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authorJakob Unterwurzacher2021-02-07 20:01:16 +0100
committerJakob Unterwurzacher2021-02-07 20:01:16 +0100
commiteaca820e876bfcdc67323eac6dd43ecc420968f2 (patch)
tree7d5fe2fef822778d6a78010fa2fa6f5c021f54d5 /internal/fusefrontend/node_xattr.go
parentbb2484f1520102f4ab6c84400f9eef53d4cdd2ad (diff)
fusefrontend: do not encrypt ACLs
Pass through system.posix_acl_access and system.posix_acl_default unencrypted to fix "cp -a" problems. "cp -a" uses "setxattr" even to set normal permissions, see https://www.spinics.net/lists/linux-nfs/msg63986.html . Fixes https://github.com/rfjakob/gocryptfs/issues/543
Diffstat (limited to 'internal/fusefrontend/node_xattr.go')
-rw-r--r--internal/fusefrontend/node_xattr.go74
1 files changed, 65 insertions, 9 deletions
diff --git a/internal/fusefrontend/node_xattr.go b/internal/fusefrontend/node_xattr.go
index cbc5804..3855b55 100644
--- a/internal/fusefrontend/node_xattr.go
+++ b/internal/fusefrontend/node_xattr.go
@@ -10,6 +10,9 @@ import (
"github.com/rfjakob/gocryptfs/internal/tlog"
)
+// -1 as uint32
+const minus1 = ^uint32(0)
+
// xattr names are encrypted like file names, but with a fixed IV.
// Padded with "_xx" for length 16.
var xattrNameIV = []byte("xattr_name_iv_xx")
@@ -22,6 +25,13 @@ var xattrStorePrefix = "user.gocryptfs."
// see https://github.com/rfjakob/gocryptfs/issues/515 for details.
var xattrCapability = "security.capability"
+// isAcl returns true if the attribute name is for storing ACLs
+//
+// ACLs are passed through without encryption
+func isAcl(attr string) bool {
+ return attr == "system.posix_acl_access" || attr == "system.posix_acl_default"
+}
+
// GetXAttr - FUSE call. Reads the value of extended attribute "attr".
//
// This function is symlink-safe through Fgetxattr.
@@ -36,15 +46,34 @@ func (n *Node) Getxattr(ctx context.Context, attr string, dest []byte) (uint32,
// and it did not cause trouble. Seems cleaner than saying ENODATA.
return 0, syscall.EOPNOTSUPP
}
- cAttr := rn.encryptXattrName(attr)
- cData, errno := n.getXAttr(cAttr)
- if errno != 0 {
- return 0, errno
+ var data []byte
+ // ACLs are passed through without encryption
+ if isAcl(attr) {
+ var errno syscall.Errno
+ data, errno = n.getXAttr(attr)
+ if errno != 0 {
+ return minus1, errno
+ }
+ } else {
+ // encrypted user xattr
+ cAttr := rn.encryptXattrName(attr)
+ cData, errno := n.getXAttr(cAttr)
+ if errno != 0 {
+ return 0, errno
+ }
+ var err error
+ data, err = rn.decryptXattrValue(cData)
+ if err != nil {
+ tlog.Warn.Printf("GetXAttr: %v", err)
+ return minus1, syscall.EIO
+ }
+ }
+ // Caller passes size zero to find out how large their buffer should be
+ if len(dest) == 0 {
+ return uint32(len(data)), 0
}
- data, err := rn.decryptXattrValue(cData)
- if err != nil {
- tlog.Warn.Printf("GetXAttr: %v", err)
- return ^uint32(0), syscall.EIO
+ if len(dest) < len(data) {
+ return minus1, syscall.ERANGE
}
l := copy(dest, data)
return uint32(l), 0
@@ -56,6 +85,12 @@ func (n *Node) Getxattr(ctx context.Context, attr string, dest []byte) (uint32,
func (n *Node) Setxattr(ctx context.Context, attr string, data []byte, flags uint32) syscall.Errno {
rn := n.rootNode()
flags = uint32(filterXattrSetFlags(int(flags)))
+
+ // ACLs are passed through without encryption
+ if isAcl(attr) {
+ return n.setXAttr(attr, data, flags)
+ }
+
cAttr := rn.encryptXattrName(attr)
cData := rn.encryptXattrValue(data)
return n.setXAttr(cAttr, cData, flags)
@@ -66,6 +101,12 @@ func (n *Node) Setxattr(ctx context.Context, attr string, data []byte, flags uin
// This function is symlink-safe through Fremovexattr.
func (n *Node) Removexattr(ctx context.Context, attr string) syscall.Errno {
rn := n.rootNode()
+
+ // ACLs are passed through without encryption
+ if isAcl(attr) {
+ return n.removeXAttr(attr)
+ }
+
cAttr := rn.encryptXattrName(attr)
return n.removeXAttr(cAttr)
}
@@ -81,6 +122,11 @@ func (n *Node) Listxattr(ctx context.Context, dest []byte) (uint32, syscall.Errn
rn := n.rootNode()
var buf bytes.Buffer
for _, curName := range cNames {
+ // ACLs are passed through without encryption
+ if isAcl(curName) {
+ buf.WriteString(curName + "\000")
+ continue
+ }
if !strings.HasPrefix(curName, xattrStorePrefix) {
continue
}
@@ -90,10 +136,20 @@ func (n *Node) Listxattr(ctx context.Context, dest []byte) (uint32, syscall.Errn
rn.reportMitigatedCorruption(curName)
continue
}
+ // We *used to* encrypt ACLs, which caused a lot of problems.
+ if isAcl(name) {
+ tlog.Warn.Printf("ListXAttr: ignoring deprecated encrypted ACL %q = %q", curName, name)
+ rn.reportMitigatedCorruption(curName)
+ continue
+ }
buf.WriteString(name + "\000")
}
+ // Caller passes size zero to find out how large their buffer should be
+ if len(dest) == 0 {
+ return uint32(buf.Len()), 0
+ }
if buf.Len() > len(dest) {
- return ^uint32(0), syscall.ERANGE
+ return minus1, syscall.ERANGE
}
return uint32(copy(dest, buf.Bytes())), 0
}