Commit 24e6dc35 authored by Brian Gerst's avatar Brian Gerst Committed by Borislav Petkov
Browse files

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


Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
parent c461ae39

arch/x86/ia32/Makefile

+0 −2
Original line number Diff line number Diff line
@@ -3,7 +3,5 @@ 
# Makefile for the ia32 kernel emulation subsystem.

#



obj-$(CONFIG_IA32_EMULATION) := ia32_signal.o



audit-class-$(CONFIG_AUDIT) := audit.o

obj-$(CONFIG_IA32_EMULATION) += $(audit-class-y)

arch/x86/include/asm/segment.h

+1 −0
Original line number Diff line number Diff line
@@ -135,6 +135,7 @@ 
#define __KERNEL_DS			(GDT_ENTRY_KERNEL_DS*8)

#define __USER_DS			(GDT_ENTRY_DEFAULT_USER_DS*8 + 3)

#define __USER_CS			(GDT_ENTRY_DEFAULT_USER_CS*8 + 3)

#define __USER32_CS			__USER_CS

#define __ESPFIX_SS			(GDT_ENTRY_ESPFIX_SS*8)



/* segment for calling fn: */

arch/x86/kernel/Makefile

+2 −2
Original line number Diff line number Diff line
@@ -53,8 +53,8 @@ obj-y += setup.o x86_init.o i8259.o irqinit.o 
obj-$(CONFIG_JUMP_LABEL)	+= jump_label.o

obj-$(CONFIG_IRQ_WORK)  += irq_work.o

obj-y			+= probe_roms.o

obj-$(CONFIG_X86_32)	+= sys_ia32.o

obj-$(CONFIG_IA32_EMULATION)	+= sys_ia32.o

obj-$(CONFIG_X86_32)	+= sys_ia32.o signal_32.o

obj-$(CONFIG_IA32_EMULATION)	+= sys_ia32.o signal_32.o

obj-$(CONFIG_X86_64)	+= sys_x86_64.o

obj-$(CONFIG_X86_ESPFIX64)	+= espfix_64.o

obj-$(CONFIG_SYSFS)	+= ksysfs.o

arch/x86/kernel/signal.c

+6 −213
Original line number Diff line number Diff line
@@ -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 @@ int x64_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs) 
	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 @@ int x32_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs) 
/*

 * 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 @@ SYSCALL_DEFINE0(rt_sigreturn) 
	signal_fault(regs, frame, "rt_sigreturn");

	return 0;

}

#endif /* CONFIG_X86_64 */



/*

 * There are four different struct types for signal frame: sigframe_ia32,

arch/x86/ia32/ia32_signal.c→arch/x86/kernel/signal_32.c

+49 −10
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 *  linux/arch/x86_64/ia32/ia32_signal.c

 *

 *  Copyright (C) 1991, 1992  Linus Torvalds

 *

 *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
@@ -26,7 +24,6 @@ 
#include <linux/uaccess.h>

#include <asm/fpu/signal.h>

#include <asm/ptrace.h>

#include <asm/ia32_unistd.h>

#include <asm/user32.h>

#include <uapi/asm/sigcontext.h>

#include <asm/proto.h>
@@ -35,6 +32,9 @@ 
#include <asm/sighandling.h>

#include <asm/smap.h>



#ifdef CONFIG_IA32_EMULATION

#include <asm/ia32_unistd.h>



static inline void reload_segments(struct sigcontext_32 *sc)

{

	unsigned int cur;
@@ -53,6 +53,21 @@ static inline void reload_segments(struct sigcontext_32 *sc) 
		loadsegment(es, sc->es | 0x03);

}



#define sigset32_t			compat_sigset_t

#define restore_altstack32		compat_restore_altstack

#define unsafe_save_altstack32		unsafe_compat_save_altstack



#else



#define sigset32_t			sigset_t

#define __NR_ia32_sigreturn		__NR_sigreturn

#define __NR_ia32_rt_sigreturn		__NR_rt_sigreturn

#define restore_altstack32		restore_altstack

#define unsafe_save_altstack32		unsafe_save_altstack

#define __copy_siginfo_to_user32	copy_siginfo_to_user



#endif



/*

 * Do a signal return; undo the signal stack.

 */
@@ -86,6 +101,7 @@ static bool ia32_restore_sigcontext(struct pt_regs *regs, 
	/* disable syscall checks */

	regs->orig_ax = -1;



#ifdef CONFIG_IA32_EMULATION

	/*

	 * Reload fs and gs if they have changed in the signal

	 * handler.  This does not handle long fs/gs base changes in
@@ -93,10 +109,17 @@ static bool ia32_restore_sigcontext(struct pt_regs *regs, 
	 * normal case.

	 */

	reload_segments(&sc);

#else

	loadsegment(gs, sc.gs);

	regs->fs = sc.fs;

	regs->es = sc.es;

	regs->ds = sc.ds;

#endif



	return fpu__restore_sig(compat_ptr(sc.fpstate), 1);

}



COMPAT_SYSCALL_DEFINE0(sigreturn)

SYSCALL32_DEFINE0(sigreturn)

{

	struct pt_regs *regs = current_pt_regs();

	struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
@@ -119,7 +142,7 @@ COMPAT_SYSCALL_DEFINE0(sigreturn) 
	return 0;

}



COMPAT_SYSCALL_DEFINE0(rt_sigreturn)

SYSCALL32_DEFINE0(rt_sigreturn)

{

	struct pt_regs *regs = current_pt_regs();

	struct rt_sigframe_ia32 __user *frame;
@@ -129,7 +152,7 @@ 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 (__get_user(*(__u64 *)&set, (__u64 __user *)&frame->uc.uc_sigmask))

		goto badframe;



	set_current_blocked(&set);
@@ -137,7 +160,7 @@ COMPAT_SYSCALL_DEFINE0(rt_sigreturn) 
	if (!ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext))

		goto badframe;



	if (compat_restore_altstack(&frame->uc.uc_stack))

	if (restore_altstack32(&frame->uc.uc_stack))

		goto badframe;



	return regs->ax;
@@ -159,9 +182,15 @@ __unsafe_setup_sigcontext32(struct sigcontext_32 __user *sc, 
			    struct pt_regs *regs, unsigned int mask)

{

	unsafe_put_user(get_user_seg(gs), (unsigned int __user *)&sc->gs, Efault);

#ifdef CONFIG_IA32_EMULATION

	unsafe_put_user(get_user_seg(fs), (unsigned int __user *)&sc->fs, Efault);

	unsafe_put_user(get_user_seg(ds), (unsigned int __user *)&sc->ds, Efault);

	unsafe_put_user(get_user_seg(es), (unsigned int __user *)&sc->es, Efault);

#else

	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



	unsafe_put_user(regs->di, &sc->di, Efault);

	unsafe_put_user(regs->si, &sc->si, Efault);
@@ -198,7 +227,7 @@ do { \ 


int ia32_setup_frame(struct ksignal *ksig, struct pt_regs *regs)

{

	compat_sigset_t *set = (compat_sigset_t *) sigmask_to_save();

	sigset32_t *set = (sigset32_t *) sigmask_to_save();

	struct sigframe_ia32 __user *frame;

	void __user *restorer;

	void __user *fp = NULL;
@@ -250,8 +279,13 @@ int ia32_setup_frame(struct ksignal *ksig, struct pt_regs *regs) 
	regs->dx = 0;

	regs->cx = 0;



#ifdef CONFIG_IA32_EMULATION

	loadsegment(ds, __USER_DS);

	loadsegment(es, __USER_DS);

#else

	regs->ds = __USER_DS;

	regs->es = __USER_DS;

#endif



	regs->cs = __USER32_CS;

	regs->ss = __USER_DS;
@@ -264,7 +298,7 @@ int ia32_setup_frame(struct ksignal *ksig, struct pt_regs *regs) 


int ia32_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)

{

	compat_sigset_t *set = (compat_sigset_t *) sigmask_to_save();

	sigset32_t *set = (sigset32_t *) sigmask_to_save();

	struct rt_sigframe_ia32 __user *frame;

	void __user *restorer;

	void __user *fp = NULL;
@@ -297,7 +331,7 @@ int ia32_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs) 
	else

		unsafe_put_user(0, &frame->uc.uc_flags, Efault);

	unsafe_put_user(0, &frame->uc.uc_link, Efault);

	unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);

	unsafe_save_altstack32(&frame->uc.uc_stack, regs->sp, Efault);



	if (ksig->ka.sa.sa_flags & SA_RESTORER)

		restorer = ksig->ka.sa.sa_restorer;
@@ -327,8 +361,13 @@ int ia32_setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs) 
	regs->dx = (unsigned long) &frame->info;

	regs->cx = (unsigned long) &frame->uc;



#ifdef CONFIG_IA32_EMULATION

	loadsegment(ds, __USER_DS);

	loadsegment(es, __USER_DS);

#else

	regs->ds = __USER_DS;

	regs->es = __USER_DS;

#endif



	regs->cs = __USER32_CS;

	regs->ss = __USER_DS;