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authorJakob Unterwurzacher2020-08-08 18:45:47 +0200
committerJakob Unterwurzacher2020-08-08 18:45:47 +0200
commit527609266386890fe1657c225c643ca448bcd71d (patch)
tree8cb9261b827118311c195cbb6324ffaf87052970 /internal
parent84ed139cd2cede9b773fe7892a0bc2515fc1f00f (diff)
v2api/reverse: implement Readlink
Diffstat (limited to 'internal')
-rw-r--r--internal/fusefrontend_reverse/node.go28
-rw-r--r--internal/fusefrontend_reverse/node_api_check.go37
-rw-r--r--internal/fusefrontend_reverse/node_helpers.go31
3 files changed, 88 insertions, 8 deletions
diff --git a/internal/fusefrontend_reverse/node.go b/internal/fusefrontend_reverse/node.go
index 713beee..884a97e 100644
--- a/internal/fusefrontend_reverse/node.go
+++ b/internal/fusefrontend_reverse/node.go
@@ -2,6 +2,7 @@ package fusefrontend_reverse
import (
"context"
+ "path/filepath"
"syscall"
"golang.org/x/sys/unix"
@@ -20,16 +21,16 @@ type Node struct {
}
// Lookup - FUSE call for discovering a file.
-func (n *Node) Lookup(ctx context.Context, name string, out *fuse.EntryOut) (ch *fs.Inode, errno syscall.Errno) {
+func (n *Node) Lookup(ctx context.Context, cName string, out *fuse.EntryOut) (ch *fs.Inode, errno syscall.Errno) {
dirfd := int(-1)
pName := ""
- t := n.lookupFileType(name)
+ t := n.lookupFileType(cName)
if t == typeDiriv {
// gocryptfs.diriv
return n.lookupDiriv(ctx, out)
} else if t == typeName {
// gocryptfs.longname.*.name
- return n.lookupLongnameName(ctx, name, out)
+ return n.lookupLongnameName(ctx, cName, out)
} else if t == typeConfig {
// gocryptfs.conf
var err error
@@ -43,7 +44,7 @@ func (n *Node) Lookup(ctx context.Context, name string, out *fuse.EntryOut) (ch
defer syscall.Close(dirfd)
} else if t == typeReal {
// real file
- dirfd, pName, errno = n.prepareAtSyscall(name)
+ dirfd, pName, errno = n.prepareAtSyscall(cName)
if errno != 0 {
return
}
@@ -58,7 +59,7 @@ func (n *Node) Lookup(ctx context.Context, name string, out *fuse.EntryOut) (ch
ch = n.newChild(ctx, st, out)
// Translate ciphertext size in `out.Attr.Size` to plaintext size
if t == typeReal {
- n.translateSize(dirfd, pName, &out.Attr)
+ n.translateSize(dirfd, cName, pName, &out.Attr)
}
return ch, 0
}
@@ -89,10 +90,25 @@ func (n *Node) Getattr(ctx context.Context, f fs.FileHandle, out *fuse.AttrOut)
out.Attr.FromStat(st)
// Translate ciphertext size in `out.Attr.Size` to plaintext size
- n.translateSize(dirfd, pName, &out.Attr)
+ cName := filepath.Base(n.Path())
+ n.translateSize(dirfd, cName, pName, &out.Attr)
if rn.args.ForceOwner != nil {
out.Owner = *rn.args.ForceOwner
}
return 0
}
+
+// Readlink - FUSE call.
+//
+// Symlink-safe through openBackingDir() + Readlinkat().
+func (n *Node) Readlink(ctx context.Context) (out []byte, errno syscall.Errno) {
+ dirfd, pName, errno := n.prepareAtSyscall("")
+ if errno != 0 {
+ return
+ }
+ defer syscall.Close(dirfd)
+
+ cName := filepath.Base(n.Path())
+ return n.readlink(dirfd, cName, pName)
+}
diff --git a/internal/fusefrontend_reverse/node_api_check.go b/internal/fusefrontend_reverse/node_api_check.go
new file mode 100644
index 0000000..e926fc3
--- /dev/null
+++ b/internal/fusefrontend_reverse/node_api_check.go
@@ -0,0 +1,37 @@
+package fusefrontend_reverse
+
+import (
+ "github.com/hanwen/go-fuse/v2/fs"
+)
+
+// Check that we have implemented the fs.Node* interfaces
+var _ = (fs.NodeGetattrer)((*Node)(nil))
+var _ = (fs.NodeLookuper)((*Node)(nil))
+var _ = (fs.NodeReaddirer)((*Node)(nil))
+var _ = (fs.NodeReadlinker)((*Node)(nil))
+
+/* TODO
+var _ = (fs.NodeOpener)((*Node)(nil))
+var _ = (fs.NodeStatfser)((*Node)(nil))
+var _ = (fs.NodeMknoder)((*Node)(nil))
+var _ = (fs.NodeGetxattrer)((*Node)(nil))
+var _ = (fs.NodeListxattrer)((*Node)(nil))
+*/
+
+/* Not needed
+var _ = (fs.NodeOpendirer)((*Node)(nil))
+*/
+
+/* Will not implement these - reverse mode is read-only!
+var _ = (fs.NodeCreater)((*Node)(nil))
+var _ = (fs.NodeMkdirer)((*Node)(nil))
+var _ = (fs.NodeRmdirer)((*Node)(nil))
+var _ = (fs.NodeUnlinker)((*Node)(nil))
+var _ = (fs.NodeSetattrer)((*Node)(nil))
+var _ = (fs.NodeLinker)((*Node)(nil))
+var _ = (fs.NodeSymlinker)((*Node)(nil))
+var _ = (fs.NodeRenamer)((*Node)(nil))
+var _ = (fs.NodeSetxattrer)((*Node)(nil))
+var _ = (fs.NodeRemovexattrer)((*Node)(nil))
+var _ = (fs.NodeCopyFileRanger)((*Node)(nil))
+*/
diff --git a/internal/fusefrontend_reverse/node_helpers.go b/internal/fusefrontend_reverse/node_helpers.go
index df9de9b..7669a17 100644
--- a/internal/fusefrontend_reverse/node_helpers.go
+++ b/internal/fusefrontend_reverse/node_helpers.go
@@ -26,12 +26,13 @@ const (
)
// translateSize translates the ciphertext size in `out` into plaintext size.
-func (n *Node) translateSize(dirfd int, cName string, out *fuse.Attr) {
+func (n *Node) translateSize(dirfd int, cName string, pName string, out *fuse.Attr) {
if out.IsRegular() {
rn := n.rootNode()
out.Size = rn.contentEnc.PlainSizeToCipherSize(out.Size)
} else if out.IsSymlink() {
- panic("todo: call readlink once it is implemented")
+ cLink, _ := n.readlink(dirfd, cName, pName)
+ out.Size = uint64(len(cLink))
}
}
@@ -151,3 +152,29 @@ func (n *Node) lookupDiriv(ctx context.Context, out *fuse.EntryOut) (ch *fs.Inod
ch = n.NewInode(ctx, vf, id)
return
}
+
+// readlink reads and encrypts a symlink. Used by Readlink, Getattr, Lookup.
+func (n *Node) readlink(dirfd int, cName string, pName string) (out []byte, errno syscall.Errno) {
+ plainTarget, err := syscallcompat.Readlinkat(dirfd, pName)
+ if err != nil {
+ errno = fs.ToErrno(err)
+ return
+ }
+ rn := n.rootNode()
+ if rn.args.PlaintextNames {
+ return []byte(plainTarget), 0
+ }
+ // Nonce is derived from the relative *ciphertext* path
+ p := filepath.Join(n.Path(), cName)
+ nonce := pathiv.Derive(p, pathiv.PurposeSymlinkIV)
+ // Symlinks are encrypted like file contents and base64-encoded
+ cBinTarget := rn.contentEnc.EncryptBlockNonce([]byte(plainTarget), 0, nil, nonce)
+ cTarget := rn.nameTransform.B64EncodeToString(cBinTarget)
+ // The kernel will reject a symlink target above 4096 chars and return
+ // and I/O error to the user. Better emit the proper error ourselves.
+ if len(cTarget) > syscallcompat.PATH_MAX {
+ errno = syscall.ENAMETOOLONG
+ return
+ }
+ return []byte(cTarget), 0
+}