These lines shouldn't actually matter, because the DSOs are using
version scripts to allow-list exported symbols.
Bug: none
Test: bionic unit tests
Change-Id: I39d3df8c4f8053624f862b3c6994e30c693e928c
During "step 1" of find_libraries, the linker finds the transitive
closure of dependencies, in BFS order. As it finds each library, it
adds the library to its primary namespace (so that, if some other
library also depends on it, find_loaded_library_by_soname can find the
library in the process of being loaded).
LD_PRELOAD libraries are automatically marked DF_1_GLOBAL, and any
DF_1_GLOBAL library is added to every linker namespace. Previously,
this secondary namespace registration happened after step 1. The result
is that across different namespaces, the order of libraries could vary.
In general, a namespace's primary members will all appear before
secondary members. This is undesirable for libsigchain.so, which we
want to have appear before any other non-preloaded library.
Instead, when an soinfo is added to its primary namespace, immediately
add it to all the other namespaces, too. This ensures that the order of
soinfo objects is the same across namespaces.
Expand the dl.exec_with_ld_config_file_with_ld_preload and
dl.exec_with_ld_config_file tests to cover the new behavior. Mark
lib1.so DF_1_GLOBAL and use a "foo" symbol to mimic the behavior of a
signal API interposed by (e.g.) libsigchain.so and a ASAN preload.
Test: bionic unit tests
Bug: http://b/143219447
Change-Id: I9fd90f6f0d14caf1aca6d414b3e9aab77deca3ff
No-one seems to understand that a crash in a random .so from call_array()
in the linker isn't a linker bug. They _seem_ to understand (or at least
claim to) when we explain that this is just the linker calling their ELF
constructors --- despite the fact that the caller of call_array() is
call_constructors().
One experiment we can try though is to inline call_array() to elide that
frame from the crash dumps. I do also wonder whether renaming
call_constructors() to call_elf_constructors() would help/hinder/make no
difference. For now I'm leaning toward "hinder" because I suspect most
people don't understand "ELF constructor" and C++ folks at least will
probably be influenced in a not wholly incorrect direction when they
hear "constructor" (whereas "ELF constructor" might mislead them back in
the direction of "strange linker magic, not my fault" again)...
(The reformatting is clang-format's decision, not mine.)
Test: treehugger
Change-Id: I65ab95ceb2e988fd053c48c66f51afba17ccfa61
For libc.so, use a special build of libunwind.a whose symbols aren't
hidden ("libunwind-exported"), because libc.so exports the _Unwind_*
APIs.
Bug: http://b/153025717
Test: bionic unit tests
Change-Id: I7435e076ec8cc4410e3e6086d3cf5d2c6011c80c
Setting the linker's soname ("ld-android.so") can allocate heap memory
now that the name uses an std::string, and it's probably a good idea to
defer doing this until after the linker has relocated itself (and after
it has called C++ constructors for global variables.)
Bug: none
Test: bionic unit tests
Test: verify that dlopen("ld-android.so", RTLD_NOLOAD) works
Change-Id: I6b9bd7552c3ae9b77e3ee9e2a98b069b8eef25ca
Once upon a time (and, indeed, to this very day if you're on LP32) the
soinfo struct used a fixed-length buffer for the soname. This caused
some issues, mainly with app developers who accidentally included a full
Windows "C:\My Computer\...\libfoo.so" style path. To avoid all this we
switched to just pointing into the ELF file itself, where the DT_SONAME
is already stored as a NUL-terminated string. And all was well for many
years.
Now though, we've seen a bunch of slow startup traces from dogfood where
`dlopen("libnativebridge.so")` in a cold start takes 125-200ms on a recent
device, despite no IO contention. Even though libnativebridge.so is only
20KiB.
Measurement showed that every library whose soname we check required
pulling in a whole page just for the (usually) very short string. Worse,
there's readahead. In one trace we saw 18 pages of libhwui.so pulled
in just for `"libhwui.so\0"`. In fact, there were 3306 pages (~13MiB)
added to the page cache during `dlopen("libnativebridge.so")`. 13MiB for
a 20KiB shared library!
This is the obvious change to use a std::string to copy the sonames
instead. This will dirty slightly more memory, but massively improve
locality.
Testing with the same pathological setup took `dlopen("libnativebridge.so")`
down from 192ms to 819us.
Bug: http://b/177102905
Test: tested with a pathologically modified kernel
Change-Id: I33837f4706adc25f93c6fa6013e8ba970911dfb9
Use a note in executables to specify
(none|sync|async) heap tagging level. To be extended with (heap x stack x
globals) in the future. A missing note disables all tagging.
Bug: b/135772972
Test: bionic-unit-tests (in a future change)
Change-Id: Iab145a922c7abe24cdce17323f9e0c1063cc1321
There are multiple build breakages with bionic when we enable ThinLTO
globally. Opt bionic out of ThinLTO for now.
#global-thinlto-opt-out
Test: TreeHugger
Bug: 169004486
Change-Id: I546a8074f9c3e0ddbd01d3b7cd730e215e3c0c49
This patch adds support to load BTI-enabled objects.
According to the ABI, BTI is recorded in the .note.gnu.property section.
The new parser evaluates the property section, if exists.
It searches for .note section with NT_GNU_PROPERTY_TYPE_0.
Once found it tries to find GNU_PROPERTY_AARCH64_FEATURE_1_AND.
The results are cached.
The main change in linker is when protection of loaded ranges gets
applied. When BTI is requested and the platform also supports it
the prot flags have to be amended with PROT_BTI for executable ranges.
Failing to add PROT_BTI flag would disable BTI protection.
Moreover, adding the new PROT flag for shared objects without BTI
compatibility would break applications.
Kernel does not add PROT_BTI to a loaded ELF which has interpreter.
Linker handles this case too.
Test: 1. Flame boots
2. Tested on FVP with BTI enabled
Change-Id: Iafdf223b74c6e75d9f17ca90500e6fe42c4c1218
As we enable arm64-based Bionic host target (linux_bionic_arm64),
linker_wrapper is added with the corresponding source.
Bug: 159685774
Test: HOST_CROSS_OS=linux_bionic HOST_CROSS_ARCH=arm64 m
Test: copy out/soong/host/linux_bionic_arm64/ to an ARM64 emulator
running Linux and execute the binaries
Change-Id: I4f367a349f7e0015318352cb7f2870fc856eab05
(Based on proposal at https://sourceware.org/glibc/wiki/ThreadPropertiesAPI)
This includes API to:
- locate static and dynamic TLS
- register thread-exit and dynamic TLS creation/destruction callbacks
Change-Id: Icd9d29a5b2f47495395645e19d3b2c96826f19c8
Update a comment in android-changes-for-ndk-developers.md about the
removed debug.ld.greylist_disabled system property.
Update language to comply with Android's inclusive language guidance
#inclusivefixit
See https://source.android.com/setup/contribute/respectful-code for reference
Bug: http://b/162536543
Test: bionic-unit-tests
Change-Id: I760ee14bce14d9d799926c43d2c14fd8ffbc6968
1. Cleanup for #inclusivefixit. (whitelisted -> allowed_libs)
2. Support the old term for backwards compatibility. (Also update test.)
3. Fix the formatting errors found by clang-format.
See https://source.android.com/setup/contribute/respectful-code
for reference.
Bug: 161896447
Test: atest linker-unit-tests linker-benchmarks
Change-Id: I19dbed27a6d874ac0049cb7b67d2cb0f75369c1b
This property provided a way to disable the greylist, for testing
whether an app targeting < 24 still works. Instead of turning off the
greylist, though, an app developer should simply target a newer API.
(If app developers really need this property for testing, they can
still use it on versions of Android between N and R, inclusive.)
Update language to comply with Android's inclusive language guidance
See https://source.android.com/setup/contribute/respectful-code for reference
#inclusivefixit
Bug: http://b/162536543
Test: bionic-unit-tests
Change-Id: Id1eb2807fbb7436dc9ed7fe47e15b7d165a26789
Add inaccessible gaps between shared libraries to make it harder for the
attackers to defeat ASLR by random probing.
To avoid excessive page table bloat, only do this when a library is
about to cross a huge page boundary, effectively allowing several
smaller libraries to be lumped together.
Bug: 158113540
Test: look at /proc/$$/maps
Change-Id: I39c0100b81f72447e8b3c6faafa561111492bf8c
This reverts commit a8cf3fef2a.
Reason for revert: memory regression due to the fragmentation of the page tables
Bug: 159810641
Bug: 158113540
Change-Id: I6212c623ff440c7f6889f0a1e82cf7a96200a411
There are some special cases - such as init process - when linker
configuration is not expected to exist. This change disables warning
message that generated linker configuration does not exist in those
cases.
Bug: 158800902
Test: Tested from cuttlefish that warning message is not generated from
init
Change-Id: Ie2fbb5210175cf1e6f2b7e638f57c3b74d395368
Improve ASLR by increasing the randomly sized gaps between shared
library mappings, and keep them mapped PROT_NONE.
Bug: 158113540
Test: look at /proc/$$/maps
Change-Id: Ie72c84047fb624fe2ac8b7744b2a2d0d255ea974
This replaces a single 2Gb readable memory region with a bunch of tiny
regions, and leaves the bulk of 2Gb mapped but unaccessible. This makes
it harder to defeat ASLR by probing for the CFI shadow region.
Sample CFI shadow mapping with this change:
7165151000-716541f000 ---p 00000000 00:00 0 [anon:cfi shadow]
716541f000-7165420000 r--p 00000000 00:00 0 [anon:cfi shadow]
7165420000-71654db000 ---p 00000000 00:00 0 [anon:cfi shadow]
71654db000-71654dc000 r--p 00000000 00:00 0 [anon:cfi shadow]
71654dc000-71654dd000 r--p 00000000 00:00 0 [anon:cfi shadow]
71654dd000-71654f0000 ---p 00000000 00:00 0 [anon:cfi shadow]
71654f0000-71654f1000 r--p 00000000 00:00 0 [anon:cfi shadow]
71654f1000-71e5151000 ---p 00000000 00:00 0 [anon:cfi shadow]
This change degrades CFI diagnostics for wild jumps and casts (i.e. when
the target of a CFI check is outside of any known library bounds). This
is acceptable, because CFI does not have much to tell about those cases
anyway. Such bugs will show up as SEGV_ACCERR crashes inside
__cfi_slowpath in libdl.so from now on.
Bug: 158113540
Test: bionic-unit-tests/cfi_test.*
Test: adb shell cat /proc/$PID/maps | grep cfi
Change-Id: I57cbd0d3f87eb1610ad99b48d98ffd497ba214b4
Merged-In: I57cbd0d3f87eb1610ad99b48d98ffd497ba214b4
In particular, add the strerror() output if mprotect() fails.
Fix the CHECK macro so that you can make assertions involving operator%
without that being confused for a printf format specifier.
Bug: https://issuetracker.google.com/158645318
Test: treehugger
Change-Id: I6817f8ca5f094c52dc2c9067bfac90385a8743f5
.whitelisted is a list of sonames seperated by ":" just like
.shared_libs and .paths properties. It makes sense to make it appendable
using += as well ass .shared_libs and .paths.
Bug: n/a
Test: atest linker-unit-tests
Change-Id: If61cc553c8080e8a58de8a3a6051c1853f7bfe5f
Change the location set in the linker
Bug: 130219528
Bug: 138994281
Test: atest CtsBionicTestCases
Test: atest CtsJniTestCases
Change-Id: I215a8e023ccc4d5ffdd7df884c809f8d12050c8f
The SYNC tagging level enables stack trace collection for allocations and
deallocations, which allows allocation and deallocation stack traces to
appear in tombstones when encountering a tag check fault in synchronous tag
checking mode.
Bug: 135772972
Change-Id: Ibda9f51b29d2c8e2c993fc74425dea7bfa23ab1e
Before this Soong added hardcoded system include paths to
bionic/libc/{include,kernel}, which won't work when Bionic libs are
packaged up as prebuilts in an SDK module snapshot.
Test: Build and boot
Test: Check in out/verbose.log.gz that a C file doesn't get any bionic
include path for linux_glibc.
Bug: 153590472
Change-Id: I13c8eb3dd7150d6e0fee001b290b53fcebebcfea
CfiFail calls find_containing_library, which searches the linker's
internal soinfo list, which could be modified by another thread.
Bug: http://b/150372650
Test: bionic-unit-tests
Change-Id: I59024a0a47913caa75702f15ec058b0a360727b5
android_get_exported_namespace searches g_exported_namespaces, which
isn't modified after process initialization, but it does the search
using a new std::string object, and the linker's malloc/free functions
aren't thread-safe. (They're protected by the same lock (g_dl_mutex) as
the rest of the linker's state.)
Bug: http://b/150372650
Test: bionic-unit-tests
Change-Id: Iafd12e5ab36ae61f0642aad59939f528d31bda16
For the bootstrap linker, insert /system/${LIB}/bootstrap in front of
/system/${LIB} in any namespace search path.
Bug: http://b/152572170
Test: bionic unit tests
Change-Id: Ia359d9f2063f4b6fff3f79b51b500ba968a18247
If ElfReader::Read fails, then it is hazardous to leave the invalid
ElfReader in the soinfo*->ElfReader table, because a future soinfo
object could happen to have the same address, then reuse the invalid
ElfReader. I'm not sure whether this can break anything, because the
linker would call ElfReader::Read on the invalid object and overwrite
its previous value.
Test: bionic unit tests
Bug: none
Change-Id: Ibabbf559443441b9caeacc34ca165feaafe5e3a7
The doc_link argument is really a URL fragment within the
android-changes-for-ndk-developers.md document, not a filename at the
root of the bionic repository.
Test: manual
Bug: none
Change-Id: I1b542e47aca132ce43ba1d50d83db1bf3c7b10c6
The search_linked_namespaces parameter to find_library_internal is
always true.
Bug: none
Test: bionic tests
Change-Id: I4b6f48afefca4f52b34ca2c9e0f4335fa895ff34
Add a few _Nonnull / _Nullable annotations. Clang may use them to issue
warnings but violating the annotation isn't undefined behavior.
Bug: none
Test: bionic tests
Change-Id: I82e442f06a2c59c69bc0008f0f686785695cdd02
