Shuah, Could you please take a quick look at this and ack it if you're OK with the tools/testing change? We'd like to get this merged soon. - Paul On Fri, 4 Oct 2019, Paul Walmsley wrote: > Hello Shuah, > > On Thu, 22 Aug 2019, David Abdurachmanov wrote: > > > This patch was extensively tested on Fedora/RISCV (applied by default on > > top of 5.2-rc7 kernel for <2 months). The patch was also tested with 5.3-rc > > on QEMU and SiFive Unleashed board. > > > > libseccomp (userspace) was rebased: > > https://github.com/seccomp/libseccomp/pull/134 > > > > Fully passes libseccomp regression testing (simulation and live). > > > > There is one failing kernel selftest: global.user_notification_signal > > > > v1 -> v2: > > - return immediatly if secure_computing(NULL) returns -1 > > - fixed whitespace issues > > - add missing seccomp.h > > - remove patch #2 (solved now) > > - add riscv to seccomp kernel selftest > > > > Cc: keescook@xxxxxxxxxxxx > > Cc: me@xxxxxxxxxxxxx > > > > Signed-off-by: David Abdurachmanov <david.abdurachmanov@xxxxxxxxxx> > > We'd like to merge this patch through the RISC-V tree. > Care to ack the change to tools/testing/selftests/seccomp/seccomp_bpf.c ? > > Kees has already reviewed it: > > https://lore.kernel.org/linux-riscv/CAJr-aD=UnCN9E_mdVJ2H5nt=6juRSWikZnA5HxDLQxXLbsRz-w@xxxxxxxxxxxxxx/ > > > - Paul > > > > --- > > arch/riscv/Kconfig | 14 ++++++++++ > > arch/riscv/include/asm/seccomp.h | 10 +++++++ > > arch/riscv/include/asm/thread_info.h | 5 +++- > > arch/riscv/kernel/entry.S | 27 +++++++++++++++++-- > > arch/riscv/kernel/ptrace.c | 10 +++++++ > > tools/testing/selftests/seccomp/seccomp_bpf.c | 8 +++++- > > 6 files changed, 70 insertions(+), 4 deletions(-) > > create mode 100644 arch/riscv/include/asm/seccomp.h > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > > index 59a4727ecd6c..441e63ff5adc 100644 > > --- a/arch/riscv/Kconfig > > +++ b/arch/riscv/Kconfig > > @@ -31,6 +31,7 @@ config RISCV > > select GENERIC_SMP_IDLE_THREAD > > select GENERIC_ATOMIC64 if !64BIT > > select HAVE_ARCH_AUDITSYSCALL > > + select HAVE_ARCH_SECCOMP_FILTER > > select HAVE_MEMBLOCK_NODE_MAP > > select HAVE_DMA_CONTIGUOUS > > select HAVE_FUTEX_CMPXCHG if FUTEX > > @@ -235,6 +236,19 @@ menu "Kernel features" > > > > 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. > > + > > endmenu > > > > menu "Boot options" > > diff --git a/arch/riscv/include/asm/seccomp.h b/arch/riscv/include/asm/seccomp.h > > new file mode 100644 > > index 000000000000..bf7744ee3b3d > > --- /dev/null > > +++ b/arch/riscv/include/asm/seccomp.h > > @@ -0,0 +1,10 @@ > > +/* SPDX-License-Identifier: GPL-2.0 */ > > + > > +#ifndef _ASM_SECCOMP_H > > +#define _ASM_SECCOMP_H > > + > > +#include <asm/unistd.h> > > + > > +#include <asm-generic/seccomp.h> > > + > > +#endif /* _ASM_SECCOMP_H */ > > diff --git a/arch/riscv/include/asm/thread_info.h b/arch/riscv/include/asm/thread_info.h > > index 905372d7eeb8..a0b2a29a0da1 100644 > > --- a/arch/riscv/include/asm/thread_info.h > > +++ b/arch/riscv/include/asm/thread_info.h > > @@ -75,6 +75,7 @@ struct thread_info { > > #define TIF_MEMDIE 5 /* is terminating due to OOM killer */ > > #define TIF_SYSCALL_TRACEPOINT 6 /* syscall tracepoint instrumentation */ > > #define TIF_SYSCALL_AUDIT 7 /* syscall auditing */ > > +#define TIF_SECCOMP 8 /* syscall secure computing */ > > > > #define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE) > > #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) > > @@ -82,11 +83,13 @@ struct thread_info { > > #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) > > #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT) > > #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) > > +#define _TIF_SECCOMP (1 << TIF_SECCOMP) > > > > #define _TIF_WORK_MASK \ > > (_TIF_NOTIFY_RESUME | _TIF_SIGPENDING | _TIF_NEED_RESCHED) > > > > #define _TIF_SYSCALL_WORK \ > > - (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_AUDIT) > > + (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_AUDIT | \ > > + _TIF_SECCOMP ) > > > > #endif /* _ASM_RISCV_THREAD_INFO_H */ > > diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S > > index bc7a56e1ca6f..0bbedfa3e47d 100644 > > --- a/arch/riscv/kernel/entry.S > > +++ b/arch/riscv/kernel/entry.S > > @@ -203,8 +203,25 @@ check_syscall_nr: > > /* Check to make sure we don't jump to a bogus syscall number. */ > > li t0, __NR_syscalls > > la s0, sys_ni_syscall > > - /* Syscall number held in a7 */ > > - bgeu a7, t0, 1f > > + /* > > + * The tracer can change syscall number to valid/invalid value. > > + * We use syscall_set_nr helper in syscall_trace_enter thus we > > + * cannot trust the current value in a7 and have to reload from > > + * the current task pt_regs. > > + */ > > + REG_L a7, PT_A7(sp) > > + /* > > + * Syscall number held in a7. > > + * If syscall number is above allowed value, redirect to ni_syscall. > > + */ > > + bge a7, t0, 1f > > + /* > > + * Check if syscall is rejected by tracer or seccomp, i.e., a7 == -1. > > + * If yes, we pretend it was executed. > > + */ > > + li t1, -1 > > + beq a7, t1, ret_from_syscall_rejected > > + /* Call syscall */ > > la s0, sys_call_table > > slli t0, a7, RISCV_LGPTR > > add s0, s0, t0 > > @@ -215,6 +232,12 @@ check_syscall_nr: > > ret_from_syscall: > > /* Set user a0 to kernel a0 */ > > REG_S a0, PT_A0(sp) > > + /* > > + * We didn't execute the actual syscall. > > + * Seccomp already set return value for the current task pt_regs. > > + * (If it was configured with SECCOMP_RET_ERRNO/TRACE) > > + */ > > +ret_from_syscall_rejected: > > /* Trace syscalls, but only if requested by the user. */ > > REG_L t0, TASK_TI_FLAGS(tp) > > andi t0, t0, _TIF_SYSCALL_WORK > > diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c > > index 368751438366..63e47c9f85f0 100644 > > --- a/arch/riscv/kernel/ptrace.c > > +++ b/arch/riscv/kernel/ptrace.c > > @@ -154,6 +154,16 @@ void do_syscall_trace_enter(struct pt_regs *regs) > > if (tracehook_report_syscall_entry(regs)) > > syscall_set_nr(current, regs, -1); > > > > + /* > > + * Do the secure computing after ptrace; failures should be fast. > > + * If this fails we might have return value in a0 from seccomp > > + * (via SECCOMP_RET_ERRNO/TRACE). > > + */ > > + if (secure_computing(NULL) == -1) { > > + syscall_set_nr(current, regs, -1); > > + return; > > + } > > + > > #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS > > if (test_thread_flag(TIF_SYSCALL_TRACEPOINT)) > > trace_sys_enter(regs, syscall_get_nr(current, regs)); > > diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c > > index 6ef7f16c4cf5..492e0adad9d3 100644 > > --- a/tools/testing/selftests/seccomp/seccomp_bpf.c > > +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c > > @@ -112,6 +112,8 @@ struct seccomp_data { > > # define __NR_seccomp 383 > > # elif defined(__aarch64__) > > # define __NR_seccomp 277 > > +# elif defined(__riscv) > > +# define __NR_seccomp 277 > > # elif defined(__hppa__) > > # define __NR_seccomp 338 > > # elif defined(__powerpc__) > > @@ -1582,6 +1584,10 @@ TEST_F(TRACE_poke, getpid_runs_normally) > > # define ARCH_REGS struct user_pt_regs > > # define SYSCALL_NUM regs[8] > > # define SYSCALL_RET regs[0] > > +#elif defined(__riscv) && __riscv_xlen == 64 > > +# define ARCH_REGS struct user_regs_struct > > +# define SYSCALL_NUM a7 > > +# define SYSCALL_RET a0 > > #elif defined(__hppa__) > > # define ARCH_REGS struct user_regs_struct > > # define SYSCALL_NUM gr[20] > > @@ -1671,7 +1677,7 @@ void change_syscall(struct __test_metadata *_metadata, > > EXPECT_EQ(0, ret) {} > > > > #if defined(__x86_64__) || defined(__i386__) || defined(__powerpc__) || \ > > - defined(__s390__) || defined(__hppa__) > > + defined(__s390__) || defined(__hppa__) || defined(__riscv) > > { > > regs.SYSCALL_NUM = syscall; > > } > > -- > > 2.21.0 > > > > > > > - Paul >
