[RFC PATCH] libsepol: validate permission identifier length

["Christian Göttsche" <cgzones@googlemail.com>]

Limit the maximum length of permission identifiers.  Otherwise
formatting an access vector might fail in the common used helper
sepol_av_to_string().

The current longest permission within the Reference Policy is
x_application_data { paste_after_confirm } with a length of 19.

Reported-by: oss-fuzz (issue 64832)
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
---
The oss-fuzz issue got closed by the latest fuzzer updates (due to
unrelated changes that invalid the current reproducer), but the issue is
still valid.
---
 libsepol/src/policydb_validate.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/libsepol/src/policydb_validate.c b/libsepol/src/policydb_validate.c
index bd8e9f8f..72681120 100644
--- a/libsepol/src/policydb_validate.c
+++ b/libsepol/src/policydb_validate.c
@@ -366,12 +366,30 @@ bad:
 	return -1;
 }
 
+static int validate_permission_wrapper(hashtab_key_t k, __attribute__((unused)) hashtab_datum_t d, void *args)
+{
+	sepol_handle_t *handle = args;
+	const char *name = k;
+	size_t len = strlen(name);
+
+	if (len == 0 || len >= 32)
+		goto bad;
+
+	return 0;
+
+bad:
+	ERR(handle, "Invalid permission");
+	return -1;
+}
+
 static int validate_common_datum(sepol_handle_t *handle, const common_datum_t *common, validate_t flavors[])
 {
 	if (validate_value(common->s.value, &flavors[SYM_COMMONS]))
 		goto bad;
 	if (common->permissions.table->nel == 0 || common->permissions.nprim > PERM_SYMTAB_SIZE)
 		goto bad;
+	if (hashtab_map(common->permissions.table, validate_permission_wrapper, handle))
+		goto bad;
 
 	return 0;
 
@@ -395,6 +413,8 @@ static int validate_class_datum(sepol_handle_t *handle, const class_datum_t *cla
 		goto bad;
 	if (class->permissions.nprim > PERM_SYMTAB_SIZE)
 		goto bad;
+	if (hashtab_map(class->permissions.table, validate_permission_wrapper, handle))
+		goto bad;
 	if (validate_constraint_nodes(handle, class->permissions.nprim, class->constraints, flavors))
 		goto bad;
 	if (validate_constraint_nodes(handle, 0, class->validatetrans, flavors))
-- 
2.43.0