From 68c3a9991679702a7adc6e040e5703a7abb50b16 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christian=20G=C3=B6ttsche?= <cgzones@googlemail.com>
Date: Tue, 28 Nov 2023 19:23:32 +0100
Subject: [PATCH] libsepol: reject invalid class datums
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Internally class values are stored in multiple placed in a 16-bit wide
integer.  Reject class values exceeding the maximum representable value.
This avoids truncations in the helper
policydb_string_to_security_class(), which gets called before validation
of the policy:

    policydb.c:4082:9: runtime error: implicit conversion from type 'uint32_t' (aka 'unsigned int') of value 2113929220 (32-bit, unsigned) to type 'sepol_security_class_t' (aka 'unsigned short') changed the value to 4 (16-bit, unsigned)

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Acked-by: James Carter <jwcart2@gmail.com>
 
Reference: https://github.com/SELinuxProject/selinux/commit/68c3a9991679702a7adc6e040e5703a7abb50b16
Conflict: Context adaptation
---
 libsepol/src/policydb.c          | 2 ++
 libsepol/src/policydb_validate.c | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/libsepol/src/policydb.c b/libsepol/src/policydb.c
index 6ba4f9168..f10a8a95a 100644
--- a/libsepol/src/policydb.c
+++ b/libsepol/src/policydb.c
@@ -2250,6 +2250,8 @@ static int class_read(policydb_t * p, hashtab_t h, struct policy_file *fp)
 	if (is_saturated(len2))
 		goto bad;
 	cladatum->s.value = le32_to_cpu(buf[2]);
+	if (cladatum->s.value > UINT16_MAX)
+		goto bad;
 
 	if (symtab_init(&cladatum->permissions, PERM_SYMTAB_SIZE))
 		goto bad;
diff --git a/libsepol/src/policydb_validate.c b/libsepol/src/policydb_validate.c
index 6d8641f..69a436b 100644
--- a/libsepol/src/policydb_validate.c
+++ b/libsepol/src/policydb_validate.c
@@ -199,7 +199,7 @@ bad:
 
 static int validate_class_datum(sepol_handle_t *handle, const class_datum_t *class, validate_t flavors[])
 {
-	if (validate_value(class->s.value, &flavors[SYM_CLASSES]))
+	if (class->s.value > UINT16_MAX || validate_value(class->s.value, &flavors[SYM_CLASSES]))
 		goto bad;
 	if (class->comdatum && validate_common_datum(handle, class->comdatum, flavors))
 		goto bad;
-- 
2.33.0