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[222.155.5.102]) by smtp.gmail.com with ESMTPSA id x66sm4291000pfb.36.2022.01.26.23.42.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Jan 2022 23:42:06 -0800 (PST) Received: by xplor.waratah.dyndns.org (Postfix, from userid 1000) id 3712B360337; Thu, 27 Jan 2022 20:42:03 +1300 (NZDT) From: Michael Schmitz To: linux-m68k@vger.kernel.org, geert@linux-m68k.org Cc: ebiederm@xmission.com, viro@zeniv.linux.org.uk, glaubitz@physik.fu-berlin.de, Michael Schmitz Subject: [PATCH v10 3/3] m68k: add kernel seccomp support Date: Thu, 27 Jan 2022 20:41:58 +1300 Message-Id: <20220127074158.25888-4-schmitzmic@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220127074158.25888-1-schmitzmic@gmail.com> References: <20220127074158.25888-1-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. seccomp_bpf self test on ARAnyM passes 63 out of 89 tests. Signed-off-by: Michael Schmitz -- 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 | 5 ++ 7 files changed, 80 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 26eec58ab819..be71f2066981 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 936e1803c7c7..c0ef187fb3ed 100644 --- a/arch/m68k/Kconfig +++ b/arch/m68k/Kconfig @@ -18,6 +18,8 @@ config M68K select GENERIC_IOMAP select GENERIC_IRQ_SHOW select HAVE_AOUT if MMU + 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 + +#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 +#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 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 0d5b7085d76f..ee0a905b5f74 100644 --- a/arch/m68k/kernel/entry.S +++ b/arch/m68k/kernel/entry.S @@ -213,6 +213,9 @@ 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 74d58a82a135..bc2490c3fb52 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; } -- 2.17.1