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Enforce seccomp syscall restrictions when kernel support exists.

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This commit is contained in:
Nicholas J. Kain
2012-07-20 07:05:56 -04:00
parent e990246207
commit f4f9d02afd
2 changed files with 132 additions and 3 deletions
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81
ncmlib/seccomp-bpf.h Normal file
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/*
* seccomp example for x86 (32-bit and 64-bit) with BPF macros
*
* Copyright (c) 2012 The Chromium OS Authors <chromium-os-dev@chromium.org>
* Authors:
* Will Drewry <wad@chromium.org>
* Kees Cook <keescook@chromium.org>
*
* The code may be used by anyone for any purpose, and can serve as a
* starting point for developing applications using mode 2 seccomp.
*/
#ifndef _SECCOMP_BPF_H_
#define _SECCOMP_BPF_H_
#define _GNU_SOURCE 1
#include <stdio.h>
#include <stddef.h>
#include <stdlib.h>
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>
#include <sys/prctl.h>
#ifndef PR_SET_NO_NEW_PRIVS
# define PR_SET_NO_NEW_PRIVS 38
#endif
#include <linux/unistd.h>
#include <linux/audit.h>
#include <linux/filter.h>
#ifdef HAVE_LINUX_SECCOMP_H
# include <linux/seccomp.h>
#endif
#ifndef SECCOMP_MODE_FILTER
# define SECCOMP_MODE_FILTER 2 /* uses user-supplied filter. */
# define SECCOMP_RET_KILL 0x00000000U /* kill the task immediately */
# define SECCOMP_RET_TRAP 0x00030000U /* disallow and force a SIGSYS */
# define SECCOMP_RET_ALLOW 0x7fff0000U /* allow */
struct seccomp_data {
int nr;
__u32 arch;
__u64 instruction_pointer;
__u64 args[6];
};
#endif
#ifndef SYS_SECCOMP
# define SYS_SECCOMP 1
#endif
#define syscall_nr (offsetof(struct seccomp_data, nr))
#define arch_nr (offsetof(struct seccomp_data, arch))
#if defined(__i386__)
# define REG_SYSCALL REG_EAX
# define ARCH_NR AUDIT_ARCH_I386
#elif defined(__x86_64__)
# define REG_SYSCALL REG_RAX
# define ARCH_NR AUDIT_ARCH_X86_64
#else
# warning "Platform does not support seccomp filter yet"
# define REG_SYSCALL 0
# define ARCH_NR 0
#endif
#define VALIDATE_ARCHITECTURE \
BPF_STMT(BPF_LD+BPF_W+BPF_ABS, arch_nr), \
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, ARCH_NR, 1, 0), \
BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_KILL)
#define EXAMINE_SYSCALL \
BPF_STMT(BPF_LD+BPF_W+BPF_ABS, syscall_nr)
#define ALLOW_SYSCALL(name) \
BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, __NR_##name, 0, 1), \
BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_ALLOW)
#define KILL_PROCESS \
BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_KILL)
#endif /* _SECCOMP_BPF_H_ */