[07/13] xfs_scrub: store bad flags with the name entry

Commit Message

Darrick J. Wong Dec. 31, 2023, 10:46 p.m. UTC

From: Darrick J. Wong <[e-mail]>

When scrub is checking unicode names, there are certain properties of
the directory/attribute/label name itself that it can complain about.
Store these in struct name_entry so that the confusable names detector
can pick this up later.

This restructuring enables a subsequent patch to detect suspicious
sequences in the NFC normalized form of the name without needing to hang
on to that NFC form until the end of processing.  IOWs, it's a memory
usage optimization.

Signed-off-by: Darrick J. Wong <[e-mail]>
---
 scrub/unicrash.c |  122 ++++++++++++++++++++++++++++--------------------------
 1 file changed, 64 insertions(+), 58 deletions(-)

Patch

diff --git a/scrub/unicrash.c b/scrub/unicrash.c
index 385e42c6acc..a770d0d7aae 100644
--- a/scrub/unicrash.c
+++ b/scrub/unicrash.c
@@ -69,6 +69,9 @@  struct name_entry {
 
 	xfs_ino_t		ino;
 
+	/* Everything that we don't like about this name. */
+	unsigned int		badflags;
+
 	/* Raw dirent name */
 	size_t			namelen;
 	char			name[0];
@@ -274,6 +277,55 @@  name_entry_compute_checknames(
 	return false;
 }
 
+/*
+ * Check a name for suspicious elements that have appeared in filename
+ * spoofing attacks.  This includes names that mixed directions or contain
+ * direction overrides control characters, both of which have appeared in
+ * filename spoofing attacks.
+ */
+static unsigned int
+name_entry_examine(
+	const struct name_entry	*entry)
+{
+	UCharIterator		uiter;
+	UChar32			uchr;
+	uint8_t			mask = 0;
+	unsigned int		ret = 0;
+
+	uiter_setString(&uiter, entry->normstr, entry->normstrlen);
+	while ((uchr = uiter_next32(&uiter)) != U_SENTINEL) {
+	/* characters are invisible */
+		if (is_nonrendering(uchr))
+			ret |= UNICRASH_ZERO_WIDTH;
+
+		/* control characters */
+		if (u_iscntrl(uchr))
+			ret |= UNICRASH_CONTROL_CHAR;
+
+		switch (u_charDirection(uchr)) {
+		case U_LEFT_TO_RIGHT:
+			mask |= 0x01;
+			break;
+		case U_RIGHT_TO_LEFT:
+			mask |= 0x02;
+			break;
+		case U_RIGHT_TO_LEFT_OVERRIDE:
+			ret |= UNICRASH_BIDI_OVERRIDE;
+			break;
+		case U_LEFT_TO_RIGHT_OVERRIDE:
+			ret |= UNICRASH_BIDI_OVERRIDE;
+			break;
+		default:
+			break;
+		}
+	}
+
+	/* mixing left-to-right and right-to-left chars */
+	if (mask == 0x3)
+		ret |= UNICRASH_BIDI_MIXED;
+	return ret;
+}
+
 /* Create a new name entry, returns false if we could not succeed. */
 static bool
 name_entry_create(
@@ -299,6 +351,7 @@  name_entry_create(
 	if (!name_entry_compute_checknames(uc, new_entry))
 		goto out;
 
+	new_entry->badflags = name_entry_examine(new_entry);
 	*entry = new_entry;
 	return true;
 
@@ -360,54 +413,6 @@  name_entry_hash(
 	}
 }
 
-/*
- * Check a name for suspicious elements that have appeared in filename
- * spoofing attacks.  This includes names that mixed directions or contain
- * direction overrides control characters, both of which have appeared in
- * filename spoofing attacks.
- */
-static void
-name_entry_examine(
-	struct name_entry	*entry,
-	unsigned int		*badflags)
-{
-	UCharIterator		uiter;
-	UChar32			uchr;
-	uint8_t			mask = 0;
-
-	uiter_setString(&uiter, entry->normstr, entry->normstrlen);
-	while ((uchr = uiter_next32(&uiter)) != U_SENTINEL) {
-		/* characters are invisible */
-		if (is_nonrendering(uchr))
-			*badflags |= UNICRASH_ZERO_WIDTH;
-
-		/* control characters */
-		if (u_iscntrl(uchr))
-			*badflags |= UNICRASH_CONTROL_CHAR;
-
-		switch (u_charDirection(uchr)) {
-		case U_LEFT_TO_RIGHT:
-			mask |= 0x01;
-			break;
-		case U_RIGHT_TO_LEFT:
-			mask |= 0x02;
-			break;
-		case U_RIGHT_TO_LEFT_OVERRIDE:
-			*badflags |= UNICRASH_BIDI_OVERRIDE;
-			break;
-		case U_LEFT_TO_RIGHT_OVERRIDE:
-			*badflags |= UNICRASH_BIDI_OVERRIDE;
-			break;
-		default:
-			break;
-		}
-	}
-
-	/* mixing left-to-right and right-to-left chars */
-	if (mask == 0x3)
-		*badflags |= UNICRASH_BIDI_MIXED;
-}
-
 /* Initialize the collision detector. */
 static int
 unicrash_init(
@@ -638,17 +643,17 @@  _("Unicode name \"%s\" in %s could be confused with \"%s\"."),
  * must be skeletonized according to Unicode TR39 to detect names that
  * could be visually confused with each other.
  */
-static void
+static unsigned int
 unicrash_add(
 	struct unicrash		*uc,
 	struct name_entry	**new_entryp,
-	unsigned int		*badflags,
 	struct name_entry	**existing_entry)
 {
 	struct name_entry	*new_entry = *new_entryp;
 	struct name_entry	*entry;
 	size_t			bucket;
 	xfs_dahash_t		hash;
+	unsigned int		badflags = new_entry->badflags;
 
 	/* Store name in hashtable. */
 	hash = name_entry_hash(new_entry);
@@ -669,28 +674,30 @@  unicrash_add(
 			uc->buckets[bucket] = new_entry->next;
 			name_entry_free(new_entry);
 			*new_entryp = NULL;
-			return;
+			return 0;
 		}
 
 		/* Same normalization? */
 		if (new_entry->normstrlen == entry->normstrlen &&
 		    !u_strcmp(new_entry->normstr, entry->normstr) &&
 		    (uc->compare_ino ? entry->ino != new_entry->ino : true)) {
-			*badflags |= UNICRASH_NOT_UNIQUE;
+			badflags |= UNICRASH_NOT_UNIQUE;
 			*existing_entry = entry;
-			return;
+			break;
 		}
 
 		/* Confusable? */
 		if (new_entry->skelstrlen == entry->skelstrlen &&
 		    !u_strcmp(new_entry->skelstr, entry->skelstr) &&
 		    (uc->compare_ino ? entry->ino != new_entry->ino : true)) {
-			*badflags |= UNICRASH_CONFUSABLE;
+			badflags |= UNICRASH_CONFUSABLE;
 			*existing_entry = entry;
-			return;
+			break;
 		}
 		entry = entry->next;
 	}
+
+	return badflags;
 }
 
 /* Check a name for unicode normalization problems or collisions. */
@@ -704,14 +711,13 @@  __unicrash_check_name(
 {
 	struct name_entry	*dup_entry = NULL;
 	struct name_entry	*new_entry = NULL;
-	unsigned int		badflags = 0;
+	unsigned int		badflags;
 
 	/* If we can't create entry data, just skip it. */
 	if (!name_entry_create(uc, name, ino, &new_entry))
 		return 0;
 
-	name_entry_examine(new_entry, &badflags);
-	unicrash_add(uc, &new_entry, &badflags, &dup_entry);
+	badflags = unicrash_add(uc, &new_entry, &dup_entry);
 	if (new_entry && badflags)
 		unicrash_complain(uc, dsc, namedescr, new_entry, badflags,
 				dup_entry);