6697ffd6e2
Unless we are mounted with -suid, we can reject these requests, and gain back some lost speed. Closes https://github.com/rfjakob/gocryptfs/issues/515
100 lines
3.0 KiB
Go
100 lines
3.0 KiB
Go
// Package fusefrontend interfaces directly with the go-fuse library.
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package fusefrontend
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import (
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"bytes"
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"context"
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"strings"
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"syscall"
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"github.com/rfjakob/gocryptfs/internal/tlog"
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)
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// xattr names are encrypted like file names, but with a fixed IV.
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// Padded with "_xx" for length 16.
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var xattrNameIV = []byte("xattr_name_iv_xx")
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// We store encrypted xattrs under this prefix plus the base64-encoded
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// encrypted original name.
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var xattrStorePrefix = "user.gocryptfs."
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// We get one read of this xattr for each write -
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// see https://github.com/rfjakob/gocryptfs/issues/515 for details.
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var xattrCapability = "security.capability"
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// GetXAttr - FUSE call. Reads the value of extended attribute "attr".
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//
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// This function is symlink-safe through Fgetxattr.
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func (n *Node) Getxattr(ctx context.Context, attr string, dest []byte) (uint32, syscall.Errno) {
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rn := n.rootNode()
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// If we are not mounted with -suid, reading the capability xattr does not
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// make a lot of sense, so reject the request and gain a massive speedup.
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// See https://github.com/rfjakob/gocryptfs/issues/515 .
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if !rn.args.Suid && attr == xattrCapability {
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// Returning EOPNOTSUPP is what we did till
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// ca9e912a28b901387e1dbb85f6c531119f2d5ef2 "fusefrontend: drop xattr user namespace restriction"
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// and it did not cause trouble. Seems cleaner than saying ENODATA.
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return 0, syscall.EOPNOTSUPP
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}
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cAttr := rn.encryptXattrName(attr)
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cData, errno := n.getXAttr(cAttr)
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if errno != 0 {
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return 0, errno
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}
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data, err := rn.decryptXattrValue(cData)
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if err != nil {
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tlog.Warn.Printf("GetXAttr: %v", err)
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return ^uint32(0), syscall.EIO
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}
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l := copy(dest, data)
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return uint32(l), 0
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}
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// SetXAttr - FUSE call. Set extended attribute.
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//
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// This function is symlink-safe through Fsetxattr.
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func (n *Node) Setxattr(ctx context.Context, attr string, data []byte, flags uint32) syscall.Errno {
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rn := n.rootNode()
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flags = uint32(filterXattrSetFlags(int(flags)))
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cAttr := rn.encryptXattrName(attr)
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cData := rn.encryptXattrValue(data)
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return n.setXAttr(cAttr, cData, flags)
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}
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// RemoveXAttr - FUSE call.
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//
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// This function is symlink-safe through Fremovexattr.
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func (n *Node) Removexattr(ctx context.Context, attr string) syscall.Errno {
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rn := n.rootNode()
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cAttr := rn.encryptXattrName(attr)
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return n.removeXAttr(cAttr)
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}
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// ListXAttr - FUSE call. Lists extended attributes on the file at "relPath".
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//
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// This function is symlink-safe through Flistxattr.
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func (n *Node) Listxattr(ctx context.Context, dest []byte) (uint32, syscall.Errno) {
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cNames, errno := n.listXAttr()
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if errno != 0 {
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return 0, errno
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}
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rn := n.rootNode()
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var buf bytes.Buffer
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for _, curName := range cNames {
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if !strings.HasPrefix(curName, xattrStorePrefix) {
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continue
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}
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name, err := rn.decryptXattrName(curName)
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if err != nil {
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tlog.Warn.Printf("ListXAttr: invalid xattr name %q: %v", curName, err)
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rn.reportMitigatedCorruption(curName)
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continue
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}
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buf.WriteString(name + "\000")
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}
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if buf.Len() > len(dest) {
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return ^uint32(0), syscall.ERANGE
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}
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return uint32(copy(dest, buf.Bytes())), 0
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}
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