Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753511AbeAQO5D convert rfc822-to-8bit (ORCPT + 1 other); Wed, 17 Jan 2018 09:57:03 -0500 Received: from seldsegrel01.sonyericsson.com ([37.139.156.29]:5068 "EHLO SELDSEGREL01.sonyericsson.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753051AbeAQO5A (ORCPT ); Wed, 17 Jan 2018 09:57:00 -0500 From: To: Paul Moore , Stephen Smalley , Eric Paris , James Morris , Daniel Jurgens , Doug Ledford , , , , Ingo Molnar , , "Serge E . Hallyn" CC: Peter Enderborg Subject: [PATCH] selinux:Significant reduce of preempt_disable holds Date: Wed, 17 Jan 2018 15:55:51 +0100 Message-ID: <20180117145551.4961-1-peter.enderborg@sony.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Peter Enderborg Holding the preempt_disable is very bad for low latency tasks as audio and therefore we need to break out the rule-set dependent part from this disable. By using a rwsem instead of rwlock we have an efficient locking and less preemption interference. Selinux uses a lot of read_locks. This patch replaces the rwlock with rwsem/percpu_down_read() that does not hold preempt_disable. Intel Xeon W3520 2.67 Ghz running FC27 with 4.15.0-rc8git (+measurement) I get preempt_disable in worst case for 1.2ms in security_compute_av(). With the patch I get 960us as the longest security_compute_av() without preempt disabeld. It very much noise in the measurement but it is not likely a degrade. And the preempt_disable times is also very dependent on the selinux rule-set. In security_get_user_sids() we have two nested for-loops and the inner part calls sittab_context_to_sid() that calls sidtab_search_context() that has a for loop() over a while() where the loops is dependent on the rules. On the test system the average lookup time is 60us and does not change with the rwsem usage. Reported-by: Björn Davidsson Signed-off-by: Peter Enderborg --- security/selinux/ss/services.c | 134 ++++++++++++++++++++--------------------- 1 file changed, 67 insertions(+), 67 deletions(-) diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c index 33cfe5d..a3daaf2 100644 --- a/security/selinux/ss/services.c +++ b/security/selinux/ss/services.c @@ -87,7 +87,7 @@ int selinux_policycap_alwaysnetwork; int selinux_policycap_cgroupseclabel; int selinux_policycap_nnp_nosuid_transition; -static DEFINE_RWLOCK(policy_rwlock); +DEFINE_STATIC_PERCPU_RWSEM(policy_rwsem); static struct sidtab sidtab; struct policydb policydb; @@ -779,7 +779,7 @@ static int security_compute_validatetrans(u32 oldsid, u32 newsid, u32 tasksid, if (!ss_initialized) return 0; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); if (!user) tclass = unmap_class(orig_tclass); @@ -833,7 +833,7 @@ static int security_compute_validatetrans(u32 oldsid, u32 newsid, u32 tasksid, } out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return rc; } @@ -867,7 +867,7 @@ int security_bounded_transition(u32 old_sid, u32 new_sid) int index; int rc; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); rc = -EINVAL; old_context = sidtab_search(&sidtab, old_sid); @@ -929,7 +929,7 @@ int security_bounded_transition(u32 old_sid, u32 new_sid) kfree(old_name); } out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return rc; } @@ -1017,7 +1017,7 @@ void security_compute_xperms_decision(u32 ssid, memset(xpermd->auditallow->p, 0, sizeof(xpermd->auditallow->p)); memset(xpermd->dontaudit->p, 0, sizeof(xpermd->dontaudit->p)); - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); if (!ss_initialized) goto allow; @@ -1070,7 +1070,7 @@ void security_compute_xperms_decision(u32 ssid, } } out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return; allow: memset(xpermd->allowed->p, 0xff, sizeof(xpermd->allowed->p)); @@ -1097,7 +1097,7 @@ void security_compute_av(u32 ssid, u16 tclass; struct context *scontext = NULL, *tcontext = NULL; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); avd_init(avd); xperms->len = 0; if (!ss_initialized) @@ -1130,7 +1130,7 @@ void security_compute_av(u32 ssid, context_struct_compute_av(scontext, tcontext, tclass, avd, xperms); map_decision(orig_tclass, avd, policydb.allow_unknown); out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return; allow: avd->allowed = 0xffffffff; @@ -1144,7 +1144,7 @@ void security_compute_av_user(u32 ssid, { struct context *scontext = NULL, *tcontext = NULL; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); avd_init(avd); if (!ss_initialized) goto allow; @@ -1175,7 +1175,7 @@ void security_compute_av_user(u32 ssid, context_struct_compute_av(scontext, tcontext, tclass, avd, NULL); out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return; allow: avd->allowed = 0xffffffff; @@ -1277,7 +1277,7 @@ static int security_sid_to_context_core(u32 sid, char **scontext, rc = -EINVAL; goto out; } - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); if (force) context = sidtab_search_force(&sidtab, sid); else @@ -1290,7 +1290,7 @@ static int security_sid_to_context_core(u32 sid, char **scontext, } rc = context_struct_to_string(context, scontext, scontext_len); out_unlock: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); out: return rc; @@ -1442,7 +1442,7 @@ static int security_context_to_sid_core(const char *scontext, u32 scontext_len, goto out; } - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); rc = string_to_context_struct(&policydb, &sidtab, scontext2, scontext_len, &context, def_sid); if (rc == -EINVAL && force) { @@ -1454,7 +1454,7 @@ static int security_context_to_sid_core(const char *scontext, u32 scontext_len, rc = sidtab_context_to_sid(&sidtab, &context, sid); context_destroy(&context); out_unlock: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); out: kfree(scontext2); kfree(str); @@ -1604,7 +1604,7 @@ static int security_compute_sid(u32 ssid, context_init(&newcontext); - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); if (kern) { tclass = unmap_class(orig_tclass); @@ -1738,7 +1738,7 @@ static int security_compute_sid(u32 ssid, /* Obtain the sid for the context. */ rc = sidtab_context_to_sid(&sidtab, &newcontext, out_sid); out_unlock: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); context_destroy(&newcontext); out: return rc; @@ -2160,7 +2160,7 @@ int security_load_policy(void *data, size_t len) sidtab_set(&oldsidtab, &sidtab); /* Install the new policydb and SID table. */ - write_lock_irq(&policy_rwlock); + percpu_down_write(&policy_rwsem); memcpy(&policydb, newpolicydb, sizeof(policydb)); sidtab_set(&sidtab, &newsidtab); security_load_policycaps(); @@ -2168,7 +2168,7 @@ int security_load_policy(void *data, size_t len) current_mapping = map; current_mapping_size = map_size; seqno = ++latest_granting; - write_unlock_irq(&policy_rwlock); + percpu_up_write(&policy_rwsem); /* Free the old policydb and SID table. */ policydb_destroy(oldpolicydb); @@ -2198,9 +2198,9 @@ size_t security_policydb_len(void) { size_t len; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); len = policydb.len; - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return len; } @@ -2216,7 +2216,7 @@ int security_port_sid(u8 protocol, u16 port, u32 *out_sid) struct ocontext *c; int rc = 0; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); c = policydb.ocontexts[OCON_PORT]; while (c) { @@ -2241,7 +2241,7 @@ int security_port_sid(u8 protocol, u16 port, u32 *out_sid) } out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return rc; } @@ -2256,7 +2256,7 @@ int security_ib_pkey_sid(u64 subnet_prefix, u16 pkey_num, u32 *out_sid) struct ocontext *c; int rc = 0; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); c = policydb.ocontexts[OCON_IBPKEY]; while (c) { @@ -2281,7 +2281,7 @@ int security_ib_pkey_sid(u64 subnet_prefix, u16 pkey_num, u32 *out_sid) *out_sid = SECINITSID_UNLABELED; out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return rc; } @@ -2296,7 +2296,7 @@ int security_ib_endport_sid(const char *dev_name, u8 port_num, u32 *out_sid) struct ocontext *c; int rc = 0; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); c = policydb.ocontexts[OCON_IBENDPORT]; while (c) { @@ -2322,7 +2322,7 @@ int security_ib_endport_sid(const char *dev_name, u8 port_num, u32 *out_sid) *out_sid = SECINITSID_UNLABELED; out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return rc; } @@ -2336,7 +2336,7 @@ int security_netif_sid(char *name, u32 *if_sid) int rc = 0; struct ocontext *c; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); c = policydb.ocontexts[OCON_NETIF]; while (c) { @@ -2363,7 +2363,7 @@ int security_netif_sid(char *name, u32 *if_sid) *if_sid = SECINITSID_NETIF; out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return rc; } @@ -2395,7 +2395,7 @@ int security_node_sid(u16 domain, int rc; struct ocontext *c; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); switch (domain) { case AF_INET: { @@ -2450,7 +2450,7 @@ int security_node_sid(u16 domain, rc = 0; out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return rc; } @@ -2489,7 +2489,7 @@ int security_get_user_sids(u32 fromsid, if (!ss_initialized) goto out; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); context_init(&usercon); @@ -2539,7 +2539,7 @@ int security_get_user_sids(u32 fromsid, } rc = 0; out_unlock: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); if (rc || !mynel) { kfree(mysids); goto out; @@ -2580,7 +2580,7 @@ int security_get_user_sids(u32 fromsid, * cannot support xattr or use a fixed labeling behavior like * transition SIDs or task SIDs. * - * The caller must acquire the policy_rwlock before calling this function. + * The caller must acquire the policy_rwsem before calling this function. */ static inline int __security_genfs_sid(const char *fstype, char *path, @@ -2639,7 +2639,7 @@ static inline int __security_genfs_sid(const char *fstype, * @sclass: file security class * @sid: SID for path * - * Acquire policy_rwlock before calling __security_genfs_sid() and release + * Acquire policy_rwsem before calling __security_genfs_sid() and release * it afterward. */ int security_genfs_sid(const char *fstype, @@ -2649,9 +2649,9 @@ int security_genfs_sid(const char *fstype, { int retval; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); retval = __security_genfs_sid(fstype, path, orig_sclass, sid); - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return retval; } @@ -2666,7 +2666,7 @@ int security_fs_use(struct super_block *sb) struct superblock_security_struct *sbsec = sb->s_security; const char *fstype = sb->s_type->name; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); c = policydb.ocontexts[OCON_FSUSE]; while (c) { @@ -2696,7 +2696,7 @@ int security_fs_use(struct super_block *sb) } out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return rc; } @@ -2704,7 +2704,7 @@ int security_get_bools(int *len, char ***names, int **values) { int i, rc; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); *names = NULL; *values = NULL; @@ -2733,7 +2733,7 @@ int security_get_bools(int *len, char ***names, int **values) } rc = 0; out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return rc; err: if (*names) { @@ -2751,7 +2751,7 @@ int security_set_bools(int len, int *values) int lenp, seqno = 0; struct cond_node *cur; - write_lock_irq(&policy_rwlock); + percpu_down_write(&policy_rwsem); rc = -EFAULT; lenp = policydb.p_bools.nprim; @@ -2784,7 +2784,7 @@ int security_set_bools(int len, int *values) seqno = ++latest_granting; rc = 0; out: - write_unlock_irq(&policy_rwlock); + percpu_up_write(&policy_rwsem); if (!rc) { avc_ss_reset(seqno); selnl_notify_policyload(seqno); @@ -2799,7 +2799,7 @@ int security_get_bool_value(int index) int rc; int len; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); rc = -EFAULT; len = policydb.p_bools.nprim; @@ -2808,7 +2808,7 @@ int security_get_bool_value(int index) rc = policydb.bool_val_to_struct[index]->state; out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return rc; } @@ -2864,7 +2864,7 @@ int security_sid_mls_copy(u32 sid, u32 mls_sid, u32 *new_sid) context_init(&newcon); - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); rc = -EINVAL; context1 = sidtab_search(&sidtab, sid); @@ -2906,7 +2906,7 @@ int security_sid_mls_copy(u32 sid, u32 mls_sid, u32 *new_sid) rc = sidtab_context_to_sid(&sidtab, &newcon, new_sid); out_unlock: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); context_destroy(&newcon); out: return rc; @@ -2963,7 +2963,7 @@ int security_net_peersid_resolve(u32 nlbl_sid, u32 nlbl_type, if (!policydb.mls_enabled) return 0; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); rc = -EINVAL; nlbl_ctx = sidtab_search(&sidtab, nlbl_sid); @@ -2990,7 +2990,7 @@ int security_net_peersid_resolve(u32 nlbl_sid, u32 nlbl_type, * expressive */ *peer_sid = xfrm_sid; out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return rc; } @@ -3011,7 +3011,7 @@ int security_get_classes(char ***classes, int *nclasses) { int rc; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); rc = -ENOMEM; *nclasses = policydb.p_classes.nprim; @@ -3029,7 +3029,7 @@ int security_get_classes(char ***classes, int *nclasses) } out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return rc; } @@ -3051,7 +3051,7 @@ int security_get_permissions(char *class, char ***perms, int *nperms) int rc, i; struct class_datum *match; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); rc = -EINVAL; match = hashtab_search(policydb.p_classes.table, class); @@ -3080,11 +3080,11 @@ int security_get_permissions(char *class, char ***perms, int *nperms) goto err; out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return rc; err: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); for (i = 0; i < *nperms; i++) kfree((*perms)[i]); kfree(*perms); @@ -3115,9 +3115,9 @@ int security_policycap_supported(unsigned int req_cap) { int rc; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); rc = ebitmap_get_bit(&policydb.policycaps, req_cap); - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return rc; } @@ -3181,7 +3181,7 @@ int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule) context_init(&tmprule->au_ctxt); - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); tmprule->au_seqno = latest_granting; @@ -3221,7 +3221,7 @@ int selinux_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule) } rc = 0; out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); if (rc) { selinux_audit_rule_free(tmprule); @@ -3271,7 +3271,7 @@ int selinux_audit_rule_match(u32 sid, u32 field, u32 op, void *vrule, return -ENOENT; } - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); if (rule->au_seqno < latest_granting) { match = -ESTALE; @@ -3362,7 +3362,7 @@ int selinux_audit_rule_match(u32 sid, u32 field, u32 op, void *vrule, } out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return match; } @@ -3448,7 +3448,7 @@ int security_netlbl_secattr_to_sid(struct netlbl_lsm_secattr *secattr, return 0; } - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); if (secattr->flags & NETLBL_SECATTR_CACHE) *sid = *(u32 *)secattr->cache->data; @@ -3484,12 +3484,12 @@ int security_netlbl_secattr_to_sid(struct netlbl_lsm_secattr *secattr, } else *sid = SECSID_NULL; - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return 0; out_free: ebitmap_destroy(&ctx_new.range.level[0].cat); out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return rc; } @@ -3511,7 +3511,7 @@ int security_netlbl_sid_to_secattr(u32 sid, struct netlbl_lsm_secattr *secattr) if (!ss_initialized) return 0; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); rc = -ENOENT; ctx = sidtab_search(&sidtab, sid); @@ -3529,7 +3529,7 @@ int security_netlbl_sid_to_secattr(u32 sid, struct netlbl_lsm_secattr *secattr) mls_export_netlbl_lvl(ctx, secattr); rc = mls_export_netlbl_cat(ctx, secattr); out: - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); return rc; } #endif /* CONFIG_NETLABEL */ @@ -3557,9 +3557,9 @@ int security_read_policy(void **data, size_t *len) fp.data = *data; fp.len = *len; - read_lock(&policy_rwlock); + percpu_down_read(&policy_rwsem); rc = policydb_write(&policydb, &fp); - read_unlock(&policy_rwlock); + percpu_up_read(&policy_rwsem); if (rc) return rc; -- 2.7.4