SECCOMP-BPF: Refactor the BPF sandbox API to use fewer "static" fields and methods.

sandbox/linux/seccomp-bpf/linux_seccomp.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_LINUX_SECCOMP_H__
+#define SANDBOX_LINUX_SECCOMP_BPF_LINUX_SECCOMP_H__
+
+// The Seccomp2 kernel ABI is not part of older versions of glibc.
+// As we can't break compilation with these versions of the library,
+// we explicitly define all missing symbols.
+// If we ever decide that we can now rely on system headers, the following
+// include files should be enabled:
+// #include <linux/audit.h>
+// #include <linux/seccomp.h>
+
+#include <asm/unistd.h>
+#include <linux/filter.h>
+
+// For audit.h
+#ifndef EM_ARM
+#define EM_ARM    40
+#endif
+#ifndef EM_386
+#define EM_386    3
+#endif
+#ifndef EM_X86_64
+#define EM_X86_64 62
+#endif
+
+#ifndef __AUDIT_ARCH_64BIT
+#define __AUDIT_ARCH_64BIT 0x80000000
+#endif
+#ifndef __AUDIT_ARCH_LE
+#define __AUDIT_ARCH_LE    0x40000000
+#endif
+#ifndef AUDIT_ARCH_ARM
+#define AUDIT_ARCH_ARM    (EM_ARM|__AUDIT_ARCH_LE)
+#endif
+#ifndef AUDIT_ARCH_I386
+#define AUDIT_ARCH_I386   (EM_386|__AUDIT_ARCH_LE)
+#endif
+#ifndef AUDIT_ARCH_X86_64
+#define AUDIT_ARCH_X86_64 (EM_X86_64|__AUDIT_ARCH_64BIT|__AUDIT_ARCH_LE)
+#endif
+
+// For prctl.h
+#ifndef PR_SET_SECCOMP
+#define PR_SET_SECCOMP               22
+#define PR_GET_SECCOMP               21
+#endif
+#ifndef PR_SET_NO_NEW_PRIVS
+#define PR_SET_NO_NEW_PRIVS          38
+#define PR_GET_NO_NEW_PRIVS          39
+#endif
+#ifndef IPC_64
+#define IPC_64                   0x0100
+#endif
+
+#ifndef BPF_MOD
+#define BPF_MOD                    0x90
+#endif
+#ifndef BPF_XOR
+#define BPF_XOR                    0xA0
+#endif
+
+// In order to build will older tool chains, we currently have to avoid
+// including <linux/seccomp.h>. Until that can be fixed (if ever). Rely on
+// our own definitions of the seccomp kernel ABI.
+#ifndef SECCOMP_MODE_FILTER
+#define SECCOMP_MODE_DISABLED         0
+#define SECCOMP_MODE_STRICT           1
+#define SECCOMP_MODE_FILTER           2  // User user-supplied filter
+#endif
+
+#ifndef SECCOMP_RET_KILL
+// Return values supported for BPF filter programs. Please note that the
+// "illegal" SECCOMP_RET_INVALID is not supported by the kernel, should only
+// ever be used internally, and would result in the kernel killing our process.
+#define SECCOMP_RET_KILL    0x00000000U  // Kill the task immediately
+#define SECCOMP_RET_INVALID 0x00010000U  // Illegal return value
+#define SECCOMP_RET_TRAP    0x00030000U  // Disallow and force a SIGSYS
+#define SECCOMP_RET_ERRNO   0x00050000U  // Returns an errno
+#define SECCOMP_RET_TRACE   0x7ff00000U  // Pass to a tracer or disallow
+#define SECCOMP_RET_ALLOW   0x7fff0000U  // Allow
+#define SECCOMP_RET_ACTION  0xffff0000U  // Masks for the return value
+#define SECCOMP_RET_DATA    0x0000ffffU  //   sections
+#else
+#define SECCOMP_RET_INVALID 0x00010000U  // Illegal return value
+#endif
+
+#ifndef SYS_SECCOMP
+#define SYS_SECCOMP                   1
+#endif
+
+// Impose some reasonable maximum BPF program size. Realistically, the
+// kernel probably has much lower limits. But by limiting to less than
+// 30 bits, we can ease requirements on some of our data types.
+#define SECCOMP_MAX_PROGRAM_SIZE (1<<30)
+
+#if defined(__i386__)
+#define MIN_SYSCALL         0u
+#define MAX_PUBLIC_SYSCALL  1024u
+#define MAX_SYSCALL         MAX_PUBLIC_SYSCALL
+#define SECCOMP_ARCH        AUDIT_ARCH_I386
+
+#define SECCOMP_REG(_ctx, _reg) ((_ctx)->uc_mcontext.gregs[(_reg)])
+#define SECCOMP_RESULT(_ctx)    SECCOMP_REG(_ctx, REG_EAX)
+#define SECCOMP_SYSCALL(_ctx)   SECCOMP_REG(_ctx, REG_EAX)
+#define SECCOMP_IP(_ctx)        SECCOMP_REG(_ctx, REG_EIP)
+#define SECCOMP_PARM1(_ctx)     SECCOMP_REG(_ctx, REG_EBX)
+#define SECCOMP_PARM2(_ctx)     SECCOMP_REG(_ctx, REG_ECX)
+#define SECCOMP_PARM3(_ctx)     SECCOMP_REG(_ctx, REG_EDX)
+#define SECCOMP_PARM4(_ctx)     SECCOMP_REG(_ctx, REG_ESI)
+#define SECCOMP_PARM5(_ctx)     SECCOMP_REG(_ctx, REG_EDI)
+#define SECCOMP_PARM6(_ctx)     SECCOMP_REG(_ctx, REG_EBP)
+#define SECCOMP_NR_IDX          (offsetof(struct arch_seccomp_data, nr))
+#define SECCOMP_ARCH_IDX        (offsetof(struct arch_seccomp_data, arch))
+#define SECCOMP_IP_MSB_IDX      (offsetof(struct arch_seccomp_data,           \
+                                          instruction_pointer) + 4)
+#define SECCOMP_IP_LSB_IDX      (offsetof(struct arch_seccomp_data,           \
+                                          instruction_pointer) + 0)
+#define SECCOMP_ARG_MSB_IDX(nr) (offsetof(struct arch_seccomp_data, args) +   \
+                                 8*(nr) + 4)
+#define SECCOMP_ARG_LSB_IDX(nr) (offsetof(struct arch_seccomp_data, args) +   \
+                                 8*(nr) + 0)
+
+#elif defined(__x86_64__)
+#define MIN_SYSCALL         0u
+#define MAX_PUBLIC_SYSCALL  1024u
+#define MAX_SYSCALL         MAX_PUBLIC_SYSCALL
+#define SECCOMP_ARCH        AUDIT_ARCH_X86_64
+
+#define SECCOMP_REG(_ctx, _reg) ((_ctx)->uc_mcontext.gregs[(_reg)])
+#define SECCOMP_RESULT(_ctx)    SECCOMP_REG(_ctx, REG_RAX)
+#define SECCOMP_SYSCALL(_ctx)   SECCOMP_REG(_ctx, REG_RAX)
+#define SECCOMP_IP(_ctx)        SECCOMP_REG(_ctx, REG_RIP)
+#define SECCOMP_PARM1(_ctx)     SECCOMP_REG(_ctx, REG_RDI)
+#define SECCOMP_PARM2(_ctx)     SECCOMP_REG(_ctx, REG_RSI)
+#define SECCOMP_PARM3(_ctx)     SECCOMP_REG(_ctx, REG_RDX)
+#define SECCOMP_PARM4(_ctx)     SECCOMP_REG(_ctx, REG_R10)
+#define SECCOMP_PARM5(_ctx)     SECCOMP_REG(_ctx, REG_R8)
+#define SECCOMP_PARM6(_ctx)     SECCOMP_REG(_ctx, REG_R9)
+#define SECCOMP_NR_IDX          (offsetof(struct arch_seccomp_data, nr))
+#define SECCOMP_ARCH_IDX        (offsetof(struct arch_seccomp_data, arch))
+#define SECCOMP_IP_MSB_IDX      (offsetof(struct arch_seccomp_data,           \
+                                          instruction_pointer) + 4)
+#define SECCOMP_IP_LSB_IDX      (offsetof(struct arch_seccomp_data,           \
+                                          instruction_pointer) + 0)
+#define SECCOMP_ARG_MSB_IDX(nr) (offsetof(struct arch_seccomp_data, args) +   \
+                                 8*(nr) + 4)
+#define SECCOMP_ARG_LSB_IDX(nr) (offsetof(struct arch_seccomp_data, args) +   \
+                                 8*(nr) + 0)
+
+#elif defined(__arm__) && (defined(__thumb__) || defined(__ARM_EABI__))
+// ARM EABI includes "ARM private" system calls starting at |__ARM_NR_BASE|,
+// and a "ghost syscall private to the kernel", cmpxchg,
+// at |__ARM_NR_BASE+0x00fff0|.
+// See </arch/arm/include/asm/unistd.h> in the Linux kernel.
+#define MIN_SYSCALL         ((unsigned int)__NR_SYSCALL_BASE)
+#define MAX_PUBLIC_SYSCALL  (MIN_SYSCALL + 1024u)
+#define MIN_PRIVATE_SYSCALL ((unsigned int)__ARM_NR_BASE)
+#define MAX_PRIVATE_SYSCALL (MIN_PRIVATE_SYSCALL + 16u)
+#define MIN_GHOST_SYSCALL   ((unsigned int)__ARM_NR_BASE + 0xfff0u)
+#define MAX_SYSCALL         (MIN_GHOST_SYSCALL + 4u)
+
+#define SECCOMP_ARCH AUDIT_ARCH_ARM
+
+// ARM sigcontext_t is different from i386/x86_64.
+// See </arch/arm/include/asm/sigcontext.h> in the Linux kernel.
+#define SECCOMP_REG(_ctx, _reg) ((_ctx)->uc_mcontext.arm_##_reg)
+// ARM EABI syscall convention.
+#define SECCOMP_RESULT(_ctx)    SECCOMP_REG(_ctx, r0)
+#define SECCOMP_SYSCALL(_ctx)   SECCOMP_REG(_ctx, r7)
+#define SECCOMP_IP(_ctx)        SECCOMP_REG(_ctx, pc)
+#define SECCOMP_PARM1(_ctx)     SECCOMP_REG(_ctx, r0)
+#define SECCOMP_PARM2(_ctx)     SECCOMP_REG(_ctx, r1)
+#define SECCOMP_PARM3(_ctx)     SECCOMP_REG(_ctx, r2)
+#define SECCOMP_PARM4(_ctx)     SECCOMP_REG(_ctx, r3)
+#define SECCOMP_PARM5(_ctx)     SECCOMP_REG(_ctx, r4)
+#define SECCOMP_PARM6(_ctx)     SECCOMP_REG(_ctx, r5)
+#define SECCOMP_NR_IDX          (offsetof(struct arch_seccomp_data, nr))
+#define SECCOMP_ARCH_IDX        (offsetof(struct arch_seccomp_data, arch))
+#define SECCOMP_IP_MSB_IDX      (offsetof(struct arch_seccomp_data,           \
+                                          instruction_pointer) + 4)
+#define SECCOMP_IP_LSB_IDX      (offsetof(struct arch_seccomp_data,           \
+                                          instruction_pointer) + 0)
+#define SECCOMP_ARG_MSB_IDX(nr) (offsetof(struct arch_seccomp_data, args) +   \
+                                 8*(nr) + 4)
+#define SECCOMP_ARG_LSB_IDX(nr) (offsetof(struct arch_seccomp_data, args) +   \
+                                 8*(nr) + 0)
+
+#else
+#error Unsupported target platform
+
+#endif
+
+#endif  // SANDBOX_LINUX_SECCOMP_BPF_LINUX_SECCOMP_H__