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authorJakob Unterwurzacher2018-01-17 20:52:52 +0100
committerJakob Unterwurzacher2018-01-17 20:54:05 +0100
commit959e1fc1e2f531480ad1353179fc94f56ff76dce (patch)
tree42f4646f9b3f1a30414451a8942aeda5547bd0f8 /internal/fusefrontend_reverse
parent8951eb2472d6af50554806df2ffd655f53da8bfe (diff)
fusefrontend_reverse: use OpenNofollow in findLongnameParent
Protects findLongnameParent against symlink races. Also add comments to several functions along the way. Reported at https://github.com/rfjakob/gocryptfs/issues/165
Diffstat (limited to 'internal/fusefrontend_reverse')
-rw-r--r--internal/fusefrontend_reverse/reverse_longnames.go22
-rw-r--r--internal/fusefrontend_reverse/rpath.go5
-rw-r--r--internal/fusefrontend_reverse/rpath_cache.go7
3 files changed, 25 insertions, 9 deletions
diff --git a/internal/fusefrontend_reverse/reverse_longnames.go b/internal/fusefrontend_reverse/reverse_longnames.go
index 2b4324e..4ddff2b 100644
--- a/internal/fusefrontend_reverse/reverse_longnames.go
+++ b/internal/fusefrontend_reverse/reverse_longnames.go
@@ -2,7 +2,6 @@ package fusefrontend_reverse
import (
"log"
- "os"
"path/filepath"
"sync"
"syscall"
@@ -13,6 +12,7 @@ import (
"github.com/rfjakob/gocryptfs/internal/nametransform"
"github.com/rfjakob/gocryptfs/internal/pathiv"
+ "github.com/rfjakob/gocryptfs/internal/syscallcompat"
"github.com/rfjakob/gocryptfs/internal/tlog"
)
@@ -27,6 +27,9 @@ const (
shortNameMax = 175
)
+// longnameParentCache maps dir+"/"+longname to plaintextname.
+// Yes, the combination of relative plaintext dir path and encrypted
+// longname is strange, but works fine as a map index.
var longnameParentCache map[string]string
var longnameCacheLock sync.Mutex
@@ -48,7 +51,9 @@ func initLongnameCache() {
go longnameCacheCleaner()
}
-// findLongnameParent converts "gocryptfs.longname.XYZ" to the plaintext name
+// findLongnameParent converts "longname" = "gocryptfs.longname.XYZ" to the
+// plaintext name. "dir" = relative plaintext path to the directory the
+// longname file is in, "dirIV" = directory IV of the directory.
func (rfs *ReverseFS) findLongnameParent(dir string, dirIV []byte, longname string) (plaintextName string, err error) {
longnameCacheLock.Lock()
hit := longnameParentCache[dir+"/"+longname]
@@ -56,26 +61,27 @@ func (rfs *ReverseFS) findLongnameParent(dir string, dirIV []byte, longname stri
if hit != "" {
return hit, nil
}
- absDir := filepath.Join(rfs.args.Cipherdir, dir)
- dirfd, err := os.Open(absDir)
+ fd, err := syscallcompat.OpenNofollow(rfs.args.Cipherdir, dir, syscall.O_RDONLY|syscall.O_DIRECTORY, 0)
if err != nil {
tlog.Warn.Printf("findLongnameParent: opendir failed: %v\n", err)
return "", err
}
- dirEntries, err := dirfd.Readdirnames(-1)
- dirfd.Close()
+ dirEntries, err := syscallcompat.Getdents(fd)
+ syscall.Close(fd)
if err != nil {
- tlog.Warn.Printf("findLongnameParent: Readdirnames failed: %v\n", err)
+ tlog.Warn.Printf("findLongnameParent: Getdents failed: %v\n", err)
return "", err
}
longnameCacheLock.Lock()
defer longnameCacheLock.Unlock()
- for _, plaintextName = range dirEntries {
+ for _, entry := range dirEntries {
+ plaintextName := entry.Name
if len(plaintextName) <= shortNameMax {
continue
}
cName := rfs.nameTransform.EncryptName(plaintextName, dirIV)
if len(cName) <= syscall.NAME_MAX {
+ // Entry should have been skipped by the "continue" above
log.Panic("logic error or wrong shortNameMax constant?")
}
hName := rfs.nameTransform.HashLongName(cName)
diff --git a/internal/fusefrontend_reverse/rpath.go b/internal/fusefrontend_reverse/rpath.go
index 2dc76e1..b783686 100644
--- a/internal/fusefrontend_reverse/rpath.go
+++ b/internal/fusefrontend_reverse/rpath.go
@@ -24,6 +24,9 @@ func (rfs *ReverseFS) abs(relPath string, err error) (string, error) {
return filepath.Join(rfs.args.Cipherdir, relPath), nil
}
+// rDecryptName decrypts the ciphertext name "cName", given the dirIV of the
+// directory "cName" lies in. The relative plaintext path to the directory
+// "pDir" is used if a "gocryptfs.longname.XYZ.name" must be resolved.
func (rfs *ReverseFS) rDecryptName(cName string, dirIV []byte, pDir string) (pName string, err error) {
nameType := nametransform.NameType(cName)
if nameType == nametransform.LongNameNone {
@@ -58,6 +61,8 @@ func (rfs *ReverseFS) rDecryptName(cName string, dirIV []byte, pDir string) (pNa
return pName, nil
}
+// decryptPath decrypts a relative ciphertext path to a relative plaintext
+// path.
func (rfs *ReverseFS) decryptPath(relPath string) (string, error) {
if rfs.args.PlaintextNames || relPath == "" {
return relPath, nil
diff --git a/internal/fusefrontend_reverse/rpath_cache.go b/internal/fusefrontend_reverse/rpath_cache.go
index f90b357..221f578 100644
--- a/internal/fusefrontend_reverse/rpath_cache.go
+++ b/internal/fusefrontend_reverse/rpath_cache.go
@@ -17,6 +17,8 @@ type rPathCacheContainer struct {
dirIV []byte
}
+// lookup relative ciphertext path "cPath". Returns dirIV, relative
+// plaintext path.
func (c *rPathCacheContainer) lookup(cPath string) ([]byte, string) {
c.Lock()
defer c.Unlock()
@@ -28,7 +30,9 @@ func (c *rPathCacheContainer) lookup(cPath string) ([]byte, string) {
return nil, ""
}
-// store - write entry for "cPath" into the cache
+// store - write entry for the directory at relative ciphertext path "cPath"
+// into the cache.
+// "dirIV" = directory IV of the directory, "pPath" = relative plaintext path
func (c *rPathCacheContainer) store(cPath string, dirIV []byte, pPath string) {
c.Lock()
defer c.Unlock()
@@ -37,4 +41,5 @@ func (c *rPathCacheContainer) store(cPath string, dirIV []byte, pPath string) {
c.pPath = pPath
}
+// rPathCache: see rPathCacheContainer above for a detailed description
var rPathCache rPathCacheContainer