diff options
| -rw-r--r-- | security/apparmor/context.c | 16 | ||||
| -rw-r--r-- | security/apparmor/domain.c | 4 | ||||
| -rw-r--r-- | security/apparmor/include/context.h | 15 | ||||
| -rw-r--r-- | security/apparmor/include/policy.h | 78 | ||||
| -rw-r--r-- | security/apparmor/lsm.c | 14 | ||||
| -rw-r--r-- | security/apparmor/policy.c | 85 |
6 files changed, 125 insertions, 87 deletions
diff --git a/security/apparmor/context.c b/security/apparmor/context.c index d5af1d1..3064c6c 100644 --- a/security/apparmor/context.c +++ b/security/apparmor/context.c @@ -112,9 +112,9 @@ int aa_replace_current_profile(struct aa_profile *profile) aa_clear_task_cxt_trans(cxt); /* be careful switching cxt->profile, when racing replacement it - * is possible that cxt->profile->replacedby is the reference keeping - * @profile valid, so make sure to get its reference before dropping - * the reference on cxt->profile */ + * is possible that cxt->profile->replacedby->profile is the reference + * keeping @profile valid, so make sure to get its reference before + * dropping the reference on cxt->profile */ aa_get_profile(profile); aa_put_profile(cxt->profile); cxt->profile = profile; @@ -175,7 +175,7 @@ int aa_set_current_hat(struct aa_profile *profile, u64 token) abort_creds(new); return -EACCES; } - cxt->profile = aa_get_profile(aa_newest_version(profile)); + cxt->profile = aa_get_newest_profile(profile); /* clear exec on switching context */ aa_put_profile(cxt->onexec); cxt->onexec = NULL; @@ -212,14 +212,8 @@ int aa_restore_previous_profile(u64 token) } aa_put_profile(cxt->profile); - cxt->profile = aa_newest_version(cxt->previous); + cxt->profile = aa_get_newest_profile(cxt->previous); BUG_ON(!cxt->profile); - if (unlikely(cxt->profile != cxt->previous)) { - aa_get_profile(cxt->profile); - aa_put_profile(cxt->previous); - } - /* ref has been transfered so avoid putting ref in clear_task_cxt */ - cxt->previous = NULL; /* clear exec && prev information when restoring to previous context */ aa_clear_task_cxt_trans(cxt); diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c index 454bcd7..5488d09 100644 --- a/security/apparmor/domain.c +++ b/security/apparmor/domain.c @@ -359,7 +359,7 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm) cxt = cred_cxt(bprm->cred); BUG_ON(!cxt); - profile = aa_get_profile(aa_newest_version(cxt->profile)); + profile = aa_get_newest_profile(cxt->profile); /* * get the namespace from the replacement profile as replacement * can change the namespace @@ -417,7 +417,7 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm) if (!(cp.allow & AA_MAY_ONEXEC)) goto audit; - new_profile = aa_get_profile(aa_newest_version(cxt->onexec)); + new_profile = aa_get_newest_profile(cxt->onexec); goto apply; } diff --git a/security/apparmor/include/context.h b/security/apparmor/include/context.h index d44ba58..6bf6579 100644 --- a/security/apparmor/include/context.h +++ b/security/apparmor/include/context.h @@ -98,7 +98,7 @@ static inline struct aa_profile *aa_cred_profile(const struct cred *cred) { struct aa_task_cxt *cxt = cred_cxt(cred); BUG_ON(!cxt || !cxt->profile); - return aa_newest_version(cxt->profile); + return cxt->profile; } /** @@ -152,15 +152,14 @@ static inline struct aa_profile *aa_current_profile(void) struct aa_profile *profile; BUG_ON(!cxt || !cxt->profile); - profile = aa_newest_version(cxt->profile); - /* - * Whether or not replacement succeeds, use newest profile so - * there is no need to update it after replacement. - */ - if (unlikely((cxt->profile != profile))) + if (PROFILE_INVALID(cxt->profile)) { + profile = aa_get_newest_profile(cxt->profile); aa_replace_current_profile(profile); + aa_put_profile(profile); + cxt = current_cxt(); + } - return profile; + return cxt->profile; } /** diff --git a/security/apparmor/include/policy.h b/security/apparmor/include/policy.h index 82487a8..e9f2baf 100644 --- a/security/apparmor/include/policy.h +++ b/security/apparmor/include/policy.h @@ -42,6 +42,8 @@ extern const char *const profile_mode_names[]; #define PROFILE_IS_HAT(_profile) ((_profile)->flags & PFLAG_HAT) +#define PROFILE_INVALID(_profile) ((_profile)->flags & PFLAG_INVALID) + #define on_list_rcu(X) (!list_empty(X) && (X)->prev != LIST_POISON2) /* @@ -65,6 +67,7 @@ enum profile_flags { PFLAG_USER_DEFINED = 0x20, /* user based profile - lower privs */ PFLAG_NO_LIST_REF = 0x40, /* list doesn't keep profile ref */ PFLAG_OLD_NULL_TRANS = 0x100, /* use // as the null transition */ + PFLAG_INVALID = 0x200, /* profile replaced/removed */ /* These flags must correspond with PATH_flags */ PFLAG_MEDIATE_DELETED = 0x10000, /* mediate instead delegate deleted */ @@ -146,6 +149,12 @@ struct aa_policydb { }; +struct aa_replacedby { + struct kref count; + struct aa_profile __rcu *profile; +}; + + /* struct aa_profile - basic confinement data * @base - base components of the profile (name, refcount, lists, lock ...) * @parent: parent of profile @@ -169,8 +178,7 @@ struct aa_policydb { * used to determine profile attachment against unconfined tasks. All other * attachments are determined by profile X transition rules. * - * The @replacedby field is write protected by the profile lock. Reads - * are assumed to be atomic. + * The @replacedby struct is write protected by the profile lock. * * Profiles have a hierarchy where hats and children profiles keep * a reference to their parent. @@ -184,14 +192,14 @@ struct aa_profile { struct aa_profile __rcu *parent; struct aa_namespace *ns; - struct aa_profile *replacedby; + struct aa_replacedby *replacedby; const char *rename; struct aa_dfa *xmatch; int xmatch_len; enum audit_mode audit; enum profile_mode mode; - u32 flags; + long flags; u32 path_flags; int size; @@ -250,6 +258,7 @@ static inline void aa_put_namespace(struct aa_namespace *ns) kref_put(&ns->base.count, aa_free_namespace_kref); } +void aa_free_replacedby_kref(struct kref *kref); struct aa_profile *aa_alloc_profile(const char *name); struct aa_profile *aa_new_null_profile(struct aa_profile *parent, int hat); void aa_free_profile_kref(struct kref *kref); @@ -265,24 +274,6 @@ ssize_t aa_remove_profiles(char *name, size_t size); #define unconfined(X) ((X)->flags & PFLAG_UNCONFINED) -/** - * aa_newest_version - find the newest version of @profile - * @profile: the profile to check for newer versions of (NOT NULL) - * - * Returns: newest version of @profile, if @profile is the newest version - * return @profile. - * - * NOTE: the profile returned is not refcounted, The refcount on @profile - * must be held until the caller decides what to do with the returned newest - * version. - */ -static inline struct aa_profile *aa_newest_version(struct aa_profile *profile) -{ - while (profile->replacedby) - profile = profile->replacedby; - - return profile; -} /** * aa_get_profile - increment refcount on profile @p @@ -335,6 +326,25 @@ static inline struct aa_profile *aa_get_profile_rcu(struct aa_profile __rcu **p) } /** + * aa_get_newest_profile - find the newest version of @profile + * @profile: the profile to check for newer versions of + * + * Returns: refcounted newest version of @profile taking into account + * replacement, renames and removals + * return @profile. + */ +static inline struct aa_profile *aa_get_newest_profile(struct aa_profile *p) +{ + if (!p) + return NULL; + + if (PROFILE_INVALID(p)) + return aa_get_profile_rcu(&p->replacedby->profile); + + return aa_get_profile(p); +} + +/** * aa_put_profile - decrement refcount on profile @p * @p: profile (MAYBE NULL) */ @@ -344,6 +354,30 @@ static inline void aa_put_profile(struct aa_profile *p) kref_put(&p->base.count, aa_free_profile_kref); } +static inline struct aa_replacedby *aa_get_replacedby(struct aa_replacedby *p) +{ + if (p) + kref_get(&(p->count)); + + return p; +} + +static inline void aa_put_replacedby(struct aa_replacedby *p) +{ + if (p) + kref_put(&p->count, aa_free_replacedby_kref); +} + +/* requires profile list write lock held */ +static inline void __aa_update_replacedby(struct aa_profile *orig, + struct aa_profile *new) +{ + struct aa_profile *tmp = rcu_dereference(orig->replacedby->profile); + rcu_assign_pointer(orig->replacedby->profile, aa_get_profile(new)); + orig->flags |= PFLAG_INVALID; + aa_put_profile(tmp); +} + static inline int AUDIT_MODE(struct aa_profile *profile) { if (aa_g_audit != AUDIT_NORMAL) diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c index 96506df..c8c148a 100644 --- a/security/apparmor/lsm.c +++ b/security/apparmor/lsm.c @@ -508,19 +508,21 @@ static int apparmor_getprocattr(struct task_struct *task, char *name, /* released below */ const struct cred *cred = get_task_cred(task); struct aa_task_cxt *cxt = cred_cxt(cred); + struct aa_profile *profile = NULL; if (strcmp(name, "current") == 0) - error = aa_getprocattr(aa_newest_version(cxt->profile), - value); + profile = aa_get_newest_profile(cxt->profile); else if (strcmp(name, "prev") == 0 && cxt->previous) - error = aa_getprocattr(aa_newest_version(cxt->previous), - value); + profile = aa_get_newest_profile(cxt->previous); else if (strcmp(name, "exec") == 0 && cxt->onexec) - error = aa_getprocattr(aa_newest_version(cxt->onexec), - value); + profile = aa_get_newest_profile(cxt->onexec); else error = -EINVAL; + if (profile) + error = aa_getprocattr(profile, value); + + aa_put_profile(profile); put_cred(cred); return error; diff --git a/security/apparmor/policy.c b/security/apparmor/policy.c index 25bbbb4..41b8f27 100644 --- a/security/apparmor/policy.c +++ b/security/apparmor/policy.c @@ -469,7 +469,7 @@ static void __remove_profile(struct aa_profile *profile) /* release any children lists first */ __profile_list_release(&profile->base.profiles); /* released by free_profile */ - profile->replacedby = aa_get_profile(profile->ns->unconfined); + __aa_update_replacedby(profile, profile->ns->unconfined); __list_remove_profile(profile); } @@ -588,6 +588,23 @@ void __init aa_free_root_ns(void) aa_put_namespace(ns); } + +static void free_replacedby(struct aa_replacedby *r) +{ + if (r) { + aa_put_profile(rcu_dereference(r->profile)); + kzfree(r); + } +} + + +void aa_free_replacedby_kref(struct kref *kref) +{ + struct aa_replacedby *r = container_of(kref, struct aa_replacedby, + count); + free_replacedby(r); +} + /** * free_profile - free a profile * @profile: the profile to free (MAYBE NULL) @@ -600,8 +617,6 @@ void __init aa_free_root_ns(void) */ static void free_profile(struct aa_profile *profile) { - struct aa_profile *p; - AA_DEBUG("%s(%p)\n", __func__, profile); if (!profile) @@ -620,28 +635,7 @@ static void free_profile(struct aa_profile *profile) aa_put_dfa(profile->xmatch); aa_put_dfa(profile->policy.dfa); - - /* put the profile reference for replacedby, but not via - * put_profile(kref_put). - * replacedby can form a long chain that can result in cascading - * frees that blows the stack because kref_put makes a nested fn - * call (it looks like recursion, with free_profile calling - * free_profile) for each profile in the chain lp#1056078. - */ - for (p = profile->replacedby; p; ) { - if (atomic_dec_and_test(&p->base.count.refcount)) { - /* no more refs on p, grab its replacedby */ - struct aa_profile *next = p->replacedby; - /* break the chain */ - p->replacedby = NULL; - /* now free p, chain is broken */ - free_profile(p); - - /* follow up with next profile in the chain */ - p = next; - } else - break; - } + aa_put_replacedby(profile->replacedby); kzfree(profile); } @@ -682,13 +676,22 @@ struct aa_profile *aa_alloc_profile(const char *hname) if (!profile) return NULL; - if (!policy_init(&profile->base, NULL, hname)) { - kzfree(profile); - return NULL; - } + profile->replacedby = kzalloc(sizeof(struct aa_replacedby), GFP_KERNEL); + if (!profile->replacedby) + goto fail; + kref_init(&profile->replacedby->count); + + if (!policy_init(&profile->base, NULL, hname)) + goto fail; /* refcount released by caller */ return profile; + +fail: + kzfree(profile->replacedby); + kzfree(profile); + + return NULL; } /** @@ -985,6 +988,7 @@ static struct aa_profile *__list_lookup_parent(struct list_head *lh, * __replace_profile - replace @old with @new on a list * @old: profile to be replaced (NOT NULL) * @new: profile to replace @old with (NOT NULL) + * @share_replacedby: transfer @old->replacedby to @new * * Will duplicate and refcount elements that @new inherits from @old * and will inherit @old children. @@ -993,7 +997,8 @@ static struct aa_profile *__list_lookup_parent(struct list_head *lh, * * Requires: namespace list lock be held, or list not be shared */ -static void __replace_profile(struct aa_profile *old, struct aa_profile *new) +static void __replace_profile(struct aa_profile *old, struct aa_profile *new, + bool share_replacedby) { struct aa_profile *child, *tmp; @@ -1008,7 +1013,7 @@ static void __replace_profile(struct aa_profile *old, struct aa_profile *new) p = __find_child(&new->base.profiles, child->base.name); if (p) { /* @p replaces @child */ - __replace_profile(child, p); + __replace_profile(child, p, share_replacedby); continue; } @@ -1027,8 +1032,11 @@ static void __replace_profile(struct aa_profile *old, struct aa_profile *new) struct aa_profile *parent = rcu_dereference(old->parent); rcu_assign_pointer(new->parent, aa_get_profile(parent)); } - /* released by free_profile */ - old->replacedby = aa_get_profile(new); + __aa_update_replacedby(old, new); + if (share_replacedby) { + aa_put_replacedby(new->replacedby); + new->replacedby = aa_get_replacedby(old->replacedby); + } if (list_empty(&new->base.list)) { /* new is not on a list already */ @@ -1152,23 +1160,24 @@ ssize_t aa_replace_profiles(void *udata, size_t size, bool noreplace) audit_policy(op, GFP_ATOMIC, ent->new->base.name, NULL, error); if (ent->old) { - __replace_profile(ent->old, ent->new); + __replace_profile(ent->old, ent->new, 1); if (ent->rename) - __replace_profile(ent->rename, ent->new); + __replace_profile(ent->rename, ent->new, 0); } else if (ent->rename) { - __replace_profile(ent->rename, ent->new); + __replace_profile(ent->rename, ent->new, 0); } else if (ent->new->parent) { struct aa_profile *parent, *newest; parent = rcu_dereference_protected(ent->new->parent, mutex_is_locked(&ns->lock)); - newest = aa_newest_version(parent); + newest = aa_get_newest_profile(parent); /* parent replaced in this atomic set? */ if (newest != parent) { aa_get_profile(newest); aa_put_profile(parent); rcu_assign_pointer(ent->new->parent, newest); - } + } else + aa_put_profile(newest); __list_add_profile(&parent->base.profiles, ent->new); } else __list_add_profile(&ns->base.profiles, ent->new); |
