Re: [PATCH 2/2] selinux: fix ENOMEM errors during policy reload

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On Wed, Oct 31, 2018 at 9:29 PM Stephen Smalley <sds@xxxxxxxxxxxxx> wrote:
> On 10/31/2018 08:27 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 <some_file> || break
> >      done
> >
> > This patchs overhauls the sidtab so it doesn't need to be frozen during
> > a policy reload, thus solving the above problem.
> >
> > The new SID table entries now contain two slots for the context. One of
> > the slots is used for the lookup and the other one is used during policy
> > reload to store the new converted context. Which slot is used for what
> > is determined by a shared index that is toggled between 0 and 1 when the
> > conversion is completed, together with the switch to the new policy.
> > After the index is toggled, the contexts in the now unused slots are
> > destroyed. The solution also gracefully handles conversion of entries
> > that are added to sidtab while the conversion is in progress.
> >
> > The downside of this solution is that the sidtab now takes up
> > approximately twice the space and half of it is used only during policy
> > reload. On the other hand, this means we do not need to deal with sidtab
> > growing while we are allocating a new one.
> >
> > Reported-by: Orion Poplawski <orion@xxxxxxxx>
> > Reported-by: Li Kun <hw.likun@xxxxxxxxxx>
> > Link: https://github.com/SELinuxProject/selinux-kernel/issues/38
> > Signed-off-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
> > ---
> >   security/selinux/ss/mls.c      |  16 ++---
> >   security/selinux/ss/mls.h      |   3 +-
> >   security/selinux/ss/services.c |  96 +++++++-------------------
> >   security/selinux/ss/sidtab.c   | 122 +++++++++++++++++++++------------
> >   security/selinux/ss/sidtab.h   |  23 ++++---
> >   5 files changed, 124 insertions(+), 136 deletions(-)
> >
> > diff --git a/security/selinux/ss/mls.c b/security/selinux/ss/mls.c
> > index cd637ee3fb11..bc3f93732658 100644
> > --- a/security/selinux/ss/mls.c
> > +++ b/security/selinux/ss/mls.c
> > @@ -441,11 +441,11 @@ int mls_setup_user_range(struct policydb *p,
> >    */
> >   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 +455,26 @@ 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 1eca02c8bc5f..00c11304f71a 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 550a00004139..292a2ccbe56f 100644
> > --- a/security/selinux/ss/services.c
> > +++ b/security/selinux/ss/services.c
> > @@ -1899,12 +1899,6 @@ int security_change_sid(struct selinux_state *state,
> >                                   out_sid, false);
> >   }
> >
> > -/* Clone the SID into the new SID table. */
> > -static int clone_sid(u32 sid, struct context *context, void *arg)
> > -{
> > -     return sidtab_insert((struct sidtab *)arg, sid, context);
> > -}
> > -
> >   static inline int convert_context_handle_invalid_context(
> >       struct selinux_state *state,
> >       struct context *context)
> > @@ -1937,12 +1931,10 @@ struct convert_context_args {
> >    * in the policy `p->newp'.  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;
> > @@ -1952,23 +1944,18 @@ static int convert_context(u32 key, struct context *c, void *p)
> >
> >       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. */
> > @@ -1977,51 +1964,42 @@ static int convert_context(u32 key, struct context *c, void *p)
> >               } 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:
> > @@ -2039,36 +2017,31 @@ static int convert_context(u32 key, struct context *c, void *p)
> >                               " 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;
> >   }
> > @@ -2113,7 +2086,6 @@ int security_load_policy(struct selinux_state *state, void *data, size_t len)
> >       struct sidtab *sidtab;
> >       struct isidtab *newisidtab = NULL;
> >       struct policydb *oldpolicydb, *newpolicydb;
> > -     struct sidtab oldsidtab, newsidtab;
> >       struct selinux_mapping *oldmapping;
> >       struct selinux_map newmap;
> >       struct convert_context_args args;
> > @@ -2187,12 +2159,6 @@ int security_load_policy(struct selinux_state *state, void *data, size_t len)
> >       if (rc)
> >               goto out;
> >
> > -     rc = sidtab_init(&newsidtab);
> > -     if (rc) {
> > -             policydb_destroy(newpolicydb);
> > -             goto out;
> > -     }
> > -
> >       newpolicydb->len = len;
> >       /* If switching between different policy types, log MLS status */
> >       if (policydb->mls_enabled && !newpolicydb->mls_enabled)
> > @@ -2203,7 +2169,6 @@ int security_load_policy(struct selinux_state *state, void *data, size_t len)
> >       rc = policydb_load_isids(newpolicydb, newisidtab);
> >       if (rc) {
> >               pr_err("SELinux:  unable to load the initial SIDs\n");
> > -             sidtab_destroy(&newsidtab);
> >               policydb_destroy(newpolicydb);
> >               goto out;
> >       }
> > @@ -2218,21 +2183,14 @@ int security_load_policy(struct selinux_state *state, void *data, size_t len)
> >               goto err;
> >       }
> >
> > -     /* Clone the SID table. */
> > -     sidtab_shutdown(sidtab);
> > -
> > -     rc = sidtab_map(sidtab, clone_sid, &newsidtab);
> > -     if (rc)
> > -             goto err;
> > -
> >       /*
> >        * Convert the internal representations of contexts
> > -      * in the new SID table.
> > +      * in the SID table.
> >        */
> >       args.state = state;
> >       args.oldp = policydb;
> >       args.newp = newpolicydb;
> > -     rc = sidtab_map(&newsidtab, convert_context, &args);
> > +     rc = sidtab_convert_start(sidtab, convert_context, &args);
> >       if (rc) {
> >               pr_err("SELinux:  unable to convert the internal"
> >                       " representation of contexts in the new SID"
> > @@ -2242,19 +2200,18 @@ int security_load_policy(struct selinux_state *state, void *data, size_t len)
> >
> >       /* Save the old policydb and SID table to free later. */
> >       memcpy(oldpolicydb, policydb, sizeof(*policydb));
> > -     sidtab_set(&oldsidtab, sidtab);
> >
> >       /* Install the new policydb and SID table. */
> >       write_lock_irq(&state->ss->policy_rwlock);
> >
> >       memcpy(policydb, newpolicydb, sizeof(*policydb));
> > -     sidtab_set(sidtab, &newsidtab);
> >
> >       isidtab_destroy(state->ss->isidtab);
> >       kfree(state->ss->isidtab);
> >       state->ss->isidtab = newisidtab;
> >       newisidtab = NULL;
> >
> > +     sidtab_convert_finish(sidtab);
> >       security_load_policycaps(state);
> >       oldmapping = state->ss->map.mapping;
> >       state->ss->map.mapping = newmap.mapping;
> > @@ -2264,8 +2221,8 @@ int security_load_policy(struct selinux_state *state, void *data, size_t len)
> >       write_unlock_irq(&state->ss->policy_rwlock);
> >
> >       /* Free the old policydb and SID table. */
> > +     sidtab_convert_cleanup(sidtab);
> >       policydb_destroy(oldpolicydb);
> > -     sidtab_destroy(&oldsidtab);
> >       kfree(oldmapping);
> >
> >       avc_ss_reset(state->avc, seqno);
> > @@ -2279,7 +2236,6 @@ int security_load_policy(struct selinux_state *state, void *data, size_t len)
> >
> >   err:
> >       kfree(newmap.mapping);
> > -     sidtab_destroy(&newsidtab);
> >       policydb_destroy(newpolicydb);
> >       isidtab_destroy(newisidtab);
> >
> > diff --git a/security/selinux/ss/sidtab.c b/security/selinux/ss/sidtab.c
> > index 98710657a596..ac4781a191d9 100644
> > --- a/security/selinux/ss/sidtab.c
> > +++ b/security/selinux/ss/sidtab.c
> > @@ -24,16 +24,17 @@ int sidtab_init(struct sidtab *s)
> >               return -ENOMEM;
> >       for (i = 0; i < SIDTAB_SIZE; i++)
> >               s->htable[i] = NULL;
> > +     s->context_index = 0;
> >       s->nel = 0;
> >       s->next_sid = SECINITSID_NUM + 1;
> > -     s->shutdown = 0;
> >       spin_lock_init(&s->lock);
> >       return 0;
> >   }
> >
> > -int sidtab_insert(struct sidtab *s, u32 sid, struct context *context)
> > +static int sidtab_insert(struct sidtab *s, u32 sid, struct context *context)
> >   {
> > -     int hvalue;
> > +     unsigned int index = s->context_index;
> > +     int hvalue, rc;
> >       struct sidtab_node *prev, *cur, *newnode;
> >
> >       if (!s)
> > @@ -55,11 +56,23 @@ int sidtab_insert(struct sidtab *s, u32 sid, struct context *context)
> >               return -ENOMEM;
> >
> >       newnode->sid = sid;
> > -     if (context_cpy(&newnode->context, context)) {
> > +     if (context_cpy(&newnode->context[index], context)) {
> >               kfree(newnode);
> >               return -ENOMEM;
> >       }
> >
> > +     newnode->new_set = 0;
> > +     if (s->convert) {
> > +             rc = s->convert(&newnode->context[index],
> > +                             &newnode->context[!index], s->convert_args);
> > +             if (rc) {
> > +                     context_destroy(&newnode->context[index]);
> > +                     kfree(newnode);
> > +                     return rc;
> > +             }
> > +             newnode->new_set = 1;
> > +     }
> > +
> >       if (prev) {
> >               newnode->next = prev->next;
> >               wmb();
> > @@ -92,34 +105,74 @@ struct context *sidtab_lookup(struct sidtab *s, u32 sid)
> >       if (!cur || sid != cur->sid)
> >               return NULL;
> >
> > -     return &cur->context;
> > +     return &cur->context[s->context_index];
> >   }
> >
> > -int sidtab_map(struct sidtab *s,
> > -            int (*apply) (u32 sid,
> > -                          struct context *context,
> > -                          void *args),
> > -            void *args)
> > +int sidtab_convert_start(struct sidtab *s, sidtab_convert_t convert, void *args)
> >   {
> > -     int i, rc = 0;
> > +     unsigned long flags;
> > +     int i, rc;
> >       struct sidtab_node *cur;
> >
> > -     if (!s)
> > -             goto out;
> > +     spin_lock_irqsave(&s->lock, flags);
> > +     s->convert = convert;
> > +     s->convert_args = args;
> > +     spin_unlock_irqrestore(&s->lock, flags);
> >
> >       for (i = 0; i < SIDTAB_SIZE; i++) {
> >               cur = s->htable[i];
> >               while (cur) {
> > -                     rc = apply(cur->sid, &cur->context, args);
> > -                     if (rc)
> > -                             goto out;
> > +                     if (!cur->new_set) {
> > +                             rc = convert(&cur->context[s->context_index],
> > +                                          &cur->context[!s->context_index],
> > +                                          args);
> > +                             if (rc)
> > +                                     goto err;
> > +
> > +                             cur->new_set = 1;
> > +                     }
> >                       cur = cur->next;
> >               }
> >       }
> > -out:
> > +
> > +     return 0;
> > +err:
> > +     /* cleanup on conversion failure */
> > +     spin_lock_irqsave(&s->lock, flags);
> > +     s->convert = NULL;
> > +     s->convert_args = NULL;
> > +     spin_unlock_irqrestore(&s->lock, flags);
> > +
> > +     sidtab_convert_cleanup(s);
> > +
> >       return rc;
> >   }
> >
> > +/* must be called with policy write lock (thus no need to lock the spinlock here) */
> > +void sidtab_convert_finish(struct sidtab *s)
> > +{
> > +     s->context_index = !s->context_index;
> > +     s->convert = NULL;
> > +     s->convert_args = NULL;
> > +}
>
> I'm not sure it is a great idea to skip the sidtab spinlock here even
> though it isn't strictly needed as you say.  It is an obvious
> inconsistency in the handling of ->context_index and ->convert, and the
> sidtab spinlock was previously being taken under the policy write lock
> by sidtab_set() so it isn't a new locking hierarchy. We'd like to
> replace the policy rwlock with RCU at some point; there is a very old
> patch that tried to do that once before, which eliminated the policy
> write lock altogether (policy switch became a single pointer update),
> but no one has yet taken that back up.

I actually skipped it because when it was there then the lock debugger
complained about some possible deadlock scenario involving an
interrupt... I think it is because I now lock the spinlock also
outside the policy rwlock, so there is a new dependency chain that
conflicts with the other one(s)... I'm not sure if it wasn't a false
positive because I thought inside a spinlock interrupts are disabled,
but after removing the spinlock calls from sidtab_convert_finish()
there was no warning, so I kept it like this...

It seems I made the locking too much of a mess, I'll try to rethink
it. Maybe it can be done in a simpler (and safer) way.

> More generally, it would likely be good to document the locking
> dependencies/assumptions being made throughout for s->context_index and
> ->convert.  IIUC, sidtab_insert is safe because of its callers holding
> the policy read lock and the sidtab spinlock.  sidtab_lookup is safe
> because of its callers holding the policy read lock.
> sidtab_convert_start takes the sidtab spinlock for setting ->convert but
> accesses ->context_index without holding the policy read lock; this
> appears to be safe only due to sel_write_load preventing interleaving
> security_load_policy calls via fsi->mutex. sidtab_convert_cleanup
> likewise appears to rely on this.

Yes, as I said, it is becoming a mess :) I don't expect that we would
want to support concurrent policy reload, but it's true that it is
quite a fragile assumption that it will always be under a mutex...
Maybe we should just wrap the dubious bits in a policydb read lock so
it is cleaner... hopefully it wouldn't have a noticeable impact on
performance (policy reload usually takes a long time anyway).

>
> > +
> > +void sidtab_convert_cleanup(struct sidtab *s)
> > +{
> > +     struct sidtab_node *cur;
> > +     int i;
> > +
> > +     for (i = 0; i < SIDTAB_SIZE; i++) {
> > +             cur = s->htable[i];
> > +             while (cur) {
> > +                     if (cur->new_set) {
> > +                             cur->new_set = 0;
> > +                             context_destroy(&cur->context[!s->context_index]);
> > +                     }
> > +                     cur = cur->next;
> > +             }
> > +     }
> > +}
> > +
> >   static void sidtab_update_cache(struct sidtab *s, struct sidtab_node *n, int loc)
> >   {
> >       BUG_ON(loc >= SIDTAB_CACHE_LEN);
> > @@ -132,7 +185,7 @@ static void sidtab_update_cache(struct sidtab *s, struct sidtab_node *n, int loc
> >   }
> >
> >   static inline u32 sidtab_search_context(struct sidtab *s,
> > -                                               struct context *context)
> > +                                     struct context *context)
> >   {
> >       int i;
> >       struct sidtab_node *cur;
> > @@ -140,7 +193,7 @@ static inline u32 sidtab_search_context(struct sidtab *s,
> >       for (i = 0; i < SIDTAB_SIZE; i++) {
> >               cur = s->htable[i];
> >               while (cur) {
> > -                     if (context_cmp(&cur->context, context)) {
> > +                     if (context_cmp(&cur->context[s->context_index], context)) {
> >                               sidtab_update_cache(s, cur, SIDTAB_CACHE_LEN - 1);
> >                               return cur->sid;
> >                       }
> > @@ -159,7 +212,7 @@ static inline u32 sidtab_search_cache(struct sidtab *s, struct context *context)
> >               node = s->cache[i];
> >               if (unlikely(!node))
> >                       return 0;
> > -             if (context_cmp(&node->context, context)) {
> > +             if (context_cmp(&node->context[s->context_index], context)) {
> >                       sidtab_update_cache(s, node, i);
> >                       return node->sid;
> >               }
> > @@ -187,7 +240,7 @@ int sidtab_context_to_sid(struct sidtab *s,
> >               if (sid)
> >                       goto unlock_out;
> >               /* No SID exists for the context.  Allocate a new one. */
> > -             if (s->next_sid == UINT_MAX || s->shutdown) {
> > +             if (s->next_sid == UINT_MAX) {
> >                       ret = -ENOMEM;
> >                       goto unlock_out;
> >               }
> > @@ -249,7 +302,9 @@ void sidtab_destroy(struct sidtab *s)
> >               while (cur) {
> >                       temp = cur;
> >                       cur = cur->next;
> > -                     context_destroy(&temp->context);
> > +                     context_destroy(&temp->context[s->context_index]);
> > +                     if (temp->new_set)
> > +                             context_destroy(&temp->context[!s->context_index]);
> >                       kfree(temp);
> >               }
> >               s->htable[i] = NULL;
> > @@ -260,26 +315,3 @@ void sidtab_destroy(struct sidtab *s)
> >       s->next_sid = 1;
> >   }
> >
> > -void sidtab_set(struct sidtab *dst, struct sidtab *src)
> > -{
> > -     unsigned long flags;
> > -     int i;
> > -
> > -     spin_lock_irqsave(&src->lock, flags);
> > -     dst->htable = src->htable;
> > -     dst->nel = src->nel;
> > -     dst->next_sid = src->next_sid;
> > -     dst->shutdown = 0;
> > -     for (i = 0; i < SIDTAB_CACHE_LEN; i++)
> > -             dst->cache[i] = NULL;
> > -     spin_unlock_irqrestore(&src->lock, flags);
> > -}
> > -
> > -void sidtab_shutdown(struct sidtab *s)
> > -{
> > -     unsigned long flags;
> > -
> > -     spin_lock_irqsave(&s->lock, flags);
> > -     s->shutdown = 1;
> > -     spin_unlock_irqrestore(&s->lock, flags);
> > -}
> > diff --git a/security/selinux/ss/sidtab.h b/security/selinux/ss/sidtab.h
> > index 2eadd09a1100..85ed33238dbb 100644
> > --- a/security/selinux/ss/sidtab.h
> > +++ b/security/selinux/ss/sidtab.h
> > @@ -11,8 +11,9 @@
> >   #include "context.h"
> >
> >   struct sidtab_node {
> > -     u32 sid;                /* security identifier */
> > -     struct context context; /* security context structure */
> > +     u32 sid;                        /* security identifier */
> > +     int new_set;                    /* is context for new policy set? */
> > +     struct context context[2];      /* security context structures */
> >       struct sidtab_node *next;
> >   };
> >
> > @@ -22,25 +23,27 @@ struct sidtab_node {
> >
> >   #define SIDTAB_SIZE SIDTAB_HASH_BUCKETS
> >
> > +typedef int (*sidtab_convert_t)(struct context *oldc, struct context *newc,
> > +                             void *args);
> > +
> >   struct sidtab {
> >       struct sidtab_node **htable;
> > +     unsigned int context_index;
> >       unsigned int nel;       /* number of elements */
> >       unsigned int next_sid;  /* next SID to allocate */
> > -     unsigned char shutdown;
> > +     sidtab_convert_t convert;
> > +     void *convert_args;
> >   #define SIDTAB_CACHE_LEN    3
> >       struct sidtab_node *cache[SIDTAB_CACHE_LEN];
> >       spinlock_t lock;
> >   };
> >
> >   int sidtab_init(struct sidtab *s);
> > -int sidtab_insert(struct sidtab *s, u32 sid, struct context *context);
> >   struct context *sidtab_lookup(struct sidtab *s, u32 sid);
> >
> > -int sidtab_map(struct sidtab *s,
> > -            int (*apply) (u32 sid,
> > -                          struct context *context,
> > -                          void *args),
> > -            void *args);
> > +int sidtab_convert_start(struct sidtab *s, sidtab_convert_t convert, void *args);
> > +void sidtab_convert_finish(struct sidtab *s);
> > +void sidtab_convert_cleanup(struct sidtab *s);
> >
> >   int sidtab_context_to_sid(struct sidtab *s,
> >                         struct context *context,
> > @@ -48,8 +51,6 @@ int sidtab_context_to_sid(struct sidtab *s,
> >
> >   void sidtab_hash_eval(struct sidtab *h, char *tag);
> >   void sidtab_destroy(struct sidtab *s);
> > -void sidtab_set(struct sidtab *dst, struct sidtab *src);
> > -void sidtab_shutdown(struct sidtab *s);
> >
> >   #endif      /* _SS_SIDTAB_H_ */
> >
> >
>


-- 
Ondrej Mosnacek <omosnace at redhat dot com>
Associate Software Engineer, Security Technologies
Red Hat, Inc.
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