parisc: Wire up seccomp, getrandom and memfd_create syscalls

With secure computing we only support the SECCOMP_MODE_STRICT mode for
now.

Signed-off-by: Helge Deller <deller@gmx.de>

6 files changed, 49 insertions, 2 deletions

diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 6e75e2030927..1554a6f2a5bb 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -321,6 +321,22 @@ source "fs/Kconfig"
 
 source "arch/parisc/Kconfig.debug"
 
+config SECCOMP
+        def_bool y
+        prompt "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.
+
+          If unsure, say Y. Only embedded should say N here.
+
 source "security/Kconfig"
 
 source "crypto/Kconfig"
diff --git a/arch/parisc/include/asm/seccomp.h b/arch/parisc/include/asm/seccomp.h
new file mode 100644
index 000000000000..015f7887aa29
--- /dev/null
+++ b/arch/parisc/include/asm/seccomp.h
@@ -0,0 +1,16 @@
+#ifndef _ASM_PARISC_SECCOMP_H
+#define _ASM_PARISC_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
+
+#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_rt_sigreturn
+
+#endif  /* _ASM_PARISC_SECCOMP_H */
diff --git a/arch/parisc/include/asm/thread_info.h b/arch/parisc/include/asm/thread_info.h
index 4b9b10ce1f9d..a84611835549 100644
--- a/arch/parisc/include/asm/thread_info.h
+++ b/arch/parisc/include/asm/thread_info.h
@@ -60,6 +60,7 @@ struct thread_info {
 #define TIF_NOTIFY_RESUME       8       /* callback before returning to user */
 #define TIF_SINGLESTEP          9       /* single stepping? */
 #define TIF_BLOCKSTEP           10      /* branch stepping? */
+#define TIF_SECCOMP             11      /* secure computing */
 
 #define _TIF_SYSCALL_TRACE      (1 << TIF_SYSCALL_TRACE)
 #define _TIF_SIGPENDING         (1 << TIF_SIGPENDING)
@@ -70,11 +71,13 @@ struct thread_info {
 #define _TIF_NOTIFY_RESUME      (1 << TIF_NOTIFY_RESUME)
 #define _TIF_SINGLESTEP         (1 << TIF_SINGLESTEP)
 #define _TIF_BLOCKSTEP          (1 << TIF_BLOCKSTEP)
+#define _TIF_SECCOMP            (1 << TIF_SECCOMP)
 
 #define _TIF_USER_WORK_MASK     (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | \
                                  _TIF_NEED_RESCHED)
 #define _TIF_SYSCALL_TRACE_MASK (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP | \
-                                 _TIF_BLOCKSTEP | _TIF_SYSCALL_AUDIT)
+                                 _TIF_BLOCKSTEP | _TIF_SYSCALL_AUDIT | \
+                                 _TIF_SECCOMP)
 
 #ifdef CONFIG_64BIT
 # ifdef CONFIG_COMPAT
diff --git a/arch/parisc/include/uapi/asm/unistd.h b/arch/parisc/include/uapi/asm/unistd.h
index 47e0e21d2272..8667f18be238 100644
--- a/arch/parisc/include/uapi/asm/unistd.h
+++ b/arch/parisc/include/uapi/asm/unistd.h
@@ -830,8 +830,11 @@
 #define __NR_sched_getattr      (__NR_Linux + 335)
 #define __NR_utimes             (__NR_Linux + 336)
 #define __NR_renameat2          (__NR_Linux + 337)
+#define __NR_seccomp            (__NR_Linux + 338)
+#define __NR_getrandom          (__NR_Linux + 339)
+#define __NR_memfd_create       (__NR_Linux + 340)
 
-#define __NR_Linux_syscalls     (__NR_renameat2 + 1)
+#define __NR_Linux_syscalls     (__NR_memfd_create + 1)
 
 
 #define __IGNORE_select         /* newselect */
diff --git a/arch/parisc/kernel/ptrace.c b/arch/parisc/kernel/ptrace.c
index e842ee233db4..3bab72462ab5 100644
--- a/arch/parisc/kernel/ptrace.c
+++ b/arch/parisc/kernel/ptrace.c
@@ -270,6 +270,12 @@ long do_syscall_trace_enter(struct pt_regs *regs)
 {
         long ret = 0;
 
+        /* Do the secure computing check first. */
+        if (secure_computing(regs->gr[20])) {
+                /* seccomp failures shouldn't expose any additional code. */
+                return -1;
+        }
+
         if (test_thread_flag(TIF_SYSCALL_TRACE) &&
             tracehook_report_syscall_entry(regs))
                 ret = -1L;
diff --git a/arch/parisc/kernel/syscall_table.S b/arch/parisc/kernel/syscall_table.S
index 84c5d3a58fa1..b563d9c8268b 100644
--- a/arch/parisc/kernel/syscall_table.S
+++ b/arch/parisc/kernel/syscall_table.S
@@ -433,6 +433,9 @@
         ENTRY_SAME(sched_getattr)       /* 335 */
         ENTRY_COMP(utimes)
         ENTRY_SAME(renameat2)
+        ENTRY_SAME(seccomp)
+        ENTRY_SAME(getrandom)
+        ENTRY_SAME(memfd_create)        /* 340 */
 
         /* Nothing yet */