Merge tag 'selinux-pr-20231030' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:

 - improve the SELinux debugging configuration controls in Kconfig

 - print additional information about the hash table chain lengths when
   when printing SELinux debugging information

 - simplify the SELinux access vector hash table calcaulations

 - use a better hashing function for the SELinux role tansition hash
   table

 - improve SELinux load policy time through the use of optimized
   functions for calculating the number of bits set in a field

 - addition of a __counted_by annotation

 - simplify the avtab_inert_node() function through a simplified
   prototype

* tag 'selinux-pr-20231030' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: simplify avtab_insert_node() prototype
  selinux: hweight optimization in avtab_read_item
  selinux: improve role transition hashing
  selinux: simplify avtab slot calculation
  selinux: improve debug configuration
  selinux: print sum of chain lengths^2 for hash tables
  selinux: Annotate struct sidtab_str_cache with __counted_by

Author: torvalds

security/selinux/Kconfig

@@ -77,3 +77,13 @@ config SECURITY_SELINUX_DEBUG
 	  This enables debugging code designed to help SELinux kernel
 	  developers, unless you know what this does in the kernel code you
 	  should leave this disabled.
+
+	  To fine control the messages to be printed enable
+	  CONFIG_DYNAMIC_DEBUG and see
+	  Documentation/admin-guide/dynamic-debug-howto.rst for additional
+	  information.
+
+	  Example usage:
+
+		echo -n 'file "security/selinux/*" +p' > \
+			/proc/dynamic_debug/control

security/selinux/Makefile

@@ -12,6 +12,8 @@ obj-$(CONFIG_SECURITY_SELINUX) := selinux.o
 
 ccflags-y := -I$(srctree)/security/selinux -I$(srctree)/security/selinux/include
 
+ccflags-$(CONFIG_SECURITY_SELINUX_DEBUG) += -DDEBUG
+
 selinux-y := avc.o hooks.o selinuxfs.o netlink.o nlmsgtab.o netif.o \
 	     netnode.o netport.o status.o \
 	     ss/ebitmap.o ss/hashtab.o ss/symtab.o ss/sidtab.o ss/avtab.o \

security/selinux/ss/avtab.c

@@ -17,6 +17,7 @@
  *	Tuned number of hash slots for avtab to reduce memory usage
  */
 
+#include <linux/bitops.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/errno.h>
@@ -66,8 +67,7 @@ static inline u32 avtab_hash(const struct avtab_key *keyp, u32 mask)
 }
 
 static struct avtab_node*
-avtab_insert_node(struct avtab *h, u32 hvalue,
-		  struct avtab_node *prev,
+avtab_insert_node(struct avtab *h, struct avtab_node **dst,
 		  const struct avtab_key *key, const struct avtab_datum *datum)
 {
 	struct avtab_node *newnode;
@@ -89,15 +89,8 @@ avtab_insert_node(struct avtab *h, u32 hvalue,
 		newnode->datum.u.data = datum->u.data;
 	}
 
-	if (prev) {
-		newnode->next = prev->next;
-		prev->next = newnode;
-	} else {
-		struct avtab_node **n = &h->htable[hvalue];
-
-		newnode->next = *n;
-		*n = newnode;
-	}
+	newnode->next = *dst;
+	*dst = newnode;
 
 	h->nel++;
 	return newnode;
@@ -137,7 +130,8 @@ static int avtab_insert(struct avtab *h, const struct avtab_key *key,
 			break;
 	}
 
-	newnode = avtab_insert_node(h, hvalue, prev, key, datum);
+	newnode = avtab_insert_node(h, prev ? &prev->next : &h->htable[hvalue],
+				    key, datum);
 	if (!newnode)
 		return -ENOMEM;
 
@@ -177,7 +171,8 @@ struct avtab_node *avtab_insert_nonunique(struct avtab *h,
 		    key->target_class < cur->key.target_class)
 			break;
 	}
-	return avtab_insert_node(h, hvalue, prev, key, datum);
+	return avtab_insert_node(h, prev ? &prev->next : &h->htable[hvalue],
+				 key, datum);
 }
 
 /* This search function returns a node pointer, and can be used in
@@ -298,13 +293,7 @@ int avtab_alloc(struct avtab *h, u32 nrules)
 	u32 nslot = 0;
 
 	if (nrules != 0) {
-		u32 shift = 1;
-		u32 work = nrules >> 3;
-		while (work) {
-			work >>= 1;
-			shift++;
-		}
-		nslot = 1 << shift;
+		nslot = nrules > 3 ? rounddown_pow_of_two(nrules / 2) : 2;
 		if (nslot > MAX_AVTAB_HASH_BUCKETS)
 			nslot = MAX_AVTAB_HASH_BUCKETS;
 
@@ -349,7 +338,7 @@ void avtab_hash_eval(struct avtab *h, const char *tag)
 	}
 
 	pr_debug("SELinux: %s:  %d entries and %d/%d buckets used, "
-	       "longest chain length %d sum of chain length^2 %llu\n",
+	       "longest chain length %d, sum of chain length^2 %llu\n",
 	       tag, h->nel, slots_used, h->nslot, max_chain_len,
 	       chain2_len_sum);
 }
@@ -477,11 +466,7 @@ int avtab_read_item(struct avtab *a, void *fp, struct policydb *pol,
 		return -EINVAL;
 	}
 
-	set = 0;
-	for (i = 0; i < ARRAY_SIZE(spec_order); i++) {
-		if (key.specified & spec_order[i])
-			set++;
-	}
+	set = hweight16(key.specified & (AVTAB_XPERMS | AVTAB_TYPE | AVTAB_AV));
 	if (!set || set > 1) {
 		pr_err("SELinux:  avtab:  more than one specifier\n");
 		return -EINVAL;

security/selinux/ss/hashtab.c

@@ -107,10 +107,12 @@ int hashtab_map(struct hashtab *h,
 void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
 {
 	u32 i, chain_len, slots_used, max_chain_len;
+	u64 chain2_len_sum;
 	struct hashtab_node *cur;
 
 	slots_used = 0;
 	max_chain_len = 0;
+	chain2_len_sum = 0;
 	for (i = 0; i < h->size; i++) {
 		cur = h->htable[i];
 		if (cur) {
@@ -123,11 +125,14 @@ void hashtab_stat(struct hashtab *h, struct hashtab_info *info)
 
 			if (chain_len > max_chain_len)
 				max_chain_len = chain_len;
+
+			chain2_len_sum += (u64)chain_len * chain_len;
 		}
 	}
 
 	info->slots_used = slots_used;
 	info->max_chain_len = max_chain_len;
+	info->chain2_len_sum = chain2_len_sum;
 }
 #endif /* CONFIG_SECURITY_SELINUX_DEBUG */
 

security/selinux/ss/hashtab.h

@@ -38,6 +38,7 @@ struct hashtab {
 struct hashtab_info {
 	u32 slots_used;
 	u32 max_chain_len;
+	u64 chain2_len_sum;
 };
 
 /*

security/selinux/ss/policydb.c

@@ -491,7 +491,7 @@ static u32 role_trans_hash(const void *k)
 {
 	const struct role_trans_key *key = k;
 
-	return key->role + (key->type << 3) + (key->tclass << 5);
+	return jhash_3words(key->role, key->type, (u32)key->tclass << 16 | key->tclass, 0);
 }
 
 static int role_trans_cmp(const void *k1, const void *k2)
@@ -684,9 +684,9 @@ static void hash_eval(struct hashtab *h, const char *hash_name)
 	struct hashtab_info info;
 
 	hashtab_stat(h, &info);
-	pr_debug("SELinux: %s:  %d entries and %d/%d buckets used, longest chain length %d\n",
+	pr_debug("SELinux: %s:  %d entries and %d/%d buckets used, longest chain length %d, sum of chain length^2 %llu\n",
 		 hash_name, h->nel, info.slots_used, h->size,
-		 info.max_chain_len);
+		 info.max_chain_len, info.chain2_len_sum);
 }
 
 static void symtab_hash_eval(struct symtab *s)

security/selinux/ss/sidtab.c

@@ -25,7 +25,7 @@ struct sidtab_str_cache {
 	struct list_head lru_member;
 	struct sidtab_entry *parent;
 	u32 len;
-	char str[];
+	char str[] __counted_by(len);
 };
 
 #define index_to_sid(index) ((index) + SECINITSID_NUM + 1)