Instead allocate hash tables with just the right size based on the
actual number of elements (which is almost always known beforehand, we
just need to defer the hashtab allocation to the right time). The only
case when we don't know the size (with the current policy format) is the
new filename transitions hashtable. Here I just left the existing value.
After this patch, the time to load Fedora policy on x86_64 decreases
from 950 ms to 220 ms. If the unconfined module is removed, it decreases
from 870 ms to 170 ms. It is also likely that other operations are going
to be faster, mainly string_to_context_struct() or mls_compute_sid(),
but I didn't try to quantify that.
The memory usage increases a bit after this patch, but only by ~1-2 MB
(it is hard to measure precisely). I believe it is a small price to pay
for the increased performance.
Signed-off-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
---
Changed in v2:
- guard against h->size == 0 in hashtab_search() and hashtab_insert()
security/selinux/ss/hashtab.c | 25 +++++++++++++---
security/selinux/ss/hashtab.h | 2 +-
security/selinux/ss/policydb.c | 53 +++++++++++++---------------------
security/selinux/ss/policydb.h | 2 --
4 files changed, 42 insertions(+), 40 deletions(-)
diff --git a/security/selinux/ss/hashtab.c b/security/selinux/ss/hashtab.c
index ebfdaa31ee32..87ad83148cbd 100644
--- a/security/selinux/ss/hashtab.c
+++ b/security/selinux/ss/hashtab.c
@@ -12,12 +12,26 @@
static struct kmem_cache *hashtab_node_cachep;
+static u32 hashtab_compute_size(u32 nel)
+{
+ u32 size;
+
+ if (nel <= 2)
+ return nel;
+
+ /* use the nearest power of two to balance size and access time */
+ size = roundup_pow_of_two(nel);
+ if (size - nel > size / 4)
+ size /= 2;
+ return size;
+}
+
struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void *key),
int (*keycmp)(struct hashtab *h, const void *key1, const void *key2),
- u32 size)
+ u32 nel_hint)
{
struct hashtab *p;
- u32 i;
+ u32 i, size = hashtab_compute_size(nel_hint);
p = kzalloc(sizeof(*p), GFP_KERNEL);
if (!p)
@@ -27,6 +41,9 @@ struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void *
p->nel = 0;
p->hash_value = hash_value;
p->keycmp = keycmp;
+ if (!size)
+ return p;
+
p->htable = kmalloc_array(size, sizeof(*p->htable), GFP_KERNEL);
if (!p->htable) {
kfree(p);
@@ -46,7 +63,7 @@ int hashtab_insert(struct hashtab *h, void *key, void *datum)
cond_resched();
- if (!h || h->nel == HASHTAB_MAX_NODES)
+ if (!h || !h->size || h->nel == HASHTAB_MAX_NODES)
return -EINVAL;
hvalue = h->hash_value(h, key);
@@ -82,7 +99,7 @@ void *hashtab_search(struct hashtab *h, const void *key)
u32 hvalue;
struct hashtab_node *cur;
- if (!h)
+ if (!h || !h->size)
return NULL;
hvalue = h->hash_value(h, key);
diff --git a/security/selinux/ss/hashtab.h b/security/selinux/ss/hashtab.h
index 3e3e42bfd150..dde54d9ff01c 100644
--- a/security/selinux/ss/hashtab.h
+++ b/security/selinux/ss/hashtab.h
@@ -42,7 +42,7 @@ struct hashtab_info {
*/
struct hashtab *hashtab_create(u32 (*hash_value)(struct hashtab *h, const void *key),
int (*keycmp)(struct hashtab *h, const void *key1, const void *key2),
- u32 size);
+ u32 nel_hint);
/*
* Inserts the specified (key, datum) pair into the specified hash table.
diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
index 32b3a8acf96f..7ca8c74efba3 100644
--- a/security/selinux/ss/policydb.c
+++ b/security/selinux/ss/policydb.c
@@ -56,17 +56,6 @@ static const char *symtab_name[SYM_NUM] = {
};
#endif
-static unsigned int symtab_sizes[SYM_NUM] = {
- 2,
- 32,
- 16,
- 512,
- 128,
- 16,
- 16,
- 16,
-};
-
struct policydb_compat_info {
int version;
int sym_num;
@@ -478,20 +467,10 @@ static int policydb_init(struct policydb *p)
memset(p, 0, sizeof(*p));
- for (i = 0; i < SYM_NUM; i++) {
- rc = symtab_init(&p->symtab[i], symtab_sizes[i]);
- if (rc)
- goto out;
- }
-
rc = avtab_init(&p->te_avtab);
if (rc)
goto out;
- rc = roles_init(p);
- if (rc)
- goto out;
-
rc = cond_policydb_init(p);
if (rc)
goto out;
@@ -503,20 +482,12 @@ static int policydb_init(struct policydb *p)
goto out;
}
- p->range_tr = hashtab_create(rangetr_hash, rangetr_cmp, 256);
- if (!p->range_tr) {
- rc = -ENOMEM;
- goto out;
- }
-
ebitmap_init(&p->filename_trans_ttypes);
ebitmap_init(&p->policycaps);
ebitmap_init(&p->permissive_map);
return 0;
out:
- hashtab_destroy(p->filename_trans);
- hashtab_destroy(p->range_tr);
for (i = 0; i < SYM_NUM; i++) {
hashtab_map(p->symtab[i].table, destroy_f[i], NULL);
hashtab_destroy(p->symtab[i].table);
@@ -1142,12 +1113,12 @@ static int common_read(struct policydb *p, struct hashtab *h, void *fp)
len = le32_to_cpu(buf[0]);
comdatum->value = le32_to_cpu(buf[1]);
+ nel = le32_to_cpu(buf[3]);
- rc = symtab_init(&comdatum->permissions, PERM_SYMTAB_SIZE);
+ rc = symtab_init(&comdatum->permissions, nel);
if (rc)
goto bad;
comdatum->permissions.nprim = le32_to_cpu(buf[2]);
- nel = le32_to_cpu(buf[3]);
rc = str_read(&key, GFP_KERNEL, fp, len);
if (rc)
@@ -1308,12 +1279,12 @@ static int class_read(struct policydb *p, struct hashtab *h, void *fp)
len = le32_to_cpu(buf[0]);
len2 = le32_to_cpu(buf[1]);
cladatum->value = le32_to_cpu(buf[2]);
+ nel = le32_to_cpu(buf[4]);
- rc = symtab_init(&cladatum->permissions, PERM_SYMTAB_SIZE);
+ rc = symtab_init(&cladatum->permissions, nel);
if (rc)
goto bad;
cladatum->permissions.nprim = le32_to_cpu(buf[3]);
- nel = le32_to_cpu(buf[4]);
ncons = le32_to_cpu(buf[5]);
@@ -1826,6 +1797,11 @@ static int range_read(struct policydb *p, void *fp)
return rc;
nel = le32_to_cpu(buf[0]);
+
+ p->range_tr = hashtab_create(rangetr_hash, rangetr_cmp, nel);
+ if (!p->range_tr)
+ return -ENOMEM;
+
for (i = 0; i < nel; i++) {
rc = -ENOMEM;
rt = kzalloc(sizeof(*rt), GFP_KERNEL);
@@ -2418,6 +2394,17 @@ int policydb_read(struct policydb *p, void *fp)
goto bad;
nprim = le32_to_cpu(buf[0]);
nel = le32_to_cpu(buf[1]);
+
+ rc = symtab_init(&p->symtab[i], nel);
+ if (rc)
+ goto out;
+
+ if (i == SYM_ROLES) {
+ rc = roles_init(p);
+ if (rc)
+ goto out;
+ }
+
for (j = 0; j < nel; j++) {
rc = read_f[i](p, p->symtab[i].table, fp);
if (rc)
diff --git a/security/selinux/ss/policydb.h b/security/selinux/ss/policydb.h
index 41ad78a1f17b..72e2932fb12d 100644
--- a/security/selinux/ss/policydb.h
+++ b/security/selinux/ss/policydb.h
@@ -321,8 +321,6 @@ extern int policydb_role_isvalid(struct policydb *p, unsigned int role);
extern int policydb_read(struct policydb *p, void *fp);
extern int policydb_write(struct policydb *p, void *fp);
-#define PERM_SYMTAB_SIZE 32
-
#define POLICYDB_CONFIG_MLS 1
/* the config flags related to unknown classes/perms are bits 2 and 3 */
--
2.24.1
