x86/shstk: Enable shadow stacks for x32

1. Add shadow stack support to x32 signal.
2. Use the 64-bit map_shadow_stack syscall for x32.
3. Set up shadow stack for x32.

Tested with shadow stack enabled x32 glibc on Intel Tiger Lake:

I configured x32 glibc with --enable-cet, build glibc and
run all glibc tests with shadow stack enabled.  There are
no regressions.  I verified that shadow stack is enabled
via /proc/pid/status.

Signed-off-by: H.J. Lu <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
Tested-by: H.J. Lu <[email protected]>
Cc: "Edgecombe, Rick P" <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
This commit is contained in:
H.J. Lu authored and Ingo Molnar committed 2024-03-22 10:17:11 +01:00
1 parent 4ae3dc83b0
commit 2883f01ec3
3 files changed
+9 -3

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+1 -1
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@@ -374,7 +374,7 @@
450 common set_mempolicy_home_node sys_set_mempolicy_home_node
451 common cachestat sys_cachestat
452 common fchmodat2 sys_fchmodat2
453 64 map_shadow_stack sys_map_shadow_stack
453 common map_shadow_stack sys_map_shadow_stack
454 common futex_wake sys_futex_wake
455 common futex_wait sys_futex_wait
456 common futex_requeue sys_futex_requeue
+2 -2
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@@ -163,8 +163,8 @@ static int shstk_setup(void)
if (features_enabled(ARCH_SHSTK_SHSTK))
return 0;
/* Also not supported for 32 bit and x32 */
if (!cpu_feature_enabled(X86_FEATURE_USER_SHSTK) || in_32bit_syscall())
/* Also not supported for 32 bit */
if (!cpu_feature_enabled(X86_FEATURE_USER_SHSTK) || in_ia32_syscall())
return -EOPNOTSUPP;
size = adjust_shstk_size(0);
+6
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@@ -315,6 +315,9 @@ int x32_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
uc_flags = frame_uc_flags(regs);
if (setup_signal_shadow_stack(ksig))
return -EFAULT;
if (!user_access_begin(frame, sizeof(*frame)))
return -EFAULT;
@@ -377,6 +380,9 @@ COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn)
if (!restore_sigcontext(regs, &frame->uc.uc_mcontext, uc_flags))
goto badframe;
if (restore_signal_shadow_stack())
goto badframe;
if (compat_restore_altstack(&frame->uc.uc_stack))
goto badframe;