGEOMETRY: 128B line size, 8-way set associative
AT_L2_CACHESIZE: 524288
AT_L2_CACHEGEOMETRY: 128B line size, 8-way set associative
AT_L3_CACHESIZE: 8388608
AT_L3_CACHEGEOMETRY: 128B line size, 8-way set associative
Some of the new types are longer than the previous ones, requiring to
increase the indentation in order to keep the values aligned.
* elf/dl-sysdep.c (auxvars): Add AT_L1I_CACHESIZE,
AT_L1I_CACHEGEOMETRY, AT_L1D_CACHESIZE, AT_L1D_CACHEGEOMETRY,
AT_L2_CACHESIZE, AT_L2_CACHEGEOMETRY, AT_L3_CACHESIZE and
AT_L3_CACHEGEOMETRY. Fix indentation when printing the other
fields.
(_dl_show_auxv): Give a special treatment to
AT_L1I_CACHEGEOMETRY, AT_L1D_CACHEGEOMETRY, AT_L2_CACHEGEOMETRY
and AT_L3_CACHEGEOMETRY.
* sysdeps/powerpc/dl-procinfo.h (cache_geometry): New function.
(_dl_procinfo): Fix indentation when printing AT_HWCAP and
AT_HWCAP2. Add support for AT_L1I_CACHEGEOMETRY,
AT_L1D_CACHEGEOMETRY, AT_L2_CACHEGEOMETRY and AT_L3_CACHEGEOMETRY.
Signed-off-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
There is a data-dependency between the fields of struct l_reloc_result
and the field used as the initialization guard. Users of the guard
expect writes to the structure to be observable when they also observe
the guard initialized. The solution for this problem is to use an acquire
and release load and store to ensure previous writes to the structure are
observable if the guard is initialized.
The previous implementation used DL_FIXUP_VALUE_ADDR (l_reloc_result->addr)
as the initialization guard, making it impossible for some architectures
to load and store it atomically, i.e. hppa and ia64, due to its larger size.
This commit adds an unsigned int to l_reloc_result to be used as the new
initialization guard of the struct, making it possible to load and store
it atomically in all architectures. The fix ensures that the values
observed in l_reloc_result are consistent and do not lead to crashes.
The algorithm is documented in the code in elf/dl-runtime.c
(_dl_profile_fixup). Not all data races have been eliminated.
Tested with build-many-glibcs and on powerpc, powerpc64, and powerpc64le.
[BZ #23690]
* elf/dl-runtime.c (_dl_profile_fixup): Guarantee memory
modification order when accessing reloc_result->addr.
* include/link.h (reloc_result): Add field init.
* nptl/Makefile (tests): Add tst-audit-threads.
(modules-names): Add tst-audit-threads-mod1 and
tst-audit-threads-mod2.
Add rules to build tst-audit-threads.
* nptl/tst-audit-threads-mod1.c: New file.
* nptl/tst-audit-threads-mod2.c: Likewise.
* nptl/tst-audit-threads.c: Likewise.
* nptl/tst-audit-threads.h: Likewise.
Signed-off-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Add support for %x, %lx and %zx to _dl_exception_create_format and pad
to the full width with 0.
* elf/Makefile (tests-internal): Add tst-create_format1.
* elf/dl-exception.c (_dl_exception_create_format): Support
%x, %lx and %zx.
* elf/tst-create_format1.c: New file.
Mark the ra register as undefined in _start, so that unwinding through
main works correctly. Also, don't use a tail call so that ra points after
the call to __libc_start_main, not after the previous call.
This patch adds NT_MIPS_DSP and NT_MIPS_FP_MODE from Linux 4.19 to
elf.h.
Tested for x86_64.
* elf/elf.h (NT_MIPS_DSP): New macro.
(NT_MIPS_FP_MODE): Likewise.
Currently, DT_TEXTREL is incompatible with IFUNC. When DT_TEXTREL or
DF_TEXTREL is seen, the dynamic linker calls __mprotect on the segments
with PROT_READ|PROT_WRITE before applying dynamic relocations. It leads
to segfault when performing IFUNC resolution (which requires PROT_EXEC
as well for the IFUNC resolver).
This patch makes it call __mprotect with extra PROT_WRITE bit, which
will keep the PROT_EXEC bit if exists, and thus fixes the segfault.
FreeBSD rtld libexec/rtld-elf/rtld.c (reloc_textrel_prot) does the same.
Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
sparc64-linux-gnu, sparcv9-linux-gnu, and armv8-linux-gnueabihf.
Adam J. Richte <adam_richter2004@yahoo.com>
Adhemerval Zanella <adhemerval.zanella@linaro.org>
Fangrui Song <maskray@google.com>
[BZ #20480]
* config.h.in (CAN_TEXTREL_IFUNC): New define.
* configure.ac: Add check if linker supports textrel relocation with
ifunc.
* elf/dl-reloc.c (_dl_relocate_object): Use all required flags on
DT_TEXTREL segments, not only PROT_READ and PROT_WRITE.
* elf/Makefile (ifunc-pie-tests): Add tst-ifunc-textrel.
(CFLAGS-tst-ifunc-textrel.c): New rule.
* elf/tst-ifunc-textrel.c: New file.
I'm testing a patch to let the compiler expand calls to floor in libm
as built-in function calls as much as possible, instead of calling
__floor, so that no architecture-specific __floor inlines are needed,
and then to arrange for non-inlined calls to end up calling __floor,
as done with sqrt and __ieee754_sqrt.
This shows up elf/tst-relsort1mod2.c calling floor, which must not be
converted to a call to __floor. Now, while an IS_IN (libm)
conditional could be added to the existing conditionals on such
redirections in include/math.h, the _ISOMAC conditional ought to
suffice (code in other glibc libraries shouldn't be calling floor or
sqrt anyway, as they aren't provided in libc and the other libraries
don't link with libm). But while tests are mostly now built with
_ISOMAC defined, test modules in modules-names aren't unless also
listed in modules-names-tests.
As far as I can see, all the modules in modules-names in elf/ are in
fact parts of tests and so listing them in modules-names-tests is
appropriate, so they get built with something closer to the headers
used for user code, except in a few cases that actually rely on
something from internal headers. This patch duly sets
modules-names-tests there accordingly (filtering out those tests that
fail to build without internal headers).
Tested for x86_64, and with build-many-glibcs.py.
* elf/Makefile (modules-names-tests): New variable.
The elf/tst-dlopen-aout.c test uses asserts to verify properties of the
test execution. Instead of using assert it should use xpthread_create
and xpthread_join to catch errors starting the threads and fail the
test. This shows up in Fedora 28 when building for i686-pc-linux-gnu
and using gcc 8.1.1.
Tested on i686, and fixes a check failure with -DNDEBUG.
Signed-off-by: Carlos O'Donell <carlos@redhat.com>
This patch adds two new constants from Linux 4.18 to elf.h,
NT_VMCOREDD and AT_MINSIGSTKSZ.
Tested for x86_64.
* elf/elf.c (NT_VMCOREDD): New macro.
(AT_MINSIGSTKSZ): Likewise.
The glibc.tune namespace is vaguely named since it is a 'tunable', so
give it a more specific name that describes what it refers to. Rename
the tunable namespace to 'cpu' to more accurately reflect what it
encompasses. Also rename glibc.tune.cpu to glibc.cpu.name since
glibc.cpu.cpu is weird.
* NEWS: Mention the change.
* elf/dl-tunables.list: Rename tune namespace to cpu.
* sysdeps/powerpc/dl-tunables.list: Likewise.
* sysdeps/x86/dl-tunables.list: Likewise.
* sysdeps/aarch64/dl-tunables.list: Rename tune.cpu to
cpu.name.
* elf/dl-hwcaps.c (_dl_important_hwcaps): Adjust.
* elf/dl-hwcaps.h (GET_HWCAP_MASK): Likewise.
* manual/README.tunables: Likewise.
* manual/tunables.texi: Likewise.
* sysdeps/powerpc/cpu-features.c: Likewise.
* sysdeps/unix/sysv/linux/aarch64/cpu-features.c
(init_cpu_features): Likewise.
* sysdeps/x86/cpu-features.c: Likewise.
* sysdeps/x86/cpu-features.h: Likewise.
* sysdeps/x86/cpu-tunables.c: Likewise.
* sysdeps/x86_64/Makefile: Likewise.
* sysdeps/x86/dl-cet.c: Likewise.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
* scripts/check-execstack.awk: Consider `xfail' variable containing a
list
of libraries whose stack executability is expected.
* elf/Makefile ($(objpfx)check-execstack.out): Pass
$(check-execstack-xfail) to check-execstack.awk through `xfail'
variable.
* sysdeps/mach/hurd/i386/Makefile (check-execstack-xfail): Set to ld.so
libc.so libpthread.so.
Intel Control-flow Enforcement Technology (CET) instructions:
https://software.intel.com/sites/default/files/managed/4d/2a/control-flow-en
forcement-technology-preview.pdf
includes Indirect Branch Tracking (IBT) and Shadow Stack (SHSTK).
GNU_PROPERTY_X86_FEATURE_1_IBT is added to GNU program property to
indicate that all executable sections are compatible with IBT when
ENDBR instruction starts each valid target where an indirect branch
instruction can land. Linker sets GNU_PROPERTY_X86_FEATURE_1_IBT on
output only if it is set on all relocatable inputs.
On an IBT capable processor, the following steps should be taken:
1. When loading an executable without an interpreter, enable IBT and
lock IBT if GNU_PROPERTY_X86_FEATURE_1_IBT is set on the executable.
2. When loading an executable with an interpreter, enable IBT if
GNU_PROPERTY_X86_FEATURE_1_IBT is set on the interpreter.
a. If GNU_PROPERTY_X86_FEATURE_1_IBT isn't set on the executable,
disable IBT.
b. Lock IBT.
3. If IBT is enabled, when loading a shared object without
GNU_PROPERTY_X86_FEATURE_1_IBT:
a. If legacy interwork is allowed, then mark all pages in executable
PT_LOAD segments in legacy code page bitmap. Failure of legacy code
page bitmap allocation causes an error.
b. If legacy interwork isn't allowed, it causes an error.
GNU_PROPERTY_X86_FEATURE_1_SHSTK is added to GNU program property to
indicate that all executable sections are compatible with SHSTK where
return address popped from shadow stack always matches return address
popped from normal stack. Linker sets GNU_PROPERTY_X86_FEATURE_1_SHSTK
on output only if it is set on all relocatable inputs.
On a SHSTK capable processor, the following steps should be taken:
1. When loading an executable without an interpreter, enable SHSTK if
GNU_PROPERTY_X86_FEATURE_1_SHSTK is set on the executable.
2. When loading an executable with an interpreter, enable SHSTK if
GNU_PROPERTY_X86_FEATURE_1_SHSTK is set on interpreter.
a. If GNU_PROPERTY_X86_FEATURE_1_SHSTK isn't set on the executable
or any shared objects loaded via the DT_NEEDED tag, disable SHSTK.
b. Otherwise lock SHSTK.
3. After SHSTK is enabled, it is an error to load a shared object
without GNU_PROPERTY_X86_FEATURE_1_SHSTK.
To enable CET support in glibc, --enable-cet is required to configure
glibc. When CET is enabled, both compiler and assembler must support
CET. Otherwise, it is a configure-time error.
To support CET run-time control,
1. _dl_x86_feature_1 is added to the writable ld.so namespace to indicate
if IBT or SHSTK are enabled at run-time. It should be initialized by
init_cpu_features.
2. For dynamic executables:
a. A l_cet field is added to struct link_map to indicate if IBT or
SHSTK is enabled in an ELF module. _dl_process_pt_note or
_rtld_process_pt_note is called to process PT_NOTE segment for
GNU program property and set l_cet.
b. _dl_open_check is added to check IBT and SHSTK compatibilty when
dlopening a shared object.
3. Replace i386 _dl_runtime_resolve and _dl_runtime_profile with
_dl_runtime_resolve_shstk and _dl_runtime_profile_shstk, respectively if
SHSTK is enabled.
CET run-time control can be changed via GLIBC_TUNABLES with
$ export GLIBC_TUNABLES=glibc.tune.x86_shstk=[permissive|on|off]
$ export GLIBC_TUNABLES=glibc.tune.x86_ibt=[permissive|on|off]
1. permissive: SHSTK is disabled when dlopening a legacy ELF module.
2. on: IBT or SHSTK are always enabled, regardless if there are IBT or
SHSTK bits in GNU program property.
3. off: IBT or SHSTK are always disabled, regardless if there are IBT or
SHSTK bits in GNU program property.
<cet.h> from CET-enabled GCC is automatically included by assembly codes
to add GNU_PROPERTY_X86_FEATURE_1_IBT and GNU_PROPERTY_X86_FEATURE_1_SHSTK
to GNU program property. _CET_ENDBR is added at the entrance of all
assembly functions whose address may be taken. _CET_NOTRACK is used to
insert NOTRACK prefix with indirect jump table to support IBT. It is
defined as notrack when _CET_NOTRACK is defined in <cet.h>.
[BZ #21598]
* configure.ac: Add --enable-cet.
* configure: Regenerated.
* elf/Makefille (all-built-dso): Add a comment.
* elf/dl-load.c (filebuf): Moved before "dynamic-link.h".
Include <dl-prop.h>.
(_dl_map_object_from_fd): Call _dl_process_pt_note on PT_NOTE
segment.
* elf/dl-open.c: Include <dl-prop.h>.
(dl_open_worker): Call _dl_open_check.
* elf/rtld.c: Include <dl-prop.h>.
(dl_main): Call _rtld_process_pt_note on PT_NOTE segment. Call
_rtld_main_check.
* sysdeps/generic/dl-prop.h: New file.
* sysdeps/i386/dl-cet.c: Likewise.
* sysdeps/unix/sysv/linux/x86/cpu-features.c: Likewise.
* sysdeps/unix/sysv/linux/x86/dl-cet.h: Likewise.
* sysdeps/x86/cet-tunables.h: Likewise.
* sysdeps/x86/check-cet.awk: Likewise.
* sysdeps/x86/configure: Likewise.
* sysdeps/x86/configure.ac: Likewise.
* sysdeps/x86/dl-cet.c: Likewise.
* sysdeps/x86/dl-procruntime.c: Likewise.
* sysdeps/x86/dl-prop.h: Likewise.
* sysdeps/x86/libc-start.h: Likewise.
* sysdeps/x86/link_map.h: Likewise.
* sysdeps/i386/dl-trampoline.S (_dl_runtime_resolve): Add
_CET_ENDBR.
(_dl_runtime_profile): Likewise.
(_dl_runtime_resolve_shstk): New.
(_dl_runtime_profile_shstk): Likewise.
* sysdeps/linux/x86/Makefile (sysdep-dl-routines): Add dl-cet
if CET is enabled.
(CFLAGS-.o): Add -fcf-protection if CET is enabled.
(CFLAGS-.os): Likewise.
(CFLAGS-.op): Likewise.
(CFLAGS-.oS): Likewise.
(asm-CPPFLAGS): Add -fcf-protection -include cet.h if CET
is enabled.
(tests-special): Add $(objpfx)check-cet.out.
(cet-built-dso): New.
(+$(cet-built-dso:=.note)): Likewise.
(common-generated): Add $(cet-built-dso:$(common-objpfx)%=%.note).
($(objpfx)check-cet.out): New.
(generated): Add check-cet.out.
* sysdeps/x86/cpu-features.c: Include <dl-cet.h> and
<cet-tunables.h>.
(TUNABLE_CALLBACK (set_x86_ibt)): New prototype.
(TUNABLE_CALLBACK (set_x86_shstk)): Likewise.
(init_cpu_features): Call get_cet_status to check CET status
and update dl_x86_feature_1 with CET status. Call
TUNABLE_CALLBACK (set_x86_ibt) and TUNABLE_CALLBACK
(set_x86_shstk). Disable and lock CET in libc.a.
* sysdeps/x86/cpu-tunables.c: Include <cet-tunables.h>.
(TUNABLE_CALLBACK (set_x86_ibt)): New function.
(TUNABLE_CALLBACK (set_x86_shstk)): Likewise.
* sysdeps/x86/sysdep.h (_CET_NOTRACK): New.
(_CET_ENDBR): Define if not defined.
(ENTRY): Add _CET_ENDBR.
* sysdeps/x86/dl-tunables.list (glibc.tune): Add x86_ibt and
x86_shstk.
* sysdeps/x86_64/dl-trampoline.h (_dl_runtime_resolve): Add
_CET_ENDBR.
(_dl_runtime_profile): Likewise.
We have this condition in `check_match' (in elf/dl-lookup.c):
if (__glibc_unlikely ((sym->st_value == 0 /* No value. */
&& stt != STT_TLS)
|| ELF_MACHINE_SYM_NO_MATCH (sym)
|| (type_class & (sym->st_shndx == SHN_UNDEF))))
return NULL;
which causes all !STT_TLS symbols whose value is zero to be silently
ignored in lookup. This may make sense for regular symbols, however not
for absolute (SHN_ABS) ones, where zero is like any value, there's no
special meaning attached to it.
Consequently legitimate programs fail, for example taking the
`elf/tst-absolute-sym' test case, substituting 0 for 0x55aa in
`elf/tst-absolute-sym-lib.lds' and then trying to run the resulting
program we get this:
$ .../elf/tst-absolute-sym
.../elf/tst-absolute-sym: symbol lookup error: .../elf/tst-absolute-sym-lib.so: undefined symbol: absolute
$
even though the symbol clearly is there:
$ readelf --dyn-syms .../elf/tst-absolute-sym-lib.so | grep '\babsolute\b'
7: 00000000 0 NOTYPE GLOBAL DEFAULT ABS absolute
$
The check for the zero value has been there since forever or commit
d66e34cd4234/08162fa88891 ("Implemented runtime dynamic linker to
support ELF shared libraries.") dating back to May 2nd 1995, and the
problem triggers regardless of commit e7feec374c ("elf: Correct
absolute (SHN_ABS) symbol run-time calculation [BZ #19818]") being
present or not.
Fix the issue then, by permitting `sym->st_value' to be 0 for SHN_ABS
symbols in lookup.
[BZ #23307]
* elf/dl-lookup.c (check_match): Do not reject a symbol whose
`st_value' is 0 if `st_shndx' is SHN_ABS.
* elf/tst-absolute-zero.c: New file.
* elf/tst-absolute-zero-lib.c: New file.
* elf/tst-absolute-zero-lib.lds: New file.
* elf/Makefile (tests): Add `tst-absolute-zero'.
(modules-names): Add `tst-absolute-zero-lib'.
(LDLIBS-tst-absolute-zero-lib.so): New variable.
($(objpfx)tst-absolute-zero-lib.so): New dependency.
($(objpfx)tst-absolute-zero: New dependency.
Some Linux distributions are experimenting with a new, separately
maintained and hopefully more agile implementation of the crypt
API. To facilitate this, add a configure option which disables
glibc's embedded libcrypt. When this option is given, libcrypt.*
and crypt.h will not be built nor installed.
The function comment suggests that _dl_map_object_deps cannot use
malloc, but it already allocates the l_initfini array on the heap, so
the additional allocation should be acceptable.
The BPF ELF format has new relocation types R_BPF_64_64 and R_BPF_64_32.
The existing R_BPF_MAP_FD was an extension that never got implemented.
Remove it, because the constant conflicts with the official R_BPF_64_64.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
The comments in _dl_dst_count is adjusted to match what the code does
which is count DSTs from the start of the string. With the removal of
DL_DST_COUNT we no longer accept an input that starts at the first $.
In _dl_dst_substitute we adjust the comment to indicate that both
conditions must be true for the SUID/SGID $ORIGIN exception.
Florian Weimer
H.J. Lu
Stefan Liebler
Alexandra Hájková
Adhemerval Zanella
Joseph Myers
DJ Delorie
Sandra Loosemore
Leandro Pereira
Andreas Schwab
Paul Eggert
Mihailo Stojanovic
Szabolcs Nagy
Mao Han
Jim Wilson
David Newall
Tulio Magno Quites Machado Filho
Zong Li
Carlos O'Donell
Siddhesh Poyarekar
Samuel Thibault
Maciej W. Rozycki
Zack Weinberg
Vincent Chen
Mark Wielaard