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In elf image activator, read and apply the stack protection mode from

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PT_GNU_STACK program header, if present and enabled. Two new sysctls
are provided, kern.elf32.nxstack and kern.elf64.nxstack, that allow to
enable PT_GNU_STACK for ABIs of specified bitsize, if ABI decided to
support shared page.

Inform rtld about access mode of the stack initial mapping by
AT_STACKPROT aux vector.

At the moment, the default is disabled, waiting for the usermode
support bits.
This commit is contained in:
Konstantin Belousov 2011-01-08 16:30:59 +00:00
parent 6297a3d843
commit 291c06a127
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=217152
1 changed files with 17 additions and 5 deletions
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22
sys/kern/imgact_elf.c
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@ -115,6 +115,11 @@ static int elf_legacy_coredump = 0;
SYSCTL_INT(_debug, OID_AUTO, __elfN(legacy_coredump), CTLFLAG_RW,
&elf_legacy_coredump, 0, "");
static int __elfN(nxstack) = 0;
SYSCTL_INT(__CONCAT(_kern_elf, __ELF_WORD_SIZE), OID_AUTO,
nxstack, CTLFLAG_RW, &__elfN(nxstack), 0,
__XSTRING(__CONCAT(ELF, __ELF_WORD_SIZE)) ": enable non-executable stack");
static Elf_Brandinfo *elf_brand_list[MAX_BRANDS];
#define trunc_page_ps(va, ps) ((va) & ~(ps - 1))
@ -724,19 +729,24 @@ __CONCAT(exec_, __elfN(imgact))(struct image_params *imgp)
n = 0;
baddr = 0;
for (i = 0; i < hdr->e_phnum; i++) {
if (phdr[i].p_type == PT_LOAD) {
switch (phdr[i].p_type) {
case PT_LOAD:
if (n == 0)
baddr = phdr[i].p_vaddr;
n++;
continue;
}
if (phdr[i].p_type == PT_INTERP) {
break;
case PT_INTERP:
/* Path to interpreter */
if (phdr[i].p_filesz > MAXPATHLEN ||
phdr[i].p_offset + phdr[i].p_filesz > PAGE_SIZE)
return (ENOEXEC);
interp = imgp->image_header + phdr[i].p_offset;
continue;
break;
case PT_GNU_STACK:
if (__elfN(nxstack))
imgp->stack_prot =
__elfN(trans_prot)(phdr[i].p_flags);
break;
}
}
@ -972,6 +982,8 @@ __elfN(freebsd_fixup)(register_t **stack_base, struct image_params *imgp)
AUXARGS_ENTRY(pos, AT_PAGESIZES, imgp->pagesizes);
AUXARGS_ENTRY(pos, AT_PAGESIZESLEN, imgp->pagesizeslen);
}
AUXARGS_ENTRY(pos, AT_STACKPROT, imgp->stack_prot != 0 ?
imgp->stack_prot : imgp->sysent->sv_stackprot);
AUXARGS_ENTRY(pos, AT_NULL, 0);
free(imgp->auxargs, M_TEMP);