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author | Alan Modra <amodra@gmail.com> | 2016-12-26 00:30:45 +1030 |
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committer | Alan Modra <amodra@gmail.com> | 2016-12-26 13:47:51 +1030 |
commit | 5474d94f03aedba2f832006dc7d680cc15792a7b (patch) | |
tree | 8fdd2bb1d2a32f1f35ef76199f9d92da95c0ec27 /bfd/elfxx-tilegx.c | |
parent | 9d19e4fdb7c684329c8b1b72796a0071708dabc7 (diff) | |
download | gdb-5474d94f03aedba2f832006dc7d680cc15792a7b.zip gdb-5474d94f03aedba2f832006dc7d680cc15792a7b.tar.gz gdb-5474d94f03aedba2f832006dc7d680cc15792a7b.tar.bz2 |
dynrelro section for read-only dynamic symbols copied into executable
Variables defined in shared libraries are copied into an executable's
.bss section when code in the executable is non-PIC and thus would
require dynamic text relocations to access the variable directly in
the shared library. Recent x86 toolchains also copy variables into
the executable to gain a small speed improvement.
The problem is that if the variable was originally read-only, the copy
in .bss is writable, potentially opening a security hole. This patch
cures that problem by putting the copy in a section that becomes
read-only after ld.so relocation, provided -z relro is in force.
The patch also fixes a microblaze linker segfault on attempting to
use dynamic bss variables.
bfd/
PR ld/20995
* elf-bfd.h (struct elf_link_hash_table): Add sdynrelro and
sreldynrelro.
(struct elf_backend_data): Add want_dynrelro.
* elfxx-target.h (elf_backend_want_dynrelro): Define.
(elfNN_bed): Update initializer.
* elflink.c (_bfd_elf_create_dynamic_sections): Create
sdynrelro and sreldynrelro sections.
* elf32-arm.c (elf32_arm_adjust_dynamic_symbol): Place variables
copied into the executable from read-only sections into sdynrelro.
(elf32_arm_size_dynamic_sections): Handle sdynrelro.
(elf32_arm_finish_dynamic_symbol): Select sreldynrelro for
dynamic relocs in sdynrelro.
(elf_backend_want_dynrelro): Define.
* elf32-hppa.c (elf32_hppa_adjust_dynamic_symbol)
(elf32_hppa_size_dynamic_sections, elf32_hppa_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf32-i386.c (elf_i386_adjust_dynamic_symbol)
(elf_i386_size_dynamic_sections, elf_i386_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf32-metag.c (elf_metag_adjust_dynamic_symbol)
(elf_metag_size_dynamic_sections, elf_metag_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf32-microblaze.c (microblaze_elf_adjust_dynamic_symbol)
(microblaze_elf_size_dynamic_sections)
(microblaze_elf_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf32-nios2.c (nios2_elf32_finish_dynamic_symbol)
(nios2_elf32_adjust_dynamic_symbol)
(nios2_elf32_size_dynamic_sections)
(elf_backend_want_dynrelro): As above.
* elf32-or1k.c (or1k_elf_finish_dynamic_symbol)
(or1k_elf_adjust_dynamic_symbol, or1k_elf_size_dynamic_sections)
(elf_backend_want_dynrelro): As above.
* elf32-ppc.c (ppc_elf_adjust_dynamic_symbol)
(ppc_elf_size_dynamic_sections, ppc_elf_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf32-s390.c (elf_s390_adjust_dynamic_symbol)
(elf_s390_size_dynamic_sections, elf_s390_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf32-tic6x.c (elf32_tic6x_adjust_dynamic_symbol)
(elf32_tic6x_size_dynamic_sections)
(elf32_tic6x_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf32-tilepro.c (tilepro_elf_adjust_dynamic_symbol)
(tilepro_elf_size_dynamic_sections)
(tilepro_elf_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf64-ppc.c (ppc64_elf_adjust_dynamic_symbol)
(ppc64_elf_size_dynamic_sections, ppc64_elf_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf64-s390.c (elf_s390_adjust_dynamic_symbol)
(elf_s390_size_dynamic_sections, elf_s390_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elf64-x86-64.c (elf_x86_64_adjust_dynamic_symbol)
(elf_x86_64_size_dynamic_sections)
(elf_x86_64_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elfnn-aarch64.c (elfNN_aarch64_adjust_dynamic_symbol)
(elfNN_aarch64_size_dynamic_sections)
(elfNN_aarch64_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elfnn-riscv.c (riscv_elf_adjust_dynamic_symbol)
(riscv_elf_size_dynamic_sections, riscv_elf_finish_dynamic_symbol)
(elf_backend_want_dynrelro): As above.
* elfxx-mips.c (_bfd_mips_elf_adjust_dynamic_symbol)
(_bfd_mips_elf_size_dynamic_sections)
(_bfd_mips_vxworks_finish_dynamic_symbol): As above.
* elfxx-sparc.c (_bfd_sparc_elf_adjust_dynamic_symbol)
(_bfd_sparc_elf_size_dynamic_sections)
(_bfd_sparc_elf_finish_dynamic_symbol): As above.
* elfxx-tilegx.c (tilegx_elf_adjust_dynamic_symbol)
(tilegx_elf_size_dynamic_sections)
(tilegx_elf_finish_dynamic_symbol): As above.
* elf32-mips.c (elf_backend_want_dynrelro): Define.
* elf64-mips.c (elf_backend_want_dynrelro): Define.
* elf32-sparc.c (elf_backend_want_dynrelro): Define.
* elf64-sparc.c (elf_backend_want_dynrelro): Define.
* elf32-tilegx.c (elf_backend_want_dynrelro): Define.
* elf64-tilegx.c (elf_backend_want_dynrelro): Define.
* elf32-microblaze.c (microblaze_elf_adjust_dynamic_symbol): Tidy.
(microblaze_elf_size_dynamic_sections): Handle sdynbss.
* elf32-nios2.c (nios2_elf32_size_dynamic_sections): Make use
of linker shortcuts to dynamic sections rather than comparing
names. Correctly set "got" flag.
ld/
PR ld/20995
* testsuite/ld-arm/farcall-mixed-app-v5.d: Update to suit changed
stub hash table traversal caused by section id increment. Accept
the previous output too.
* testsuite/ld-arm/farcall-mixed-app.d: Likewise.
* testsuite/ld-arm/farcall-mixed-lib-v4t.d: Likewise.
* testsuite/ld-arm/farcall-mixed-lib.d: Likewise.
* testsuite/ld-elf/pr20995a.s, * testsuite/ld-elf/pr20995b.s,
* testsuite/ld-elf/pr20995.r: New test.
* testsuite/ld-elf/elf.exp: Run it.
Diffstat (limited to 'bfd/elfxx-tilegx.c')
-rw-r--r-- | bfd/elfxx-tilegx.c | 24 |
1 files changed, 19 insertions, 5 deletions
diff --git a/bfd/elfxx-tilegx.c b/bfd/elfxx-tilegx.c index 92b9de8..ce4fb07 100644 --- a/bfd/elfxx-tilegx.c +++ b/bfd/elfxx-tilegx.c @@ -2327,7 +2327,7 @@ tilegx_elf_adjust_dynamic_symbol (struct bfd_link_info *info, struct tilegx_elf_link_hash_entry * eh; struct tilegx_elf_dyn_relocs *p; bfd *dynobj; - asection *s; + asection *s, *srel; htab = tilegx_elf_hash_table (info); BFD_ASSERT (htab != NULL); @@ -2431,13 +2431,23 @@ tilegx_elf_adjust_dynamic_symbol (struct bfd_link_info *info, to copy the initial value out of the dynamic object and into the runtime process image. We need to remember the offset into the .rel.bss section we are going to use. */ + if ((h->root.u.def.section->flags & SEC_READONLY) != 0) + { + s = htab->elf.sdynrelro; + srel = htab->elf.sreldynrelro; + } + else + { + s = htab->elf.sdynbss; + srel = htab->elf.srelbss; + } if ((h->root.u.def.section->flags & SEC_ALLOC) != 0 && h->size != 0) { - htab->elf.srelbss->size += TILEGX_ELF_RELA_BYTES (htab); + srel->size += TILEGX_ELF_RELA_BYTES (htab); h->needs_copy = 1; } - return _bfd_elf_adjust_dynamic_copy (info, h, htab->elf.sdynbss); + return _bfd_elf_adjust_dynamic_copy (info, h, s); } /* Allocate space in .plt, .got and associated reloc sections for @@ -2826,7 +2836,8 @@ tilegx_elf_size_dynamic_sections (bfd *output_bfd ATTRIBUTE_UNUSED, if (s == htab->elf.splt || s == htab->elf.sgot || s == htab->elf.sgotplt - || s == htab->elf.sdynbss) + || s == htab->elf.sdynbss + || s == htab->elf.sdynrelro) { /* Strip this section if we don't need it; see the comment below. */ @@ -4187,7 +4198,10 @@ tilegx_elf_finish_dynamic_symbol (bfd *output_bfd, /* This symbols needs a copy reloc. Set it up. */ BFD_ASSERT (h->dynindx != -1); - s = htab->elf.srelbss; + if ((h->root.u.def.section->flags & SEC_READONLY) != 0) + s = htab->elf.sreldynrelro; + else + s = htab->elf.srelbss; BFD_ASSERT (s != NULL); rela.r_offset = (h->root.u.def.value |