hardcoresushi/libgocryptfs
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nametransform: reject all-zero dirIV

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This should never happen in normal operation and is a sign of
data corruption. Catch it early.
This commit is contained in:
Jakob Unterwurzacher 2017-05-25 14:21:55 +02:00
parent 2ce269ec63
commit 9a3f9350fe
1 changed files with 8 additions and 0 deletions
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8
internal/nametransform/diriv.go
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@ -1,6 +1,7 @@
package nametransform package nametransform
import ( import (
"bytes"
"io" "io"
"os" "os"
"path/filepath" "path/filepath"
@ -46,6 +47,9 @@ func ReadDirIVAt(dirfd *os.File) (iv []byte, err error) {
return fdReadDirIV(fd) return fdReadDirIV(fd)
} }
// allZeroDirIV is preallocated to quickly check if the data read from disk is all zero
var allZeroDirIV = make([]byte, DirIVLen)
// fdReadDirIV reads and verifies the DirIV from an opened gocryptfs.diriv file. // fdReadDirIV reads and verifies the DirIV from an opened gocryptfs.diriv file.
func fdReadDirIV(fd *os.File) (iv []byte, err error) { func fdReadDirIV(fd *os.File) (iv []byte, err error) {
// We want to detect if the file is bigger than DirIVLen, so // We want to detect if the file is bigger than DirIVLen, so
@ -61,6 +65,10 @@ func fdReadDirIV(fd *os.File) (iv []byte, err error) {
tlog.Warn.Printf("ReadDirIVAt: wanted %d bytes, got %d. Returning EINVAL.", DirIVLen, len(iv)) tlog.Warn.Printf("ReadDirIVAt: wanted %d bytes, got %d. Returning EINVAL.", DirIVLen, len(iv))
return nil, syscall.EINVAL return nil, syscall.EINVAL
} }
if bytes.Equal(iv, allZeroDirIV) {
tlog.Warn.Printf("ReadDirIVAt: diriv is all-zero. Returning EINVAL.")
return nil, syscall.EINVAL
}
return iv, nil return iv, nil
} }