[S390] secure computing arch backend

Enable secure computing on s390 as well.

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

6 files changed, 51 insertions, 9 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 2eca5fe0e75b..1094787e97e5 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -567,6 +567,24 @@ bool "s390 guest support for KVM (EXPERIMENTAL)"
           the KVM hypervisor. This will add detection for KVM as well  as a
           virtio transport. If KVM is detected, the virtio console will be
           the default console.
+
+config SECCOMP
+        bool "Enable seccomp to safely compute untrusted bytecode"
+        depends on PROC_FS
+        default y
+        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 /proc/<pid>/seccomp, it cannot be disabled
+          and the task is only allowed to execute a few safe syscalls
+          defined by each seccomp mode.
+
+          If unsure, say Y.
+
 endmenu
 
 source "net/Kconfig"
diff --git a/arch/s390/include/asm/seccomp.h b/arch/s390/include/asm/seccomp.h
new file mode 100644
index 000000000000..781a9cf9b002
--- /dev/null
+++ b/arch/s390/include/asm/seccomp.h
@@ -0,0 +1,16 @@
+#ifndef _ASM_S390_SECCOMP_H
+#define _ASM_S390_SECCOMP_H
+
+#include <linux/unistd.h>
+
+#define __NR_seccomp_read       __NR_read
+#define __NR_seccomp_write      __NR_write
+#define __NR_seccomp_exit       __NR_exit
+#define __NR_seccomp_sigreturn  __NR_sigreturn
+
+#define __NR_seccomp_read_32    __NR_read
+#define __NR_seccomp_write_32   __NR_write
+#define __NR_seccomp_exit_32    __NR_exit
+#define __NR_seccomp_sigreturn_32 __NR_sigreturn
+
+#endif  /* _ASM_S390_SECCOMP_H */
diff --git a/arch/s390/include/asm/thread_info.h b/arch/s390/include/asm/thread_info.h
index 461f2abd2e6f..2f86653dda69 100644
--- a/arch/s390/include/asm/thread_info.h
+++ b/arch/s390/include/asm/thread_info.h
@@ -83,14 +83,15 @@ static inline struct thread_info *current_thread_info(void)
 /*
  * thread information flags bit numbers
  */
-#define TIF_SYSCALL_TRACE       0       /* syscall trace active */
 #define TIF_NOTIFY_RESUME       1       /* callback before returning to user */
 #define TIF_SIGPENDING          2       /* signal pending */
 #define TIF_NEED_RESCHED        3       /* rescheduling necessary */
 #define TIF_RESTART_SVC         4       /* restart svc with new svc number */
-#define TIF_SYSCALL_AUDIT       5       /* syscall auditing active */
 #define TIF_SINGLE_STEP         6       /* deliver sigtrap on return to user */
 #define TIF_MCCK_PENDING        7       /* machine check handling is pending */
+#define TIF_SYSCALL_TRACE       8       /* syscall trace active */
+#define TIF_SYSCALL_AUDIT       9       /* syscall auditing active */
+#define TIF_SECCOMP             10      /* secure computing */
 #define TIF_USEDFPU             16      /* FPU was used by this task this quantum (SMP) */
 #define TIF_POLLING_NRFLAG      17      /* true if poll_idle() is polling 
                                            TIF_NEED_RESCHED */
@@ -99,15 +100,16 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_RESTORE_SIGMASK     20      /* restore signal mask in do_signal() */
 #define TIF_FREEZE              21      /* thread is freezing for suspend */
 
-#define _TIF_SYSCALL_TRACE      (1<<TIF_SYSCALL_TRACE)
 #define _TIF_NOTIFY_RESUME      (1<<TIF_NOTIFY_RESUME)
 #define _TIF_RESTORE_SIGMASK    (1<<TIF_RESTORE_SIGMASK)
 #define _TIF_SIGPENDING         (1<<TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED       (1<<TIF_NEED_RESCHED)
 #define _TIF_RESTART_SVC        (1<<TIF_RESTART_SVC)
-#define _TIF_SYSCALL_AUDIT      (1<<TIF_SYSCALL_AUDIT)
 #define _TIF_SINGLE_STEP        (1<<TIF_SINGLE_STEP)
 #define _TIF_MCCK_PENDING       (1<<TIF_MCCK_PENDING)
+#define _TIF_SYSCALL_TRACE      (1<<TIF_SYSCALL_TRACE)
+#define _TIF_SYSCALL_AUDIT      (1<<TIF_SYSCALL_AUDIT)
+#define _TIF_SECCOMP            (1<<TIF_SECCOMP)
 #define _TIF_USEDFPU            (1<<TIF_USEDFPU)
 #define _TIF_POLLING_NRFLAG     (1<<TIF_POLLING_NRFLAG)
 #define _TIF_31BIT              (1<<TIF_31BIT)
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index f3e275934213..db25cdc21e12 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -53,6 +53,7 @@ _TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
                  _TIF_MCCK_PENDING | _TIF_RESTART_SVC | _TIF_SINGLE_STEP )
 _TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
                  _TIF_MCCK_PENDING)
+_TIF_SYSCALL = (_TIF_SYSCALL_TRACE>>8 | _TIF_SYSCALL_AUDIT>>8 | _TIF_SECCOMP>>8)
 
 STACK_SHIFT = PAGE_SHIFT + THREAD_ORDER
 STACK_SIZE  = 1 << STACK_SHIFT
@@ -265,7 +266,7 @@ sysc_do_restart:
         sth     %r7,SP_SVCNR(%r15)
         sll     %r7,2             # svc number *4
         l       %r8,BASED(.Lsysc_table)
-        tm      __TI_flags+3(%r9),(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
+        tm      __TI_flags+2(%r9),_TIF_SYSCALL
         l       %r8,0(%r7,%r8)    # get system call addr.
         bnz     BASED(sysc_tracesys)
         basr    %r14,%r8          # call sys_xxxx
@@ -405,7 +406,7 @@ sysc_tracego:
         basr    %r14,%r8                # call sys_xxx
         st      %r2,SP_R2(%r15)         # store return value
 sysc_tracenogo:
-        tm      __TI_flags+3(%r9),(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
+        tm      __TI_flags+2(%r9),_TIF_SYSCALL
         bz      BASED(sysc_return)
         l       %r1,BASED(.Ltrace_exit)
         la      %r2,SP_PTREGS(%r15)     # load pt_regs
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 84a105838e03..3cec9b504f5f 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -56,6 +56,7 @@ _TIF_WORK_SVC = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
                  _TIF_MCCK_PENDING | _TIF_RESTART_SVC | _TIF_SINGLE_STEP )
 _TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
                  _TIF_MCCK_PENDING)
+_TIF_SYSCALL = (_TIF_SYSCALL_TRACE>>8 | _TIF_SYSCALL_AUDIT>>8 | _TIF_SECCOMP>>8)
 
 #define BASED(name) name-system_call(%r13)
 
@@ -260,7 +261,7 @@ sysc_do_restart:
         larl    %r10,sys_call_table_emu  # use 31 bit emulation system calls
 sysc_noemu:
 #endif
-        tm      __TI_flags+7(%r9),(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
+        tm      __TI_flags+6(%r9),_TIF_SYSCALL
         lgf     %r8,0(%r7,%r10) # load address of system call routine
         jnz     sysc_tracesys
         basr    %r14,%r8        # call sys_xxxx
@@ -391,7 +392,7 @@ sysc_tracego:
         basr    %r14,%r8                # call sys_xxx
         stg     %r2,SP_R2(%r15)         # store return value
 sysc_tracenogo:
-        tm      __TI_flags+7(%r9),(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)
+        tm      __TI_flags+6(%r9),_TIF_SYSCALL
         jz      sysc_return
         la      %r2,SP_PTREGS(%r15)     # load pt_regs
         larl    %r14,sysc_return        # return point is sysc_return
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index 99eef179e903..b6fc1ae2ffcb 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -36,7 +36,8 @@
 #include <linux/elf.h>
 #include <linux/regset.h>
 #include <linux/tracehook.h>
-#include <linux/compat.h>
+#include <linux/seccomp.h>
+#include <asm/compat.h>
 #include <asm/segment.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
@@ -640,6 +641,9 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
 {
         long ret;
 
+        /* Do the secure computing check first. */
+        secure_computing(regs->gprs[2]);
+
         /*
          * The sysc_tracesys code in entry.S stored the system
          * call number to gprs[2].