[tip: x86/shstk] x86/shstk: Enable shadow stacks for x32
From: tip-bot2 for H.J. Lu
Date: Fri Mar 22 2024 - 07:01:15 EST
The following commit has been merged into the x86/shstk branch of tip:
Commit-ID: 2883f01ec37dd8668e7222dfdb5980c86fdfe277
Gitweb: https://git.kernel.org/tip/2883f01ec37dd8668e7222dfdb5980c86fdfe277
Author: H.J. Lu <hjl.tools@xxxxxxxxx>
AuthorDate: Fri, 15 Mar 2024 07:04:33 -07:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Fri, 22 Mar 2024 10:17:11 +01:00
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 <hjl.tools@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Tested-by: H.J. Lu <hjl.tools@xxxxxxxxx>
Cc: "Edgecombe, Rick P" <rick.p.edgecombe@xxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240315140433.1966543-1-hjl.tools@xxxxxxxxx
---
arch/x86/entry/syscalls/syscall_64.tbl | 2 +-
arch/x86/kernel/shstk.c | 4 ++--
arch/x86/kernel/signal_64.c | 6 ++++++
3 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 7e8d46f..cc78226 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -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
diff --git a/arch/x86/kernel/shstk.c b/arch/x86/kernel/shstk.c
index 59e15dd..6f1e988 100644
--- a/arch/x86/kernel/shstk.c
+++ b/arch/x86/kernel/shstk.c
@@ -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);
diff --git a/arch/x86/kernel/signal_64.c b/arch/x86/kernel/signal_64.c
index 23d8aaf..8a94053 100644
--- a/arch/x86/kernel/signal_64.c
+++ b/arch/x86/kernel/signal_64.c
@@ -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;