Add mode to procfs dump

Updates #4805

PiperOrigin-RevId: 456284312

runsc/boot/procfs/BUILD

@@ -7,6 +7,7 @@ go_library(
     srcs = ["dump.go"],
     visibility = ["//runsc:__subpackages__"],
     deps = [
+        "//pkg/abi/linux",
         "//pkg/context",
         "//pkg/log",
         "//pkg/sentry/fsimpl/proc",

runsc/boot/procfs/dump.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"strings"
 
+	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/log"
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/proc"
@@ -36,6 +37,8 @@ type FDInfo struct {
 	Number int32 `json:"number,omitempty"`
 	// Path is the path of the file that FD represents.
 	Path string `json:"path,omitempty"`
+	// Mode is the file mode.
+	Mode uint16 `json:"mode,omitempty"`
 }
 
 // UIDGID contains information for /proc/[pid]/status/{uid,gid}.
@@ -185,7 +188,13 @@ func getFDs(ctx context.Context, t *kernel.Task, pid kernel.ThreadID) []FDInfo {
 			log.Warningf("PathnameWithDeleted failed to find path for fd %d in PID %s: %v", fd.no, pid, err)
 			path = ""
 		}
-		res = append(res, FDInfo{Number: fd.no, Path: path})
+		mode := uint16(0)
+		if statx, err := fd.fd.Stat(ctx, vfs.StatOptions{Mask: linux.STATX_MODE}); err != nil {
+			log.Warningf("Stat(STATX_MODE) failed for fd %d in PID %s: %v", fd.no, pid, err)
+		} else {
+			mode = statx.Mode
+		}
+		res = append(res, FDInfo{Number: fd.no, Path: path, Mode: mode})
 	}
 	return res
 }

runsc/container/trace_test.go

@@ -22,6 +22,7 @@ import (
 	"time"
 
 	specs "github.com/opencontainers/runtime-spec/specs-go"
+	"golang.org/x/sys/unix"
 	"google.golang.org/protobuf/proto"
 	"gvisor.dev/gvisor/pkg/sentry/kernel"
 	"gvisor.dev/gvisor/pkg/sentry/limits"
@@ -374,12 +375,16 @@ func TestProcfsDump(t *testing.T) {
 	if len(procfsDump[0].FDs) < 3 {
 		t.Errorf("expected at least 3 FDs for the sleep process, got %+v", procfsDump[0].FDs)
 	} else {
+		modes := []uint16{unix.S_IFCHR, unix.S_IFIFO, unix.S_IFREG}
 		for i, fd := range procfsDump[0].FDs[:3] {
 			if want := int32(i); fd.Number != want {
 				t.Errorf("expected FD number %d, got %d", want, fd.Number)
 			}
 			if wantSubStr := "host"; !strings.Contains(fd.Path, wantSubStr) {
-				t.Errorf("expected FD path to contain %q, got %q", wantSubStr, fd.Path)
+				t.Errorf("expected FD %d path to contain %q, got %q", fd.Number, wantSubStr, fd.Path)
+			}
+			if want, got := modes[i], fd.Mode&unix.S_IFMT; uint16(want) != got {
+				t.Errorf("wrong mode FD %d, want: %#o, got: %#o", fd.Number, want, got)
 			}
 		}
 	}