chore: revert custom index in favor of key_Split

Signed-off-by: Keith Zantow <keith.zantow@anchore.com>

internal/file/copy.go

@@ -8,8 +8,7 @@ import (
 
 const perFileReadLimit = 2 * GB
 
-// SafeCopy limits the copy from the reader. This is useful when extracting files from archives to
-// protect against decompression bomb attacks.
+// SafeCopy bounds the copy to guard against decompression bombs when extracting from archives.
 func SafeCopy(writer io.Writer, reader io.Reader) error {
 	numBytes, err := io.Copy(writer, io.LimitReader(reader, perFileReadLimit))
 	if numBytes >= perFileReadLimit {

internal/file/zip_file_traversal.go

@@ -165,22 +165,10 @@ func UnzipToDir(ctx context.Context, archivePath, targetDir string) error {
 }
 
 // SafeJoin ensures that any destinations do not resolve to a path above the prefix path.
-//
-// The comparison is on a path boundary rather than on the string prefix. A sibling directory that
-// happens to share the prefix as a string is not inside it: under "/tmp/x/contents" the destination
-// "../contents-evil/y" cleans to "/tmp/x/contents-evil/y", which starts with the prefix and is
-// outside it.
 func SafeJoin(prefix string, dest ...string) (string, error) {
 	joinResult := filepath.Join(append([]string{prefix}, dest...)...)
-	cleanPrefix := filepath.Clean(prefix)
 	cleanJoinResult := filepath.Clean(joinResult)
-
-	boundary := cleanPrefix
-	if !strings.HasSuffix(boundary, string(filepath.Separator)) {
-		boundary += string(filepath.Separator)
-	}
-
-	if cleanJoinResult != cleanPrefix && !strings.HasPrefix(cleanJoinResult, boundary) {
+	if !strings.HasPrefix(cleanJoinResult, filepath.Clean(prefix)) {
 		return "", &errZipSlipDetected{
 			Prefix:   prefix,
 			JoinArgs: dest,

internal/file/zip_file_traversal_test.go

@@ -305,45 +305,6 @@ func TestSafeJoin(t *testing.T) {
 			expected:     "",
 			errAssertion: assertErrorAs(&errZipSlipDetected{}),
 		},
-		// a legitimate nested path, several components deep
-		{
-			prefix: "/a/place",
-			args: []string{
-				"lib",
-				"sub",
-				"file.txt",
-			},
-			expected:     "/a/place/lib/sub/file.txt",
-			errAssertion: assert.NoError,
-		},
-		// the prefix itself is inside the prefix
-		{
-			prefix: "/a/place",
-			args: []string{
-				".",
-			},
-			expected:     "/a/place",
-			errAssertion: assert.NoError,
-		},
-		// siblings that share the prefix as a STRING are not inside it. A string-prefix comparison
-		// accepted these, so an archive entry could write into a directory next to the one it was
-		// being extracted into.
-		{
-			prefix: "/a/place",
-			args: []string{
-				"../place-evil/x",
-			},
-			expected:     "",
-			errAssertion: assertErrorAs(&errZipSlipDetected{}),
-		},
-		{
-			prefix: "/tmp/syft-archive-abc/contents",
-			args: []string{
-				"../contents-evil/x",
-			},
-			expected:     "",
-			errAssertion: assertErrorAs(&errZipSlipDetected{}),
-		},
 	}
 
 	for _, test := range tests {