Merge release-20200907.0-56-gdcd532e2e (automated)

6 files changed, 292 insertions, 0 deletions

diff --git a/runsc/specutils/seccomp/audit_amd64.go b/runsc/specutils/seccomp/audit_amd64.go
new file mode 100644
index 000000000..417cf4a7a
--- /dev/null
+++ b/runsc/specutils/seccomp/audit_amd64.go
@@ -0,0 +1,25 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build amd64
+
+package seccomp
+
+import (
+	"gvisor.dev/gvisor/pkg/abi/linux"
+)
+
+const (
+	nativeArchAuditNo = linux.AUDIT_ARCH_X86_64
+)
diff --git a/runsc/specutils/seccomp/audit_arm64.go b/runsc/specutils/seccomp/audit_arm64.go
new file mode 100644
index 000000000..b727ceff2
--- /dev/null
+++ b/runsc/specutils/seccomp/audit_arm64.go
@@ -0,0 +1,25 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build arm64
+
+package seccomp
+
+import (
+	"gvisor.dev/gvisor/pkg/abi/linux"
+)
+
+const (
+	nativeArchAuditNo = linux.AUDIT_ARCH_AARCH64
+)
diff --git a/runsc/specutils/seccomp/seccomp.go b/runsc/specutils/seccomp/seccomp.go
new file mode 100644
index 000000000..5932f7a41
--- /dev/null
+++ b/runsc/specutils/seccomp/seccomp.go
@@ -0,0 +1,229 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package seccomp implements some features of libseccomp in order to support
+// OCI.
+package seccomp
+
+import (
+	"fmt"
+	"syscall"
+
+	specs "github.com/opencontainers/runtime-spec/specs-go"
+	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/bpf"
+	"gvisor.dev/gvisor/pkg/log"
+	"gvisor.dev/gvisor/pkg/seccomp"
+	"gvisor.dev/gvisor/pkg/sentry/kernel"
+	slinux "gvisor.dev/gvisor/pkg/sentry/syscalls/linux"
+)
+
+var (
+	killThreadAction = linux.SECCOMP_RET_KILL_THREAD
+	trapAction       = linux.SECCOMP_RET_TRAP
+	// runc always returns EPERM as the errorcode for SECCOMP_RET_ERRNO
+	errnoAction = linux.SECCOMP_RET_ERRNO.WithReturnCode(uint16(syscall.EPERM))
+	// runc always returns EPERM as the errorcode for SECCOMP_RET_TRACE
+	traceAction = linux.SECCOMP_RET_TRACE.WithReturnCode(uint16(syscall.EPERM))
+	allowAction = linux.SECCOMP_RET_ALLOW
+)
+
+// BuildProgram generates a bpf program based on the given OCI seccomp
+// config.
+func BuildProgram(s *specs.LinuxSeccomp) (bpf.Program, error) {
+	defaultAction, err := convertAction(s.DefaultAction)
+	if err != nil {
+		return bpf.Program{}, fmt.Errorf("secomp default action: %w", err)
+	}
+	ruleset, err := convertRules(s)
+	if err != nil {
+		return bpf.Program{}, fmt.Errorf("invalid seccomp rules: %w", err)
+	}
+
+	instrs, err := seccomp.BuildProgram(ruleset, defaultAction, killThreadAction)
+	if err != nil {
+		return bpf.Program{}, fmt.Errorf("building seccomp program: %w", err)
+	}
+
+	program, err := bpf.Compile(instrs)
+	if err != nil {
+		return bpf.Program{}, fmt.Errorf("compiling seccomp program: %w", err)
+	}
+
+	return program, nil
+}
+
+// lookupSyscallNo gets the syscall number for the syscall with the given name
+// for the given architecture.
+func lookupSyscallNo(arch uint32, name string) (uint32, error) {
+	var table *kernel.SyscallTable
+	switch arch {
+	case linux.AUDIT_ARCH_X86_64:
+		table = slinux.AMD64
+	case linux.AUDIT_ARCH_AARCH64:
+		table = slinux.ARM64
+	}
+	if table == nil {
+		return 0, fmt.Errorf("unsupported architecture: %d", arch)
+	}
+	n, err := table.LookupNo(name)
+	if err != nil {
+		return 0, err
+	}
+	return uint32(n), nil
+}
+
+// convertAction converts a LinuxSeccompAction to BPFAction
+func convertAction(act specs.LinuxSeccompAction) (linux.BPFAction, error) {
+	// TODO(gvisor.dev/issue/3124): Update specs package to include ActLog and ActKillProcess.
+	switch act {
+	case specs.ActKill:
+		return killThreadAction, nil
+	case specs.ActTrap:
+		return trapAction, nil
+	case specs.ActErrno:
+		return errnoAction, nil
+	case specs.ActTrace:
+		return traceAction, nil
+	case specs.ActAllow:
+		return allowAction, nil
+	default:
+		return 0, fmt.Errorf("invalid action: %v", act)
+	}
+}
+
+// convertRules converts OCI linux seccomp rules into RuleSets that can be used by
+// the seccomp package to build a seccomp program.
+func convertRules(s *specs.LinuxSeccomp) ([]seccomp.RuleSet, error) {
+	// NOTE: Architectures are only really relevant when calling 32bit syscalls
+	// on a 64bit system. Since we don't support that in gVisor anyway, we
+	// ignore Architectures and only test against the native architecture.
+
+	ruleset := []seccomp.RuleSet{}
+
+	for _, syscall := range s.Syscalls {
+		sysRules := seccomp.NewSyscallRules()
+
+		action, err := convertAction(syscall.Action)
+		if err != nil {
+			return nil, err
+		}
+
+		// Args
+		rules, err := convertArgs(syscall.Args)
+		if err != nil {
+			return nil, err
+		}
+
+		for _, name := range syscall.Names {
+			syscallNo, err := lookupSyscallNo(nativeArchAuditNo, name)
+			if err != nil {
+				// If there is an error looking up the syscall number, assume it is
+				// not supported on this architecture and ignore it. This is, for
+				// better or worse, what runc does.
+				log.Warningf("OCI seccomp: ignoring syscall %q", name)
+				continue
+			}
+
+			for _, rule := range rules {
+				sysRules.AddRule(uintptr(syscallNo), rule)
+			}
+		}
+
+		ruleset = append(ruleset, seccomp.RuleSet{
+			Rules:  sysRules,
+			Action: action,
+		})
+	}
+
+	return ruleset, nil
+}
+
+// convertArgs converts an OCI seccomp argument rule to a list of seccomp.Rule.
+func convertArgs(args []specs.LinuxSeccompArg) ([]seccomp.Rule, error) {
+	argCounts := make([]uint, 6)
+
+	for _, arg := range args {
+		if arg.Index > 6 {
+			return nil, fmt.Errorf("invalid index: %d", arg.Index)
+		}
+
+		argCounts[arg.Index]++
+	}
+
+	// NOTE: If multiple rules apply to the same argument (same index) the
+	// action is triggered if any one of the rules matches (OR). If not, then
+	// all rules much match in order to trigger the action (AND). This appears to
+	// be some kind of legacy behavior of runc that nevertheless needs to be
+	// supported to maintain compatibility.
+
+	hasMultipleArgs := false
+	for _, count := range argCounts {
+		if count > 1 {
+			hasMultipleArgs = true
+			break
+		}
+	}
+
+	if hasMultipleArgs {
+		rules := []seccomp.Rule{}
+
+		// Old runc behavior - do this for compatibility.
+		// Add rules as ORs by adding separate Rules.
+		for _, arg := range args {
+			rule := seccomp.Rule{nil, nil, nil, nil, nil, nil}
+
+			if err := convertRule(arg, &rule); err != nil {
+				return nil, err
+			}
+
+			rules = append(rules, rule)
+		}
+
+		return rules, nil
+	}
+
+	// Add rules as ANDs by adding to the same Rule.
+	rule := seccomp.Rule{nil, nil, nil, nil, nil, nil}
+	for _, arg := range args {
+		if err := convertRule(arg, &rule); err != nil {
+			return nil, err
+		}
+	}
+
+	return []seccomp.Rule{rule}, nil
+}
+
+// convertRule converts and adds the arg to a rule.
+func convertRule(arg specs.LinuxSeccompArg, rule *seccomp.Rule) error {
+	switch arg.Op {
+	case specs.OpEqualTo:
+		rule[arg.Index] = seccomp.EqualTo(arg.Value)
+	case specs.OpNotEqual:
+		rule[arg.Index] = seccomp.NotEqual(arg.Value)
+	case specs.OpGreaterThan:
+		rule[arg.Index] = seccomp.GreaterThan(arg.Value)
+	case specs.OpGreaterEqual:
+		rule[arg.Index] = seccomp.GreaterThanOrEqual(arg.Value)
+	case specs.OpLessThan:
+		rule[arg.Index] = seccomp.LessThan(arg.Value)
+	case specs.OpLessEqual:
+		rule[arg.Index] = seccomp.LessThanOrEqual(arg.Value)
+	case specs.OpMaskedEqual:
+		rule[arg.Index] = seccomp.MaskedEqual(uintptr(arg.Value), uintptr(arg.ValueTwo))
+	default:
+		return fmt.Errorf("unsupported operand: %q", arg.Op)
+	}
+	return nil
+}
diff --git a/runsc/specutils/seccomp/seccomp_amd64_state_autogen.go b/runsc/specutils/seccomp/seccomp_amd64_state_autogen.go
new file mode 100644
index 000000000..27a96018b
--- /dev/null
+++ b/runsc/specutils/seccomp/seccomp_amd64_state_autogen.go
@@ -0,0 +1,5 @@
+// automatically generated by stateify.
+
+// +build amd64
+
+package seccomp
diff --git a/runsc/specutils/seccomp/seccomp_arm64_state_autogen.go b/runsc/specutils/seccomp/seccomp_arm64_state_autogen.go
new file mode 100644
index 000000000..96c64c23d
--- /dev/null
+++ b/runsc/specutils/seccomp/seccomp_arm64_state_autogen.go
@@ -0,0 +1,5 @@
+// automatically generated by stateify.
+
+// +build arm64
+
+package seccomp
diff --git a/runsc/specutils/seccomp/seccomp_state_autogen.go b/runsc/specutils/seccomp/seccomp_state_autogen.go
new file mode 100644
index 000000000..e16b5d7c2
--- /dev/null
+++ b/runsc/specutils/seccomp/seccomp_state_autogen.go
@@ -0,0 +1,3 @@
+// automatically generated by stateify.
+
+package seccomp