Add seccomp filter to fsgofer

PiperOrigin-RevId: 211011542
Change-Id: Ib5a83a00f8eb6401603c6fb5b59afc93bac52558

8 files changed, 342 insertions, 0 deletions

diff --git a/runsc/cmd/BUILD b/runsc/cmd/BUILD
index 5dee26a5c..f9c091ba2 100644
--- a/runsc/cmd/BUILD
+++ b/runsc/cmd/BUILD
@@ -42,6 +42,7 @@ go_library(
         "//runsc/console",
         "//runsc/container",
         "//runsc/fsgofer",
+        "//runsc/fsgofer/filter",
         "//runsc/specutils",
         "@com_github_google_subcommands//:go_default_library",
         "@com_github_opencontainers_runtime-spec//specs-go:go_default_library",
diff --git a/runsc/cmd/gofer.go b/runsc/cmd/gofer.go
index ab76734fc..f28e02798 100644
--- a/runsc/cmd/gofer.go
+++ b/runsc/cmd/gofer.go
@@ -28,6 +28,7 @@ import (
 	"gvisor.googlesource.com/gvisor/pkg/p9"
 	"gvisor.googlesource.com/gvisor/pkg/unet"
 	"gvisor.googlesource.com/gvisor/runsc/fsgofer"
+	"gvisor.googlesource.com/gvisor/runsc/fsgofer/filter"
 	"gvisor.googlesource.com/gvisor/runsc/specutils"
 )
 
@@ -151,6 +152,10 @@ func (g *Gofer) Execute(_ context.Context, f *flag.FlagSet, args ...interface{})
 		Fatalf("too many FDs passed for mounts. mounts: %d, FDs: %d", mountIdx, len(g.ioFDs))
 	}
 
+	if err := filter.Install(); err != nil {
+		Fatalf("Failed to install seccomp filters: %v", err)
+	}
+
 	runServers(ats, g.ioFDs)
 	return subcommands.ExitSuccess
 }
diff --git a/runsc/fsgofer/filter/BUILD b/runsc/fsgofer/filter/BUILD
new file mode 100644
index 000000000..40f4f2205
--- /dev/null
+++ b/runsc/fsgofer/filter/BUILD
@@ -0,0 +1,24 @@
+package(licenses = ["notice"])  # Apache 2.0
+
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "filter",
+    srcs = [
+        "config.go",
+        "extra_filters.go",
+        "extra_filters_msan.go",
+        "extra_filters_race.go",
+        "filter.go",
+    ],
+    importpath = "gvisor.googlesource.com/gvisor/runsc/fsgofer/filter",
+    visibility = [
+        "//runsc:__subpackages__",
+    ],
+    deps = [
+        "//pkg/abi/linux",
+        "//pkg/log",
+        "//pkg/seccomp",
+        "@org_golang_x_sys//unix:go_default_library",
+    ],
+)
diff --git a/runsc/fsgofer/filter/config.go b/runsc/fsgofer/filter/config.go
new file mode 100644
index 000000000..97e556ceb
--- /dev/null
+++ b/runsc/fsgofer/filter/config.go
@@ -0,0 +1,175 @@
+// Copyright 2018 Google Inc.
+//
+// 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 filter
+
+import (
+	"os"
+	"syscall"
+
+	"golang.org/x/sys/unix"
+	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
+	"gvisor.googlesource.com/gvisor/pkg/seccomp"
+)
+
+// allowedSyscalls is the set of syscalls executed by the gofer.
+var allowedSyscalls = seccomp.SyscallRules{
+	syscall.SYS_ACCEPT: {},
+	syscall.SYS_ARCH_PRCTL: []seccomp.Rule{
+		{seccomp.AllowValue(linux.ARCH_GET_FS)},
+		{seccomp.AllowValue(linux.ARCH_SET_FS)},
+	},
+	syscall.SYS_CLOCK_GETTIME: {},
+	syscall.SYS_CLONE: []seccomp.Rule{
+		{
+			seccomp.AllowValue(
+				syscall.CLONE_VM |
+					syscall.CLONE_FS |
+					syscall.CLONE_FILES |
+					syscall.CLONE_SIGHAND |
+					syscall.CLONE_SYSVSEM |
+					syscall.CLONE_THREAD),
+		},
+	},
+	syscall.SYS_CLOSE:     {},
+	syscall.SYS_DUP:       {},
+	syscall.SYS_EPOLL_CTL: {},
+	syscall.SYS_EPOLL_PWAIT: []seccomp.Rule{
+		{
+			seccomp.AllowAny{},
+			seccomp.AllowAny{},
+			seccomp.AllowAny{},
+			seccomp.AllowAny{},
+			seccomp.AllowValue(0),
+		},
+	},
+	syscall.SYS_EVENTFD2: []seccomp.Rule{
+		{
+			seccomp.AllowValue(0),
+			seccomp.AllowValue(0),
+		},
+	},
+	syscall.SYS_EXIT:       {},
+	syscall.SYS_EXIT_GROUP: {},
+	syscall.SYS_FCHMOD:     {},
+	syscall.SYS_FCHOWNAT:   {},
+	syscall.SYS_FCNTL: []seccomp.Rule{
+		seccomp.Rule{
+			seccomp.AllowAny{},
+			seccomp.AllowValue(syscall.F_GETFL),
+		},
+		seccomp.Rule{
+			seccomp.AllowAny{},
+			seccomp.AllowValue(syscall.F_SETFL),
+		},
+		seccomp.Rule{
+			seccomp.AllowAny{},
+			seccomp.AllowValue(syscall.F_GETFD),
+		},
+	},
+	syscall.SYS_FSTAT:     {},
+	syscall.SYS_FSTATFS:   {},
+	syscall.SYS_FSYNC:     {},
+	syscall.SYS_FTRUNCATE: {},
+	syscall.SYS_FUTEX: {
+		seccomp.Rule{
+			seccomp.AllowAny{},
+			seccomp.AllowValue(linux.FUTEX_WAIT | linux.FUTEX_PRIVATE_FLAG),
+			seccomp.AllowAny{},
+			seccomp.AllowAny{},
+			seccomp.AllowValue(0),
+		},
+		seccomp.Rule{
+			seccomp.AllowAny{},
+			seccomp.AllowValue(linux.FUTEX_WAKE | linux.FUTEX_PRIVATE_FLAG),
+			seccomp.AllowAny{},
+			seccomp.AllowAny{},
+			seccomp.AllowValue(0),
+		},
+	},
+	syscall.SYS_GETDENTS64:   {},
+	syscall.SYS_GETPID:       {},
+	unix.SYS_GETRANDOM:       {},
+	syscall.SYS_GETTID:       {},
+	syscall.SYS_GETTIMEOFDAY: {},
+	syscall.SYS_LINKAT:       {},
+	syscall.SYS_LSEEK:        {},
+	syscall.SYS_MKDIRAT:      {},
+	syscall.SYS_MMAP: []seccomp.Rule{
+		{
+			seccomp.AllowAny{},
+			seccomp.AllowAny{},
+			seccomp.AllowAny{},
+			seccomp.AllowValue(syscall.MAP_SHARED),
+		},
+		{
+			seccomp.AllowAny{},
+			seccomp.AllowAny{},
+			seccomp.AllowAny{},
+			seccomp.AllowValue(syscall.MAP_PRIVATE | syscall.MAP_ANONYMOUS),
+		},
+		{
+			seccomp.AllowAny{},
+			seccomp.AllowAny{},
+			seccomp.AllowAny{},
+			seccomp.AllowValue(syscall.MAP_PRIVATE | syscall.MAP_ANONYMOUS | syscall.MAP_FIXED),
+		},
+	},
+	syscall.SYS_MPROTECT:   {},
+	syscall.SYS_MUNMAP:     {},
+	syscall.SYS_NANOSLEEP:  {},
+	syscall.SYS_NEWFSTATAT: {},
+	syscall.SYS_OPENAT:     {},
+	syscall.SYS_POLL:       {},
+	syscall.SYS_PREAD64:    {},
+	syscall.SYS_PWRITE64:   {},
+	syscall.SYS_READ:       {},
+	syscall.SYS_READLINKAT: {},
+	syscall.SYS_RECVMSG: []seccomp.Rule{
+		{
+			seccomp.AllowAny{},
+			seccomp.AllowAny{},
+			seccomp.AllowValue(syscall.MSG_DONTWAIT | syscall.MSG_TRUNC),
+		},
+		{
+			seccomp.AllowAny{},
+			seccomp.AllowAny{},
+			seccomp.AllowValue(syscall.MSG_DONTWAIT | syscall.MSG_TRUNC | syscall.MSG_PEEK),
+		},
+	},
+	syscall.SYS_RENAMEAT:        {},
+	syscall.SYS_RESTART_SYSCALL: {},
+	syscall.SYS_RT_SIGPROCMASK:  {},
+	syscall.SYS_SCHED_YIELD:     {},
+	syscall.SYS_SENDMSG: []seccomp.Rule{
+		{
+			seccomp.AllowAny{},
+			seccomp.AllowAny{},
+			seccomp.AllowValue(syscall.MSG_DONTWAIT | syscall.MSG_NOSIGNAL),
+		},
+	},
+	syscall.SYS_SHUTDOWN: []seccomp.Rule{
+		{seccomp.AllowAny{}, seccomp.AllowValue(syscall.SHUT_RDWR)},
+	},
+	syscall.SYS_SIGALTSTACK: {},
+	syscall.SYS_SYMLINKAT:   {},
+	syscall.SYS_TGKILL: []seccomp.Rule{
+		{
+			seccomp.AllowValue(uint64(os.Getpid())),
+		},
+	},
+	syscall.SYS_UNLINKAT:  {},
+	syscall.SYS_UTIMENSAT: {},
+	syscall.SYS_WRITE:     {},
+}
diff --git a/runsc/fsgofer/filter/extra_filters.go b/runsc/fsgofer/filter/extra_filters.go
new file mode 100644
index 000000000..82cf00dfb
--- /dev/null
+++ b/runsc/fsgofer/filter/extra_filters.go
@@ -0,0 +1,28 @@
+// Copyright 2018 Google Inc.
+//
+// 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 !msan,!race
+
+package filter
+
+import (
+	"gvisor.googlesource.com/gvisor/pkg/seccomp"
+)
+
+// instrumentationFilters returns additional filters for syscalls used by
+// Go intrumentation tools, e.g. -race, -msan.
+// Returns empty when disabled.
+func instrumentationFilters() seccomp.SyscallRules {
+	return nil
+}
diff --git a/runsc/fsgofer/filter/extra_filters_msan.go b/runsc/fsgofer/filter/extra_filters_msan.go
new file mode 100644
index 000000000..169a79ed8
--- /dev/null
+++ b/runsc/fsgofer/filter/extra_filters_msan.go
@@ -0,0 +1,33 @@
+// Copyright 2018 Google Inc.
+//
+// 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 msan
+
+package filter
+
+import (
+	"syscall"
+
+	"gvisor.googlesource.com/gvisor/pkg/log"
+	"gvisor.googlesource.com/gvisor/pkg/seccomp"
+)
+
+// instrumentationFilters returns additional filters for syscalls used by MSAN.
+func instrumentationFilters() seccomp.SyscallRules {
+	log.Warningf("*** SECCOMP WARNING: MSAN is enabled: syscall filters less restrictive!")
+	return seccomp.SyscallRules{
+		syscall.SYS_SCHED_GETAFFINITY: {},
+		syscall.SYS_SET_ROBUST_LIST:   {},
+	}
+}
diff --git a/runsc/fsgofer/filter/extra_filters_race.go b/runsc/fsgofer/filter/extra_filters_race.go
new file mode 100644
index 000000000..9e6512d8c
--- /dev/null
+++ b/runsc/fsgofer/filter/extra_filters_race.go
@@ -0,0 +1,42 @@
+// Copyright 2018 Google Inc.
+//
+// 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 race
+
+package filter
+
+import (
+	"syscall"
+
+	"gvisor.googlesource.com/gvisor/pkg/log"
+	"gvisor.googlesource.com/gvisor/pkg/seccomp"
+)
+
+// instrumentationFilters returns additional filters for syscalls used by TSAN.
+func instrumentationFilters() seccomp.SyscallRules {
+	log.Warningf("*** SECCOMP WARNING: TSAN is enabled: syscall filters less restrictive!")
+	return seccomp.SyscallRules{
+		syscall.SYS_BRK:             {},
+		syscall.SYS_CLONE:           {},
+		syscall.SYS_FUTEX:           {},
+		syscall.SYS_MADVISE:         {},
+		syscall.SYS_MMAP:            {},
+		syscall.SYS_MUNLOCK:         {},
+		syscall.SYS_NANOSLEEP:       {},
+		syscall.SYS_OPEN:            {},
+		syscall.SYS_SET_ROBUST_LIST: {},
+		// Used within glibc's malloc.
+		syscall.SYS_TIME: {},
+	}
+}
diff --git a/runsc/fsgofer/filter/filter.go b/runsc/fsgofer/filter/filter.go
new file mode 100644
index 000000000..6f341f688
--- /dev/null
+++ b/runsc/fsgofer/filter/filter.go
@@ -0,0 +1,34 @@
+// Copyright 2018 Google Inc.
+//
+// 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 filter defines all syscalls the gofer is allowed to make, and
+// installs seccomp filters to prevent prohibited syscalls in case it's
+// compromised.
+package filter
+
+import (
+	"gvisor.googlesource.com/gvisor/pkg/seccomp"
+)
+
+// Install installs seccomp filters.
+func Install() error {
+	s := allowedSyscalls
+
+	// Set of additional filters used by -race and -msan. Returns empty
+	// when not enabled.
+	s.Merge(instrumentationFilters())
+
+	// TODO: Set kill=true when SECCOMP_RET_KILL_PROCESS is supported.
+	return seccomp.Install(s, false)
+}