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csky: Add SECCOMP_FILTER supported

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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@linux.alibaba.com>
Cc: Arnd Bergmann <arnd@arndb.de>
This commit is contained in:
Guo Ren 2020-05-26 08:11:52 +00:00
parent c23dd2405f
commit e95a4f8cb9
6 changed files with 37 additions and 4 deletions
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14
arch/csky/Kconfig
View File

@ -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.

1
arch/csky/include/asm/Kbuild
View File

@ -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

2
arch/csky/include/asm/thread_info.h
View File

@ -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 */

3
arch/csky/kernel/entry.S
View File

@ -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

8
arch/csky/kernel/ptrace.c
View File

@ -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)

13
tools/testing/selftests/seccomp/seccomp_bpf.c
View File

@ -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;
}