Add secure_computing() call to syscall_trace_enter to actually
filter system calls.
Add necessary arch Kconfig options, define TIF_SECCOMP trace
flag and provide basic seccomp filter support in asm/syscall.h
syscall_get_nr currently uses the syscall nr stored in orig_d0
because we change d0 to a default return code before starting a
syscall trace. This may be inconsistent with syscall_rollback
copying orig_d0 to d0 (which we never check upon return from
trace). We use d0 for the return code from syscall_trace_enter
in entry.S currently, and could perhaps expand that to store
a new syscall number returned by the seccomp filter before
executing the syscall. This clearly needs some discussion.
seccomp_bpf self test on ARAnyM passes 63 out of 89 tests.
Signed-off-by: Michael Schmitz <schmitzmic@xxxxxxxxx>
--
Changes from v10:
- fix merge conflicts
Changes from v9:
- add test for TIF_SECCOMP bit to call syscall_trace_enter()
if seccomp syscall filtering is active
Changes from v6:
Geert Uytterhoeven:
- add syscall_get_error(), syscall_get_return_value(), and
syscall_set_arguments() (not needed to compile!)
Changes from v5:
Geert Uytterhoeven:
- correct wrong offset for d1-d5 register copy
- update Documentation/features/seccomp/seccomp-filter/arch-support.txt
add syscall_get_error(), syscall_get_return_value(), syscall_set_arguments()
---
.../seccomp/seccomp-filter/arch-support.txt | 2 +-
arch/m68k/Kconfig | 2 +
arch/m68k/include/asm/seccomp.h | 11 ++++
arch/m68k/include/asm/syscall.h | 56 +++++++++++++++++++
arch/m68k/include/asm/thread_info.h | 2 +
arch/m68k/kernel/entry.S | 3 +
arch/m68k/kernel/ptrace.c | 6 +-
7 files changed, 80 insertions(+), 2 deletions(-)
create mode 100644 arch/m68k/include/asm/seccomp.h
diff --git a/Documentation/features/seccomp/seccomp-filter/arch-support.txt b/Documentation/features/seccomp/seccomp-filter/arch-support.txt
index dc71bf7b1a7e..3a7237b989cd 100644
--- a/Documentation/features/seccomp/seccomp-filter/arch-support.txt
+++ b/Documentation/features/seccomp/seccomp-filter/arch-support.txt
@@ -14,7 +14,7 @@
| hexagon: | TODO |
| ia64: | TODO |
| loongarch: | ok |
- | m68k: | TODO |
+ | m68k: | ok |
| microblaze: | TODO |
| mips: | ok |
| nios2: | TODO |
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 7bff88118507..82154952e574 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -18,6 +18,8 @@ config M68K
select GENERIC_CPU_DEVICES
select GENERIC_IOMAP
select GENERIC_IRQ_SHOW
+ select HAVE_ARCH_SECCOMP
+ select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ASM_MODVERSIONS
select HAVE_DEBUG_BUGVERBOSE
select HAVE_EFFICIENT_UNALIGNED_ACCESS if !CPU_HAS_NO_UNALIGNED
diff --git a/arch/m68k/include/asm/seccomp.h b/arch/m68k/include/asm/seccomp.h
new file mode 100644
index 000000000000..de8a94e1fb3f
--- /dev/null
+++ b/arch/m68k/include/asm/seccomp.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _ASM_SECCOMP_H
+#define _ASM_SECCOMP_H
+
+#include <asm-generic/seccomp.h>
+
+#define SECCOMP_ARCH_NATIVE AUDIT_ARCH_M68K
+#define SECCOMP_ARCH_NATIVE_NR NR_syscalls
+#define SECCOMP_ARCH_NATIVE_NAME "m68k"
+
+#endif /* _ASM_SECCOMP_H */
diff --git a/arch/m68k/include/asm/syscall.h b/arch/m68k/include/asm/syscall.h
index 465ac039be09..2b49ad725655 100644
--- a/arch/m68k/include/asm/syscall.h
+++ b/arch/m68k/include/asm/syscall.h
@@ -4,6 +4,62 @@
#include <uapi/linux/audit.h>
+#include <asm/unistd.h>
+
+extern const unsigned long sys_call_table[];
+
+static inline int syscall_get_nr(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ return regs->orig_d0;
+}
+
+static inline void syscall_rollback(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ regs->d0 = regs->orig_d0;
+}
+
+static inline long syscall_get_error(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ unsigned long error = regs->d0;
+ return IS_ERR_VALUE(error) ? error : 0;
+}
+
+static inline long syscall_get_return_value(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ return regs->d0;
+}
+
+static inline void syscall_set_return_value(struct task_struct *task,
+ struct pt_regs *regs,
+ int error, long val)
+{
+ regs->d0 = (long) error ? error : val;
+}
+
+static inline void syscall_get_arguments(struct task_struct *task,
+ struct pt_regs *regs,
+ unsigned long *args)
+{
+ args[0] = regs->orig_d0;
+ args++;
+
+ memcpy(args, ®s->d1, 5 * sizeof(args[0]));
+}
+
+static inline void syscall_set_arguments(struct task_struct *task,
+ struct pt_regs *regs,
+ unsigned long *args)
+{
+ regs->orig_d0 = args[0];
+ args++;
+
+ memcpy(®s->d1, args, 5 * sizeof(args[0]));
+}
+
static inline int syscall_get_arch(struct task_struct *task)
{
return AUDIT_ARCH_M68K;
diff --git a/arch/m68k/include/asm/thread_info.h b/arch/m68k/include/asm/thread_info.h
index c952658ba792..31be2ad999ca 100644
--- a/arch/m68k/include/asm/thread_info.h
+++ b/arch/m68k/include/asm/thread_info.h
@@ -61,6 +61,7 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_NOTIFY_RESUME 5 /* callback before returning to user */
#define TIF_SIGPENDING 6 /* signal pending */
#define TIF_NEED_RESCHED 7 /* rescheduling necessary */
+#define TIF_SECCOMP 13 /* seccomp syscall filtering active */
#define TIF_DELAYED_TRACE 14 /* single step a syscall */
#define TIF_SYSCALL_TRACE 15 /* syscall trace active */
#define TIF_MEMDIE 16 /* is terminating due to OOM killer */
@@ -69,6 +70,7 @@ static inline struct thread_info *current_thread_info(void)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
+#define _TIF_SECCOMP (1 << TIF_SECCOMP)
#define _TIF_DELAYED_TRACE (1 << TIF_DELAYED_TRACE)
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_MEMDIE (1 << TIF_MEMDIE)
diff --git a/arch/m68k/kernel/entry.S b/arch/m68k/kernel/entry.S
index 42879e6eb651..4dd2fd7acba9 100644
--- a/arch/m68k/kernel/entry.S
+++ b/arch/m68k/kernel/entry.S
@@ -214,6 +214,9 @@ ENTRY(system_call)
| syscall trace?
tstb %a1@(TINFO_FLAGS+2)
jmi do_trace_entry
+ | seccomp filter active?
+ btst #5,%a1@(TINFO_FLAGS+2)
+ bnes do_trace_entry
cmpl #NR_syscalls,%d0
jcc badsys
syscall:
diff --git a/arch/m68k/kernel/ptrace.c b/arch/m68k/kernel/ptrace.c
index 0a4184a37461..cd0172d29430 100644
--- a/arch/m68k/kernel/ptrace.c
+++ b/arch/m68k/kernel/ptrace.c
@@ -21,7 +21,7 @@
#include <linux/signal.h>
#include <linux/regset.h>
#include <linux/elf.h>
-
+#include <linux/seccomp.h>
#include <linux/uaccess.h>
#include <asm/page.h>
#include <asm/processor.h>
@@ -278,6 +278,10 @@ asmlinkage int syscall_trace_enter(void)
if (test_thread_flag(TIF_SYSCALL_TRACE))
ret = ptrace_report_syscall_entry(task_pt_regs(current));
+
+ if (secure_computing() == -1)
+ return -1;
+
return ret;
}
--
2.17.1
