@@ -104,6 +104,13 @@ COMPAT_SYSCALL_DEFINE0(sigreturn)
struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
sigset_t set;
+ /*
+ * Verify legacy sigreturn does not have IBT enabled.
+ */
+#ifdef CONFIG_X86_IBT
+ if (current->thread.shstk.ibt)
+ goto badframe;
+#endif
if (!access_ok(frame, sizeof(*frame)))
goto badframe;
if (__get_user(set.sig[0], &frame->sc.oldmask)
@@ -6,6 +6,7 @@
* ELF register definitions..
*/
#include <linux/thread_info.h>
+#include <uapi/linux/elf.h>
#include <asm/ptrace.h>
#include <asm/user.h>
@@ -399,7 +400,17 @@ struct arch_elf_state {
}
#define arch_elf_pt_proc(ehdr, phdr, elf, interp, state) (0)
-#define arch_check_elf(ehdr, interp, interp_ehdr, state) (0)
+static inline int arch_check_elf(void *ehdr, bool interp,
+ void *interp_ehdr,
+ struct arch_elf_state *state)
+{
+ /*
+ * Disable IBT for ia32
+ */
+ if (elf_check_arch_ia32((struct elf32_hdr *)ehdr))
+ state->gnu_property &= ~GNU_PROPERTY_X86_FEATURE_1_IBT;
+ return 0;
+}
/* Do not change the values. See get_align_mask() */
enum align_flags {
In a signal, a task's IBT status needs to be saved to the signal frame, and later restored in sigreturn. For the purpose, previous versions of the series add a new struct to the signal frame. However, a new signal frame format (or re-using a reserved space) introduces complex compatibility issues. In the discussion (see link below), Andy Lutomirski proposed using a ucontext flag. The approach is clean and eliminates most compatibility issues. However, a legacy IA32 signal frame does not have ucontext and cannot support a uc flag. Thus, - Disable IBT for ia32. - In ia32 sigreturn, verify ibt is disabled. Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Cc: Florian Weimer <fweimer@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/linux-api/f6e61dae-9805-c855-8873-7481ceb7ea79@intel.com/ --- arch/x86/ia32/ia32_signal.c | 7 +++++++ arch/x86/include/asm/elf.h | 13 ++++++++++++- 2 files changed, 19 insertions(+), 1 deletion(-)