ipn,cmd/tailscale,client/tailscale: add support for renaming TailFS shares

- Updates API to support renaming TailFS shares.
- Adds a CLI rename subcommand for renaming a share.
- Renames the CLI subcommand 'add' to 'set' to make it clear that
  this is an add or update.
- Adds a unit test for TailFS in ipnlocal

Updates tailscale/corp#16827

Signed-off-by: Percy Wegmann <percy@tailscale.com>

client/tailscale/localclient.go

@@ -1426,10 +1426,10 @@ func (lc *LocalClient) TailFSSetFileServerAddr(ctx context.Context, addr string)
 	return err
 }
 
-// TailFSShareAdd adds the given share to the list of shares that TailFS will
-// serve to remote nodes. If a share with the same name already exists, the
-// existing share is replaced/updated.
-func (lc *LocalClient) TailFSShareAdd(ctx context.Context, share *tailfs.Share) error {
+// TailFSShareSet adds or updates the given share in the list of shares that
+// TailFS will serve to remote nodes. If a share with the same name already
+// exists, the existing share is replaced/updated.
+func (lc *LocalClient) TailFSShareSet(ctx context.Context, share *tailfs.Share) error {
 	_, err := lc.send(ctx, "PUT", "/localapi/v0/tailfs/shares", http.StatusCreated, jsonBody(share))
 	return err
 }
@@ -1442,9 +1442,18 @@ func (lc *LocalClient) TailFSShareRemove(ctx context.Context, name string) error
 		"DELETE",
 		"/localapi/v0/tailfs/shares",
 		http.StatusNoContent,
-		jsonBody(&tailfs.Share{
-			Name: name,
-		}))
+		strings.NewReader(name))
+	return err
+}
+
+// TailFSShareRename renames the share from old to new name.
+func (lc *LocalClient) TailFSShareRename(ctx context.Context, oldName, newName string) error {
+	_, err := lc.send(
+		ctx,
+		"POST",
+		"/localapi/v0/tailfs/shares",
+		http.StatusNoContent,
+		jsonBody([2]string{oldName, newName}))
 	return err
 }
 

cmd/tailscale/cli/share.go

@@ -14,7 +14,8 @@
 )
 
 const (
-	shareAddUsage    = "share add <name> <path>"
+	shareSetUsage    = "share set <name> <path>"
+	shareRenameUsage = "share rename <oldname> <newname>"
 	shareRemoveUsage = "share remove <name>"
 	shareListUsage   = "share list"
 )
@@ -23,7 +24,7 @@
 	Name:      "share",
 	ShortHelp: "Share a directory with your tailnet",
 	ShortUsage: strings.Join([]string{
-		shareAddUsage,
+		shareSetUsage,
 		shareRemoveUsage,
 		shareListUsage,
 	}, "\n  "),
@@ -31,9 +32,15 @@
 	UsageFunc: usageFuncNoDefaultValues,
 	Subcommands: []*ffcli.Command{
 		{
-			Name:      "add",
-			Exec:      runShareAdd,
-			ShortHelp: "[ALPHA] add a share",
+			Name:      "set",
+			Exec:      runShareSet,
+			ShortHelp: "[ALPHA] set a share",
+			UsageFunc: usageFunc,
+		},
+		{
+			Name:      "rename",
+			ShortHelp: "[ALPHA] rename a share",
+			Exec:      runShareRename,
 			UsageFunc: usageFunc,
 		},
 		{
@@ -54,20 +61,20 @@
 	},
 }
 
-// runShareAdd is the entry point for the "tailscale share add" command.
-func runShareAdd(ctx context.Context, args []string) error {
+// runShareSet is the entry point for the "tailscale share set" command.
+func runShareSet(ctx context.Context, args []string) error {
 	if len(args) != 2 {
-		return fmt.Errorf("usage: tailscale %v", shareAddUsage)
+		return fmt.Errorf("usage: tailscale %v", shareSetUsage)
 	}
 
 	name, path := args[0], args[1]
 
-	err := localClient.TailFSShareAdd(ctx, &tailfs.Share{
+	err := localClient.TailFSShareSet(ctx, &tailfs.Share{
 		Name: name,
 		Path: path,
 	})
 	if err == nil {
-		fmt.Printf("Added share %q at %q\n", name, path)
+		fmt.Printf("Set share %q at %q\n", name, path)
 	}
 	return err
 }
@@ -86,6 +93,21 @@ func runShareRemove(ctx context.Context, args []string) error {
 	return err
 }
 
+// runShareRename is the entry point for the "tailscale share rename" command.
+func runShareRename(ctx context.Context, args []string) error {
+	if len(args) != 2 {
+		return fmt.Errorf("usage: tailscale %v", shareRenameUsage)
+	}
+	oldName := args[0]
+	newName := args[1]
+
+	err := localClient.TailFSShareRename(ctx, oldName, newName)
+	if err == nil {
+		fmt.Printf("Renamed share %q to %q\n", oldName, newName)
+	}
+	return err
+}
+
 // runShareList is the entry point for the "tailscale share list" command.
 func runShareList(ctx context.Context, args []string) error {
 	if len(args) != 0 {
@@ -148,7 +170,7 @@ func buildShareLongHelp() string {
 
 Each share is identified by a name and points to a directory at a specific path. For example, to share the path /Users/me/Documents under the name "docs", you would run:
 
-  $ tailscale share add docs /Users/me/Documents
+  $ tailscale share set docs /Users/me/Documents
 
 Note that the system forces share names to lowercase to avoid problems with clients that don't support case-sensitive filenames.
 
@@ -202,9 +224,13 @@ func buildShareLongHelp() string {
 
 Whenever either you or anyone in the group "home" connects to the share, they connect as if they are using your local machine user. They'll be able to read the same files as your user and if they create files, those files will be owned by your user.%s
 
+You can rename shares, for example you could rename the above share by running:
+
+  $ tailscale share rename docs newdocs
+
 You can remove shares by name, for example you could remove the above share by running:
 
-  $ tailscale share remove docs
+  $ tailscale share remove newdocs
 
 You can get a list of currently published shares by running:
 
@@ -214,4 +240,4 @@ func buildShareLongHelp() string {
 
 If you want a share to be accessed as a different user, you can use sudo to accomplish this. For example, to create the aforementioned share as "theuser", you could run:
 
-	$ sudo -u theuser tailscale share add docs /Users/theuser/Documents`
+	$ sudo -u theuser tailscale share set docs /Users/theuser/Documents`

ipn/ipnlocal/local_test.go

@@ -5,16 +5,20 @@
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"net"
 	"net/http"
 	"net/netip"
+	"os"
 	"reflect"
 	"slices"
+	"sync"
 	"testing"
 	"time"
 
+	"github.com/google/go-cmp/cmp"
 	"go4.org/netipx"
 	"golang.org/x/net/dns/dnsmessage"
 	"tailscale.com/appc"
@@ -25,6 +29,8 @@
 	"tailscale.com/net/interfaces"
 	"tailscale.com/net/tsaddr"
 	"tailscale.com/tailcfg"
+	"tailscale.com/tailfs"
+	"tailscale.com/tailfs/tailfsimpl"
 	"tailscale.com/tsd"
 	"tailscale.com/tstest"
 	"tailscale.com/types/dnstype"
@@ -34,6 +40,7 @@
 	"tailscale.com/types/netmap"
 	"tailscale.com/types/opt"
 	"tailscale.com/types/ptr"
+	"tailscale.com/types/views"
 	"tailscale.com/util/dnsname"
 	"tailscale.com/util/mak"
 	"tailscale.com/util/must"
@@ -2238,3 +2245,227 @@ func TestTCPHandlerForDst(t *testing.T) {
 		})
 	}
 }
+
+func TestTailFSManageShares(t *testing.T) {
+	tests := []struct {
+		name     string
+		disabled bool
+		existing []*tailfs.Share
+		add      *tailfs.Share
+		remove   string
+		rename   [2]string
+		expect   any
+	}{
+		{
+			name: "append",
+			existing: []*tailfs.Share{
+				{Name: "b"},
+				{Name: "d"},
+			},
+			add: &tailfs.Share{Name: "  E  "},
+			expect: []*tailfs.Share{
+				{Name: "b"},
+				{Name: "d"},
+				{Name: "e"},
+			},
+		},
+		{
+			name: "prepend",
+			existing: []*tailfs.Share{
+				{Name: "b"},
+				{Name: "d"},
+			},
+			add: &tailfs.Share{Name: "  A  "},
+			expect: []*tailfs.Share{
+				{Name: "a"},
+				{Name: "b"},
+				{Name: "d"},
+			},
+		},
+		{
+			name: "insert",
+			existing: []*tailfs.Share{
+				{Name: "b"},
+				{Name: "d"},
+			},
+			add: &tailfs.Share{Name: "  C  "},
+			expect: []*tailfs.Share{
+				{Name: "b"},
+				{Name: "c"},
+				{Name: "d"},
+			},
+		},
+		{
+			name: "replace",
+			existing: []*tailfs.Share{
+				{Name: "b", Path: "i"},
+				{Name: "d"},
+			},
+			add: &tailfs.Share{Name: "  B  ", Path: "ii"},
+			expect: []*tailfs.Share{
+				{Name: "b", Path: "ii"},
+				{Name: "d"},
+			},
+		},
+		{
+			name:   "add_bad_name",
+			add:    &tailfs.Share{Name: "$"},
+			expect: ErrInvalidShareName,
+		},
+		{
+			name:     "add_disabled",
+			disabled: true,
+			add:      &tailfs.Share{Name: "a"},
+			expect:   ErrTailFSNotEnabled,
+		},
+		{
+			name: "remove",
+			existing: []*tailfs.Share{
+				{Name: "a"},
+				{Name: "b"},
+				{Name: "c"},
+			},
+			remove: "b",
+			expect: []*tailfs.Share{
+				{Name: "a"},
+				{Name: "c"},
+			},
+		},
+		{
+			name: "remove_non_existing",
+			existing: []*tailfs.Share{
+				{Name: "a"},
+				{Name: "b"},
+				{Name: "c"},
+			},
+			remove: "D",
+			expect: os.ErrNotExist,
+		},
+		{
+			name:     "remove_disabled",
+			disabled: true,
+			remove:   "b",
+			expect:   ErrTailFSNotEnabled,
+		},
+		{
+			name: "rename",
+			existing: []*tailfs.Share{
+				{Name: "a"},
+				{Name: "b"},
+			},
+			rename: [2]string{"a", "  C  "},
+			expect: []*tailfs.Share{
+				{Name: "b"},
+				{Name: "c"},
+			},
+		},
+		{
+			name: "rename_not_exist",
+			existing: []*tailfs.Share{
+				{Name: "a"},
+				{Name: "b"},
+			},
+			rename: [2]string{"d", "c"},
+			expect: os.ErrNotExist,
+		},
+		{
+			name: "rename_exists",
+			existing: []*tailfs.Share{
+				{Name: "a"},
+				{Name: "b"},
+			},
+			rename: [2]string{"a", "b"},
+			expect: os.ErrExist,
+		},
+		{
+			name:   "rename_bad_name",
+			rename: [2]string{"a", "$"},
+			expect: ErrInvalidShareName,
+		},
+		{
+			name:     "rename_disabled",
+			disabled: true,
+			rename:   [2]string{"a", "c"},
+			expect:   ErrTailFSNotEnabled,
+		},
+	}
+
+	tailfs.DisallowShareAs = true
+	t.Cleanup(func() {
+		tailfs.DisallowShareAs = false
+	})
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			b := newTestBackend(t)
+			b.mu.Lock()
+			if tt.existing != nil {
+				b.tailFSSetSharesLocked(tt.existing)
+			}
+			if !tt.disabled {
+				self := b.netMap.SelfNode.AsStruct()
+				self.CapMap = tailcfg.NodeCapMap{tailcfg.NodeAttrsTailFSShare: nil}
+				b.netMap.SelfNode = self.View()
+				b.sys.Set(tailfsimpl.NewFileSystemForRemote(b.logf))
+			}
+			b.mu.Unlock()
+
+			ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+			t.Cleanup(cancel)
+
+			result := make(chan views.SliceView[*tailfs.Share, tailfs.ShareView], 1)
+
+			var wg sync.WaitGroup
+			wg.Add(1)
+			go b.WatchNotifications(
+				ctx,
+				0,
+				func() { wg.Done() },
+				func(n *ipn.Notify) bool {
+					select {
+					case result <- n.TailFSShares:
+					default:
+						//
+					}
+					return false
+				},
+			)
+			wg.Wait()
+
+			var err error
+			switch {
+			case tt.add != nil:
+				err = b.TailFSSetShare(tt.add)
+			case tt.remove != "":
+				err = b.TailFSRemoveShare(tt.remove)
+			default:
+				err = b.TailFSRenameShare(tt.rename[0], tt.rename[1])
+			}
+
+			switch e := tt.expect.(type) {
+			case error:
+				if !errors.Is(err, e) {
+					t.Errorf("expected error, want: %v got: %v", e, err)
+				}
+			case []*tailfs.Share:
+				if err != nil {
+					t.Errorf("unexpected error: %v", err)
+				} else {
+					r := <-result
+
+					got, err := json.MarshalIndent(r, "", "  ")
+					if err != nil {
+						t.Fatalf("can't marshal got: %v", err)
+					}
+					want, err := json.MarshalIndent(e, "", "  ")
+					if err != nil {
+						t.Fatalf("can't marshal want: %v", err)
+					}
+					if diff := cmp.Diff(string(got), string(want)); diff != "" {
+						t.Errorf("wrong shares; (-got+want):%v", diff)
+					}
+				}
+			}
+		})
+	}
+}

ipn/ipnlocal/tailfs.go

@@ -6,7 +6,9 @@
 import (
 	"errors"
 	"fmt"
+	"os"
 	"regexp"
+	"slices"
 	"strings"
 
 	"tailscale.com/ipn"
@@ -24,7 +26,8 @@
 
 var (
 	shareNameRegex      = regexp.MustCompile(`^[a-z0-9_\(\) ]+$`)
-	errInvalidShareName = errors.New("Share names may only contain the letters a-z, underscore _, parentheses (), or spaces")
+	ErrTailFSNotEnabled = errors.New("TailFS not enabled")
+	ErrInvalidShareName = errors.New("Share names may only contain the letters a-z, underscore _, parentheses (), or spaces")
 )
 
 // TailFSSharingEnabled reports whether sharing to remote nodes via tailfs is
@@ -59,18 +62,18 @@ func (b *LocalBackend) tailFSAccessEnabledLocked() bool {
 func (b *LocalBackend) TailFSSetFileServerAddr(addr string) error {
 	fs, ok := b.sys.TailFSForRemote.GetOK()
 	if !ok {
-		return errors.New("tailfs not enabled")
+		return ErrTailFSNotEnabled
 	}
 
 	fs.SetFileServerAddr(addr)
 	return nil
 }
 
-// TailFSAddShare adds the given share if no share with that name exists, or
-// replaces the existing share if one with the same name already exists.
-// To avoid potential incompatibilities across file systems, share names are
+// TailFSSetShare adds the given share if no share with that name exists, or
+// replaces the existing share if one with the same name already exists. To
+// avoid potential incompatibilities across file systems, share names are
 // limited to alphanumeric characters and the underscore _.
-func (b *LocalBackend) TailFSAddShare(share *tailfs.Share) error {
+func (b *LocalBackend) TailFSSetShare(share *tailfs.Share) error {
 	var err error
 	share.Name, err = normalizeShareName(share.Name)
 	if err != nil {
@@ -78,7 +81,7 @@ func (b *LocalBackend) TailFSAddShare(share *tailfs.Share) error {
 	}
 
 	b.mu.Lock()
-	shares, err := b.tailFSAddShareLocked(share)
+	shares, err := b.tailFSSetShareLocked(share)
 	b.mu.Unlock()
 	if err != nil {
 		return err
@@ -99,18 +102,18 @@ func normalizeShareName(name string) (string, error) {
 	name = strings.TrimSpace(name)
 
 	if !shareNameRegex.MatchString(name) {
-		return "", errInvalidShareName
+		return "", ErrInvalidShareName
 	}
 
 	return name, nil
 }
 
-func (b *LocalBackend) tailFSAddShareLocked(share *tailfs.Share) (views.SliceView[*tailfs.Share, tailfs.ShareView], error) {
+func (b *LocalBackend) tailFSSetShareLocked(share *tailfs.Share) (views.SliceView[*tailfs.Share, tailfs.ShareView], error) {
 	existingShares := b.pm.prefs.TailFSShares()
 
 	fs, ok := b.sys.TailFSForRemote.GetOK()
 	if !ok {
-		return existingShares, errors.New("tailfs not enabled")
+		return existingShares, ErrTailFSNotEnabled
 	}
 
 	addedShare := false
@@ -139,6 +142,70 @@ func (b *LocalBackend) tailFSAddShareLocked(share *tailfs.Share) (views.SliceVie
 	return b.pm.prefs.TailFSShares(), nil
 }
 
+// TailFSRenameShare renames the share at old name to new name. To avoid
+// potential incompatibilities across file systems, the new share name is
+// limited to alphanumeric characters and the underscore _.
+// Any of the following will result in an error.
+// - no share found under old name
+// - new share name contains disallowed characters
+// - share already exists under new name
+func (b *LocalBackend) TailFSRenameShare(oldName, newName string) error {
+	var err error
+	newName, err = normalizeShareName(newName)
+	if err != nil {
+		return err
+	}
+
+	b.mu.Lock()
+	shares, err := b.tailFSRenameShareLocked(oldName, newName)
+	b.mu.Unlock()
+	if err != nil {
+		return err
+	}
+
+	b.tailFSNotifyShares(shares)
+	return nil
+}
+
+func (b *LocalBackend) tailFSRenameShareLocked(oldName, newName string) (views.SliceView[*tailfs.Share, tailfs.ShareView], error) {
+	existingShares := b.pm.prefs.TailFSShares()
+
+	fs, ok := b.sys.TailFSForRemote.GetOK()
+	if !ok {
+		return existingShares, ErrTailFSNotEnabled
+	}
+
+	found := false
+	var shares []*tailfs.Share
+	for i := 0; i < existingShares.Len(); i++ {
+		existing := existingShares.At(i)
+		if existing.Name() == newName {
+			return existingShares, os.ErrExist
+		}
+		if existing.Name() == oldName {
+			share := existing.AsStruct()
+			share.Name = newName
+			shares = append(shares, share)
+			found = true
+		} else {
+			shares = append(shares, existing.AsStruct())
+		}
+	}
+
+	if !found {
+		return existingShares, os.ErrNotExist
+	}
+
+	slices.SortFunc(shares, tailfs.CompareShares)
+	err := b.tailFSSetSharesLocked(shares)
+	if err != nil {
+		return existingShares, err
+	}
+	fs.SetShares(shares)
+
+	return b.pm.prefs.TailFSShares(), nil
+}
+
 // TailFSRemoveShare removes the named share. Share names are forced to
 // lowercase.
 func (b *LocalBackend) TailFSRemoveShare(name string) error {
@@ -166,17 +233,24 @@ func (b *LocalBackend) tailFSRemoveShareLocked(name string) (views.SliceView[*ta
 
 	fs, ok := b.sys.TailFSForRemote.GetOK()
 	if !ok {
-		return existingShares, errors.New("tailfs not enabled")
+		return existingShares, ErrTailFSNotEnabled
 	}
 
+	found := false
 	var shares []*tailfs.Share
 	for i := 0; i < existingShares.Len(); i++ {
 		existing := existingShares.At(i)
 		if existing.Name() != name {
 			shares = append(shares, existing.AsStruct())
+		} else {
+			found = true
 		}
 	}
 
+	if !found {
+		return existingShares, os.ErrNotExist
+	}
+
 	err := b.tailFSSetSharesLocked(shares)
 	if err != nil {
 		return existingShares, err

ipn/ipnlocal/tailfs_test.go

@@ -20,11 +20,11 @@ func TestNormalizeShareName(t *testing.T) {
 		},
 		{
 			name: "",
-			err:  errInvalidShareName,
+			err:  ErrInvalidShareName,
 		},
 		{
 			name: "generally good except for .",
-			err:  errInvalidShareName,
+			err:  ErrInvalidShareName,
 		},
 	}
 	for _, tt := range tests {

ipn/localapi/localapi.go

@@ -2571,9 +2571,14 @@ func (h *Handler) serveTailFSFileServerAddr(w http.ResponseWriter, r *http.Reque
 }
 
 // serveShares handles the management of tailfs shares.
+//
+// PUT - adds or updates an existing share
+// DELETE - removes a share
+// GET - gets a list of all shares, sorted by name
+// POST - renames an existing share
 func (h *Handler) serveShares(w http.ResponseWriter, r *http.Request) {
 	if !h.b.TailFSSharingEnabled() {
-		http.Error(w, `tailfs sharing not enabled, please add the attribute "tailfs:share" to this node in your ACLs' "nodeAttrs" section`, http.StatusInternalServerError)
+		http.Error(w, `tailfs sharing not enabled, please add the attribute "tailfs:share" to this node in your ACLs' "nodeAttrs" section`, http.StatusForbidden)
 		return
 	}
 	switch r.Method {
@@ -2603,20 +2608,23 @@ func (h *Handler) serveShares(w http.ResponseWriter, r *http.Request) {
 			}
 			share.As = username
 		}
-		err = h.b.TailFSAddShare(&share)
+		err = h.b.TailFSSetShare(&share)
 		if err != nil {
+			if errors.Is(err, ipnlocal.ErrInvalidShareName) {
+				http.Error(w, "invalid share name", http.StatusBadRequest)
+				return
+			}
 			http.Error(w, err.Error(), http.StatusInternalServerError)
 			return
 		}
 		w.WriteHeader(http.StatusCreated)
 	case "DELETE":
-		var share tailfs.Share
-		err := json.NewDecoder(r.Body).Decode(&share)
+		b, err := io.ReadAll(r.Body)
 		if err != nil {
 			http.Error(w, err.Error(), http.StatusBadRequest)
 			return
 		}
-		err = h.b.TailFSRemoveShare(share.Name)
+		err = h.b.TailFSRemoveShare(string(b))
 		if err != nil {
 			if os.IsNotExist(err) {
 				http.Error(w, "share not found", http.StatusNotFound)
@@ -2626,6 +2634,31 @@ func (h *Handler) serveShares(w http.ResponseWriter, r *http.Request) {
 			return
 		}
 		w.WriteHeader(http.StatusNoContent)
+	case "POST":
+		var names [2]string
+		err := json.NewDecoder(r.Body).Decode(&names)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusBadRequest)
+			return
+		}
+		err = h.b.TailFSRenameShare(names[0], names[1])
+		if err != nil {
+			if os.IsNotExist(err) {
+				http.Error(w, "share not found", http.StatusNotFound)
+				return
+			}
+			if os.IsExist(err) {
+				http.Error(w, "share name already used", http.StatusBadRequest)
+				return
+			}
+			if errors.Is(err, ipnlocal.ErrInvalidShareName) {
+				http.Error(w, "invalid share name", http.StatusBadRequest)
+				return
+			}
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		w.WriteHeader(http.StatusNoContent)
 	case "GET":
 		shares := h.b.TailFSGetShares()
 		err := json.NewEncoder(w).Encode(shares)