Date: Sat, 8 Jan 2011 16:30:59 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r217152 - head/sys/kern Message-ID: <201101081630.p08GUxOC097391@svn.freebsd.org>
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Author: kib Date: Sat Jan 8 16:30:59 2011 New Revision: 217152 URL: http://svn.freebsd.org/changeset/base/217152 Log: In elf image activator, read and apply the stack protection mode from 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. Modified: head/sys/kern/imgact_elf.c Modified: head/sys/kern/imgact_elf.c ============================================================================== --- head/sys/kern/imgact_elf.c Sat Jan 8 16:13:44 2011 (r217151) +++ head/sys/kern/imgact_elf.c Sat Jan 8 16:30:59 2011 (r217152) @@ -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 i 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 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);
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