From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> secure_computing() is called first in syscall_trace_enter() so that a system call will be aborted quickly without doing succeeding syscall tracing if seccomp rules want to deny that system call. TODO: - Update https://github.com/seccomp/libseccomp csky support Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> --- arch/csky/Kconfig | 14 ++++++++++++++ arch/csky/include/asm/Kbuild | 1 + arch/csky/include/asm/thread_info.h | 2 +- arch/csky/kernel/entry.S | 3 +++ arch/csky/kernel/ptrace.c | 8 ++++++-- tools/testing/selftests/seccomp/seccomp_bpf.c | 13 ++++++++++++- 6 files changed, 37 insertions(+), 4 deletions(-) diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig index bd31ab1..822362d 100644 --- a/arch/csky/Kconfig +++ b/arch/csky/Kconfig @@ -38,6 +38,7 @@ config CSKY select GX6605S_TIMER if CPU_CK610 select HAVE_ARCH_TRACEHOOK select HAVE_ARCH_AUDITSYSCALL + select HAVE_ARCH_SECCOMP_FILTER select HAVE_COPY_THREAD_TLS select HAVE_DEBUG_BUGVERBOSE select HAVE_DYNAMIC_FTRACE @@ -296,3 +297,16 @@ endmenu source "arch/csky/Kconfig.platforms" source "kernel/Kconfig.hz" + +config SECCOMP + bool "Enable seccomp to safely compute untrusted bytecode" + help + This kernel feature is useful for number crunching applications + that may need to compute untrusted bytecode during their + execution. By using pipes or other transports made available to + the process as file descriptors supporting the read/write + syscalls, it's possible to isolate those applications in + their own address space using seccomp. Once seccomp is + enabled via prctl(PR_SET_SECCOMP), it cannot be disabled + and the task is only allowed to execute a few safe syscalls + defined by each seccomp mode. diff --git a/arch/csky/include/asm/Kbuild b/arch/csky/include/asm/Kbuild index 9337225..64876e59 100644 --- a/arch/csky/include/asm/Kbuild +++ b/arch/csky/include/asm/Kbuild @@ -4,5 +4,6 @@ generic-y += gpio.h generic-y += kvm_para.h generic-y += local64.h generic-y += qrwlock.h +generic-y += seccomp.h generic-y += user.h generic-y += vmlinux.lds.h diff --git a/arch/csky/include/asm/thread_info.h b/arch/csky/include/asm/thread_info.h index 8980e4e..68e7a12 100644 --- a/arch/csky/include/asm/thread_info.h +++ b/arch/csky/include/asm/thread_info.h @@ -85,6 +85,6 @@ static inline struct thread_info *current_thread_info(void) _TIF_NOTIFY_RESUME | _TIF_UPROBE) #define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \ - _TIF_SYSCALL_TRACEPOINT) + _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP) #endif /* _ASM_CSKY_THREAD_INFO_H */ diff --git a/arch/csky/kernel/entry.S b/arch/csky/kernel/entry.S index f138003..efd2e69 100644 --- a/arch/csky/kernel/entry.S +++ b/arch/csky/kernel/entry.S @@ -168,6 +168,8 @@ ENTRY(csky_systemcall) csky_syscall_trace: mov a0, sp /* sp = pt_regs pointer */ jbsr syscall_trace_enter + cmpnei a0, 0 + bt 1f /* Prepare args before do system call */ ldw a0, (sp, LSAVE_A0) ldw a1, (sp, LSAVE_A1) @@ -188,6 +190,7 @@ csky_syscall_trace: #endif stw a0, (sp, LSAVE_A0) /* Save return value */ +1: #ifdef CONFIG_DEBUG_RSEQ mov a0, sp jbsr rseq_syscall diff --git a/arch/csky/kernel/ptrace.c b/arch/csky/kernel/ptrace.c index 944ca2f..0de10f7 100644 --- a/arch/csky/kernel/ptrace.c +++ b/arch/csky/kernel/ptrace.c @@ -320,16 +320,20 @@ long arch_ptrace(struct task_struct *child, long request, return ret; } -asmlinkage void syscall_trace_enter(struct pt_regs *regs) +asmlinkage int syscall_trace_enter(struct pt_regs *regs) { if (test_thread_flag(TIF_SYSCALL_TRACE)) if (tracehook_report_syscall_entry(regs)) - syscall_set_nr(current, regs, -1); + return -1; + + if (secure_computing() == -1) + return -1; if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) trace_sys_enter(regs, syscall_get_nr(current, regs)); audit_syscall_entry(regs_syscallid(regs), regs->a0, regs->a1, regs->a2, regs->a3); + return 0; } asmlinkage void syscall_trace_exit(struct pt_regs *regs) diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c index 252140a..8d18a0d 100644 --- a/tools/testing/selftests/seccomp/seccomp_bpf.c +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c @@ -116,6 +116,8 @@ struct seccomp_data { # define __NR_seccomp 277 # elif defined(__riscv) # define __NR_seccomp 277 +# elif defined(__csky__) +# define __NR_seccomp 277 # elif defined(__hppa__) # define __NR_seccomp 338 # elif defined(__powerpc__) @@ -1603,6 +1605,14 @@ TEST_F(TRACE_poke, getpid_runs_normally) # define ARCH_REGS struct user_regs_struct # define SYSCALL_NUM a7 # define SYSCALL_RET a0 +#elif defined(__csky__) +# define ARCH_REGS struct pt_regs +#if defined(__CSKYABIV2__) +# define SYSCALL_NUM regs[3] +#else +# define SYSCALL_NUM regs[9] +#endif +# define SYSCALL_RET a0 #elif defined(__hppa__) # define ARCH_REGS struct user_regs_struct # define SYSCALL_NUM gr[20] @@ -1693,7 +1703,8 @@ void change_syscall(struct __test_metadata *_metadata, EXPECT_EQ(0, ret) {} #if defined(__x86_64__) || defined(__i386__) || defined(__powerpc__) || \ - defined(__s390__) || defined(__hppa__) || defined(__riscv) + defined(__s390__) || defined(__hppa__) || defined(__riscv) || \ + defined(__csky__) { regs.SYSCALL_NUM = syscall; } -- 2.7.4
