From ecdeaac05f73c29eca92eecd55ad4fb8513c7771 Mon Sep 17 00:00:00 2001 From: Roland McGrath Date: Tue, 23 Sep 2003 12:06:48 +0000 Subject: 2003-09-23 Roland McGrath * sysdeps/generic/ldsodefs.h (struct rtld_global): Add _dl_stack_flags and _dl_make_stack_executable_hook. Declare _dl_make_stack_executable. * elf/rtld.c (_rtld_global): Add initializer for _dl_stack_flags. (dl_main): Reset _dl_stack_flags according to PT_GNU_STACK phdr. Initialize _dl_make_stack_executable_hook. * elf/dl-support.c: Define those new variables. (_dl_non_dynamic_init): Scan phdrs for PT_GNU_STACK. (_dl_phdr): Fix type. * elf/dl-load.c (_dl_map_object_from_fd): Grok PT_GNU_STACK phdr and enable execute permission for the stack if necessary. * sysdeps/generic/dl-execstack.c: New file. * elf/Makefile (dl-routines): Add it. * elf/Versions (ld: GLIBC_PRIVATE): Add _dl_make_stack_executable. * sysdeps/unix/sysv/linux/dl-execstack.c: New file. --- elf/dl-support.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'elf/dl-support.c') diff --git a/elf/dl-support.c b/elf/dl-support.c index 8c58b2ba69..448f4c6848 100644 --- a/elf/dl-support.c +++ b/elf/dl-support.c @@ -129,6 +129,16 @@ ElfW(Phdr) *_dl_phdr; size_t _dl_phnum; unsigned long int _dl_hwcap __attribute__ ((nocommon)); +/* Prevailing state of the stack, PF_X indicating it's executable. */ +ElfW(Word) _dl_stack_flags = PF_R|PF_W|PF_X; + +/* If loading a shared object requires that we make the stack executable + when it was not, we do it by calling this function. + It returns an errno code or zero on success. */ +int (*_dl_make_stack_executable_hook) (void) internal_function + = _dl_make_stack_executable; + + #ifdef NEED_DL_SYSINFO /* Needed for improved syscall handling on at least x86/Linux. */ uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT; @@ -264,6 +274,15 @@ _dl_non_dynamic_init (void) /* Now determine the length of the platform string. */ 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) + { + _dl_stack_flags = _dl_phdr[i].p_flags; + break; + } } -- cgit v1.2.3