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[PATCH 5/7] elf: Enable relro for static build
- From: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- To: libc-alpha at sourceware dot org
- Date: Fri, 29 Nov 2019 18:03:25 -0300
- Subject: [PATCH 5/7] elf: Enable relro for static build
- References: <20191129210327.26434-1-adhemerval.zanella@linaro.org>
The code is similar to the one at rtld.c, where its check for the
PT_GNU_RELRO header values from program headers and call
_dl_protected_relro with the updated l_relro_{addr,size} values.
Checked on x86_64-linux-gnu, i686-linux-gnu, powerpc64le-linux-gnu,
aarch64-linux-gnu, s390x-linux-gnu, and sparc64-linux-gnu.
---
elf/dl-support.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/elf/dl-support.c b/elf/dl-support.c
index 5526d5ee6e..bdb5c2ae91 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)
+ _dl_protect_relro (&_dl_main_map);
}
#ifdef DL_SYSINFO_IMPLEMENTATION
--
2.17.1