Update from chromium 62675d9fb31fb8cedc40f68e78e8445a74f362e7

sandbox/linux/seccomp-bpf/syscall.h

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_H__
+#define SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_H__
+
+#include <signal.h>
+#include <stdint.h>
+
+#include "base/macros.h"
+#include "sandbox/sandbox_export.h"
+
+// Android's signal.h doesn't define ucontext etc.
+#if defined(OS_ANDROID)
+#include "sandbox/linux/services/android_ucontext.h"
+#endif
+
+namespace sandbox {
+
+// This purely static class can be used to perform system calls with some
+// low-level control.
+class SANDBOX_EXPORT Syscall {
+ public:
+  // InvalidCall() invokes Call() with a platform-appropriate syscall
+  // number that is guaranteed to not be implemented (i.e., normally
+  // returns -ENOSYS).
+  // This is primarily meant to be useful for writing sandbox policy
+  // unit tests.
+  static intptr_t InvalidCall();
+
+  // System calls can take up to six parameters (up to eight on some
+  // architectures). Traditionally, glibc
+  // implements this property by using variadic argument lists. This works, but
+  // confuses modern tools such as valgrind, because we are nominally passing
+  // uninitialized data whenever we call through this function and pass less
+  // than the full six arguments.
+  // So, instead, we use C++'s template system to achieve a very similar
+  // effect. C++ automatically sets the unused parameters to zero for us, and
+  // it also does the correct type expansion (e.g. from 32bit to 64bit) where
+  // necessary.
+  // We have to use C-style cast operators as we want to be able to accept both
+  // integer and pointer types.
+  template <class T0,
+            class T1,
+            class T2,
+            class T3,
+            class T4,
+            class T5,
+            class T6,
+            class T7>
+  static inline intptr_t
+  Call(int nr, T0 p0, T1 p1, T2 p2, T3 p3, T4 p4, T5 p5, T6 p6, T7 p7) {
+    return Call(nr,
+                (intptr_t)p0,
+                (intptr_t)p1,
+                (intptr_t)p2,
+                (intptr_t)p3,
+                (intptr_t)p4,
+                (intptr_t)p5,
+                (intptr_t)p6,
+                (intptr_t)p7);
+  }
+
+  template <class T0,
+            class T1,
+            class T2,
+            class T3,
+            class T4,
+            class T5,
+            class T6>
+  static inline intptr_t
+  Call(int nr, T0 p0, T1 p1, T2 p2, T3 p3, T4 p4, T5 p5, T6 p6) {
+    return Call(nr,
+                (intptr_t)p0,
+                (intptr_t)p1,
+                (intptr_t)p2,
+                (intptr_t)p3,
+                (intptr_t)p4,
+                (intptr_t)p5,
+                (intptr_t)p6,
+                0);
+  }
+
+  template <class T0, class T1, class T2, class T3, class T4, class T5>
+  static inline intptr_t
+  Call(int nr, T0 p0, T1 p1, T2 p2, T3 p3, T4 p4, T5 p5) {
+    return Call(nr,
+                (intptr_t)p0,
+                (intptr_t)p1,
+                (intptr_t)p2,
+                (intptr_t)p3,
+                (intptr_t)p4,
+                (intptr_t)p5,
+                0,
+                0);
+  }
+
+  template <class T0, class T1, class T2, class T3, class T4>
+  static inline intptr_t Call(int nr, T0 p0, T1 p1, T2 p2, T3 p3, T4 p4) {
+    return Call(nr, p0, p1, p2, p3, p4, 0, 0, 0);
+  }
+
+  template <class T0, class T1, class T2, class T3>
+  static inline intptr_t Call(int nr, T0 p0, T1 p1, T2 p2, T3 p3) {
+    return Call(nr, p0, p1, p2, p3, 0, 0, 0, 0);
+  }
+
+  template <class T0, class T1, class T2>
+  static inline intptr_t Call(int nr, T0 p0, T1 p1, T2 p2) {
+    return Call(nr, p0, p1, p2, 0, 0, 0, 0, 0);
+  }
+
+  template <class T0, class T1>
+  static inline intptr_t Call(int nr, T0 p0, T1 p1) {
+    return Call(nr, p0, p1, 0, 0, 0, 0, 0, 0);
+  }
+
+  template <class T0>
+  static inline intptr_t Call(int nr, T0 p0) {
+    return Call(nr, p0, 0, 0, 0, 0, 0, 0, 0);
+  }
+
+  static inline intptr_t Call(int nr) {
+    return Call(nr, 0, 0, 0, 0, 0, 0, 0, 0);
+  }
+
+  // Set the registers in |ctx| to match what they would be after a system call
+  // returning |ret_val|. |ret_val| must follow the Syscall::Call() convention
+  // of being -errno on errors.
+  static void PutValueInUcontext(intptr_t ret_val, ucontext_t* ctx);
+
+ private:
+  // This performs system call |nr| with the arguments p0 to p7 from a constant
+  // userland address, which is for instance observable by seccomp-bpf filters.
+  // The constant userland address from which these system calls are made will
+  // be returned if |nr| is passed as -1.
+  // On error, this function will return a value between -1 and -4095 which
+  // should be interpreted as -errno.
+  static intptr_t Call(int nr,
+                       intptr_t p0,
+                       intptr_t p1,
+                       intptr_t p2,
+                       intptr_t p3,
+                       intptr_t p4,
+                       intptr_t p5,
+                       intptr_t p6,
+                       intptr_t p7);
+
+#if defined(__mips__)
+  // This function basically does on MIPS what SandboxSyscall() is doing on
+  // other architectures. However, because of specificity of MIPS regarding
+  // handling syscall errors, SandboxSyscall() is made as a wrapper for this
+  // function in order for SandboxSyscall() to behave more like on other
+  // architectures on places where return value from SandboxSyscall() is used
+  // directly (like in most tests).
+  // The syscall "nr" is called with arguments that are set in an array on which
+  // pointer "args" points to and an information weather there is an error or no
+  // is returned to SandboxSyscall() by err_stat.
+  static intptr_t SandboxSyscallRaw(int nr,
+                                    const intptr_t* args,
+                                    intptr_t* err_stat);
+#endif  // defined(__mips__)
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(Syscall);
+};
+
+}  // namespace sandbox
+
+#endif  // SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_H__