s390/seccomp: add support for system call filtering using BPF

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 17 insertions, 1 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 76de6b68487c..107610e01a29 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -124,6 +124,7 @@ config S390
         select GENERIC_TIME_VSYSCALL
         select GENERIC_CLOCKEVENTS
         select KTIME_SCALAR if 32BIT
+        select HAVE_ARCH_SECCOMP_FILTER
 
 config SCHED_OMIT_FRAME_POINTER
         def_bool y
diff --git a/arch/s390/include/asm/syscall.h b/arch/s390/include/asm/syscall.h
index fb214dd9b7e0..fe7b99759e12 100644
--- a/arch/s390/include/asm/syscall.h
+++ b/arch/s390/include/asm/syscall.h
@@ -12,6 +12,7 @@
 #ifndef _ASM_SYSCALL_H
 #define _ASM_SYSCALL_H  1
 
+#include <linux/audit.h>
 #include <linux/sched.h>
 #include <linux/err.h>
 #include <asm/ptrace.h>
@@ -87,4 +88,13 @@ static inline void syscall_set_arguments(struct task_struct *task,
                 regs->orig_gpr2 = args[0];
 }
 
+static inline int syscall_get_arch(struct task_struct *task,
+                                   struct pt_regs *regs)
+{
+#ifdef CONFIG_COMPAT
+        if (test_tsk_thread_flag(task, TIF_31BIT))
+                return AUDIT_ARCH_S390;
+#endif
+        return sizeof(long) == 8 ? AUDIT_ARCH_S390X : AUDIT_ARCH_S390;
+}
 #endif  /* _ASM_SYSCALL_H */
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index f4eb37680b91..e4be113fbac6 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -719,7 +719,11 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
         long ret = 0;
 
         /* Do the secure computing check first. */
-        secure_computing_strict(regs->gprs[2]);
+        if (secure_computing(regs->gprs[2])) {
+                /* seccomp failures shouldn't expose any additional code. */
+                ret = -1;
+                goto out;
+        }
 
         /*
          * The sysc_tracesys code in entry.S stored the system
@@ -745,6 +749,7 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
                             regs->gprs[2], regs->orig_gpr2,
                             regs->gprs[3], regs->gprs[4],
                             regs->gprs[5]);
+out:
         return ret ?: regs->gprs[2];
 }