2019-04-29 21:25:05 +00:00
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// Copyright 2018 The gVisor Authors.
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2018-04-27 17:37:02 +00:00
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package seccomp
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import (
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"syscall"
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"unsafe"
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2019-06-13 23:49:09 +00:00
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"gvisor.dev/gvisor/pkg/abi/linux"
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2018-04-27 17:37:02 +00:00
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)
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// sockFprog is sock_fprog taken from <linux/filter.h>.
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type sockFprog struct {
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Len uint16
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pad [6]byte
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Filter *linux.BPFInstruction
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}
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2018-10-11 05:39:32 +00:00
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// SetFilter installs the given BPF program.
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//
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// This is safe to call from an afterFork context.
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//
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//go:nosplit
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func SetFilter(instrs []linux.BPFInstruction) syscall.Errno {
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2018-04-27 17:37:02 +00:00
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// PR_SET_NO_NEW_PRIVS is required in order to enable seccomp. See seccomp(2) for details.
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2019-09-25 06:46:08 +00:00
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if _, _, errno := syscall.RawSyscall6(syscall.SYS_PRCTL, linux.PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0, 0); errno != 0 {
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2018-10-11 05:39:32 +00:00
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return errno
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2018-04-27 17:37:02 +00:00
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}
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2018-10-11 05:39:32 +00:00
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sockProg := sockFprog{
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Len: uint16(len(instrs)),
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Filter: (*linux.BPFInstruction)(unsafe.Pointer(&instrs[0])),
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2018-04-27 17:37:02 +00:00
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}
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2018-11-21 06:55:41 +00:00
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return seccomp(linux.SECCOMP_SET_MODE_FILTER, linux.SECCOMP_FILTER_FLAG_TSYNC, unsafe.Pointer(&sockProg))
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}
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func isKillProcessAvailable() (bool, error) {
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action := uint32(linux.SECCOMP_RET_KILL_PROCESS)
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if errno := seccomp(linux.SECCOMP_GET_ACTION_AVAIL, 0, unsafe.Pointer(&action)); errno != 0 {
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// EINVAL: SECCOMP_GET_ACTION_AVAIL not in this kernel yet.
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// EOPNOTSUPP: SECCOMP_RET_KILL_PROCESS not supported.
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if errno == syscall.EINVAL || errno == syscall.EOPNOTSUPP {
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return false, nil
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}
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return false, errno
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2018-10-11 05:39:32 +00:00
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}
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2018-11-21 06:55:41 +00:00
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return true, nil
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}
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2018-10-11 05:39:32 +00:00
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2018-11-21 06:55:41 +00:00
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// seccomp calls seccomp(2). This is safe to call from an afterFork context.
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//
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//go:nosplit
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func seccomp(op, flags uint32, ptr unsafe.Pointer) syscall.Errno {
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if _, _, errno := syscall.RawSyscall(SYS_SECCOMP, uintptr(op), uintptr(flags), uintptr(ptr)); errno != 0 {
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return errno
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}
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2018-10-11 05:39:32 +00:00
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return 0
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2018-04-27 17:37:02 +00:00
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}
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