elf: Fix runtime linker auditing on aarch64 (BZ #26643)
authorBen Woodard <woodard@redhat.com>
Mon, 24 Jan 2022 13:46:18 +0000 (10:46 -0300)
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>
Tue, 1 Feb 2022 17:49:46 +0000 (14:49 -0300)
commitce9a68c57c260c8417afc93972849ac9ad243ec4
treeadedf6275c170675cdd751e0d59f569f4b3c69ca
parent32612615c58b394c3eb09f020f31310797ad3854
elf: Fix runtime linker auditing on aarch64 (BZ #26643)

The rtld audit support show two problems on aarch64:

  1. _dl_runtime_resolve does not preserve x8, the indirect result
      location register, which might generate wrong result calls
      depending of the function signature.

  2. The NEON Q registers pushed onto the stack by _dl_runtime_resolve
     were twice the size of D registers extracted from the stack frame by
     _dl_runtime_profile.

While 2. might result in wrong information passed on the PLT tracing,
1. generates wrong runtime behaviour.

The aarch64 rtld audit support is changed to:

  * Both La_aarch64_regs and La_aarch64_retval are expanded to include
    both x8 and the full sized NEON V registers, as defined by the
    ABI.

  * dl_runtime_profile needed to extract registers saved by
    _dl_runtime_resolve and put them into the new correctly sized
    La_aarch64_regs structure.

  * The LAV_CURRENT check is change to only accept new audit modules
    to avoid the undefined behavior of not save/restore x8.

  * Different than other architectures, audit modules older than
    LAV_CURRENT are rejected (both La_aarch64_regs and La_aarch64_retval
    changed their layout and there are no requirements to support multiple
    audit interface with the inherent aarch64 issues).

  * A new field is also reserved on both La_aarch64_regs and
    La_aarch64_retval to support variant pcs symbols.

Similar to x86, a new La_aarch64_vector type to represent the NEON
register is added on the La_aarch64_regs (so each type can be accessed
directly).

Since LAV_CURRENT was already bumped to support bind-now, there is
no need to increase it again.

Checked on aarch64-linux-gnu.

Co-authored-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Tested-by: Carlos O'Donell <carlos@redhat.com>
16 files changed:
NEWS
elf/rtld.c
sysdeps/aarch64/Makefile
sysdeps/aarch64/bits/link.h
sysdeps/aarch64/dl-audit-check.h [new file with mode: 0644]
sysdeps/aarch64/dl-link.sym
sysdeps/aarch64/dl-trampoline.S
sysdeps/aarch64/tst-audit26.c [new file with mode: 0644]
sysdeps/aarch64/tst-audit26mod.c [new file with mode: 0644]
sysdeps/aarch64/tst-audit26mod.h [new file with mode: 0644]
sysdeps/aarch64/tst-audit27.c [new file with mode: 0644]
sysdeps/aarch64/tst-audit27mod.c [new file with mode: 0644]
sysdeps/aarch64/tst-audit27mod.h [new file with mode: 0644]
sysdeps/aarch64/tst-auditmod26.c [new file with mode: 0644]
sysdeps/aarch64/tst-auditmod27.c [new file with mode: 0644]
sysdeps/generic/dl-audit-check.h [new file with mode: 0644]