syscall_user_dispatch: Make it configurable in Kconfig

Syscall User Dispatch is presently built under CONFIG_GENERIC_SYSCALL and cannot be disabled independently. Add CONFIG_SYSCALL_USER_DISPATCH to make it an optional feature.

Gregory Price committed 4 months ago

Commit ee935e81 parent 8cdeaa56 files · +42 −9Browse files

Unified · Split

6 files

arch/Kconfig +10 −0
include/linux/entry-common.h +2 −4
include/linux/syscall_user_dispatch.h +26 −2
include/linux/syscall_user_dispatch_types.h +1 −1
kernel/entry/Makefile +2 −1
tools/testing/selftests/syscall_user_dispatch/config +1 −1

arch/Kconfig+10−0

@@ -114,6 +114,16 @@ config GENERIC_ENTRY · 113 unmodified lines
114	select GENERIC_IRQ_ENTRY	114	select GENERIC_IRQ_ENTRY
115	select GENERIC_SYSCALL	115	select GENERIC_SYSCALL
116		116
		117	config SYSCALL_USER_DISPATCH
		118	bool "Syscall User Dispatch"
		119	depends on GENERIC_ENTRY
		120	default y
		121	help
		122	Syscall User Dispatch lets a thread have its own system calls
		123	intercepted and redirected to a userspace signal handler based
		124	on a prctl() configured instruction pointer range.
		125	If unsure, say Y.
		126
117	config KPROBES	127	config KPROBES
118	bool "Kprobes"	128	bool "Kprobes"
119	depends on HAVE_KPROBES	129	depends on HAVE_KPROBES

include/linux/entry-common.h+2−4

 #include <linux/resume_user_mode.h>
 #include <linux/seccomp.h>
 #include <linux/sched.h>
+#include <linux/syscall_user_dispatch.h>
 #include <asm/entry-common.h>
 #include <asm/syscall.h>
 }
 #endif
-bool syscall_user_dispatch(struct pt_regs *regs);
 long trace_syscall_enter(struct pt_regs *regs, long syscall);
 void trace_syscall_exit(struct pt_regs *regs, long ret);
 	 * of these syscalls is unknown.
 	 */
 	if (work & SYSCALL_WORK_SYSCALL_USER_DISPATCH) {
-		if (unlikely(current->syscall_dispatch.on_dispatch)) {
+		if (syscall_user_dispatch_clear_on_dispatch())
-			current->syscall_dispatch.on_dispatch = false;
 			return;
-		}
 	}
 	audit_syscall_exit(regs);

include/linux/syscall_user_dispatch.h+26−2

@@ -6,9 +6,23 @@ · 5 unmodified lines
6	#define _SYSCALL_USER_DISPATCH_H	6	#define _SYSCALL_USER_DISPATCH_H
7		7
8	#include <linux/thread_info.h>	8	#include <linux/thread_info.h>
		9	#include <linux/sched.h>
9	#include <linux/syscall_user_dispatch_types.h>	10	#include <linux/syscall_user_dispatch_types.h>
10		11
11	#ifdef CONFIG_GENERIC_ENTRY	12	struct pt_regs;
		13
		14	#ifdef CONFIG_SYSCALL_USER_DISPATCH
		15
		16	bool syscall_user_dispatch(struct pt_regs *regs);
		17
		18	static __always_inline bool syscall_user_dispatch_clear_on_dispatch(void)
		19	{
		20	if (likely(!current->syscall_dispatch.on_dispatch))
		21	return false;
		22
		23	current->syscall_dispatch.on_dispatch = false;
		24	return true;
		25	}
12		26
13	int set_syscall_user_dispatch(unsigned long mode, unsigned long offset,	27	int set_syscall_user_dispatch(unsigned long mode, unsigned long offset,
14	unsigned long len, char __user *selector);	28	unsigned long len, char __user *selector);
@@ -24,6 +38,16 @@ int syscall_user_dispatch_set_config(struct task_struct *task, unsigned long siz · 9 unmodified lines
24		38
25	#else	39	#else
26		40
		41	static __always_inline bool syscall_user_dispatch(struct pt_regs *regs)
		42	{
		43	return false;
		44	}
		45
		46	static __always_inline bool syscall_user_dispatch_clear_on_dispatch(void)
		47	{
		48	return false;
		49	}
		50
27	static inline int set_syscall_user_dispatch(unsigned long mode, unsigned long offset,	51	static inline int set_syscall_user_dispatch(unsigned long mode, unsigned long offset,
28	unsigned long len, char __user *selector)	52	unsigned long len, char __user *selector)
29	{	53	{
@@ -46,6 +70,6 @@ static inline int syscall_user_dispatch_set_config(struct task_struct *task, · 16 unmodified lines
46	return -EINVAL;	70	return -EINVAL;
47	}	71	}
48		72
49	#endif /* CONFIG_GENERIC_ENTRY */	73	#endif /* CONFIG_SYSCALL_USER_DISPATCH */
50		74
51	#endif /* _SYSCALL_USER_DISPATCH_H */	75	#endif /* _SYSCALL_USER_DISPATCH_H */

include/linux/syscall_user_dispatch_types.h+1−1

@@ -4,7 +4,7 @@ · 3 unmodified lines
4		4
5	#include <linux/types.h>	5	#include <linux/types.h>
6		6
7	#ifdef CONFIG_GENERIC_ENTRY	7	#ifdef CONFIG_SYSCALL_USER_DISPATCH
8		8
9	struct syscall_user_dispatch {	9	struct syscall_user_dispatch {
10	char __user *selector;	10	char __user *selector;

kernel/entry/Makefile+2−1

@@ -13,5 +13,6 @@ CFLAGS_REMOVE_common.o = -fstack-protector -fstack-protector-strong · 12 unmodified lines
13	CFLAGS_common.o += -fno-stack-protector	13	CFLAGS_common.o += -fno-stack-protector
14		14
15	obj-$(CONFIG_GENERIC_IRQ_ENTRY) += common.o	15	obj-$(CONFIG_GENERIC_IRQ_ENTRY) += common.o
16	obj-$(CONFIG_GENERIC_SYSCALL) += syscall-common.o syscall_user_dispatch.o	16	obj-$(CONFIG_GENERIC_SYSCALL) += syscall-common.o
		17	obj-$(CONFIG_SYSCALL_USER_DISPATCH) += syscall_user_dispatch.o
17	obj-$(CONFIG_VIRT_XFER_TO_GUEST_WORK) += virt.o	18	obj-$(CONFIG_VIRT_XFER_TO_GUEST_WORK) += virt.o

tools/testing/selftests/syscall_user_dispatch/config+1−1

@@ -1 +1 @@
1	CONFIG_GENERIC_ENTRY=y	1	CONFIG_SYSCALL_USER_DISPATCH=y

syscall_user_dispatch: Make it configurable in Kconfig

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