x86/signal/32: Merge native and compat 32-bit signal code

There are significant differences between signal handling on 32-bit vs.
64-bit, like different structure layouts and legacy syscalls.  Instead
of duplicating that code for native and compat, merge both versions
into one file.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Link: https://lore.kernel.org/r/20220606203802.158958-8-brgerst@gmail.com
Signed-off-by: Borislav Petkov <bp@suse.de>

1 files changed, 6 insertions, 213 deletions

diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 0511e050d24a..962cfd835c90 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -92,10 +92,6 @@ static void force_valid_ss(struct pt_regs *regs)
 	    ar != (AR_DPL3 | AR_S | AR_P | AR_TYPE_RWDATA_EXPDOWN))
 		regs->ss = __USER_DS;
 }
-# define CONTEXT_COPY_SIZE	offsetof(struct sigcontext, reserved1)
-#else
-# define CONTEXT_COPY_SIZE	sizeof(struct sigcontext)
-#endif
 
 static bool restore_sigcontext(struct pt_regs *regs,
 			       struct sigcontext __user *usc,
@@ -106,16 +102,9 @@ static bool restore_sigcontext(struct pt_regs *regs,
 	/* Always make any pending restarted system calls return -EINTR */
 	current->restart_block.fn = do_no_restart_syscall;
 
-	if (copy_from_user(&sc, usc, CONTEXT_COPY_SIZE))
+	if (copy_from_user(&sc, usc, offsetof(struct sigcontext, reserved1)))
 		return false;
 
-#ifdef CONFIG_X86_32
-	loadsegment(gs, sc.gs);
-	regs->fs = sc.fs;
-	regs->es = sc.es;
-	regs->ds = sc.ds;
-#endif /* CONFIG_X86_32 */
-
 	regs->bx = sc.bx;
 	regs->cx = sc.cx;
 	regs->dx = sc.dx;
@@ -125,8 +114,6 @@ static bool restore_sigcontext(struct pt_regs *regs,
 	regs->ax = sc.ax;
 	regs->sp = sc.sp;
 	regs->ip = sc.ip;
-
-#ifdef CONFIG_X86_64
 	regs->r8 = sc.r8;
 	regs->r9 = sc.r9;
 	regs->r10 = sc.r10;
@@ -135,7 +122,6 @@ static bool restore_sigcontext(struct pt_regs *regs,
 	regs->r13 = sc.r13;
 	regs->r14 = sc.r14;
 	regs->r15 = sc.r15;
-#endif /* CONFIG_X86_64 */
 
 	/* Get CS/SS and force CPL3 */
 	regs->cs = sc.cs | 0x03;
@@ -145,33 +131,20 @@ static bool restore_sigcontext(struct pt_regs *regs,
 	/* disable syscall checks */
 	regs->orig_ax = -1;
 
-#ifdef CONFIG_X86_64
 	/*
 	 * Fix up SS if needed for the benefit of old DOSEMU and
 	 * CRIU.
 	 */
 	if (unlikely(!(uc_flags & UC_STRICT_RESTORE_SS) && user_64bit_mode(regs)))
 		force_valid_ss(regs);
-#endif
 
-	return fpu__restore_sig((void __user *)sc.fpstate,
-			       IS_ENABLED(CONFIG_X86_32));
+	return fpu__restore_sig((void __user *)sc.fpstate, 0);
 }
 
 static __always_inline int
 __unsafe_setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
 		     struct pt_regs *regs, unsigned long mask)
 {
-#ifdef CONFIG_X86_32
-	unsigned int gs;
-	savesegment(gs, gs);
-
-	unsafe_put_user(gs,	  (unsigned int __user *)&sc->gs, Efault);
-	unsafe_put_user(regs->fs, (unsigned int __user *)&sc->fs, Efault);
-	unsafe_put_user(regs->es, (unsigned int __user *)&sc->es, Efault);
-	unsafe_put_user(regs->ds, (unsigned int __user *)&sc->ds, Efault);
-#endif /* CONFIG_X86_32 */
-
 	unsafe_put_user(regs->di, &sc->di, Efault);
 	unsafe_put_user(regs->si, &sc->si, Efault);
 	unsafe_put_user(regs->bp, &sc->bp, Efault);
@@ -180,7 +153,6 @@ __unsafe_setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
 	unsafe_put_user(regs->dx, &sc->dx, Efault);
 	unsafe_put_user(regs->cx, &sc->cx, Efault);
 	unsafe_put_user(regs->ax, &sc->ax, Efault);
-#ifdef CONFIG_X86_64
 	unsafe_put_user(regs->r8, &sc->r8, Efault);
 	unsafe_put_user(regs->r9, &sc->r9, Efault);
 	unsafe_put_user(regs->r10, &sc->r10, Efault);
@@ -189,23 +161,15 @@ __unsafe_setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
 	unsafe_put_user(regs->r13, &sc->r13, Efault);
 	unsafe_put_user(regs->r14, &sc->r14, Efault);
 	unsafe_put_user(regs->r15, &sc->r15, Efault);
-#endif /* CONFIG_X86_64 */
 
 	unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault);
 	unsafe_put_user(current->thread.error_code, &sc->err, Efault);
 	unsafe_put_user(regs->ip, &sc->ip, Efault);
-#ifdef CONFIG_X86_32
-	unsafe_put_user(regs->cs, (unsigned int __user *)&sc->cs, Efault);
-	unsafe_put_user(regs->flags, &sc->flags, Efault);
-	unsafe_put_user(regs->sp, &sc->sp_at_signal, Efault);
-	unsafe_put_user(regs->ss, (unsigned int __user *)&sc->ss, Efault);
-#else /* !CONFIG_X86_32 */
 	unsafe_put_user(regs->flags, &sc->flags, Efault);
 	unsafe_put_user(regs->cs, &sc->cs, Efault);
 	unsafe_put_user(0, &sc->gs, Efault);
 	unsafe_put_user(0, &sc->fs, Efault);
 	unsafe_put_user(regs->ss, &sc->ss, Efault);
-#endif /* CONFIG_X86_32 */
 
 	unsafe_put_user(fpstate, (unsigned long __user *)&sc->fpstate, Efault);
 
@@ -228,6 +192,8 @@ do {									\
 			(__u64 __user *)&(frame)->uc.uc_sigmask, \
 			label)
 
+#endif /* CONFIG_X86_64 */
+
 /*
  * Set up a signal frame.
  */
@@ -313,148 +279,7 @@ get_sigframe(struct ksignal *ksig, struct pt_regs *regs, size_t frame_size,
 	return (void __user *)sp;
 }
 
-#ifdef CONFIG_X86_32
-static const struct {
-	u16 poplmovl;
-	u32 val;
-	u16 int80;
-} __attribute__((packed)) retcode = {
-	0xb858,		/* popl %eax; movl $..., %eax */
-	__NR_sigreturn,
-	0x80cd,		/* int $0x80 */
-};
-
-static const struct {
-	u8  movl;
-	u32 val;
-	u16 int80;
-	u8  pad;
-} __attribute__((packed)) rt_retcode = {
-	0xb8,		/* movl $..., %eax */
-	__NR_rt_sigreturn,
-	0x80cd,		/* int $0x80 */
-	0
-};
-
-int ia32_setup_frame(struct ksignal *ksig, struct pt_regs *regs)
-{
-	sigset_t *set = sigmask_to_save();
-	struct sigframe __user *frame;
-	void __user *restorer;
-	void __user *fp = NULL;
-
-	frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
-
-	if (!user_access_begin(frame, sizeof(*frame)))
-		return -EFAULT;
-
-	unsafe_put_user(ksig->sig, &frame->sig, Efault);
-	unsafe_put_sigcontext(&frame->sc, fp, regs, set, Efault);
-	unsafe_put_user(set->sig[1], &frame->extramask[0], Efault);
-	if (current->mm->context.vdso)
-		restorer = current->mm->context.vdso +
-			vdso_image_32.sym___kernel_sigreturn;
-	else
-		restorer = &frame->retcode;
-	if (ksig->ka.sa.sa_flags & SA_RESTORER)
-		restorer = ksig->ka.sa.sa_restorer;
-
-	/* Set up to return from userspace.  */
-	unsafe_put_user(restorer, &frame->pretcode, Efault);
-
-	/*
-	 * This is popl %eax ; movl $__NR_sigreturn, %eax ; int $0x80
-	 *
-	 * WE DO NOT USE IT ANY MORE! It's only left here for historical
-	 * reasons and because gdb uses it as a signature to notice
-	 * signal handler stack frames.
-	 */
-	unsafe_put_user(*((u64 *)&retcode), (u64 *)frame->retcode, Efault);
-	user_access_end();
-
-	/* Set up registers for signal handler */
-	regs->sp = (unsigned long)frame;
-	regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
-	regs->ax = (unsigned long)ksig->sig;
-	regs->dx = 0;
-	regs->cx = 0;
-
-	regs->ds = __USER_DS;
-	regs->es = __USER_DS;
-	regs->ss = __USER_DS;
-	regs->cs = __USER_CS;
-
-	return 0;
-
-Efault:
-	user_access_end();
-	return -EFAULT;
-}
-
-int ia32_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
-{
-	sigset_t *set = sigmask_to_save();
-	struct rt_sigframe __user *frame;
-	void __user *restorer;
-	void __user *fp = NULL;
-
-	frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
-
-	if (!user_access_begin(frame, sizeof(*frame)))
-		return -EFAULT;
-
-	unsafe_put_user(ksig->sig, &frame->sig, Efault);
-	unsafe_put_user(&frame->info, &frame->pinfo, Efault);
-	unsafe_put_user(&frame->uc, &frame->puc, Efault);
-
-	/* Create the ucontext.  */
-	if (static_cpu_has(X86_FEATURE_XSAVE))
-		unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault);
-	else
-		unsafe_put_user(0, &frame->uc.uc_flags, Efault);
-	unsafe_put_user(0, &frame->uc.uc_link, Efault);
-	unsafe_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
-
-	/* Set up to return from userspace.  */
-	restorer = current->mm->context.vdso +
-		vdso_image_32.sym___kernel_rt_sigreturn;
-	if (ksig->ka.sa.sa_flags & SA_RESTORER)
-		restorer = ksig->ka.sa.sa_restorer;
-	unsafe_put_user(restorer, &frame->pretcode, Efault);
-
-	/*
-	 * This is movl $__NR_rt_sigreturn, %ax ; int $0x80
-	 *
-	 * WE DO NOT USE IT ANY MORE! It's only left here for historical
-	 * reasons and because gdb uses it as a signature to notice
-	 * signal handler stack frames.
-	 */
-	unsafe_put_user(*((u64 *)&rt_retcode), (u64 *)frame->retcode, Efault);
-	unsafe_put_sigcontext(&frame->uc.uc_mcontext, fp, regs, set, Efault);
-	unsafe_put_sigmask(set, frame, Efault);
-	user_access_end();
-	
-	if (copy_siginfo_to_user(&frame->info, &ksig->info))
-		return -EFAULT;
-
-	/* Set up registers for signal handler */
-	regs->sp = (unsigned long)frame;
-	regs->ip = (unsigned long)ksig->ka.sa.sa_handler;
-	regs->ax = (unsigned long)ksig->sig;
-	regs->dx = (unsigned long)&frame->info;
-	regs->cx = (unsigned long)&frame->uc;
-
-	regs->ds = __USER_DS;
-	regs->es = __USER_DS;
-	regs->ss = __USER_DS;
-	regs->cs = __USER_CS;
-
-	return 0;
-Efault:
-	user_access_end();
-	return -EFAULT;
-}
-#else /* !CONFIG_X86_32 */
+#ifdef CONFIG_X86_64
 static unsigned long frame_uc_flags(struct pt_regs *regs)
 {
 	unsigned long flags;
@@ -545,7 +370,6 @@ Efault:
 	user_access_end();
 	return -EFAULT;
 }
-#endif /* CONFIG_X86_32 */
 
 #ifdef CONFIG_X86_X32_ABI
 static int x32_copy_siginfo_to_user(struct compat_siginfo __user *to,
@@ -631,38 +455,6 @@ Efault:
 /*
  * Do a signal return; undo the signal stack.
  */
-#ifdef CONFIG_X86_32
-SYSCALL_DEFINE0(sigreturn)
-{
-	struct pt_regs *regs = current_pt_regs();
-	struct sigframe __user *frame;
-	sigset_t set;
-
-	frame = (struct sigframe __user *)(regs->sp - 8);
-
-	if (!access_ok(frame, sizeof(*frame)))
-		goto badframe;
-	if (__get_user(set.sig[0], &frame->sc.oldmask) ||
-	    __get_user(set.sig[1], &frame->extramask[0]))
-		goto badframe;
-
-	set_current_blocked(&set);
-
-	/*
-	 * x86_32 has no uc_flags bits relevant to restore_sigcontext.
-	 * Save a few cycles by skipping the __get_user.
-	 */
-	if (!restore_sigcontext(regs, &frame->sc, 0))
-		goto badframe;
-	return regs->ax;
-
-badframe:
-	signal_fault(regs, frame, "sigreturn");
-
-	return 0;
-}
-#endif /* CONFIG_X86_32 */
-
 SYSCALL_DEFINE0(rt_sigreturn)
 {
 	struct pt_regs *regs = current_pt_regs();
@@ -692,6 +484,7 @@ badframe:
 	signal_fault(regs, frame, "rt_sigreturn");
 	return 0;
 }
+#endif /* CONFIG_X86_64 */
 
 /*
  * There are four different struct types for signal frame: sigframe_ia32,