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

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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>
This commit is contained in:
Brian Gerst 2022-06-06 16:38:01 -04:00 committed by Borislav Petkov
parent c461ae3937
commit 24e6dc35cc
6 changed files with 60 additions and 227 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/ia32/Makefile
View File

@ -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)

1
arch/x86/include/asm/segment.h
View File

@ -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: */

4
arch/x86/kernel/Makefile
View File

@ -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

219
arch/x86/kernel/signal.c
View File

@ -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,

59
arch/x86/ia32/ia32_signal.c → arch/x86/kernel/signal_32.c
View File

@ -1,7 +1,5 @@
// 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 @@ badframe:
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 @@ Efault:
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;

2
include/linux/syscalls.h
View File

@ -264,6 +264,7 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event)
#define SC_VAL64(type, name) ((type) name##_hi << 32 | name##_lo)
#ifdef CONFIG_COMPAT
#define SYSCALL32_DEFINE0 COMPAT_SYSCALL_DEFINE0
#define SYSCALL32_DEFINE1 COMPAT_SYSCALL_DEFINE1
#define SYSCALL32_DEFINE2 COMPAT_SYSCALL_DEFINE2
#define SYSCALL32_DEFINE3 COMPAT_SYSCALL_DEFINE3
@ -271,6 +272,7 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event)
#define SYSCALL32_DEFINE5 COMPAT_SYSCALL_DEFINE5
#define SYSCALL32_DEFINE6 COMPAT_SYSCALL_DEFINE6
#else
#define SYSCALL32_DEFINE0 SYSCALL_DEFINE0
#define SYSCALL32_DEFINE1 SYSCALL_DEFINE1
#define SYSCALL32_DEFINE2 SYSCALL_DEFINE2
#define SYSCALL32_DEFINE3 SYSCALL_DEFINE3