diff options
-rw-r--r-- | pkg/abi/linux/membarrier.go | 27 | ||||
-rw-r--r-- | pkg/sentry/hostmm/membarrier.go | 90 | ||||
-rw-r--r-- | pkg/sentry/mm/mm.go | 8 | ||||
-rw-r--r-- | pkg/sentry/mm/mm_state_autogen.go | 3 | ||||
-rw-r--r-- | pkg/sentry/mm/syscalls.go | 13 | ||||
-rw-r--r-- | pkg/sentry/platform/kvm/filters_amd64.go | 13 | ||||
-rw-r--r-- | pkg/sentry/platform/kvm/filters_arm64.go | 11 | ||||
-rw-r--r-- | pkg/sentry/platform/kvm/kvm.go | 3 | ||||
-rw-r--r-- | pkg/sentry/platform/platform.go | 51 | ||||
-rw-r--r-- | pkg/sentry/platform/ptrace/ptrace.go | 1 | ||||
-rw-r--r-- | pkg/sentry/syscalls/linux/linux64.go | 4 | ||||
-rw-r--r-- | pkg/sentry/syscalls/linux/sys_membarrier.go | 70 | ||||
-rw-r--r-- | runsc/boot/filter/config.go | 6 |
13 files changed, 295 insertions, 5 deletions
diff --git a/pkg/abi/linux/membarrier.go b/pkg/abi/linux/membarrier.go new file mode 100644 index 000000000..0f3c03e63 --- /dev/null +++ b/pkg/abi/linux/membarrier.go @@ -0,0 +1,27 @@ +// 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 linux + +// membarrier(2) commands, from include/uapi/linux/membarrier.h +const ( + MEMBARRIER_CMD_QUERY = 0 + MEMBARRIER_CMD_GLOBAL = (1 << 0) + MEMBARRIER_CMD_GLOBAL_EXPEDITED = (1 << 1) + MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED = (1 << 2) + MEMBARRIER_CMD_PRIVATE_EXPEDITED = (1 << 3) + MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED = (1 << 4) + MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE = (1 << 5) + MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE = (1 << 6) +) diff --git a/pkg/sentry/hostmm/membarrier.go b/pkg/sentry/hostmm/membarrier.go new file mode 100644 index 000000000..4468d75f1 --- /dev/null +++ b/pkg/sentry/hostmm/membarrier.go @@ -0,0 +1,90 @@ +// 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 hostmm + +import ( + "syscall" + + "golang.org/x/sys/unix" + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/log" +) + +var ( + haveMembarrierGlobal = false + haveMembarrierPrivateExpedited = false +) + +func init() { + supported, _, e := syscall.RawSyscall(unix.SYS_MEMBARRIER, linux.MEMBARRIER_CMD_QUERY, 0 /* flags */, 0 /* unused */) + if e != 0 { + if e != syscall.ENOSYS { + log.Warningf("membarrier(MEMBARRIER_CMD_QUERY) failed: %s", e.Error()) + } + return + } + // We don't use MEMBARRIER_CMD_GLOBAL_EXPEDITED because this sends IPIs to + // all CPUs running tasks that have previously invoked + // MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED, which presents a DOS risk. + // (MEMBARRIER_CMD_GLOBAL is synchronize_rcu(), i.e. it waits for an RCU + // grace period to elapse without bothering other CPUs. + // MEMBARRIER_CMD_PRIVATE_EXPEDITED sends IPIs only to CPUs running tasks + // sharing the caller's MM.) + if supported&linux.MEMBARRIER_CMD_GLOBAL != 0 { + haveMembarrierGlobal = true + } + if req := uintptr(linux.MEMBARRIER_CMD_PRIVATE_EXPEDITED | linux.MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED); supported&req == req { + if _, _, e := syscall.RawSyscall(unix.SYS_MEMBARRIER, linux.MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED, 0 /* flags */, 0 /* unused */); e != 0 { + log.Warningf("membarrier(MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED) failed: %s", e.Error()) + } else { + haveMembarrierPrivateExpedited = true + } + } +} + +// HaveGlobalMemoryBarrier returns true if GlobalMemoryBarrier is supported. +func HaveGlobalMemoryBarrier() bool { + return haveMembarrierGlobal +} + +// GlobalMemoryBarrier blocks until "all running threads [in the host OS] have +// passed through a state where all memory accesses to user-space addresses +// match program order between entry to and return from [GlobalMemoryBarrier]", +// as for membarrier(2). +// +// Preconditions: HaveGlobalMemoryBarrier() == true. +func GlobalMemoryBarrier() error { + if _, _, e := syscall.Syscall(unix.SYS_MEMBARRIER, linux.MEMBARRIER_CMD_GLOBAL, 0 /* flags */, 0 /* unused */); e != 0 { + return e + } + return nil +} + +// HaveProcessMemoryBarrier returns true if ProcessMemoryBarrier is supported. +func HaveProcessMemoryBarrier() bool { + return haveMembarrierPrivateExpedited +} + +// ProcessMemoryBarrier is equivalent to GlobalMemoryBarrier, but only +// synchronizes with threads sharing a virtual address space (from the host OS' +// perspective) with the calling thread. +// +// Preconditions: HaveProcessMemoryBarrier() == true. +func ProcessMemoryBarrier() error { + if _, _, e := syscall.RawSyscall(unix.SYS_MEMBARRIER, linux.MEMBARRIER_CMD_PRIVATE_EXPEDITED, 0 /* flags */, 0 /* unused */); e != 0 { + return e + } + return nil +} diff --git a/pkg/sentry/mm/mm.go b/pkg/sentry/mm/mm.go index 8c9f11cce..43567b92c 100644 --- a/pkg/sentry/mm/mm.go +++ b/pkg/sentry/mm/mm.go @@ -235,6 +235,14 @@ type MemoryManager struct { // vdsoSigReturnAddr is the address of 'vdso_sigreturn'. vdsoSigReturnAddr uint64 + + // membarrierPrivateEnabled is non-zero if EnableMembarrierPrivate has + // previously been called. Since, as of this writing, + // MEMBARRIER_CMD_PRIVATE_EXPEDITED is implemented as a global memory + // barrier, membarrierPrivateEnabled has no other effect. + // + // membarrierPrivateEnabled is accessed using atomic memory operations. + membarrierPrivateEnabled uint32 } // vma represents a virtual memory area. diff --git a/pkg/sentry/mm/mm_state_autogen.go b/pkg/sentry/mm/mm_state_autogen.go index 8ab51450c..a4e826a4f 100644 --- a/pkg/sentry/mm/mm_state_autogen.go +++ b/pkg/sentry/mm/mm_state_autogen.go @@ -315,6 +315,7 @@ func (x *MemoryManager) StateFields() []string { "aioManager", "sleepForActivation", "vdsoSigReturnAddr", + "membarrierPrivateEnabled", } } @@ -348,6 +349,7 @@ func (x *MemoryManager) StateSave(m state.Sink) { m.Save(19, &x.aioManager) m.Save(20, &x.sleepForActivation) m.Save(21, &x.vdsoSigReturnAddr) + m.Save(22, &x.membarrierPrivateEnabled) } func (x *MemoryManager) StateLoad(m state.Source) { @@ -373,6 +375,7 @@ func (x *MemoryManager) StateLoad(m state.Source) { m.Load(19, &x.aioManager) m.Load(20, &x.sleepForActivation) m.Load(21, &x.vdsoSigReturnAddr) + m.Load(22, &x.membarrierPrivateEnabled) m.AfterLoad(x.afterLoad) } diff --git a/pkg/sentry/mm/syscalls.go b/pkg/sentry/mm/syscalls.go index a2555ba1a..0a66b1cdd 100644 --- a/pkg/sentry/mm/syscalls.go +++ b/pkg/sentry/mm/syscalls.go @@ -17,6 +17,7 @@ package mm import ( "fmt" mrand "math/rand" + "sync/atomic" "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/context" @@ -1274,3 +1275,15 @@ func (mm *MemoryManager) VirtualDataSize() uint64 { defer mm.mappingMu.RUnlock() return mm.dataAS } + +// EnableMembarrierPrivate causes future calls to IsMembarrierPrivateEnabled to +// return true. +func (mm *MemoryManager) EnableMembarrierPrivate() { + atomic.StoreUint32(&mm.membarrierPrivateEnabled, 1) +} + +// IsMembarrierPrivateEnabled returns true if mm.EnableMembarrierPrivate() has +// previously been called. +func (mm *MemoryManager) IsMembarrierPrivateEnabled() bool { + return atomic.LoadUint32(&mm.membarrierPrivateEnabled) != 0 +} diff --git a/pkg/sentry/platform/kvm/filters_amd64.go b/pkg/sentry/platform/kvm/filters_amd64.go index 7d949f1dd..d3d216aa5 100644 --- a/pkg/sentry/platform/kvm/filters_amd64.go +++ b/pkg/sentry/platform/kvm/filters_amd64.go @@ -17,14 +17,23 @@ package kvm import ( "syscall" + "golang.org/x/sys/unix" + + "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/seccomp" ) // SyscallFilters returns syscalls made exclusively by the KVM platform. func (*KVM) SyscallFilters() seccomp.SyscallRules { return seccomp.SyscallRules{ - syscall.SYS_ARCH_PRCTL: {}, - syscall.SYS_IOCTL: {}, + syscall.SYS_ARCH_PRCTL: {}, + syscall.SYS_IOCTL: {}, + unix.SYS_MEMBARRIER: []seccomp.Rule{ + { + seccomp.EqualTo(linux.MEMBARRIER_CMD_PRIVATE_EXPEDITED), + seccomp.EqualTo(0), + }, + }, syscall.SYS_MMAP: {}, syscall.SYS_RT_SIGSUSPEND: {}, syscall.SYS_RT_SIGTIMEDWAIT: {}, diff --git a/pkg/sentry/platform/kvm/filters_arm64.go b/pkg/sentry/platform/kvm/filters_arm64.go index 9245d07c2..21abc2a3d 100644 --- a/pkg/sentry/platform/kvm/filters_arm64.go +++ b/pkg/sentry/platform/kvm/filters_arm64.go @@ -17,13 +17,22 @@ package kvm import ( "syscall" + "golang.org/x/sys/unix" + + "gvisor.dev/gvisor/pkg/abi/linux" "gvisor.dev/gvisor/pkg/seccomp" ) // SyscallFilters returns syscalls made exclusively by the KVM platform. func (*KVM) SyscallFilters() seccomp.SyscallRules { return seccomp.SyscallRules{ - syscall.SYS_IOCTL: {}, + syscall.SYS_IOCTL: {}, + unix.SYS_MEMBARRIER: []seccomp.Rule{ + { + seccomp.EqualTo(linux.MEMBARRIER_CMD_PRIVATE_EXPEDITED), + seccomp.EqualTo(0), + }, + }, syscall.SYS_MMAP: {}, syscall.SYS_RT_SIGSUSPEND: {}, syscall.SYS_RT_SIGTIMEDWAIT: {}, diff --git a/pkg/sentry/platform/kvm/kvm.go b/pkg/sentry/platform/kvm/kvm.go index d46946402..dd45ad10b 100644 --- a/pkg/sentry/platform/kvm/kvm.go +++ b/pkg/sentry/platform/kvm/kvm.go @@ -63,6 +63,9 @@ type runData struct { type KVM struct { platform.NoCPUPreemptionDetection + // KVM never changes mm_structs. + platform.UseHostProcessMemoryBarrier + // machine is the backing VM. machine *machine } diff --git a/pkg/sentry/platform/platform.go b/pkg/sentry/platform/platform.go index 530e779b0..dcfe839a7 100644 --- a/pkg/sentry/platform/platform.go +++ b/pkg/sentry/platform/platform.go @@ -25,6 +25,7 @@ import ( "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/seccomp" "gvisor.dev/gvisor/pkg/sentry/arch" + "gvisor.dev/gvisor/pkg/sentry/hostmm" "gvisor.dev/gvisor/pkg/sentry/memmap" "gvisor.dev/gvisor/pkg/usermem" ) @@ -52,6 +53,10 @@ type Platform interface { // can reliably return ErrContextCPUPreempted. DetectsCPUPreemption() bool + // HaveGlobalMemoryBarrier returns true if the GlobalMemoryBarrier method + // is supported. + HaveGlobalMemoryBarrier() bool + // MapUnit returns the alignment used for optional mappings into this // platform's AddressSpaces. Higher values indicate lower per-page costs // for AddressSpace.MapFile. As a special case, a MapUnit of 0 indicates @@ -97,6 +102,15 @@ type Platform interface { // called. PreemptAllCPUs() error + // GlobalMemoryBarrier blocks until all threads running application code + // (via Context.Switch) and all task goroutines "have passed through a + // state where all memory accesses to user-space addresses match program + // order between entry to and return from [GlobalMemoryBarrier]", as for + // membarrier(2). + // + // Preconditions: HaveGlobalMemoryBarrier() == true. + GlobalMemoryBarrier() error + // SyscallFilters returns syscalls made exclusively by this platform. SyscallFilters() seccomp.SyscallRules } @@ -115,6 +129,43 @@ func (NoCPUPreemptionDetection) PreemptAllCPUs() error { panic("This platform does not support CPU preemption detection") } +// UseHostGlobalMemoryBarrier implements Platform.HaveGlobalMemoryBarrier and +// Platform.GlobalMemoryBarrier by invoking equivalent functionality on the +// host. +type UseHostGlobalMemoryBarrier struct{} + +// HaveGlobalMemoryBarrier implements Platform.HaveGlobalMemoryBarrier. +func (UseHostGlobalMemoryBarrier) HaveGlobalMemoryBarrier() bool { + return hostmm.HaveGlobalMemoryBarrier() +} + +// GlobalMemoryBarrier implements Platform.GlobalMemoryBarrier. +func (UseHostGlobalMemoryBarrier) GlobalMemoryBarrier() error { + return hostmm.GlobalMemoryBarrier() +} + +// UseHostProcessMemoryBarrier implements Platform.HaveGlobalMemoryBarrier and +// Platform.GlobalMemoryBarrier by invoking a process-local memory barrier. +// This is faster than UseHostGlobalMemoryBarrier, but is only appropriate for +// platforms for which application code executes while using the sentry's +// mm_struct. +type UseHostProcessMemoryBarrier struct{} + +// HaveGlobalMemoryBarrier implements Platform.HaveGlobalMemoryBarrier. +func (UseHostProcessMemoryBarrier) HaveGlobalMemoryBarrier() bool { + // Fall back to a global memory barrier if a process-local one isn't + // available. + return hostmm.HaveProcessMemoryBarrier() || hostmm.HaveGlobalMemoryBarrier() +} + +// GlobalMemoryBarrier implements Platform.GlobalMemoryBarrier. +func (UseHostProcessMemoryBarrier) GlobalMemoryBarrier() error { + if hostmm.HaveProcessMemoryBarrier() { + return hostmm.ProcessMemoryBarrier() + } + return hostmm.GlobalMemoryBarrier() +} + // MemoryManager represents an abstraction above the platform address space // which manages memory mappings and their contents. type MemoryManager interface { diff --git a/pkg/sentry/platform/ptrace/ptrace.go b/pkg/sentry/platform/ptrace/ptrace.go index b52d0fbd8..f56aa3b79 100644 --- a/pkg/sentry/platform/ptrace/ptrace.go +++ b/pkg/sentry/platform/ptrace/ptrace.go @@ -192,6 +192,7 @@ func (c *context) PullFullState(as platform.AddressSpace, ac arch.Context) {} type PTrace struct { platform.MMapMinAddr platform.NoCPUPreemptionDetection + platform.UseHostGlobalMemoryBarrier } // New returns a new ptrace-based implementation of the platform interface. diff --git a/pkg/sentry/syscalls/linux/linux64.go b/pkg/sentry/syscalls/linux/linux64.go index b293669de..9c9def7cd 100644 --- a/pkg/sentry/syscalls/linux/linux64.go +++ b/pkg/sentry/syscalls/linux/linux64.go @@ -376,7 +376,7 @@ var AMD64 = &kernel.SyscallTable{ 321: syscalls.CapError("bpf", linux.CAP_SYS_ADMIN, "", nil), 322: syscalls.Supported("execveat", Execveat), 323: syscalls.ErrorWithEvent("userfaultfd", syserror.ENOSYS, "", []string{"gvisor.dev/issue/266"}), // TODO(b/118906345) - 324: syscalls.ErrorWithEvent("membarrier", syserror.ENOSYS, "", []string{"gvisor.dev/issue/267"}), // TODO(gvisor.dev/issue/267) + 324: syscalls.PartiallySupported("membarrier", Membarrier, "Not supported on all platforms.", nil), 325: syscalls.PartiallySupported("mlock2", Mlock2, "Stub implementation. The sandbox lacks appropriate permissions.", nil), // Syscalls implemented after 325 are "backports" from versions @@ -695,7 +695,7 @@ var ARM64 = &kernel.SyscallTable{ 280: syscalls.CapError("bpf", linux.CAP_SYS_ADMIN, "", nil), 281: syscalls.Supported("execveat", Execveat), 282: syscalls.ErrorWithEvent("userfaultfd", syserror.ENOSYS, "", []string{"gvisor.dev/issue/266"}), // TODO(b/118906345) - 283: syscalls.ErrorWithEvent("membarrier", syserror.ENOSYS, "", []string{"gvisor.dev/issue/267"}), // TODO(gvisor.dev/issue/267) + 283: syscalls.PartiallySupported("membarrier", Membarrier, "Not supported on all platforms.", nil), 284: syscalls.PartiallySupported("mlock2", Mlock2, "Stub implementation. The sandbox lacks appropriate permissions.", nil), // Syscalls after 284 are "backports" from versions of Linux after 4.4. diff --git a/pkg/sentry/syscalls/linux/sys_membarrier.go b/pkg/sentry/syscalls/linux/sys_membarrier.go new file mode 100644 index 000000000..288cd8512 --- /dev/null +++ b/pkg/sentry/syscalls/linux/sys_membarrier.go @@ -0,0 +1,70 @@ +// 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 linux + +import ( + "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/sentry/arch" + "gvisor.dev/gvisor/pkg/sentry/kernel" + "gvisor.dev/gvisor/pkg/syserror" +) + +// Membarrier implements syscall membarrier(2). +func Membarrier(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) { + cmd := args[0].Int() + flags := args[1].Int() + + p := t.Kernel().Platform + if !p.HaveGlobalMemoryBarrier() { + // Event for applications that want membarrier on a configuration that + // doesn't support them. + t.Kernel().EmitUnimplementedEvent(t) + return 0, nil, syserror.ENOSYS + } + + if flags != 0 { + return 0, nil, syserror.EINVAL + } + + switch cmd { + case linux.MEMBARRIER_CMD_QUERY: + const supportedCommands = linux.MEMBARRIER_CMD_GLOBAL | + linux.MEMBARRIER_CMD_GLOBAL_EXPEDITED | + linux.MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED | + linux.MEMBARRIER_CMD_PRIVATE_EXPEDITED | + linux.MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED + return supportedCommands, nil, nil + case linux.MEMBARRIER_CMD_PRIVATE_EXPEDITED: + if !t.MemoryManager().IsMembarrierPrivateEnabled() { + return 0, nil, syserror.EPERM + } + fallthrough + case linux.MEMBARRIER_CMD_GLOBAL, linux.MEMBARRIER_CMD_GLOBAL_EXPEDITED: + return 0, nil, p.GlobalMemoryBarrier() + case linux.MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED: + // no-op + return 0, nil, nil + case linux.MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED: + t.MemoryManager().EnableMembarrierPrivate() + return 0, nil, nil + case linux.MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE, linux.MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE: + // We're aware of these, but they aren't implemented since no platform + // supports them yet. + t.Kernel().EmitUnimplementedEvent(t) + fallthrough + default: + return 0, nil, syserror.EINVAL + } +} diff --git a/runsc/boot/filter/config.go b/runsc/boot/filter/config.go index 6ac19668f..a7c4ebb0c 100644 --- a/runsc/boot/filter/config.go +++ b/runsc/boot/filter/config.go @@ -162,6 +162,12 @@ var allowedSyscalls = seccomp.SyscallRules{ }, syscall.SYS_LSEEK: {}, syscall.SYS_MADVISE: {}, + unix.SYS_MEMBARRIER: []seccomp.Rule{ + { + seccomp.EqualTo(linux.MEMBARRIER_CMD_GLOBAL), + seccomp.EqualTo(0), + }, + }, syscall.SYS_MINCORE: {}, // Used by the Go runtime as a temporarily workaround for a Linux // 5.2-5.4 bug. |