linux-kernel - [PATCH v3 1/7] selinux: avoid implicit conversions in avtab code

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Message-Id: <20230807171143.208481-7-cgzones@googlemail.com>
Date:   Mon,  7 Aug 2023 19:11:42 +0200
From:   Christian Göttsche <cgzones@...glemail.com>
To:     selinux@...r.kernel.org
Cc:     Paul Moore <paul@...l-moore.com>,
        Stephen Smalley <stephen.smalley.work@...il.com>,
        Eric Paris <eparis@...isplace.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 1/7] selinux: avoid implicit conversions in avtab code

Return u32 from avtab_hash() instead of int, since the hashing is done
on u32 and the result is used as an index on the hash array.

Use the type of the limit in for loops.

Avoid signed to unsigned conversion of multiplication result in
avtab_hash_eval() and perform multiplication in destination type.

Use unsigned loop iterator for index operations, to avoid sign
extension.

Signed-off-by: Christian Göttsche <cgzones@...glemail.com>
---
v3:
  - use fixed sized counters in avtab_hash_eval()
  - perform multiplication in avtab_hash_eval() in destination type
v2: avoid declarations in init-clauses of for loops
---
 security/selinux/ss/avtab.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/security/selinux/ss/avtab.c b/security/selinux/ss/avtab.c
index 243e5dabfa86..86d98a8e291b 100644
--- a/security/selinux/ss/avtab.c
+++ b/security/selinux/ss/avtab.c
@@ -29,7 +29,7 @@ static struct kmem_cache *avtab_xperms_cachep __ro_after_init;
 /* Based on MurmurHash3, written by Austin Appleby and placed in the
  * public domain.
  */
-static inline int avtab_hash(const struct avtab_key *keyp, u32 mask)
+static inline u32 avtab_hash(const struct avtab_key *keyp, u32 mask)
 {
 	static const u32 c1 = 0xcc9e2d51;
 	static const u32 c2 = 0x1b873593;
@@ -66,7 +66,7 @@ static inline int avtab_hash(const struct avtab_key *keyp, u32 mask)
 }
 
 static struct avtab_node*
-avtab_insert_node(struct avtab *h, int hvalue,
+avtab_insert_node(struct avtab *h, u32 hvalue,
 		  struct avtab_node *prev,
 		  const struct avtab_key *key, const struct avtab_datum *datum)
 {
@@ -106,7 +106,7 @@ avtab_insert_node(struct avtab *h, int hvalue,
 static int avtab_insert(struct avtab *h, const struct avtab_key *key,
 			const struct avtab_datum *datum)
 {
-	int hvalue;
+	u32 hvalue;
 	struct avtab_node *prev, *cur, *newnode;
 	u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
 
@@ -152,7 +152,7 @@ struct avtab_node *avtab_insert_nonunique(struct avtab *h,
 					  const struct avtab_key *key,
 					  const struct avtab_datum *datum)
 {
-	int hvalue;
+	u32 hvalue;
 	struct avtab_node *prev, *cur;
 	u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
 
@@ -186,7 +186,7 @@ struct avtab_node *avtab_insert_nonunique(struct avtab *h,
 struct avtab_node *avtab_search_node(struct avtab *h,
 				     const struct avtab_key *key)
 {
-	int hvalue;
+	u32 hvalue;
 	struct avtab_node *cur;
 	u16 specified = key->specified & ~(AVTAB_ENABLED|AVTAB_ENABLED_OLD);
 
@@ -246,7 +246,7 @@ avtab_search_node_next(struct avtab_node *node, u16 specified)
 
 void avtab_destroy(struct avtab *h)
 {
-	int i;
+	u32 i;
 	struct avtab_node *cur, *temp;
 
 	if (!h)
@@ -325,7 +325,7 @@ int avtab_alloc_dup(struct avtab *new, const struct avtab *orig)
 #ifdef CONFIG_SECURITY_SELINUX_DEBUG
 void avtab_hash_eval(struct avtab *h, const char *tag)
 {
-	int i, chain_len, slots_used, max_chain_len;
+	u32 i, chain_len, slots_used, max_chain_len;
 	unsigned long long chain2_len_sum;
 	struct avtab_node *cur;
 
@@ -344,7 +344,7 @@ void avtab_hash_eval(struct avtab *h, const char *tag)
 
 			if (chain_len > max_chain_len)
 				max_chain_len = chain_len;
-			chain2_len_sum += chain_len * chain_len;
+			chain2_len_sum += (unsigned long long)chain_len * chain_len;
 		}
 	}
 
@@ -374,13 +374,13 @@ int avtab_read_item(struct avtab *a, void *fp, struct policydb *pol,
 {
 	__le16 buf16[4];
 	u16 enabled;
-	u32 items, items2, val, vers = pol->policyvers;
+	u32 items, items2, val, i;
 	struct avtab_key key;
 	struct avtab_datum datum;
 	struct avtab_extended_perms xperms;
 	__le32 buf32[ARRAY_SIZE(xperms.perms.p)];
-	int i, rc;
-	unsigned set;
+	int rc;
+	unsigned int set, vers = pol->policyvers;
 
 	memset(&key, 0, sizeof(struct avtab_key));
 	memset(&datum, 0, sizeof(struct avtab_datum));
@@ -616,7 +616,7 @@ int avtab_write_item(struct policydb *p, const struct avtab_node *cur, void *fp)
 
 int avtab_write(struct policydb *p, struct avtab *a, void *fp)
 {
-	unsigned int i;
+	u32 i;
 	int rc = 0;
 	struct avtab_node *cur;
 	__le32 buf[1];
-- 
2.40.1