mbox

[v4,00/10] fix ifunc with static pie [BZ #27072]

Message ID cover.1610986541.git.szabolcs.nagy@arm.com
Headers

Message

Szabolcs Nagy Jan. 18, 2021, 4:22 p.m. UTC 
  v4:
- added patches from H.J.Lu:
	- x86: fix libmvec tests
	- x86: fix syscalls in libc_enable_secure
	- x86: avoid relative reloc for _dl_sysinfo
	- x86: add ifunc test
- i386 cannot mark all symbols hidden, so use fine grain
  marking in files that participate in early code before
  static pie self relocation.
- the patch that makes all libc symbols hidden is still
  included: it is now only an optimization for non-i386
  targets.

v3:
- refactor tunables: move internals out of dl-tunables.h
- use generated max string length in the tunables list
  instead of magic values.

v2:
- check PI_STATIC_AND_HIDDEN for --enable-static-pie
- change string buffer sizes in the tunables
- fix env_alias == NULL logic in __tunables_init
- move __ehdr_start processing after self relocation


force pushed into nsz/bug27072 branch.

Issues that are not addressed:
- tunables try to allocate memory even with non-suid exe.
  allocation is only needed for rewriting the GLIBC_TUNABLES
  env var. (i think a case can be made that if anything there
  is TUNABLE_SECLEVEL_SXID_ERASE then this env var would be
  simply dropped, that would simplify this significantly).
- __sbrk only needs the hidden visibility magic because of
  tunables, ideally we would not do allocations before self
  relocation.
- tunable list data structure is not optimized for compactness.
- all symbols are forced hidden in libc.a, but i think lib*.a
  should do the same. (other than lib*_nonshared.a)
- i386 introduced a fair bit of complications: may be avoiding
  relative relocs is too much to ask for and relocations should
  be done in two steps after all: relative first, then irelative
  when tunable etc are set up.

H.J. Lu (4):
  libmvec: Add extra-test-objs to test-extras
  elf: Avoid RELATIVE relocation for _dl_sysinfo
  Use <startup.h> in __libc_init_secure
  x86: Check ifunc resolver with CPU_FEATURE_USABLE [BZ #27072]

Szabolcs Nagy (6):
  configure: Require PI_STATIC_AND_HIDDEN for static pie
  elf: Make the tunable struct definition internal only
  elf: Avoid RELATIVE relocs in __tunables_init
  Use hidden visibility for early static PIE code
  csu: Move static pie self relocation later [BZ #27072]
  Make libc symbols hidden in static PIE

 configure                                    |  14 +++
 configure.ac                                 |   5 +
 csu/libc-start.c                             |  48 +++++---
 elf/dl-reloc-static-pie.c                    |   2 +
 elf/dl-support.c                             |  18 ++-
 elf/dl-tunable-types.h                       |  42 +++++--
 elf/dl-tunables.c                            |   6 +-
 elf/dl-tunables.h                            |  35 ++----
 elf/enbl-secure.c                            |  10 +-
 include/libc-symbols.h                       |   9 +-
 misc/sbrk.c                                  |   4 +
 scripts/gen-tunables.awk                     |  16 ++-
 sysdeps/generic/startup.h                    |  26 ++++
 sysdeps/unix/sysv/linux/aarch64/libc-start.c |   5 +
 sysdeps/unix/sysv/linux/i386/startup.h       |  29 ++++-
 sysdeps/x86/Makefile                         |  14 +++
 sysdeps/x86/libc-start.c                     |   5 +
 sysdeps/x86/tst-ifunc-isa-1-static.c         |   1 +
 sysdeps/x86/tst-ifunc-isa-1.c                | 115 ++++++++++++++++++
 sysdeps/x86/tst-ifunc-isa-2-static.c         |   1 +
 sysdeps/x86/tst-ifunc-isa-2.c                | 119 +++++++++++++++++++
 sysdeps/x86_64/fpu/Makefile                  |   8 ++
 22 files changed, 465 insertions(+), 67 deletions(-)
 create mode 100644 sysdeps/x86/tst-ifunc-isa-1-static.c
 create mode 100644 sysdeps/x86/tst-ifunc-isa-1.c
 create mode 100644 sysdeps/x86/tst-ifunc-isa-2-static.c
 create mode 100644 sysdeps/x86/tst-ifunc-isa-2.c