linux-kernel - [RFC PATCH 2/8] signals: Put the full signal mask on the signal stack for x86

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Message-Id: <20220103181956.983342-3-walt@drummond.us>
Date:   Mon,  3 Jan 2022 10:19:50 -0800
From:   Walt Drummond <walt@...mmond.us>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>
Cc:     linux-kernel@...r.kernel.org, Walt Drummond <walt@...mmond.us>
Subject: [RFC PATCH 2/8] signals: Put the full signal mask on the signal stack for x86_64, X32 and ia32 compatibility mode

Put the complete sigset_t in the real-tme signal stack frame for
x86_64, x32 and ia32 compatibility mode on x86.

Signed-off-by: Walt Drummond <walt@...mmond.us>
---
 arch/x86/ia32/ia32_signal.c        |  5 +++--
 arch/x86/include/asm/sighandling.h | 34 ++++++++++++++++++++++++++++++
 arch/x86/kernel/signal.c           | 11 +++-------
 3 files changed, 40 insertions(+), 10 deletions(-)

diff --git a/arch/x86/ia32/ia32_signal.c b/arch/x86/ia32/ia32_signal.c
index 5e3d9b7fd5fb..03a0ecd8c7f3 100644
--- a/arch/x86/ia32/ia32_signal.c
+++ b/arch/x86/ia32/ia32_signal.c
@@ -130,7 +130,8 @@ COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
 
 	if (!access_ok(frame, sizeof(*frame)))
 		goto badframe;
-	if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask))
+	if (copy_from_user(&set, &frame->uc.uc_sigmask,
+			   sizeof(frame->uc.uc_sigmask)))
 		goto badframe;
 
 	set_current_blocked(&set);
@@ -347,7 +348,7 @@ int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
 	 */
 	unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
 	unsafe_put_sigcontext32(&frame->uc.uc_mcontext, fp, regs, set, Efault);
-	unsafe_put_user(*(__u64 *)set, (__u64 __user *)&frame->uc.uc_sigmask, Efault);
+	unsafe_put_compat_sigmask(set, frame, Efault);
 	user_access_end();
 
 	if (__copy_siginfo_to_user32(&frame->info, &ksig->info))
diff --git a/arch/x86/include/asm/sighandling.h b/arch/x86/include/asm/sighandling.h
index 65e667279e0f..e247bea06a17 100644
--- a/arch/x86/include/asm/sighandling.h
+++ b/arch/x86/include/asm/sighandling.h
@@ -15,4 +15,38 @@
 
 void signal_fault(struct pt_regs *regs, void __user *frame, char *where);
 
+static inline int
+__unsafe_put_sigmask(char *set, char __user *fp, size_t size)
+{
+	char *src;
+	char __user *dst;
+	size_t len;
+
+	len = size;
+	src = set;
+	dst = fp;
+	unsafe_copy_loop(dst, src, len, unsigned long, Efault);
+
+	return 0;
+Efault:
+	return -EFAULT;
+}
+
+#define unsafe_put_sigmask(set, frame, label)				\
+do {									\
+	if (__unsafe_put_sigmask((char *) set,				\
+				 (char __user *) &(frame)->uc.uc_sigmask, \
+				 sizeof(sigset_t)))			\
+		goto label;						\
+} while (0)
+
+#define unsafe_put_compat_sigmask(set, frame, label)			\
+do {									\
+	if (__unsafe_put_sigmask((char *) set,				\
+				 (char __user *) &(frame)->uc.uc_sigmask, \
+				 sizeof(compat_sigset_t)))		\
+		goto label;						\
+} while (0)
+
+
 #endif /* _ASM_X86_SIGHANDLING_H */
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index f4d21e470083..bb5f3f39c412 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -203,11 +203,6 @@ do {									\
 		goto label;						\
 } while(0);
 
-#define unsafe_put_sigmask(set, frame, label) \
-	unsafe_put_user(*(__u64 *)(set), \
-			(__u64 __user *)&(frame)->uc.uc_sigmask, \
-			label)
-
 /*
  * Set up a signal frame.
  */
@@ -587,7 +582,7 @@ static int x32_setup_rt_frame(struct ksignal *ksig,
 	restorer = ksig->ka.sa.sa_restorer;
 	unsafe_put_user(restorer, (unsigned long __user *)&frame->pretcode, Efault);
 	unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
-	unsafe_put_sigmask(set, frame, Efault);
+	unsafe_put_compat_sigmask(set, frame, Efault);
 	user_access_end();
 
 	if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
@@ -664,7 +659,7 @@ SYSCALL_DEFINE0(rt_sigreturn)
 	frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long));
 	if (!access_ok(frame, sizeof(*frame)))
 		goto badframe;
-	if (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask))
+	if (copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(sigset_t)))
 		goto badframe;
 	if (__get_user(uc_flags, &frame->uc.uc_flags))
 		goto badframe;
@@ -922,7 +917,7 @@ COMPAT_SYSCALL_DEFINE0(x32_rt_sigreturn)
 
 	if (!access_ok(frame, sizeof(*frame)))
 		goto badframe;
-	if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask))
+	if (copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(compat_sigset_t)))
 		goto badframe;
 	if (__get_user(uc_flags, &frame->uc.uc_flags))
 		goto badframe;
-- 
2.30.2