* [PATCH v7 0/2] Add kernel seccomp support for m68k
@ 2021-06-28 23:55 Michael Schmitz
2021-06-28 23:55 ` [PATCH v7 1/2] m68k/kernel - wire up syscall_trace_enter/leave " Michael Schmitz
2021-06-28 23:55 ` [PATCH v7 2/2] m68k: add kernel seccomp support Michael Schmitz
0 siblings, 2 replies; 3+ messages in thread
From: Michael Schmitz @ 2021-06-28 23:55 UTC (permalink / raw)
To: linux-m68k, geert; +Cc: glaubitz, schwab
Respin of m68k kernel seccomp support.
I have added syscall_trace_enter() return code checks for
coldfire and 68000 in patch 1, and syscall_get_error(),
syscall_get_return_value() and syscall_set_arguments() defs
in patch 2 (the latter are not used without adding further
code to support tracehooks or syscall tracepoints though).
Cheers,
Michael
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH v7 1/2] m68k/kernel - wire up syscall_trace_enter/leave for m68k
2021-06-28 23:55 [PATCH v7 0/2] Add kernel seccomp support for m68k Michael Schmitz
@ 2021-06-28 23:55 ` Michael Schmitz
2021-06-28 23:55 ` [PATCH v7 2/2] m68k: add kernel seccomp support Michael Schmitz
1 sibling, 0 replies; 3+ messages in thread
From: Michael Schmitz @ 2021-06-28 23:55 UTC (permalink / raw)
To: linux-m68k, geert; +Cc: glaubitz, schwab, Michael Schmitz
m68k (other than Coldfire) uses syscall_trace for both trace entry
and trace exit. Seccomp support requires separate entry points for
trace entry and exit which are already provided for Coldfire.
Replace syscall_trace by syscall_trace_enter and syscall_trace_leave
in preparation for seccomp support. Check return code of
syscall_trace_enter(), and skip syscall if -1. Return code will be
left at what had been set by ptrace or seccomp (in regs->d0).
No regression seen in testing with strace on ARAnyM.
Signed-off-by: Michael Schmitz <schmitzmic@gmail.com>
--
Changes from v6:
Geert Uytterhoeven:
- add syscall_trace_enter() return code check for 68000
and coldfire
Changes from v5:
- add comment to explain optimization
Changes from v4:
Andreas Schwab:
- optimize return code test (addql #1,%d0 for cmpil #-1,%d0)
- spelling fix in commit message
Changes from v3:
- change syscall_trace_enter return code test from !=0 to ==-1
---
arch/m68k/68000/entry.S | 2 ++
arch/m68k/coldfire/entry.S | 2 ++
arch/m68k/kernel/entry.S | 8 +++++---
arch/m68k/kernel/ptrace.c | 17 -----------------
4 files changed, 9 insertions(+), 20 deletions(-)
diff --git a/arch/m68k/68000/entry.S b/arch/m68k/68000/entry.S
index 259b366..94abf3d 100644
--- a/arch/m68k/68000/entry.S
+++ b/arch/m68k/68000/entry.S
@@ -47,6 +47,8 @@ do_trace:
jbsr syscall_trace_enter
RESTORE_SWITCH_STACK
addql #4,%sp
+ addql #1,%d0
+ jeq ret_from_exception
movel %sp@(PT_OFF_ORIG_D0),%d1
movel #-ENOSYS,%d0
cmpl #NR_syscalls,%d1
diff --git a/arch/m68k/coldfire/entry.S b/arch/m68k/coldfire/entry.S
index d43a027..f1d41a9 100644
--- a/arch/m68k/coldfire/entry.S
+++ b/arch/m68k/coldfire/entry.S
@@ -92,6 +92,8 @@ ENTRY(system_call)
jbsr syscall_trace_enter
RESTORE_SWITCH_STACK
addql #4,%sp
+ addql #1,%d0
+ jeq ret_from_exception
movel %d3,%a0
jbsr %a0@
movel %d0,%sp@(PT_OFF_D0) /* save the return value */
diff --git a/arch/m68k/kernel/entry.S b/arch/m68k/kernel/entry.S
index 9dd76fb..d6f941d 100644
--- a/arch/m68k/kernel/entry.S
+++ b/arch/m68k/kernel/entry.S
@@ -164,9 +164,11 @@ do_trace_entry:
movel #-ENOSYS,%sp@(PT_OFF_D0)| needed for strace
subql #4,%sp
SAVE_SWITCH_STACK
- jbsr syscall_trace
+ jbsr syscall_trace_enter
RESTORE_SWITCH_STACK
addql #4,%sp
+ addql #1,%d0 | optimization for cmpil #-1,%d0
+ jeq ret_from_syscall
movel %sp@(PT_OFF_ORIG_D0),%d0
cmpl #NR_syscalls,%d0
jcs syscall
@@ -177,7 +179,7 @@ badsys:
do_trace_exit:
subql #4,%sp
SAVE_SWITCH_STACK
- jbsr syscall_trace
+ jbsr syscall_trace_leave
RESTORE_SWITCH_STACK
addql #4,%sp
jra .Lret_from_exception
@@ -186,7 +188,7 @@ ENTRY(ret_from_signal)
movel %curptr@(TASK_STACK),%a1
tstb %a1@(TINFO_FLAGS+2)
jge 1f
- jbsr syscall_trace
+ jbsr syscall_trace_leave
1: RESTORE_SWITCH_STACK
addql #4,%sp
/* on 68040 complete pending writebacks if any */
diff --git a/arch/m68k/kernel/ptrace.c b/arch/m68k/kernel/ptrace.c
index 94b3b27..74d58a8 100644
--- a/arch/m68k/kernel/ptrace.c
+++ b/arch/m68k/kernel/ptrace.c
@@ -271,22 +271,6 @@ long arch_ptrace(struct task_struct *child, long request,
return -EIO;
}
-asmlinkage void syscall_trace(void)
-{
- ptrace_notify(SIGTRAP | ((current->ptrace & PT_TRACESYSGOOD)
- ? 0x80 : 0));
- /*
- * this isn't the same as continuing with a signal, but it will do
- * for normal use. strace only continues with a signal if the
- * stopping signal is not SIGTRAP. -brl
- */
- if (current->exit_code) {
- send_sig(current->exit_code, current, 1);
- current->exit_code = 0;
- }
-}
-
-#if defined(CONFIG_COLDFIRE) || !defined(CONFIG_MMU)
asmlinkage int syscall_trace_enter(void)
{
int ret = 0;
@@ -301,4 +285,3 @@ asmlinkage void syscall_trace_leave(void)
if (test_thread_flag(TIF_SYSCALL_TRACE))
tracehook_report_syscall_exit(task_pt_regs(current), 0);
}
-#endif /* CONFIG_COLDFIRE */
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH v7 2/2] m68k: add kernel seccomp support
2021-06-28 23:55 [PATCH v7 0/2] Add kernel seccomp support for m68k Michael Schmitz
2021-06-28 23:55 ` [PATCH v7 1/2] m68k/kernel - wire up syscall_trace_enter/leave " Michael Schmitz
@ 2021-06-28 23:55 ` Michael Schmitz
1 sibling, 0 replies; 3+ messages in thread
From: Michael Schmitz @ 2021-06-28 23:55 UTC (permalink / raw)
To: linux-m68k, geert; +Cc: glaubitz, schwab, Michael Schmitz
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.
Compiles (for Atari) and boots on ARAnyM, otherwise untested.
Signed-off-by: Michael Schmitz <schmitzmic@gmail.com>
--
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/ptrace.c | 5 ++
6 files changed, 77 insertions(+), 1 deletion(-)
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 26eec58..be71f20 100644
--- a/Documentation/features/seccomp/seccomp-filter/arch-support.txt
+++ b/Documentation/features/seccomp/seccomp-filter/arch-support.txt
@@ -14,7 +14,7 @@
| h8300: | TODO |
| hexagon: | TODO |
| ia64: | TODO |
- | m68k: | TODO |
+ | m68k: | ok |
| microblaze: | TODO |
| mips: | ok |
| nds32: | TODO |
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 372e4e6..deaea88 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -19,6 +19,8 @@ config M68K
select GENERIC_STRNCPY_FROM_USER if MMU
select GENERIC_STRNLEN_USER if MMU
select HAVE_AOUT if MMU
+ select HAVE_ARCH_SECCOMP
+ select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ASM_MODVERSIONS
select HAVE_DEBUG_BUGVERBOSE
select HAVE_FUTEX_CMPXCHG if MMU && FUTEX
diff --git a/arch/m68k/include/asm/seccomp.h b/arch/m68k/include/asm/seccomp.h
new file mode 100644
index 0000000..de8a94e
--- /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 465ac03..2b49ad7 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 15a7570..d813fed 100644
--- a/arch/m68k/include/asm/thread_info.h
+++ b/arch/m68k/include/asm/thread_info.h
@@ -64,6 +64,7 @@ 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 */
@@ -72,6 +73,7 @@ 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/ptrace.c b/arch/m68k/kernel/ptrace.c
index 74d58a8..bc2490c 100644
--- a/arch/m68k/kernel/ptrace.c
+++ b/arch/m68k/kernel/ptrace.c
@@ -19,6 +19,7 @@
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/signal.h>
+#include <linux/seccomp.h>
#include <linux/tracehook.h>
#include <linux/uaccess.h>
@@ -277,6 +278,10 @@ asmlinkage int syscall_trace_enter(void)
if (test_thread_flag(TIF_SYSCALL_TRACE))
ret = tracehook_report_syscall_entry(task_pt_regs(current));
+
+ if (secure_computing() == -1)
+ return -1;
+
return ret;
}
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
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