From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 13D57C43441 for ; Tue, 27 Nov 2018 20:04:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A05302086B for ; Tue, 27 Nov 2018 20:04:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A05302086B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=selinux-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725764AbeK1HDO (ORCPT ); Wed, 28 Nov 2018 02:03:14 -0500 Received: from mail-oi1-f196.google.com ([209.85.167.196]:36261 "EHLO mail-oi1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725752AbeK1HDO (ORCPT ); Wed, 28 Nov 2018 02:03:14 -0500 Received: by mail-oi1-f196.google.com with SMTP id x23so20470202oix.3 for ; Tue, 27 Nov 2018 12:04:11 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=vfid93xA1xH0I4tItFdYurwDs6k3R6MbJX7kn+7Q92k=; b=U4X+4t6KI3wLpwsp6MLAK9wGXmNOK1r/yKE9Y6s/Q4Cgou8krvp0UGlTbohw5Z6BMo c6KsTO+jwQ8m/6Sn2ESzqKHyuZUDOfqqlrvL8FhoF7hRfgEDhYQfC8pQZLEKRx/vCa+i JUlJaZE+sNcNZGsbH9f1PFk9ay79kdtvgrfvWVHIuKWYwnFmOlctq7BO2S0ijUQg8o5c K72+8+gaeH7E6b7KD388G3R24qoMHY8QLUpd2vds1P24suzkgD3VdVCRA7lN19Yu6V3T H3un8GJOtbnre1T9Y9ZAPvPaF33Wjdvou3mdgmcKtvT5j3NRWDR6PdKRlP5JXryIOpSv ssHg== X-Gm-Message-State: AGRZ1gL8CQfVPtdjDC88HTiK8hljXSNr9T8vKW1SdxLJJxkM7H2tCaHK 9zxERfanIbeUNEV3kdM8N9aTqey8LvPKO7sHXd0fHiqK X-Google-Smtp-Source: AJdET5fLGbmL1vbWez6GhTXz00q5I3+Q7kKEG6atT7cQv8Xn6+n+pPF1YvUsYq0EDoJTIWDrq7QiOEIXHhMTSpoi8KE= X-Received: by 2002:aca:40c1:: with SMTP id n184-v6mr17426042oia.119.1543349051314; Tue, 27 Nov 2018 12:04:11 -0800 (PST) MIME-Version: 1.0 References: <20181127103605.32765-1-omosnace@redhat.com> <20181127103605.32765-4-omosnace@redhat.com> <6b8cea64-8a39-09d7-f2fd-d7dd73374de1@tycho.nsa.gov> In-Reply-To: <6b8cea64-8a39-09d7-f2fd-d7dd73374de1@tycho.nsa.gov> From: Ondrej Mosnacek Date: Tue, 27 Nov 2018 21:03:59 +0100 Message-ID: Subject: Re: [RFC PATCH v2 3/4] selinux: overhaul sidtab to fix bug and improve performance To: Stephen Smalley Cc: selinux@vger.kernel.org, Paul Moore Content-Type: text/plain; charset="UTF-8" Sender: selinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org On Tue, Nov 27, 2018 at 8:38 PM Stephen Smalley wrote: > On 11/27/18 5:36 AM, Ondrej Mosnacek wrote: > > Before this patch, during a policy reload the sidtab would become frozen > > and trying to map a new context to SID would be unable to add a new > > entry to sidtab and fail with -ENOMEM. > > > > Such failures are usually propagated into userspace, which has no way of > > distignuishing them from actual allocation failures and thus doesn't > > handle them gracefully. Such situation can be triggered e.g. by the > > following reproducer: > > > > while true; do load_policy; echo -n .; sleep 0.1; done & > > for (( i = 0; i < 1024; i++ )); do > > runcon -l s0:c$i echo -n x || break > > # or: > > # chcon -l s0:c$i || break > > done > > > > This patch overhauls the sidtab so it doesn't need to be frozen during > > policy reload, thus solving the above problem. > > > > The new SID table leverages the fact that SIDs are allocated > > sequentially and are never invalidated and stores them in linear buckets > > indexed by a tree structure. This brings several advantages: > > 1. Fast SID -> context lookup - this lookup can now be done in > > logarithmic time complexity (usually in less than 4 array lookups) > > and can still be done safely without locking. > > 2. No need to re-search the whole table on reverse lookup miss - after > > acquiring the spinlock only the newly added entries need to be > > searched, which means that reverse lookups that end up inserting a > > new entry are now about twice as fast. > > 3. No need to freeze sidtab during policy reload - it is now possible > > to handle insertion of new entries even during sidtab conversion. > > > > The tree structure of the new sidtab is able to grow automatically to up > > to about 2^31 entries (at which point it should not have more than about > > 4 tree levels). The old sidtab had a theoretical capacity of almost 2^32 > > entries, but half of that is still more than enough since by that point > > the reverse table lookups would become unusably slow anyway... > > > > The number of entries per tree node is selected automatically so that > > each node fits into a single page, which should be the easiest size for > > kmalloc() to handle. > > > > Note that the new implementation does not have a cache for recent > > reverse lookups as the old one had. Such cache is, however, added in a > > subsequent patch. > > > > Tested by selinux-testsuite and thoroughly tortured by this simple > > stress test: > > ``` > > function rand_cat() { > > echo $(( $RANDOM % 1024 )) > > } > > > > function do_work() { > > while true; do > > echo -n "system_u:system_r:kernel_t:s0:c$(rand_cat),c$(rand_cat)" \ > > >/sys/fs/selinux/context 2>/dev/null || true > > done > > } > > > > do_work >/dev/null & > > do_work >/dev/null & > > do_work >/dev/null & > > > > while load_policy; do echo -n .; sleep 0.1; done > > > > kill %1 > > kill %2 > > kill %3 > > ``` > > > > Reported-by: Orion Poplawski > > Reported-by: Li Kun > > Link: https://github.com/SELinuxProject/selinux-kernel/issues/38 > > Signed-off-by: Ondrej Mosnacek > > --- > > security/selinux/ss/mls.c | 23 +- > > security/selinux/ss/mls.h | 3 +- > > security/selinux/ss/services.c | 90 +++--- > > security/selinux/ss/sidtab.c | 522 +++++++++++++++++++-------------- > > security/selinux/ss/sidtab.h | 75 +++-- > > 5 files changed, 402 insertions(+), 311 deletions(-) > > > > diff --git a/security/selinux/ss/mls.c b/security/selinux/ss/mls.c > > index 2fe459df3c85..267ae4f9be79 100644 > > --- a/security/selinux/ss/mls.c > > +++ b/security/selinux/ss/mls.c > > @@ -436,16 +436,17 @@ int mls_setup_user_range(struct policydb *p, > > > > /* > > * Convert the MLS fields in the security context > > - * structure `c' from the values specified in the > > - * policy `oldp' to the values specified in the policy `newp'. > > + * structure `oldc' from the values specified in the > > + * policy `oldp' to the values specified in the policy `newp', > > + * storing the resulting context in `newc'. > > */ > > int mls_convert_context(struct policydb *oldp, > > struct policydb *newp, > > - struct context *c) > > + struct context *oldc, > > + struct context *newc) > > { > > struct level_datum *levdatum; > > struct cat_datum *catdatum; > > - struct ebitmap bitmap; > > struct ebitmap_node *node; > > int l, i; > > > > @@ -455,28 +456,24 @@ int mls_convert_context(struct policydb *oldp, > > for (l = 0; l < 2; l++) { > > levdatum = hashtab_search(newp->p_levels.table, > > sym_name(oldp, SYM_LEVELS, > > - c->range.level[l].sens - 1)); > > + oldc->range.level[l].sens - 1)); > > > > if (!levdatum) > > return -EINVAL; > > - c->range.level[l].sens = levdatum->level->sens; > > + newc->range.level[l].sens = levdatum->level->sens; > > > > - ebitmap_init(&bitmap); > > - ebitmap_for_each_positive_bit(&c->range.level[l].cat, node, i) { > > + ebitmap_for_each_positive_bit(&oldc->range.level[l].cat, node, i) { > > int rc; > > > > catdatum = hashtab_search(newp->p_cats.table, > > sym_name(oldp, SYM_CATS, i)); > > if (!catdatum) > > return -EINVAL; > > - rc = ebitmap_set_bit(&bitmap, catdatum->value - 1, 1); > > + rc = ebitmap_set_bit(&newc->range.level[l].cat, > > + catdatum->value - 1, 1); > > if (rc) > > return rc; > > - > > - cond_resched(); > > } > > - ebitmap_destroy(&c->range.level[l].cat); > > - c->range.level[l].cat = bitmap; > > } > > > > return 0; > > diff --git a/security/selinux/ss/mls.h b/security/selinux/ss/mls.h > > index 67093647576d..7954b1e60b64 100644 > > --- a/security/selinux/ss/mls.h > > +++ b/security/selinux/ss/mls.h > > @@ -46,7 +46,8 @@ int mls_range_set(struct context *context, struct mls_range *range); > > > > int mls_convert_context(struct policydb *oldp, > > struct policydb *newp, > > - struct context *context); > > + struct context *oldc, > > + struct context *newc); > > > > int mls_compute_sid(struct policydb *p, > > struct context *scontext, > > diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c > > index 30170d4c567a..3c5887838e12 100644 > > --- a/security/selinux/ss/services.c > > +++ b/security/selinux/ss/services.c > > @@ -1907,19 +1907,16 @@ struct convert_context_args { > > > > /* > > * Convert the values in the security context > > - * structure `c' from the values specified > > + * structure `oldc' from the values specified > > * in the policy `p->oldp' to the values specified > > - * in the policy `p->newp'. Verify that the > > - * context is valid under the new policy. > > + * in the policy `p->newp', storing the new context > > + * in `newc'. Verify that the context is valid > > + * under the new policy. > > */ > > -static int convert_context(u32 key, > > - struct context *c, > > - void *p) > > +static int convert_context(struct context *oldc, struct context *newc, void *p) > > { > > struct convert_context_args *args; > > - struct context oldc; > > struct ocontext *oc; > > - struct mls_range *range; > > struct role_datum *role; > > struct type_datum *typdatum; > > struct user_datum *usrdatum; > > @@ -1929,23 +1926,18 @@ static int convert_context(u32 key, > > > > args = p; > > > > - if (c->str) { > > - struct context ctx; > > - > > + if (oldc->str) { > > rc = -ENOMEM; > > - s = kstrdup(c->str, GFP_KERNEL); > > + s = kstrdup(oldc->str, GFP_KERNEL); > > if (!s) > > goto out; > > > > rc = string_to_context_struct(args->newp, NULL, s, > > - &ctx, SECSID_NULL); > > + newc, SECSID_NULL); > > kfree(s); > > if (!rc) { > > pr_info("SELinux: Context %s became valid (mapped).\n", > > - c->str); > > - /* Replace string with mapped representation. */ > > - kfree(c->str); > > - memcpy(c, &ctx, sizeof(*c)); > > + oldc->str); > > goto out; > > } else if (rc == -EINVAL) { > > /* Retain string representation for later mapping. */ > I haven't looked closely at the new sidtab implementation yet, but I was > encountering KASAN failures in testing and noticed that they seemed to > be tied to invalid/unmapped contexts in the filesystem. > > Reproducer: > $ su > # setenforce 0 > # touch foo > # setfattr -n security.selinux -v thisisnotavalidcontext foo > # ls -Z foo > # load_policy > # ls -Z foo > > The issue in this case seems to be that you aren't actually retaining > the string representation of the invalid/unmapped context across a > reload after this patch because you never copy it to newc, e.g. replace > the rc = 0; line with rc = context_cpy(newc, oldc); in the EINVAL case > above. Otherwise, you'll be left with an uninitialized newc. > Previously we didn't have to do anything here because we were just > leaving c (oldc) intact. Indeed, thanks for spotting that! I will have a closer look tomorrow. > > > @@ -1954,51 +1946,42 @@ static int convert_context(u32 key, > > } else { > > /* Other error condition, e.g. ENOMEM. */ > > pr_err("SELinux: Unable to map context %s, rc = %d.\n", > > - c->str, -rc); > > + oldc->str, -rc); > > goto out; > > } > > } > > > > - rc = context_cpy(&oldc, c); > > - if (rc) > > - goto out; > > + context_init(newc); > > > > /* Convert the user. */ > > rc = -EINVAL; > > usrdatum = hashtab_search(args->newp->p_users.table, > > - sym_name(args->oldp, SYM_USERS, c->user - 1)); > > + sym_name(args->oldp, SYM_USERS, oldc->user - 1)); > > if (!usrdatum) > > goto bad; > > - c->user = usrdatum->value; > > + newc->user = usrdatum->value; > > > > /* Convert the role. */ > > rc = -EINVAL; > > role = hashtab_search(args->newp->p_roles.table, > > - sym_name(args->oldp, SYM_ROLES, c->role - 1)); > > + sym_name(args->oldp, SYM_ROLES, oldc->role - 1)); > > if (!role) > > goto bad; > > - c->role = role->value; > > + newc->role = role->value; > > > > /* Convert the type. */ > > rc = -EINVAL; > > typdatum = hashtab_search(args->newp->p_types.table, > > - sym_name(args->oldp, SYM_TYPES, c->type - 1)); > > + sym_name(args->oldp, SYM_TYPES, oldc->type - 1)); > > if (!typdatum) > > goto bad; > > - c->type = typdatum->value; > > + newc->type = typdatum->value; > > > > /* Convert the MLS fields if dealing with MLS policies */ > > if (args->oldp->mls_enabled && args->newp->mls_enabled) { > > - rc = mls_convert_context(args->oldp, args->newp, c); > > + rc = mls_convert_context(args->oldp, args->newp, oldc, newc); > > if (rc) > > goto bad; > > - } else if (args->oldp->mls_enabled && !args->newp->mls_enabled) { > > - /* > > - * Switching between MLS and non-MLS policy: > > - * free any storage used by the MLS fields in the > > - * context for all existing entries in the sidtab. > > - */ > > - mls_context_destroy(c); > > } else if (!args->oldp->mls_enabled && args->newp->mls_enabled) { > > /* > > * Switching between non-MLS and MLS policy: > > @@ -2016,36 +1999,31 @@ static int convert_context(u32 key, > > " the initial SIDs list\n"); > > goto bad; > > } > > - range = &oc->context[0].range; > > - rc = mls_range_set(c, range); > > + rc = mls_range_set(newc, &oc->context[0].range); > > if (rc) > > goto bad; > > } > > > > /* Check the validity of the new context. */ > > - if (!policydb_context_isvalid(args->newp, c)) { > > - rc = convert_context_handle_invalid_context(args->state, > > - &oldc); > > + if (!policydb_context_isvalid(args->newp, newc)) { > > + rc = convert_context_handle_invalid_context(args->state, oldc); > > if (rc) > > goto bad; > > } > > > > - context_destroy(&oldc); > > - > > rc = 0; > > out: > > return rc; > > bad: > > /* Map old representation to string and save it. */ > > - rc = context_struct_to_string(args->oldp, &oldc, &s, &len); > > + rc = context_struct_to_string(args->oldp, oldc, &s, &len); > > if (rc) > > return rc; > > - context_destroy(&oldc); > > - context_destroy(c); > > - c->str = s; > > - c->len = len; > > + context_destroy(newc); > > + newc->str = s; > > + newc->len = len; > > pr_info("SELinux: Context %s became invalid (unmapped).\n", > > - c->str); > > + newc->str); > > rc = 0; > > goto out; > > } > > @@ -2091,6 +2069,7 @@ int security_load_policy(struct selinux_state *state, void *data, size_t len) > > struct policydb *oldpolicydb, *newpolicydb; > > struct selinux_mapping *oldmapping; > > struct selinux_map newmap; > > + struct sidtab_convert_params convert_params; > > struct convert_context_args args; > > u32 seqno; > > int rc = 0; > > @@ -2147,12 +2126,6 @@ int security_load_policy(struct selinux_state *state, void *data, size_t len) > > goto out; > > } > > > > - oldsidtab = state->ss->sidtab; > > - > > -#if 0 > > - sidtab_hash_eval(oldsidtab, "sids"); > > -#endif > > - > > rc = policydb_read(newpolicydb, fp); > > if (rc) { > > kfree(newsidtab); > > @@ -2184,6 +2157,8 @@ int security_load_policy(struct selinux_state *state, void *data, size_t len) > > goto err; > > } > > > > + oldsidtab = state->ss->sidtab; > > + > > /* > > * Convert the internal representations of contexts > > * in the new SID table. > > @@ -2191,7 +2166,12 @@ int security_load_policy(struct selinux_state *state, void *data, size_t len) > > args.state = state; > > args.oldp = policydb; > > args.newp = newpolicydb; > > - rc = sidtab_convert(oldsidtab, newsidtab, convert_context, &args); > > + > > + convert_params.func = convert_context; > > + convert_params.args = &args; > > + convert_params.target = newsidtab; > > + > > + rc = sidtab_convert(oldsidtab, &convert_params); > > if (rc) { > > pr_err("SELinux: unable to convert the internal" > > " representation of contexts in the new SID" > > diff --git a/security/selinux/ss/sidtab.c b/security/selinux/ss/sidtab.c > > index e157d8240cf1..a82deecfac09 100644 > > --- a/security/selinux/ss/sidtab.c > > +++ b/security/selinux/ss/sidtab.c > > @@ -2,88 +2,38 @@ > > /* > > * Implementation of the SID table type. > > * > > - * Author : Stephen Smalley, > > + * Original author: Stephen Smalley, > > + * Author: Ondrej Mosnacek, > > + * > > + * Copyright (C) 2018 Red Hat, Inc. > > */ > > +#include > > #include > > #include > > +#include > > #include > > -#include > > +#include > > #include "flask.h" > > #include "security.h" > > #include "sidtab.h" > > > > -#define SIDTAB_HASH(sid) \ > > -(sid & SIDTAB_HASH_MASK) > > - > > int sidtab_init(struct sidtab *s) > > { > > - int i; > > + u32 i; > > > > - s->htable = kmalloc_array(SIDTAB_SIZE, sizeof(*s->htable), GFP_ATOMIC); > > - if (!s->htable) > > - return -ENOMEM; > > + memset(s->roots, 0, sizeof(s->roots)); > > > > for (i = 0; i < SECINITSID_NUM; i++) > > s->isids[i].set = 0; > > > > - for (i = 0; i < SIDTAB_SIZE; i++) > > - s->htable[i] = NULL; > > + atomic_set(&s->count, 0); > > > > - for (i = 0; i < SIDTAB_CACHE_LEN; i++) > > - s->cache[i] = NULL; > > + s->convert = NULL; > > > > - s->nel = 0; > > - s->next_sid = 0; > > - s->shutdown = 0; > > spin_lock_init(&s->lock); > > return 0; > > } > > > > -static int sidtab_insert(struct sidtab *s, u32 sid, struct context *context) > > -{ > > - int hvalue; > > - struct sidtab_node *prev, *cur, *newnode; > > - > > - if (!s) > > - return -ENOMEM; > > - > > - hvalue = SIDTAB_HASH(sid); > > - prev = NULL; > > - cur = s->htable[hvalue]; > > - while (cur && sid > cur->sid) { > > - prev = cur; > > - cur = cur->next; > > - } > > - > > - if (cur && sid == cur->sid) > > - return -EEXIST; > > - > > - newnode = kmalloc(sizeof(*newnode), GFP_ATOMIC); > > - if (!newnode) > > - return -ENOMEM; > > - > > - newnode->sid = sid; > > - if (context_cpy(&newnode->context, context)) { > > - kfree(newnode); > > - return -ENOMEM; > > - } > > - > > - if (prev) { > > - newnode->next = prev->next; > > - wmb(); > > - prev->next = newnode; > > - } else { > > - newnode->next = s->htable[hvalue]; > > - wmb(); > > - s->htable[hvalue] = newnode; > > - } > > - > > - s->nel++; > > - if (sid >= s->next_sid) > > - s->next_sid = sid + 1; > > - return 0; > > -} > > - > > int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context) > > { > > struct sidtab_isid_entry *entry; > > @@ -102,20 +52,90 @@ int sidtab_set_initial(struct sidtab *s, u32 sid, struct context *context) > > return 0; > > } > > > > -static struct context *sidtab_lookup(struct sidtab *s, u32 sid) > > +static u32 sidtab_level_from_count(u32 count) > > { > > - int hvalue; > > - struct sidtab_node *cur; > > + u32 capacity = SIDTAB_LEAF_ENTRIES; > > + u32 level = 0; > > > > - hvalue = SIDTAB_HASH(sid); > > - cur = s->htable[hvalue]; > > - while (cur && sid > cur->sid) > > - cur = cur->next; > > + while (count > capacity) { > > + capacity <<= SIDTAB_INNER_SHIFT; > > + ++level; > > + } > > + return level; > > +} > > + > > +static int sidtab_alloc_roots(struct sidtab *s, u32 level) > > +{ > > + u32 l; > > + > > + if (!s->roots[0].ptr_leaf) { > > + s->roots[0].ptr_leaf = kzalloc(SIDTAB_NODE_ALLOC_SIZE, > > + GFP_ATOMIC); > > + if (!s->roots[0].ptr_leaf) > > + return -ENOMEM; > > + } > > + for (l = 1; l <= level; ++l) > > + if (!s->roots[l].ptr_inner) { > > + s->roots[l].ptr_inner = kzalloc(SIDTAB_NODE_ALLOC_SIZE, > > + GFP_ATOMIC); > > + if (!s->roots[l].ptr_inner) > > + return -ENOMEM; > > + s->roots[l].ptr_inner->entries[0] = s->roots[l - 1]; > > + } > > + return 0; > > +} > > > > - if (!cur || sid != cur->sid) > > +static struct context *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; > > + > > + /* find the level of the subtree we need */ > > + level = sidtab_level_from_count(index + 1); > > + capacity_shift = level * SIDTAB_INNER_SHIFT; > > + > > + /* allocate roots if needed */ > > + if (alloc && sidtab_alloc_roots(s, level) != 0) > > return NULL; > > > > - return &cur->context; > > + /* lookup inside the subtree */ > > + entry = &s->roots[level]; > > + while (level != 0) { > > + capacity_shift -= SIDTAB_INNER_SHIFT; > > + --level; > > + > > + entry = &entry->ptr_inner->entries[leaf_index >> capacity_shift]; > > + leaf_index &= ((u32)1 << capacity_shift) - 1; > > + > > + if (!entry->ptr_inner) { > > + if (alloc) > > + entry->ptr_inner = kzalloc(SIDTAB_NODE_ALLOC_SIZE, > > + GFP_ATOMIC); > > + if (!entry->ptr_inner) > > + return NULL; > > + } > > + } > > + if (!entry->ptr_leaf) { > > + if (alloc) > > + entry->ptr_leaf = kzalloc(SIDTAB_NODE_ALLOC_SIZE, > > + GFP_ATOMIC); > > + if (!entry->ptr_leaf) > > + return NULL; > > + } > > + return &entry->ptr_leaf->entries[index % SIDTAB_LEAF_ENTRIES].context; > > +} > > + > > +static struct context *sidtab_lookup(struct sidtab *s, u32 index) > > +{ > > + u32 count = (u32)atomic_read(&s->count); > > + > > + if (index >= count) > > + return NULL; > > + > > + /* read entries after reading count */ > > + smp_rmb(); > > + > > + return sidtab_do_lookup(s, index, 0); > > } > > > > static struct context *sidtab_search_core(struct sidtab *s, u32 sid, int force) > > @@ -123,7 +143,7 @@ static struct context *sidtab_search_core(struct sidtab *s, u32 sid, int force) > > struct context *context; > > struct sidtab_isid_entry *entry; > > > > - if (!s || sid == 0) > > + if (sid == 0) > > return NULL; > > > > if (sid > SECINITSID_NUM) { > > @@ -149,140 +169,126 @@ struct context *sidtab_search_force(struct sidtab *s, u32 sid) > > return sidtab_search_core(s, sid, 1); > > } > > > > -static int sidtab_map(struct sidtab *s, > > - int (*apply)(u32 sid, > > - struct context *context, > > - void *args), > > - void *args) > > +static int sidtab_find_context(union sidtab_entry_inner entry, > > + u32 *pos, u32 count, u32 level, > > + struct context *context, u32 *index) > > { > > - int i, rc = 0; > > - struct sidtab_node *cur; > > + int rc; > > + u32 i; > > > > - if (!s) > > - goto out; > > + if (level != 0) { > > + struct sidtab_node_inner *node = entry.ptr_inner; > > > > - for (i = 0; i < SIDTAB_SIZE; i++) { > > - cur = s->htable[i]; > > - while (cur) { > > - rc = apply(cur->sid, &cur->context, args); > > - if (rc) > > - goto out; > > - cur = cur->next; > > + i = 0; > > + while (i < SIDTAB_INNER_ENTRIES && *pos < count) { > > + rc = sidtab_find_context(node->entries[i], > > + pos, count, level - 1, > > + context, index); > > + if (rc == 0) > > + return 0; > > + i++; > > } > > - } > > -out: > > - return rc; > > -} > > + } else { > > + struct sidtab_node_leaf *node = entry.ptr_leaf; > > > > -/* Clone the SID into the new SID table. */ > > -static int clone_sid(u32 sid, struct context *context, void *arg) > > -{ > > - struct sidtab *s = arg; > > - return sidtab_insert(s, sid, context); > > + i = 0; > > + while (i < SIDTAB_LEAF_ENTRIES && *pos < count) { > > + if (context_cmp(&node->entries[i].context, context)) { > > + *index = *pos; > > + return 0; > > + } > > + (*pos)++; > > + i++; > > + } > > + } > > + return -ENOENT; > > } > > > > -int sidtab_convert(struct sidtab *s, struct sidtab *news, > > - int (*convert)(u32 sid, > > - struct context *context, > > - void *args), > > - void *args) > > +static int sidtab_reverse_lookup(struct sidtab *s, struct context *context, > > + u32 *index) > > { > > unsigned long flags; > > + u32 count = (u32)atomic_read(&s->count); > > + u32 count_locked, level, pos; > > + struct sidtab_convert_params *convert; > > + struct context *dst, *dst_convert; > > int rc; > > > > - spin_lock_irqsave(&s->lock, flags); > > - s->shutdown = 1; > > - spin_unlock_irqrestore(&s->lock, flags); > > + level = sidtab_level_from_count(count); > > > > - rc = sidtab_map(s, clone_sid, news); > > - if (rc) > > - return rc; > > + /* read entries after reading count */ > > + smp_rmb(); > > > > - return sidtab_map(news, convert, args); > > -} > > + pos = 0; > > + rc = sidtab_find_context(s->roots[level], &pos, count, level, > > + context, index); > > + if (rc == 0) > > + return 0; > > > > -static void sidtab_update_cache(struct sidtab *s, struct sidtab_node *n, int loc) > > -{ > > - BUG_ON(loc >= SIDTAB_CACHE_LEN); > > + /* lock-free search failed: lock, re-search, and insert if not found */ > > + spin_lock_irqsave(&s->lock, flags); > > > > - while (loc > 0) { > > - s->cache[loc] = s->cache[loc - 1]; > > - loc--; > > - } > > - s->cache[0] = n; > > -} > > + convert = s->convert; > > + count_locked = (u32)atomic_read(&s->count); > > + level = sidtab_level_from_count(count_locked); > > > > -static inline int sidtab_search_context(struct sidtab *s, > > - struct context *context, u32 *sid) > > -{ > > - int i; > > - struct sidtab_node *cur; > > - > > - for (i = 0; i < SIDTAB_SIZE; i++) { > > - cur = s->htable[i]; > > - while (cur) { > > - if (context_cmp(&cur->context, context)) { > > - sidtab_update_cache(s, cur, SIDTAB_CACHE_LEN - 1); > > - *sid = cur->sid; > > - return 0; > > - } > > - cur = cur->next; > > + /* if count has changed before we acquired the lock, then catch up */ > > + while (count < count_locked) { > > + if (context_cmp(sidtab_do_lookup(s, count, 0), context)) { > > + rc = 0; > > + *index = count; > > + goto out_unlock; > > } > > + ++count; > > } > > - return -ENOENT; > > -} > > > > -static inline int sidtab_search_cache(struct sidtab *s, struct context *context, > > - u32 *sid) > > -{ > > - int i; > > - struct sidtab_node *node; > > - > > - for (i = 0; i < SIDTAB_CACHE_LEN; i++) { > > - node = s->cache[i]; > > - if (unlikely(!node)) > > - return -ENOENT; > > - if (context_cmp(&node->context, context)) { > > - sidtab_update_cache(s, node, i); > > - *sid = node->sid; > > - return 0; > > - } > > - } > > - return -ENOENT; > > -} > > + /* insert context into new entry */ > > + rc = -ENOMEM; > > + dst = sidtab_do_lookup(s, count, 1); > > + if (!dst) > > + goto out_unlock; > > > > -static int sidtab_reverse_lookup(struct sidtab *s, struct context *context, > > - u32 *sid) > > -{ > > - int ret; > > - unsigned long flags; > > + rc = context_cpy(dst, context); > > + if (rc) > > + goto out_unlock; > > + > > + /* > > + * if we are building a new sidtab, we need to convert the context > > + * and insert it there as well > > + */ > > + if (convert) { > > + rc = -ENOMEM; > > + dst_convert = sidtab_do_lookup(convert->target, count, 1); > > + if (!dst_convert) { > > + context_destroy(dst); > > + goto out_unlock; > > + } > > > > - ret = sidtab_search_cache(s, context, sid); > > - if (ret) > > - ret = sidtab_search_context(s, context, sid); > > - if (ret) { > > - spin_lock_irqsave(&s->lock, flags); > > - /* Rescan now that we hold the lock. */ > > - ret = sidtab_search_context(s, context, sid); > > - if (!ret) > > - goto unlock_out; > > - /* No SID exists for the context. Allocate a new one. */ > > - if (s->next_sid == (UINT_MAX - SECINITSID_NUM - 1) || s->shutdown) { > > - ret = -ENOMEM; > > - goto unlock_out; > > + rc = convert->func(context, dst_convert, convert->args); > > + if (rc) { > > + context_destroy(dst); > > + goto out_unlock; > > } > > - *sid = s->next_sid++; > > - if (context->len) > > - pr_info("SELinux: Context %s is not valid (left unmapped).\n", > > - context->str); > > - ret = sidtab_insert(s, *sid, context); > > - if (ret) > > - s->next_sid--; > > -unlock_out: > > - spin_unlock_irqrestore(&s->lock, flags); > > + > > + /* at this point we know the insert won't fail */ > > + atomic_set(&convert->target->count, count + 1); > > } > > > > - return ret; > > + if (context->len) > > + pr_info("SELinux: Context %s is not valid (left unmapped).\n", > > + context->str); > > + > > + *index = count; > > + > > + /* write entries before writing new count */ > > + smp_wmb(); > > + > > + atomic_set(&s->count, count + 1); > > + > > + rc = 0; > > +out_unlock: > > + spin_unlock_irqrestore(&s->lock, flags); > > + return rc; > > } > > > > int sidtab_context_to_sid(struct sidtab *s, struct context *context, u32 *sid) > > @@ -306,58 +312,134 @@ int sidtab_context_to_sid(struct sidtab *s, struct context *context, u32 *sid) > > return 0; > > } > > > > -void sidtab_hash_eval(struct sidtab *h, char *tag) > > +static int sidtab_convert_tree(union sidtab_entry_inner *edst, > > + union sidtab_entry_inner *esrc, > > + u32 *pos, u32 count, u32 level, > > + struct sidtab_convert_params *convert) > > { > > - int i, chain_len, slots_used, max_chain_len; > > - struct sidtab_node *cur; > > - > > - slots_used = 0; > > - max_chain_len = 0; > > - for (i = 0; i < SIDTAB_SIZE; i++) { > > - cur = h->htable[i]; > > - if (cur) { > > - slots_used++; > > - chain_len = 0; > > - while (cur) { > > - chain_len++; > > - cur = cur->next; > > - } > > + int rc; > > + u32 i; > > > > - if (chain_len > max_chain_len) > > - max_chain_len = chain_len; > > + if (level != 0) { > > + if (!edst->ptr_inner) { > > + edst->ptr_inner = kzalloc(SIDTAB_NODE_ALLOC_SIZE, GFP_KERNEL); > > + if (!edst->ptr_inner) > > + return -ENOMEM; > > + } > > + i = 0; > > + while (i < SIDTAB_INNER_ENTRIES && *pos < count) { > > + rc = sidtab_convert_tree(&edst->ptr_inner->entries[i], > > + &esrc->ptr_inner->entries[i], > > + pos, count, level - 1, convert); > > + if (rc) > > + return rc; > > + i++; > > } > > + } else { > > + if (!edst->ptr_leaf) { > > + edst->ptr_leaf = kzalloc(SIDTAB_NODE_ALLOC_SIZE, GFP_KERNEL); > > + if (!edst->ptr_leaf) > > + return -ENOMEM; > > + } > > + i = 0; > > + while (i < SIDTAB_LEAF_ENTRIES && *pos < count) { > > + rc = convert->func(&esrc->ptr_leaf->entries[i].context, > > + &edst->ptr_leaf->entries[i].context, > > + convert->args); > > + if (rc) > > + return rc; > > + (*pos)++; > > + i++; > > + } > > + cond_resched(); > > + } > > + return 0; > > +} > > + > > +int sidtab_convert(struct sidtab *s, struct sidtab_convert_params *params) > > +{ > > + unsigned long flags; > > + u32 count, level, pos; > > + int rc; > > + > > + spin_lock_irqsave(&s->lock, flags); > > + > > + /* concurrent policy loads are not allowed */ > > + if (s->convert) { > > + spin_unlock_irqrestore(&s->lock, flags); > > + return -EBUSY; > > + } > > + > > + count = (u32)atomic_read(&s->count); > > + level = sidtab_level_from_count(count); > > + > > + /* allocate last leaf in the new sidtab (to avoid race with live convert) */ > > + rc = sidtab_do_lookup(params->target, count - 1, 1) ? 0 : -ENOMEM; > > + if (rc) { > > + spin_unlock_irqrestore(&s->lock, flags); > > + return rc; > > + } > > + > > + /* set count in case no new entries are added during conversion */ > > + atomic_set(¶ms->target->count, count); > > + > > + /* enable live convert of new entries */ > > + s->convert = params; > > + > > + /* we can safely do the rest of the conversion outside the lock */ > > + spin_unlock_irqrestore(&s->lock, flags); > > + > > + pr_info("SELinux: Converting %u SID table entries...\n", count); > > + > > + /* convert all entries not covered by live convert */ > > + pos = 0; > > + rc = sidtab_convert_tree(¶ms->target->roots[level], &s->roots[level], > > + &pos, count, level, params); > > + if (rc) { > > + /* we need to keep the old table - disable live convert */ > > + spin_lock_irqsave(&s->lock, flags); > > + s->convert = NULL; > > + spin_unlock_irqrestore(&s->lock, flags); > > } > > + return rc; > > +} > > + > > +static void sidtab_destroy_tree(union sidtab_entry_inner entry, u32 level) > > +{ > > + u32 i; > > + > > + if (level != 0) { > > + struct sidtab_node_inner *node = entry.ptr_inner; > > > > - pr_debug("%s: %d entries and %d/%d buckets used, longest " > > - "chain length %d\n", tag, h->nel, slots_used, SIDTAB_SIZE, > > - max_chain_len); > > + if (!node) > > + return; > > + > > + for (i = 0; i < SIDTAB_INNER_ENTRIES; i++) > > + sidtab_destroy_tree(node->entries[i], level - 1); > > + kfree(node); > > + } else { > > + struct sidtab_node_leaf *node = entry.ptr_leaf; > > + > > + if (!node) > > + return; > > + > > + for (i = 0; i < SIDTAB_LEAF_ENTRIES; i++) > > + context_destroy(&node->entries[i].context); > > + kfree(node); > > + } > > } > > > > void sidtab_destroy(struct sidtab *s) > > { > > - int i; > > - struct sidtab_node *cur, *temp; > > - > > - if (!s) > > - return; > > + u32 i, level; > > > > for (i = 0; i < SECINITSID_NUM; i++) > > if (s->isids[i].set) > > context_destroy(&s->isids[i].context); > > > > + level = SIDTAB_MAX_LEVEL; > > + while (level && !s->roots[level].ptr_inner) > > + --level; > > > > - for (i = 0; i < SIDTAB_SIZE; i++) { > > - cur = s->htable[i]; > > - while (cur) { > > - temp = cur; > > - cur = cur->next; > > - context_destroy(&temp->context); > > - kfree(temp); > > - } > > - s->htable[i] = NULL; > > - } > > - kfree(s->htable); > > - s->htable = NULL; > > - s->nel = 0; > > - s->next_sid = 1; > > + sidtab_destroy_tree(s->roots[level], level); > > } > > diff --git a/security/selinux/ss/sidtab.h b/security/selinux/ss/sidtab.h > > index e657ae6bf996..292512792a70 100644 > > --- a/security/selinux/ss/sidtab.h > > +++ b/security/selinux/ss/sidtab.h > > @@ -1,39 +1,75 @@ > > /* SPDX-License-Identifier: GPL-2.0 */ > > /* > > - * A security identifier table (sidtab) is a hash table > > + * A security identifier table (sidtab) is a lookup table > > * of security context structures indexed by SID value. > > * > > - * Author : Stephen Smalley, > > + * Original author: Stephen Smalley, > > + * Author: Ondrej Mosnacek, > > + * > > + * Copyright (C) 2018 Red Hat, Inc. > > */ > > #ifndef _SS_SIDTAB_H_ > > #define _SS_SIDTAB_H_ > > > > +#include > > +#include > > + > > #include "context.h" > > > > -struct sidtab_node { > > - u32 sid; /* security identifier */ > > - struct context context; /* security context structure */ > > - struct sidtab_node *next; > > +struct sidtab_entry_leaf { > > + struct context context; > > +}; > > + > > +struct sidtab_node_inner; > > +struct sidtab_node_leaf; > > + > > +union sidtab_entry_inner { > > + struct sidtab_node_inner *ptr_inner; > > + struct sidtab_node_leaf *ptr_leaf; > > }; > > > > -#define SIDTAB_HASH_BITS 7 > > -#define SIDTAB_HASH_BUCKETS (1 << SIDTAB_HASH_BITS) > > -#define SIDTAB_HASH_MASK (SIDTAB_HASH_BUCKETS-1) > > +/* align node size to page boundary */ > > +#define SIDTAB_NODE_ALLOC_SHIFT PAGE_SHIFT > > +#define SIDTAB_NODE_ALLOC_SIZE PAGE_SIZE > > + > > +#define size_to_shift(size) ((size) == 1 ? 1 : (const_ilog2((size) - 1) + 1)) > > + > > +#define SIDTAB_INNER_SHIFT \ > > + (SIDTAB_NODE_ALLOC_SHIFT - size_to_shift(sizeof(union sidtab_entry_inner))) > > > > -#define SIDTAB_SIZE SIDTAB_HASH_BUCKETS > > +#define SIDTAB_LEAF_ENTRIES (PAGE_SIZE / sizeof(struct sidtab_entry_leaf)) > > +#define SIDTAB_INNER_ENTRIES ((size_t)1 << SIDTAB_INNER_SHIFT) > > + > > +#define SIDTAB_MAX_BITS 31 /* limited to INT_MAX due to atomic_t range */ > > +#define SIDTAB_MAX (((u32)1 << SIDTAB_MAX_BITS) - 1) > > +/* ensure enough tree levels for SIDTAB_MAX entries */ > > +#define SIDTAB_MAX_LEVEL \ > > + DIV_ROUND_UP(SIDTAB_MAX_BITS - size_to_shift(SIDTAB_LEAF_ENTRIES), \ > > + SIDTAB_INNER_SHIFT) > > + > > +struct sidtab_node_leaf { > > + struct sidtab_entry_leaf entries[SIDTAB_LEAF_ENTRIES]; > > +}; > > + > > +struct sidtab_node_inner { > > + union sidtab_entry_inner entries[SIDTAB_INNER_ENTRIES]; > > +}; > > > > struct sidtab_isid_entry { > > int set; > > struct context context; > > }; > > > > +struct sidtab_convert_params { > > + int (*func)(struct context *oldc, struct context *newc, void *args); > > + void *args; > > + struct sidtab *target; > > +}; > > + > > struct sidtab { > > - struct sidtab_node **htable; > > - unsigned int nel; /* number of elements */ > > - unsigned int next_sid; /* next SID to allocate */ > > - unsigned char shutdown; > > -#define SIDTAB_CACHE_LEN 3 > > - struct sidtab_node *cache[SIDTAB_CACHE_LEN]; > > + union sidtab_entry_inner roots[SIDTAB_MAX_LEVEL + 1]; > > + atomic_t count; > > + struct sidtab_convert_params *convert; > > spinlock_t lock; > > > > /* index == SID - 1 (no entry for SECSID_NULL) */ > > @@ -45,15 +81,10 @@ 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); > > > > -int sidtab_convert(struct sidtab *s, struct sidtab *news, > > - int (*apply)(u32 sid, > > - struct context *context, > > - void *args), > > - void *args); > > +int sidtab_convert(struct sidtab *s, struct sidtab_convert_params *params); > > > > int sidtab_context_to_sid(struct sidtab *s, struct context *context, u32 *sid); > > > > -void sidtab_hash_eval(struct sidtab *h, char *tag); > > void sidtab_destroy(struct sidtab *s); > > > > #endif /* _SS_SIDTAB_H_ */ > > > -- Ondrej Mosnacek Associate Software Engineer, Security Technologies Red Hat, Inc.