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[Bug dynamic-link/21598] i386 _dl_runtime_resolve/_dl_runtime_profile is incompatible with shadow stack


https://sourceware.org/bugzilla/show_bug.cgi?id=21598

--- Comment #35 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
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- Log -----------------------------------------------------------------
2a355dbc4700bea275b413738a7e1cb0252cb4b4 i386: Add
_dl_runtime_resolve_shstk/_dl_runtime_profile_shstk [BZ #21598]
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--- Comment #36 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "GNU C Library master sources".

The branch, hjl/cet/property has been created
        at  7cd333874be8923a26de570813f176ca0ea252fb (commit)

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https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=7cd333874be8923a26de570813f176ca0ea252fb

commit 7cd333874be8923a26de570813f176ca0ea252fb
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Wed Jun 28 15:16:46 2017 -0700

    i386: Add _dl_runtime_resolve_shstk/_dl_runtime_profile_shstk [BZ #21598]

    Add SHSTK compatible symbol resolvers to support Shadow Stack in Intel
    Control-flow Enforcement Technology (CET) instructions:

   
https://software.intel.com/sites/default/files/managed/4d/2a/control-flow-enforcement-technology-preview.pdf

    Replace _dl_runtime_resolve and _dl_runtime_profile with
    _dl_runtime_resolve_shstk and _dl_runtime_profile_shstk, respectively if
    SHSTK is enabled.

         [BZ #21598]
         * sysdeps/i386/dl-trampoline.S (_dl_runtime_resolve_shstk): New.
         (_dl_runtime_profile_shstk): Likewise.
         * sysdeps/unix/sysv/linux/i386/dl-cet.c: New file.

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=042f0cdda83c0057ebb43ccd3c264f7bdc738694

commit 042f0cdda83c0057ebb43ccd3c264f7bdc738694
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Thu Jun 22 04:15:39 2017 -0700

    x86: Support IBT and SHSTK from Intel CET

    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.  GNU_PROPERTY_X86_FEATURE_1_IBT is set 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, if GNU_PROPERTY_X86_FEATURE_1_IBT is
    set on the executable, enable IBT.
    2. 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.  GNU_PROPERTY_X86_FEATURE_1_SHSTK is set 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, if GNU_PROPERTY_X86_FEATURE_1_SHSTK is
    set on the executable as well as all shared objects loaded via the
    DT_NEEDED tag, enable SHSTK.
    2. After SHSTK is enabled, it is an error to load a shared object
    without GNU_PROPERTY_X86_FEATURE_1_SHSTK.

    When glibc is built with a compiler which defines defines __IBT__ and
    __SHSTK__, CET is enabled, unless --disable-cet is used 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.
    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.  The optional DL_PROCESS_PT_NOTE
          is called to process PT_NOTE segment for GNU program property and
          set l_cet.
       b. _dl_start_user calls _dl_cet_init, instead of _dl_init, which sets
         _dl_x86_feature_1 as well as sets up IBT and SHSTK.
    3. For static executables, _dl_setup_cet is called to process PT_NOTE
    segment for GNU program property to set _dl_x86_feature_1 as well as set
    up IBT and SHSTK.

    <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 if __IBT__ or __SHSTK__ is defined.

        * config.h.in (ENABLE_CET): New #undef.
        * configure.ac: Add --enable-cet.
        * configure: Regenerated.
        * elf/dl-load.c (filebuf): Moved before "dynamic-link.h".
        (_dl_map_object_from_fd): Call DL_PROCESS_PT_NOTE on PT_NOTE
        segment if DL_PROCESS_PT_NOTE is defined.
        * elf/rtld.c (dl_main): Likewise.
        * elf/dl-support.c: Include <dl-procruntime.c>.
        * include/link.h: Include <link_map.h>.
        * sysdeps/generic/dl-procruntime.c: New file.
        * sysdeps/generic/link_map.h: Likewise.
        * sysdeps/unix/sysv/linux/i386/dl-machine.h: Likewise.
        * sysdeps/unix/sysv/linux/x86/configure: Likewise.
        * sysdeps/unix/sysv/linux/x86/configure.ac: Likewise.
        * sysdeps/unix/sysv/linux/x86/dl-cet-nonshared.c: Likewise.
        * sysdeps/unix/sysv/linux/x86/dl-cet.c: Likewise.
        * sysdeps/unix/sysv/linux/x86/dl-cet.h: Likewise.
        * sysdeps/unix/sysv/linux/x86/dl-procruntime.c: Likewise.
        * sysdeps/unix/sysv/linux/x86/libc-start.c: Likewise.
        * sysdeps/unix/sysv/linux/x86/link_map.h: Likewise.
        * sysdeps/unix/sysv/linux/x86_64/dl-machine.h: Likewise.
        * sysdeps/generic/ldsodefs.h: Include <dl-procruntime.c> in
        the writable ld.so namespace.
        * sysdeps/i386/dl-machine.h (DL_INIT): New.
        (_dl_start_user): Replace _dl_init with DL_INIT.
        * sysdeps/i386/function-attrs.h (private_function): Pass 2
        parameters in registers for -finstrument-control-flow -mshstk.
        * sysdeps/unix/sysv/linux/x86/Makefile (sysdep_routines): Add
        dl-cet-nonshared if CET is enabled.
        (sysdep-dl-routines): Add dl-cet if CET is enabled.
        (asm-CPPFLAGS): Include cet.h if CET is enabled.
        * sysdeps/x86/libc-start.c (ARCH_INIT_CPU_FEATURES): Define
        only if it is undefined.
        * sysdeps/x86_64/dl-machine.h (DL_INIT): New.
        (_dl_start_user): Replace _dl_init with DL_INIT.

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=9951556257fa959aedbdd078664f82cdcf1d7297

commit 9951556257fa959aedbdd078664f82cdcf1d7297
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Wed Jun 21 13:07:05 2017 -0700

    Add NT_GNU_PROPERTY_TYPE_0 macros

    Add macros used in GNU .note.gnu.property notes (NT_GNU_PROPERTY_TYPE_0).

        * elf/elf.h (NT_GNU_PROPERTY_TYPE_0): New.
        (NOTE_GNU_PROPERTY_SECTION_NAME): Likewise.
        (GNU_PROPERTY_STACK_SIZE): Likewie.
        (GNU_PROPERTY_NO_COPY_ON_PROTECTED): Likewie.
        (GNU_PROPERTY_LOPROC): Likewise.
        (GNU_PROPERTY_HIPROC): Likewise.
        (GNU_PROPERTY_LOUSER): Likewise.
        (GNU_PROPERTY_HIUSER): Likewise.
        (GNU_PROPERTY_X86_ISA_1_USED): Likwise.
        (GNU_PROPERTY_X86_ISA_1_NEEDED): Likwise.
        (GNU_PROPERTY_X86_FEATURE_1_AND): Likwise.
        (GNU_PROPERTY_X86_ISA_1_486): Likwise.
        (GNU_PROPERTY_X86_ISA_1_586): Likwise.
        (GNU_PROPERTY_X86_ISA_1_686): Likwise.
        (GNU_PROPERTY_X86_ISA_1_SSE): Likwise.
        (GNU_PROPERTY_X86_ISA_1_SSE2): Likwise.
        (GNU_PROPERTY_X86_ISA_1_SSE3): Likwise.
        (GNU_PROPERTY_X86_ISA_1_SSSE3): Likwise.
        (GNU_PROPERTY_X86_ISA_1_SSE4_1): Likwise.
        (GNU_PROPERTY_X86_ISA_1_SSE4_2): Likwise.
        (GNU_PROPERTY_X86_ISA_1_AVX): Likwise.
        (GNU_PROPERTY_X86_ISA_1_AVX2): Likwise.
        (GNU_PROPERTY_X86_ISA_1_AVX512F): Likwise.
        (GNU_PROPERTY_X86_ISA_1_AVX512CD): Likwise.
        (GNU_PROPERTY_X86_ISA_1_AVX512ER): Likwise.
        (GNU_PROPERTY_X86_ISA_1_AVX512PF): Likwise.
        (GNU_PROPERTY_X86_ISA_1_AVX512VL): Likwise.
        (GNU_PROPERTY_X86_ISA_1_AVX512DQ): Likwise.
        (GNU_PROPERTY_X86_ISA_1_AVX512BW): Likwise.
        (GNU_PROPERTY_X86_FEATURE_1_IBT): Likwise.
        (GNU_PROPERTY_X86_FEATURE_1_SHSTK): Likwise.

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=09ac8f3aceb029f54cbfd60ed044a175b726c5ab

commit 09ac8f3aceb029f54cbfd60ed044a175b726c5ab
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Thu Jun 22 08:51:42 2017 -0700

    x86: Add IBT/SHSTK bits to cpu-features

    Add IBT/SHSTK bits to cpu-features for Shadow Stack in Intel Control-flow
    Enforcement Technology (CET) instructions:

   
https://software.intel.com/sites/default/files/managed/4d/2a/control-flow-enforcement-technology-preview.pdf

        * sysdeps/x86/cpu-features.h (bit_cpu_BIT): New.
        (bit_cpu_SHSTK): Likewise.
        (index_cpu_IBT): Likewise.
        (index_cpu_SHSTK): Likewise.
        (reg_IBT): Likewise.
        (reg_SHSTK): Likewise.
        * sysdeps/x86/cpu-tunables.c (TUNABLE_CALLBACK (set_hwcaps)):
        Handle index_cpu_IBT and index_cpu_SHSTK.

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a31a4ba5016f7afce2fc314b0dd2992b2c2872f3

commit a31a4ba5016f7afce2fc314b0dd2992b2c2872f3
Author: Florian Weimer <fweimer@redhat.com>
Date:   Fri Aug 11 15:36:08 2017 +0200

    Add private_function for private functions within glibc [BZ #21598]

    USE_REGPARMS in config.h.in is only used to control how parameters are
    passed for internal functions on i386.  On i386, we define

     #define internal_function __attribute__ ((regparm (3), stdcall))

    so that we pass up to 3 integer parameters in registers for internal
    functuons on i386.  i386 has

    _dl_runtime_resolve:

            movl (%esp), %ecx
            movl %eax, (%esp)       # Store the function address.
            movl 4(%esp), %eax
            ret $12                 # Jump to function address.

    which is incompatible with Shadow Stack in Intel Control-flow Enforcement
    Technology (CET) instructions:

   
https://software.intel.com/sites/default/files/managed/4d/2a/control-flow-enforcement-technology-preview.pdf

    since shadow stack doesn't match return stack.  We need to use register
    indirect branch via %ecx.  That means only 2 parameters can be passed
    in registers for external function calls with lazy binding when shadow
    stack is enabled.  However, internal_function, which should be used only
    with hidden function within libc.so, are also used with private function
    calls between different shared objects of glibc.

    This patch removes USE_REGPARMS and internal_function from config.h.in.
    It adds a new header file, function-attrs.h, to define internal_function
    and private_function, which is for private function calls between
    different shared objects.  Currently, sysdeps/i386/function-attrs.h
    defines private_function as

     #define private_function __attribute__ ((regparm (3), stdcall))

    There is no change in shared objects on Linux/i686 nor Linux/x86_64.

    When shadow stack is enabled, private_function will be defined as

     #define private_function __attribute__ ((regparm (2), stdcall))

    so that %ecx can be used as scratch register by _dl_runtime_resolve.

        [BZ #21598]
        * config.h.in (USE_REGPARMS): Removed.
        (internal_function): Likewise.
        * debug/fortify_fail.c (__fortify_fail): Replace internal_function
        with private_function.
        * elf/dl-addr.c (_dl_addr): Likewise.
        * elf/dl-error-skeleton.c (_dl_signal_error): Likewise.
        (_dl_catch_error): Likewise.
        * elf/dl-execstack.c (_dl_make_stack_executable): Likewise.
        * elf/dl-load.c (_dl_rtld_di_serinfo): Likewise.
        * elf/dl-open.c (_dl_find_dso_for_object): Likewise.
        * elf/dl-support.c (_dl_make_stack_executable_hook): Likewise.
        * elf/dl-sym.c (_dl_vsym): Likewise.
        (_dl_sym): Likewise.
        * elf/dl-tls.c (_dl_get_tls_static_info): Likewise.
        (_dl_allocate_tls_init): Likewise.
        (_dl_allocate_tls): Likewise.
        (_dl_deallocate_tls): Likewise.
        * grp/grp-merge.c (__copy_grp): Likewise.
        (__merge_grp): Likewise.
        * grp/grp-merge.h (__copy_grp): Likewise.
        (__merge_grp): Likewise.
        * include/dlfcn.h (_dl_addr): Likewise.
        (_dl_sym): Likewise.
        (_dl_vsym): Likewise.
        * include/rpc/pmap_clnt.h (__libc_rpc_getport): Likewise.
        * include/stdio.h (__fortify_fail): Likewise.
        * include/stdlib.h (__strtof_nan): Likewise.
        (__strtod_nan): Likewise.
        (__strtold_nan): Likewise.
        (__wcstof_nan): Likewise.
        (__wcstod_nan): Likewise.
        (__wcstold_nan): Likewise.
        (__strtof128_nan): Likewise.
        (__wcstof128_nan): Likewise.
        * nptl/allocatestack.c (__make_stacks_executable): Likewise.
        * nptl/libc_pthread_init.c (__libc_pthread_init): Likewise.
        * nptl/pthreadP.h (__make_stacks_executable): Likewise.
        (__libc_pthread_init): Likewise.
        * nss/XXX-lookup.c (DB_LOOKUP_FCT): Likewise.
        (DB_COMPAT_FCT): Likewise.
        * nss/getXXbyYY_r.c (DB_LOOKUP_FCT): Likewise.
        * nss/getXXent_r.c (DB_LOOKUP_FCT): Likewise.
        * nss/nsswitch.h (db_lookup_function): Likewise.
        * resolv/gai_misc.h (__gai_sigqueue): Likewise.
        * resolv/gai_sigqueue.c (__gai_sigqueue): Likewise.
        * stdlib/strtod_nan_main.c (STRTOD_NAN): Likewise.
        * sunrpc/pm_getport.c (__libc_rpc_getport): Likewise.
        * sysdeps/generic/ldsodefs.h (_dl_make_stack_executable_hook):
        Likewise.
        (_dl_make_stack_executable): Likewise.
        (_dl_signal_error): Likewise.
        (_dl_catch_error): Likewise.
        (_dl_rtld_di_serinfo): Likewise.
        (_dl_allocate_tls): Likewise.
        (_dl_get_tls_static_info): Likewise.
        (_dl_allocate_tls_init): Likewise.
        (_dl_deallocate_tls): Likewise.
        (_dl_find_dso_for_object): Likewise.
        * sysdeps/unix/sysv/linux/dl-execstack.c
        (_dl_make_stack_executable): Likewise.
        * sysdeps/unix/sysv/linux/gai_sigqueue.c (__gai_sigqueue):
        Likewise.
        * sysdeps/unix/sysv/linux/netlink_assert_response.c
        (__netlink_assert_response): Likewise.
        * sysdeps/unix/sysv/linux/netlinkaccess.h
        (__netlink_assert_response): Likewise.
        * include/libc-symbols.h (internal_function): Removed.
        Include <function-attrs.h>.
        * sysdeps/generic/function-attrs.h: New file.
        * sysdeps/i386/function-attrs.h: Likewise.
        * sysdeps/i386/configure.ac (USE_REGPARMS): Removed.
        * sysdeps/i386/configure: Regenerated.

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