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authorAdhemerval Zanella <adhemerval.zanella@linaro.org>2019-11-29 10:26:30 -0300
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2020-01-03 11:22:07 -0300
commit57013650f7e796428ac2c0b7512757e99327bfc9 (patch)
tree9ff129f0545943210666229fa5335d0acd1b4ee6 /elf
parente760874ee3315ca3a8a2978b5f8e4dba1e336197 (diff)
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elf: Enable relro for static build
The code is similar to the one at elf/dl-reloc.c, where it checks for the l_relro_size from the link_map (obtained from PT_GNU_RELRO header from program headers) and calls_dl_protected_relro. For testing I will use the ones proposed by Florian's patch 'elf: Add tests for working RELRO protection' [1]. Checked on x86_64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu, aarch64-linux-gnu, s390x-linux-gnu, and sparc64-linux-gnu. I also check with --enable-static pie on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu which seems the only architectures where static PIE is actually working (as per 9d7a3741c9e, on arm-linux-gnueabihf, powerpc64{le}-linux-gnu, and s390x-linux-gnu I am seeing runtime issues not related to my patch). [1] https://sourceware.org/ml/libc-alpha/2019-10/msg00059.html Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Diffstat (limited to 'elf')
-rw-r--r--elf/dl-support.c18
1 files changed, 14 insertions, 4 deletions
diff --git a/elf/dl-support.c b/elf/dl-support.c
index 957a810..508a5c1 100644
--- a/elf/dl-support.c
+++ b/elf/dl-support.c
@@ -367,14 +367,24 @@ _dl_non_dynamic_init (void)
if (_dl_platform != NULL)
_dl_platformlen = strlen (_dl_platform);
- /* Scan for a program header telling us the stack is nonexecutable. */
if (_dl_phdr != NULL)
- for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
- if (_dl_phdr[i].p_type == PT_GNU_STACK)
+ for (const ElfW(Phdr) *ph = _dl_phdr; ph < &_dl_phdr[_dl_phnum]; ++ph)
+ switch (ph->p_type)
{
- _dl_stack_flags = _dl_phdr[i].p_flags;
+ /* Check if the stack is nonexecutable. */
+ case PT_GNU_STACK:
+ _dl_stack_flags = ph->p_flags;
+ break;
+
+ case PT_GNU_RELRO:
+ _dl_main_map.l_relro_addr = ph->p_vaddr;
+ _dl_main_map.l_relro_size = ph->p_memsz;
break;
}
+
+ /* Setup relro on the binary itself. */
+ if (_dl_main_map.l_relro_size != 0)
+ _dl_protect_relro (&_dl_main_map);
}
#ifdef DL_SYSINFO_IMPLEMENTATION