sh: seccomp support.

This hooks up the seccomp thread flag and associated callback from the
syscall tracer.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

5 files changed, 37 insertions, 2 deletions

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index cb992c3..0ae5411 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -483,6 +483,23 @@ config CRASH_DUMP
 
 	  For more details see Documentation/kdump/kdump.txt
 
+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 prctl, it cannot be disabled and the task is only
+	  allowed to execute a few safe syscalls defined by each seccomp
+	  mode.
+
+	  If unsure, say N.
+
 config SMP
 	bool "Symmetric multi-processing support"
 	depends on SYS_SUPPORTS_SMP
diff --git a/arch/sh/include/asm/seccomp.h b/arch/sh/include/asm/seccomp.h
new file mode 100644
index 0000000..3280ed3
--- /dev/null
+++ b/arch/sh/include/asm/seccomp.h
@@ -0,0 +1,10 @@
+#ifndef __ASM_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_rt_sigreturn
+
+#endif /* __ASM_SECCOMP_H */
diff --git a/arch/sh/include/asm/thread_info.h b/arch/sh/include/asm/thread_info.h
index c05b1af..03d1e38 100644
--- a/arch/sh/include/asm/thread_info.h
+++ b/arch/sh/include/asm/thread_info.h
@@ -117,7 +117,8 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_NEED_RESCHED	2	/* rescheduling necessary */
 #define TIF_RESTORE_SIGMASK	3	/* restore signal mask in do_signal() */
 #define TIF_SINGLESTEP		4	/* singlestepping active */
-#define TIF_SYSCALL_AUDIT	5
+#define TIF_SYSCALL_AUDIT	5	/* syscall auditing active */
+#define TIF_SECCOMP		6	/* 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 */
 #define TIF_MEMDIE		18
@@ -129,6 +130,7 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)
 #define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
 #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_FREEZE		(1 << TIF_FREEZE)
@@ -141,7 +143,7 @@ static inline struct thread_info *current_thread_info(void)
 
 /* work to do in syscall trace */
 #define _TIF_WORK_SYSCALL_MASK	(_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP | \
-				 _TIF_SYSCALL_AUDIT)
+				 _TIF_SYSCALL_AUDIT | _TIF_SECCOMP)
 
 /* work to do on any return to u-space */
 #define _TIF_ALLWORK_MASK	(_TIF_SYSCALL_TRACE | _TIF_SIGPENDING    | \
diff --git a/arch/sh/kernel/ptrace_32.c b/arch/sh/kernel/ptrace_32.c
index 2bc72de..e9bd4b2 100644
--- a/arch/sh/kernel/ptrace_32.c
+++ b/arch/sh/kernel/ptrace_32.c
@@ -20,6 +20,7 @@
 #include <linux/signal.h>
 #include <linux/io.h>
 #include <linux/audit.h>
+#include <linux/seccomp.h>
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
 #include <asm/system.h>
@@ -276,6 +277,8 @@ asmlinkage void do_syscall_trace(struct pt_regs *regs, int entryexit)
 {
 	struct task_struct *tsk = current;
 
+	secure_computing(regs->regs[0]);
+
 	if (unlikely(current->audit_context) && entryexit)
 		audit_syscall_exit(AUDITSC_RESULT(regs->regs[0]),
 				   regs->regs[0]);
diff --git a/arch/sh/kernel/ptrace_64.c b/arch/sh/kernel/ptrace_64.c
index d453c47..7d87762 100644
--- a/arch/sh/kernel/ptrace_64.c
+++ b/arch/sh/kernel/ptrace_64.c
@@ -27,6 +27,7 @@
 #include <linux/signal.h>
 #include <linux/syscalls.h>
 #include <linux/audit.h>
+#include <linux/seccomp.h>
 #include <asm/io.h>
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -277,6 +278,8 @@ asmlinkage void syscall_trace(struct pt_regs *regs, int entryexit)
 {
 	struct task_struct *tsk = current;
 
+	secure_computing(regs->regs[9]);
+
 	if (unlikely(current->audit_context) && entryexit)
 		audit_syscall_exit(AUDITSC_RESULT(regs->regs[9]),
 				   regs->regs[9]);