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authorMichael Schmitz <schmitzmic@gmail.com>2023-01-12 16:55:28 +1300
committerGeert Uytterhoeven <geert@linux-m68k.org>2023-01-30 16:40:15 +0100
commit6baaade15594b28195da369962208b1f658e7342 (patch)
tree52b25795388cc48527daad004758e1d7d539315c /arch/m68k
parent2ca8a1de4437f21562e57f9ac123914747a8e7a1 (diff)
downloadlwn-6baaade15594b28195da369962208b1f658e7342.tar.gz
lwn-6baaade15594b28195da369962208b1f658e7342.zip
m68k: Add kernel seccomp support
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 81 out of 94 tests. Signed-off-by: Michael Schmitz <schmitzmic@gmail.com> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Link: https://lore.kernel.org/r/20230112035529.13521-3-schmitzmic@gmail.com Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Diffstat (limited to 'arch/m68k')
-rw-r--r--arch/m68k/Kconfig2
-rw-r--r--arch/m68k/include/asm/seccomp.h11
-rw-r--r--arch/m68k/include/asm/syscall.h57
-rw-r--r--arch/m68k/include/asm/thread_info.h2
-rw-r--r--arch/m68k/kernel/entry.S3
-rw-r--r--arch/m68k/kernel/ptrace.c6
6 files changed, 80 insertions, 1 deletions
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..d1453e850cdd 100644
--- a/arch/m68k/include/asm/syscall.h
+++ b/arch/m68k/include/asm/syscall.h
@@ -4,6 +4,63 @@
#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 ?: 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, &regs->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(&regs->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;
}