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authorOndrej Mosnacek <omosnace@redhat.com>2019-11-26 14:57:00 +0100
committerPaul Moore <paul@paul-moore.com>2019-12-09 16:14:51 -0500
commitd97bd23c2d7d866e99eb3a927c742715c85a90ef (patch)
treed5c29d661384fbc83a0244623b9daac7f3715d5a /security/selinux
parent66f8e2f03c02e812002f8e9e465681cc62edda5b (diff)
selinux: cache the SID -> context string translation
Translating a context struct to string can be quite slow, especially if the context has a lot of category bits set. This can cause quite noticeable performance impact in situations where the translation needs to be done repeatedly. A common example is a UNIX datagram socket with the SO_PASSSEC option enabled, which is used e.g. by systemd-journald when receiving log messages via datagram socket. This scenario can be reproduced with: cat /dev/urandom | base64 | logger & timeout 30s perf record -p $(pidof systemd-journald) -a -g kill %1 perf report -g none --pretty raw | grep security_secid_to_secctx Before the caching introduced by this patch, computing the context string (security_secid_to_secctx() function) takes up ~65% of systemd-journald's CPU time (assuming a context with 1024 categories set and Fedora x86_64 release kernel configs). After this patch (assuming near-perfect cache hit ratio) this overhead is reduced to just ~2%. This patch addresses the issue by caching a certain number (compile-time configurable) of recently used context strings to speed up repeated translations of the same context, while using only a small amount of memory. The cache is integrated into the existing sidtab table by adding a field to each entry, which when not NULL contains an RCU-protected pointer to a cache entry containing the cached string. The cache entries are kept in a linked list sorted according to how recently they were used. On a cache miss when the cache is full, the least recently used entry is removed to make space for the new entry. The patch migrates security_sid_to_context_core() to use the cache (also a few other functions where it was possible without too much fuss, but these mostly use the translation for logging in case of error, which is rare). Link: https://bugzilla.redhat.com/show_bug.cgi?id=1733259 Cc: Michal Sekletar <msekleta@redhat.com> Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov> Tested-by: Stephen Smalley <sds@tycho.nsa.gov> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> [PM: lots of merge fixups due to collisions with other sidtab patches] Signed-off-by: Paul Moore <paul@paul-moore.com>
Diffstat (limited to 'security/selinux')
-rw-r--r--security/selinux/Kconfig11
-rw-r--r--security/selinux/ss/services.c138
-rw-r--r--security/selinux/ss/sidtab.c175
-rw-r--r--security/selinux/ss/sidtab.h58
4 files changed, 288 insertions, 94 deletions
diff --git a/security/selinux/Kconfig b/security/selinux/Kconfig
index c9e576c430c2..996d35d950f7 100644
--- a/security/selinux/Kconfig
+++ b/security/selinux/Kconfig
@@ -97,3 +97,14 @@ config SECURITY_SELINUX_SIDTAB_HASH_BITS
collisions may be viewed at /sys/fs/selinux/ss/sidtab_hash_stats. If
chain lengths are high (e.g. > 20) then selecting a higher value here
will ensure that lookups times are short and stable.
+
+config SECURITY_SELINUX_SID2STR_CACHE_SIZE
+ int "NSA SELinux SID to context string translation cache size"
+ depends on SECURITY_SELINUX
+ default 256
+ help
+ This option defines the size of the internal SID -> context string
+ cache, which improves the performance of context to string
+ conversion. Setting this option to 0 disables the cache completely.
+
+ If unsure, keep the default value.
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 38fb6fdd65ca..743b85ede4ef 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -91,6 +91,12 @@ static int context_struct_to_string(struct policydb *policydb,
char **scontext,
u32 *scontext_len);
+static int sidtab_entry_to_string(struct policydb *policydb,
+ struct sidtab *sidtab,
+ struct sidtab_entry *entry,
+ char **scontext,
+ u32 *scontext_len);
+
static void context_struct_compute_av(struct policydb *policydb,
struct context *scontext,
struct context *tcontext,
@@ -716,20 +722,21 @@ static void context_struct_compute_av(struct policydb *policydb,
}
static int security_validtrans_handle_fail(struct selinux_state *state,
- struct context *ocontext,
- struct context *ncontext,
- struct context *tcontext,
+ struct sidtab_entry *oentry,
+ struct sidtab_entry *nentry,
+ struct sidtab_entry *tentry,
u16 tclass)
{
struct policydb *p = &state->ss->policydb;
+ struct sidtab *sidtab = state->ss->sidtab;
char *o = NULL, *n = NULL, *t = NULL;
u32 olen, nlen, tlen;
- if (context_struct_to_string(p, ocontext, &o, &olen))
+ if (sidtab_entry_to_string(p, sidtab, oentry, &o, &olen))
goto out;
- if (context_struct_to_string(p, ncontext, &n, &nlen))
+ if (sidtab_entry_to_string(p, sidtab, nentry, &n, &nlen))
goto out;
- if (context_struct_to_string(p, tcontext, &t, &tlen))
+ if (sidtab_entry_to_string(p, sidtab, tentry, &t, &tlen))
goto out;
audit_log(audit_context(), GFP_ATOMIC, AUDIT_SELINUX_ERR,
"op=security_validate_transition seresult=denied"
@@ -751,9 +758,9 @@ static int security_compute_validatetrans(struct selinux_state *state,
{
struct policydb *policydb;
struct sidtab *sidtab;
- struct context *ocontext;
- struct context *ncontext;
- struct context *tcontext;
+ struct sidtab_entry *oentry;
+ struct sidtab_entry *nentry;
+ struct sidtab_entry *tentry;
struct class_datum *tclass_datum;
struct constraint_node *constraint;
u16 tclass;
@@ -779,24 +786,24 @@ static int security_compute_validatetrans(struct selinux_state *state,
}
tclass_datum = policydb->class_val_to_struct[tclass - 1];
- ocontext = sidtab_search(sidtab, oldsid);
- if (!ocontext) {
+ oentry = sidtab_search_entry(sidtab, oldsid);
+ if (!oentry) {
pr_err("SELinux: %s: unrecognized SID %d\n",
__func__, oldsid);
rc = -EINVAL;
goto out;
}
- ncontext = sidtab_search(sidtab, newsid);
- if (!ncontext) {
+ nentry = sidtab_search_entry(sidtab, newsid);
+ if (!nentry) {
pr_err("SELinux: %s: unrecognized SID %d\n",
__func__, newsid);
rc = -EINVAL;
goto out;
}
- tcontext = sidtab_search(sidtab, tasksid);
- if (!tcontext) {
+ tentry = sidtab_search_entry(sidtab, tasksid);
+ if (!tentry) {
pr_err("SELinux: %s: unrecognized SID %d\n",
__func__, tasksid);
rc = -EINVAL;
@@ -805,15 +812,16 @@ static int security_compute_validatetrans(struct selinux_state *state,
constraint = tclass_datum->validatetrans;
while (constraint) {
- if (!constraint_expr_eval(policydb, ocontext, ncontext,
- tcontext, constraint->expr)) {
+ if (!constraint_expr_eval(policydb, &oentry->context,
+ &nentry->context, &tentry->context,
+ constraint->expr)) {
if (user)
rc = -EPERM;
else
rc = security_validtrans_handle_fail(state,
- ocontext,
- ncontext,
- tcontext,
+ oentry,
+ nentry,
+ tentry,
tclass);
goto out;
}
@@ -855,7 +863,7 @@ int security_bounded_transition(struct selinux_state *state,
{
struct policydb *policydb;
struct sidtab *sidtab;
- struct context *old_context, *new_context;
+ struct sidtab_entry *old_entry, *new_entry;
struct type_datum *type;
int index;
int rc;
@@ -869,16 +877,16 @@ int security_bounded_transition(struct selinux_state *state,
sidtab = state->ss->sidtab;
rc = -EINVAL;
- old_context = sidtab_search(sidtab, old_sid);
- if (!old_context) {
+ old_entry = sidtab_search_entry(sidtab, old_sid);
+ if (!old_entry) {
pr_err("SELinux: %s: unrecognized SID %u\n",
__func__, old_sid);
goto out;
}
rc = -EINVAL;
- new_context = sidtab_search(sidtab, new_sid);
- if (!new_context) {
+ new_entry = sidtab_search_entry(sidtab, new_sid);
+ if (!new_entry) {
pr_err("SELinux: %s: unrecognized SID %u\n",
__func__, new_sid);
goto out;
@@ -886,10 +894,10 @@ int security_bounded_transition(struct selinux_state *state,
rc = 0;
/* type/domain unchanged */
- if (old_context->type == new_context->type)
+ if (old_entry->context.type == new_entry->context.type)
goto out;
- index = new_context->type;
+ index = new_entry->context.type;
while (true) {
type = policydb->type_val_to_struct[index - 1];
BUG_ON(!type);
@@ -901,7 +909,7 @@ int security_bounded_transition(struct selinux_state *state,
/* @newsid is bounded by @oldsid */
rc = 0;
- if (type->bounds == old_context->type)
+ if (type->bounds == old_entry->context.type)
break;
index = type->bounds;
@@ -912,10 +920,10 @@ int security_bounded_transition(struct selinux_state *state,
char *new_name = NULL;
u32 length;
- if (!context_struct_to_string(policydb, old_context,
- &old_name, &length) &&
- !context_struct_to_string(policydb, new_context,
- &new_name, &length)) {
+ if (!sidtab_entry_to_string(policydb, sidtab, old_entry,
+ &old_name, &length) &&
+ !sidtab_entry_to_string(policydb, sidtab, new_entry,
+ &new_name, &length)) {
audit_log(audit_context(),
GFP_ATOMIC, AUDIT_SELINUX_ERR,
"op=security_bounded_transition "
@@ -1255,6 +1263,23 @@ static int context_struct_to_string(struct policydb *p,
return 0;
}
+static int sidtab_entry_to_string(struct policydb *p,
+ struct sidtab *sidtab,
+ struct sidtab_entry *entry,
+ char **scontext, u32 *scontext_len)
+{
+ int rc = sidtab_sid2str_get(sidtab, entry, scontext, scontext_len);
+
+ if (rc != -ENOENT)
+ return rc;
+
+ rc = context_struct_to_string(p, &entry->context, scontext,
+ scontext_len);
+ if (!rc && scontext)
+ sidtab_sid2str_put(sidtab, entry, *scontext, *scontext_len);
+ return rc;
+}
+
#include "initial_sid_to_string.h"
int security_sidtab_hash_stats(struct selinux_state *state, char *page)
@@ -1282,7 +1307,7 @@ static int security_sid_to_context_core(struct selinux_state *state,
{
struct policydb *policydb;
struct sidtab *sidtab;
- struct context *context;
+ struct sidtab_entry *entry;
int rc = 0;
if (scontext)
@@ -1313,21 +1338,23 @@ static int security_sid_to_context_core(struct selinux_state *state,
read_lock(&state->ss->policy_rwlock);
policydb = &state->ss->policydb;
sidtab = state->ss->sidtab;
+
if (force)
- context = sidtab_search_force(sidtab, sid);
+ entry = sidtab_search_entry_force(sidtab, sid);
else
- context = sidtab_search(sidtab, sid);
- if (!context) {
+ entry = sidtab_search_entry(sidtab, sid);
+ if (!entry) {
pr_err("SELinux: %s: unrecognized SID %d\n",
__func__, sid);
rc = -EINVAL;
goto out_unlock;
}
- if (only_invalid && !context->len)
- rc = 0;
- else
- rc = context_struct_to_string(policydb, context, scontext,
- scontext_len);
+ if (only_invalid && !entry->context.len)
+ goto out_unlock;
+
+ rc = sidtab_entry_to_string(policydb, sidtab, entry, scontext,
+ scontext_len);
+
out_unlock:
read_unlock(&state->ss->policy_rwlock);
out:
@@ -1621,19 +1648,20 @@ int security_context_to_sid_force(struct selinux_state *state,
static int compute_sid_handle_invalid_context(
struct selinux_state *state,
- struct context *scontext,
- struct context *tcontext,
+ struct sidtab_entry *sentry,
+ struct sidtab_entry *tentry,
u16 tclass,
struct context *newcontext)
{
struct policydb *policydb = &state->ss->policydb;
+ struct sidtab *sidtab = state->ss->sidtab;
char *s = NULL, *t = NULL, *n = NULL;
u32 slen, tlen, nlen;
struct audit_buffer *ab;
- if (context_struct_to_string(policydb, scontext, &s, &slen))
+ if (sidtab_entry_to_string(policydb, sidtab, sentry, &s, &slen))
goto out;
- if (context_struct_to_string(policydb, tcontext, &t, &tlen))
+ if (sidtab_entry_to_string(policydb, sidtab, tentry, &t, &tlen))
goto out;
if (context_struct_to_string(policydb, newcontext, &n, &nlen))
goto out;
@@ -1692,7 +1720,8 @@ static int security_compute_sid(struct selinux_state *state,
struct policydb *policydb;
struct sidtab *sidtab;
struct class_datum *cladatum = NULL;
- struct context *scontext = NULL, *tcontext = NULL, newcontext;
+ struct context *scontext, *tcontext, newcontext;
+ struct sidtab_entry *sentry, *tentry;
struct role_trans *roletr = NULL;
struct avtab_key avkey;
struct avtab_datum *avdatum;
@@ -1729,21 +1758,24 @@ static int security_compute_sid(struct selinux_state *state,
policydb = &state->ss->policydb;
sidtab = state->ss->sidtab;
- scontext = sidtab_search(sidtab, ssid);
- if (!scontext) {
+ sentry = sidtab_search_entry(sidtab, ssid);
+ if (!sentry) {
pr_err("SELinux: %s: unrecognized SID %d\n",
__func__, ssid);
rc = -EINVAL;
goto out_unlock;
}
- tcontext = sidtab_search(sidtab, tsid);
- if (!tcontext) {
+ tentry = sidtab_search_entry(sidtab, tsid);
+ if (!tentry) {
pr_err("SELinux: %s: unrecognized SID %d\n",
__func__, tsid);
rc = -EINVAL;
goto out_unlock;
}
+ scontext = &sentry->context;
+ tcontext = &tentry->context;
+
if (tclass && tclass <= policydb->p_classes.nprim)
cladatum = policydb->class_val_to_struct[tclass - 1];
@@ -1844,10 +1876,8 @@ static int security_compute_sid(struct selinux_state *state,
/* Check the validity of the context. */
if (!policydb_context_isvalid(policydb, &newcontext)) {
- rc = compute_sid_handle_invalid_context(state, scontext,
- tcontext,
- tclass,
- &newcontext);
+ rc = compute_sid_handle_invalid_context(state, sentry, tentry,
+ tclass, &newcontext);
if (rc)
goto out_unlock;
}
diff --git a/security/selinux/ss/sidtab.c b/security/selinux/ss/sidtab.c
index d9d8599e8e63..a308ce1e6a13 100644
--- a/security/selinux/ss/sidtab.c
+++ b/security/selinux/ss/sidtab.c
@@ -9,6 +9,8 @@
*/
#include <linux/errno.h>
#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/rcupdate.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
@@ -17,6 +19,14 @@
#include "security.h"
#include "sidtab.h"
+struct sidtab_str_cache {
+ struct rcu_head rcu_member;
+ struct list_head lru_member;
+ struct sidtab_entry *parent;
+ u32 len;
+ char str[];
+};
+
#define index_to_sid(index) (index + SECINITSID_NUM + 1)
#define sid_to_index(sid) (sid - (SECINITSID_NUM + 1))
@@ -34,12 +44,19 @@ int sidtab_init(struct sidtab *s)
hash_init(s->context_to_sid);
spin_lock_init(&s->lock);
+
+#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
+ s->cache_free_slots = CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE;
+ INIT_LIST_HEAD(&s->cache_lru_list);
+ spin_lock_init(&s->cache_lock);
+#endif
+
return 0;
}
static u32 context_to_sid(struct sidtab *s, struct context *context)
{
- struct sidtab_entry_leaf *entry;
+ struct sidtab_entry *entry;
u32 sid = 0;
rcu_read_lock();
@@ -56,19 +73,22 @@ static u32 context_to_sid(struct sidtab *s, struct context *context)
int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context)
{
- struct sidtab_isid_entry *entry;
+ struct sidtab_isid_entry *isid;
int rc;
if (sid == 0 || sid > SECINITSID_NUM)
return -EINVAL;
- entry = &s->isids[sid - 1];
+ isid = &s->isids[sid - 1];
- rc = context_cpy(&entry->leaf.context, context);
+ rc = context_cpy(&isid->entry.context, context);
if (rc)
return rc;
- entry->set = 1;
+#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
+ isid->entry.cache = NULL;
+#endif
+ isid->set = 1;
/*
* Multiple initial sids may map to the same context. Check that this
@@ -77,8 +97,8 @@ int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context)
* collision.
*/
if (!context_to_sid(s, context)) {
- entry->leaf.sid = sid;
- hash_add(s->context_to_sid, &entry->leaf.list, context->hash);
+ isid->entry.sid = sid;
+ hash_add(s->context_to_sid, &isid->entry.list, context->hash);
}
return 0;
@@ -92,7 +112,7 @@ int sidtab_hash_stats(struct sidtab *sidtab, char *page)
int entries = 0;
int max_chain_len = 0;
int cur_bucket = 0;
- struct sidtab_entry_leaf *entry;
+ struct sidtab_entry *entry;
rcu_read_lock();
hash_for_each_rcu(sidtab->context_to_sid, i, entry, list) {
@@ -151,8 +171,8 @@ static int sidtab_alloc_roots(struct sidtab *s, u32 level)
return 0;
}
-static struct sidtab_entry_leaf *sidtab_do_lookup(struct sidtab *s, u32 index,
- int alloc)
+static struct sidtab_entry *sidtab_do_lookup(struct sidtab *s, u32 index,
+ int alloc)
{
union sidtab_entry_inner *entry;
u32 level, capacity_shift, leaf_index = index / SIDTAB_LEAF_ENTRIES;
@@ -192,7 +212,7 @@ static struct sidtab_entry_leaf *sidtab_do_lookup(struct sidtab *s, u32 index,
return &entry->ptr_leaf->entries[index % SIDTAB_LEAF_ENTRIES];
}
-static struct context *sidtab_lookup(struct sidtab *s, u32 index)
+static struct sidtab_entry *sidtab_lookup(struct sidtab *s, u32 index)
{
/* read entries only after reading count */
u32 count = smp_load_acquire(&s->count);
@@ -200,36 +220,37 @@ static struct context *sidtab_lookup(struct sidtab *s, u32 index)
if (index >= count)
return NULL;
- return &sidtab_do_lookup(s, index, 0)->context;
+ return sidtab_do_lookup(s, index, 0);
}
-static struct context *sidtab_lookup_initial(struct sidtab *s, u32 sid)
+static struct sidtab_entry *sidtab_lookup_initial(struct sidtab *s, u32 sid)
{
- return s->isids[sid - 1].set ? &s->isids[sid - 1].leaf.context : NULL;
+ return s->isids[sid - 1].set ? &s->isids[sid - 1].entry : NULL;
}
-static struct context *sidtab_search_core(struct sidtab *s, u32 sid, int force)
+static struct sidtab_entry *sidtab_search_core(struct sidtab *s, u32 sid,
+ int force)
{
- struct context *context;
-
if (sid != 0) {
+ struct sidtab_entry *entry;
+
if (sid > SECINITSID_NUM)
- context = sidtab_lookup(s, sid_to_index(sid));
+ entry = sidtab_lookup(s, sid_to_index(sid));
else
- context = sidtab_lookup_initial(s, sid);
- if (context && (!context->len || force))
- return context;
+ entry = sidtab_lookup_initial(s, sid);
+ if (entry && (!entry->context.len || force))
+ return entry;
}
return sidtab_lookup_initial(s, SECINITSID_UNLABELED);
}
-struct context *sidtab_search(struct sidtab *s, u32 sid)
+struct sidtab_entry *sidtab_search_entry(struct sidtab *s, u32 sid)
{
return sidtab_search_core(s, sid, 0);
}
-struct context *sidtab_search_force(struct sidtab *s, u32 sid)
+struct sidtab_entry *sidtab_search_entry_force(struct sidtab *s, u32 sid)
{
return sidtab_search_core(s, sid, 1);
}
@@ -240,7 +261,7 @@ int sidtab_context_to_sid(struct sidtab *s, struct context *context,
unsigned long flags;
u32 count;
struct sidtab_convert_params *convert;
- struct sidtab_entry_leaf *dst, *dst_convert;
+ struct sidtab_entry *dst, *dst_convert;
int rc;
*sid = context_to_sid(s, context);
@@ -289,7 +310,7 @@ int sidtab_context_to_sid(struct sidtab *s, struct context *context,
}
rc = convert->func(context, &dst_convert->context,
- convert->args);
+ convert->args);
if (rc) {
context_destroy(&dst->context);
goto out_unlock;
@@ -298,7 +319,7 @@ int sidtab_context_to_sid(struct sidtab *s, struct context *context,
convert->target->count = count + 1;
hash_add_rcu(convert->target->context_to_sid,
- &dst_convert->list, dst_convert->context.hash);
+ &dst_convert->list, dst_convert->context.hash);
}
if (context->len)
@@ -319,7 +340,7 @@ out_unlock:
static void sidtab_convert_hashtable(struct sidtab *s, u32 count)
{
- struct sidtab_entry_leaf *entry;
+ struct sidtab_entry *entry;
u32 i;
for (i = 0; i < count; i++) {
@@ -327,7 +348,7 @@ static void sidtab_convert_hashtable(struct sidtab *s, u32 count)
entry->sid = index_to_sid(i);
hash_add_rcu(s->context_to_sid, &entry->list,
- entry->context.hash);
+ entry->context.hash);
}
}
@@ -376,7 +397,6 @@ static int sidtab_convert_tree(union sidtab_entry_inner *edst,
}
cond_resched();
}
-
return 0;
}
@@ -439,6 +459,14 @@ int sidtab_convert(struct sidtab *s, struct sidtab_convert_params *params)
return 0;
}
+static void sidtab_destroy_entry(struct sidtab_entry *entry)
+{
+ context_destroy(&entry->context);
+#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
+ kfree(rcu_dereference_raw(entry->cache));
+#endif
+}
+
static void sidtab_destroy_tree(union sidtab_entry_inner entry, u32 level)
{
u32 i;
@@ -459,7 +487,7 @@ static void sidtab_destroy_tree(union sidtab_entry_inner entry, u32 level)
return;
for (i = 0; i < SIDTAB_LEAF_ENTRIES; i++)
- context_destroy(&node->entries[i].context);
+ sidtab_destroy_entry(&node->entries[i]);
kfree(node);
}
}
@@ -470,7 +498,7 @@ void sidtab_destroy(struct sidtab *s)
for (i = 0; i < SECINITSID_NUM; i++)
if (s->isids[i].set)
- context_destroy(&s->isids[i].leaf.context);
+ sidtab_destroy_entry(&s->isids[i].entry);
level = SIDTAB_MAX_LEVEL;
while (level && !s->roots[level].ptr_inner)
@@ -483,3 +511,88 @@ void sidtab_destroy(struct sidtab *s)
* to be cleaned up here.
*/
}
+
+#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
+
+void sidtab_sid2str_put(struct sidtab *s, struct sidtab_entry *entry,
+ const char *str, u32 str_len)
+{
+ struct sidtab_str_cache *cache, *victim = NULL;
+
+ /* do not cache invalid contexts */
+ if (entry->context.len)
+ return;
+
+ /*
+ * Skip the put operation when in non-task context to avoid the need
+ * to disable interrupts while holding s->cache_lock.
+ */
+ if (!in_task())
+ return;
+
+ spin_lock(&s->cache_lock);
+
+ cache = rcu_dereference_protected(entry->cache,
+ lockdep_is_held(&s->cache_lock));
+ if (cache) {
+ /* entry in cache - just bump to the head of LRU list */
+ list_move(&cache->lru_member, &s->cache_lru_list);
+ goto out_unlock;
+ }
+
+ cache = kmalloc(sizeof(struct sidtab_str_cache) + str_len, GFP_ATOMIC);
+ if (!cache)
+ goto out_unlock;
+
+ if (s->cache_free_slots == 0) {
+ /* pop a cache entry from the tail and free it */
+ victim = container_of(s->cache_lru_list.prev,
+ struct sidtab_str_cache, lru_member);
+ list_del(&victim->lru_member);
+ rcu_assign_pointer(victim->parent->cache, NULL);
+ } else {
+ s->cache_free_slots--;
+ }
+ cache->parent = entry;
+ cache->len = str_len;
+ memcpy(cache->str, str, str_len);
+ list_add(&cache->lru_member, &s->cache_lru_list);
+
+ rcu_assign_pointer(entry->cache, cache);
+
+out_unlock:
+ spin_unlock(&s->cache_lock);
+ kfree_rcu(victim, rcu_member);
+}
+
+int sidtab_sid2str_get(struct sidtab *s, struct sidtab_entry *entry,
+ char **out, u32 *out_len)
+{
+ struct sidtab_str_cache *cache;
+ int rc = 0;
+
+ if (entry->context.len)
+ return -ENOENT; /* do not cache invalid contexts */
+
+ rcu_read_lock();
+
+ cache = rcu_dereference(entry->cache);
+ if (!cache) {
+ rc = -ENOENT;
+ } else {
+ *out_len = cache->len;
+ if (out) {
+ *out = kmemdup(cache->str, cache->len, GFP_ATOMIC);
+ if (!*out)
+ rc = -ENOMEM;
+ }
+ }
+
+ rcu_read_unlock();
+
+ if (!rc && out)
+ sidtab_sid2str_put(s, entry, *out, *out_len);
+ return rc;
+}
+
+#endif /* CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 */
diff --git a/security/selinux/ss/sidtab.h b/security/selinux/ss/sidtab.h
index e2809401c417..3311d9f236c0 100644
--- a/security/selinux/ss/sidtab.h
+++ b/security/selinux/ss/sidtab.h
@@ -17,15 +17,15 @@
#include "context.h"
-struct sidtab_entry_leaf {
+struct sidtab_entry {
u32 sid;
struct context context;
+#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
+ struct sidtab_str_cache __rcu *cache;
+#endif
struct hlist_node list;
};
-struct sidtab_node_inner;
-struct sidtab_node_leaf;
-
union sidtab_entry_inner {
struct sidtab_node_inner *ptr_inner;
struct sidtab_node_leaf *ptr_leaf;
@@ -41,7 +41,7 @@ union sidtab_entry_inner {
(SIDTAB_NODE_ALLOC_SHIFT - size_to_shift(sizeof(union sidtab_entry_inner)))
#define SIDTAB_INNER_ENTRIES ((size_t)1 << SIDTAB_INNER_SHIFT)
#define SIDTAB_LEAF_ENTRIES \
- (SIDTAB_NODE_ALLOC_SIZE / sizeof(struct sidtab_entry_leaf))
+ (SIDTAB_NODE_ALLOC_SIZE / sizeof(struct sidtab_entry))
#define SIDTAB_MAX_BITS 32
#define SIDTAB_MAX U32_MAX
@@ -51,7 +51,7 @@ union sidtab_entry_inner {
SIDTAB_INNER_SHIFT)
struct sidtab_node_leaf {
- struct sidtab_entry_leaf entries[SIDTAB_LEAF_ENTRIES];
+ struct sidtab_entry entries[SIDTAB_LEAF_ENTRIES];
};
struct sidtab_node_inner {
@@ -60,7 +60,7 @@ struct sidtab_node_inner {
struct sidtab_isid_entry {
int set;
- struct sidtab_entry_leaf leaf;
+ struct sidtab_entry entry;
};
struct sidtab_convert_params {
@@ -87,6 +87,13 @@ struct sidtab {
struct sidtab_convert_params *convert;
spinlock_t lock;
+#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
+ /* SID -> context string cache */
+ u32 cache_free_slots;
+ struct list_head cache_lru_list;
+ spinlock_t cache_lock;
+#endif
+
/* index == SID - 1 (no entry for SECSID_NULL) */
struct sidtab_isid_entry isids[SECINITSID_NUM];
@@ -96,8 +103,22 @@ struct sidtab {
int sidtab_init(struct sidtab *s);
int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context);
-struct context *sidtab_search(struct sidtab *s, u32 sid);
-struct context *sidtab_search_force(struct sidtab *s, u32 sid);
+struct sidtab_entry *sidtab_search_entry(struct sidtab *s, u32 sid);
+struct sidtab_entry *sidtab_search_entry_force(struct sidtab *s, u32 sid);
+
+static inline struct context *sidtab_search(struct sidtab *s, u32 sid)
+{
+ struct sidtab_entry *entry = sidtab_search_entry(s, sid);
+
+ return entry ? &entry->context : NULL;
+}
+
+static inline struct context *sidtab_search_force(struct sidtab *s, u32 sid)
+{
+ struct sidtab_entry *entry = sidtab_search_entry_force(s, sid);
+
+ return entry ? &entry->context : NULL;
+}
int sidtab_convert(struct sidtab *s, struct sidtab_convert_params *params);
@@ -107,6 +128,25 @@ void sidtab_destroy(struct sidtab *s);
int sidtab_hash_stats(struct sidtab *sidtab, char *page);
+#if CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0
+void sidtab_sid2str_put(struct sidtab *s, struct sidtab_entry *entry,
+ const char *str, u32 str_len);
+int sidtab_sid2str_get(struct sidtab *s, struct sidtab_entry *entry,
+ char **out, u32 *out_len);
+#else
+static inline void sidtab_sid2str_put(struct sidtab *s,
+ struct sidtab_entry *entry,
+ const char *str, u32 str_len)
+{
+}
+static inline int sidtab_sid2str_get(struct sidtab *s,
+ struct sidtab_entry *entry,
+ char **out, u32 *out_len)
+{
+ return -ENOENT;
+}
+#endif /* CONFIG_SECURITY_SELINUX_SID2STR_CACHE_SIZE > 0 */
+
#endif /* _SS_SIDTAB_H_ */