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[222.152.189.137]) by smtp.gmail.com with ESMTPSA id y1sm15733924pfe.72.2021.06.28.16.55.25 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 28 Jun 2021 16:55:26 -0700 (PDT) Received: by xplor.waratah.dyndns.org (Postfix, from userid 1000) id 271D1360413; Tue, 29 Jun 2021 11:55:23 +1200 (NZST) From: Michael Schmitz To: linux-m68k@vger.kernel.org, geert@linux-m68k.org Cc: glaubitz@physik.fu-berlin.de, schwab@linux-m68k.org, Michael Schmitz Subject: [PATCH v7 2/2] m68k: add kernel seccomp support Date: Tue, 29 Jun 2021 11:55:20 +1200 Message-Id: <1624924520-17567-3-git-send-email-schmitzmic@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1624924520-17567-1-git-send-email-schmitzmic@gmail.com> References: <1624924520-17567-1-git-send-email-schmitzmic@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-m68k@vger.kernel.org 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 -- 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 + +#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 +#include + +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 #include #include +#include #include #include @@ -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