Implement rseq(2)

PiperOrigin-RevId: 288342928

4 files changed, 51 insertions, 2 deletions

diff --git a/pkg/sentry/syscalls/linux/BUILD b/pkg/sentry/syscalls/linux/BUILD
index 6766ba587..a76975cee 100644
--- a/pkg/sentry/syscalls/linux/BUILD
+++ b/pkg/sentry/syscalls/linux/BUILD
@@ -30,6 +30,7 @@ go_library(
         "sys_random.go",
         "sys_read.go",
         "sys_rlimit.go",
+        "sys_rseq.go",
         "sys_rusage.go",
         "sys_sched.go",
         "sys_seccomp.go",
diff --git a/pkg/sentry/syscalls/linux/linux64_amd64.go b/pkg/sentry/syscalls/linux/linux64_amd64.go
index 272ae9991..479c5f6ff 100644
--- a/pkg/sentry/syscalls/linux/linux64_amd64.go
+++ b/pkg/sentry/syscalls/linux/linux64_amd64.go
@@ -377,7 +377,7 @@ var AMD64 = &kernel.SyscallTable{
 		331: syscalls.ErrorWithEvent("pkey_free", syserror.ENOSYS, "", nil),
 		332: syscalls.Supported("statx", Statx),
 		333: syscalls.ErrorWithEvent("io_pgetevents", syserror.ENOSYS, "", nil),
-		334: syscalls.ErrorWithEvent("rseq", syserror.ENOSYS, "", nil),
+		334: syscalls.PartiallySupported("rseq", RSeq, "Not supported on all platforms.", nil),
 
 		// Linux skips ahead to syscall 424 to sync numbers between arches.
 		424: syscalls.ErrorWithEvent("pidfd_send_signal", syserror.ENOSYS, "", nil),
diff --git a/pkg/sentry/syscalls/linux/linux64_arm64.go b/pkg/sentry/syscalls/linux/linux64_arm64.go
index 3b584eed9..d3f61f5e8 100644
--- a/pkg/sentry/syscalls/linux/linux64_arm64.go
+++ b/pkg/sentry/syscalls/linux/linux64_arm64.go
@@ -307,7 +307,7 @@ var ARM64 = &kernel.SyscallTable{
 		290: syscalls.ErrorWithEvent("pkey_free", syserror.ENOSYS, "", nil),
 		291: syscalls.Supported("statx", Statx),
 		292: syscalls.ErrorWithEvent("io_pgetevents", syserror.ENOSYS, "", nil),
-		293: syscalls.ErrorWithEvent("rseq", syserror.ENOSYS, "", nil),
+		293: syscalls.PartiallySupported("rseq", RSeq, "Not supported on all platforms.", nil),
 
 		// Linux skips ahead to syscall 424 to sync numbers between arches.
 		424: syscalls.ErrorWithEvent("pidfd_send_signal", syserror.ENOSYS, "", nil),
diff --git a/pkg/sentry/syscalls/linux/sys_rseq.go b/pkg/sentry/syscalls/linux/sys_rseq.go
new file mode 100644
index 000000000..90db10ea6
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/sys_rseq.go
@@ -0,0 +1,48 @@
+// Copyright 2019 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"
+)
+
+// RSeq implements syscall rseq(2).
+func RSeq(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	addr := args[0].Pointer()
+	length := args[1].Uint()
+	flags := args[2].Int()
+	signature := args[3].Uint()
+
+	if !t.RSeqAvailable() {
+		// Event for applications that want rseq on a configuration
+		// that doesn't support them.
+		t.Kernel().EmitUnimplementedEvent(t)
+		return 0, nil, syserror.ENOSYS
+	}
+
+	switch flags {
+	case 0:
+		// Register.
+		return 0, nil, t.SetRSeq(addr, length, signature)
+	case linux.RSEQ_FLAG_UNREGISTER:
+		return 0, nil, t.ClearRSeq(addr, length, signature)
+	default:
+		// Unknown flag.
+		return 0, nil, syserror.EINVAL
+	}
+}