selinux: move policy mutex to selinux_state, use in lockdep checks

Move the mutex used to synchronize policy changes (reloads and setting
of booleans) from selinux_fs_info to selinux_state and use it in
lockdep checks for rcu_dereference_protected() calls in the security
server functions.  This makes the dependency on the mutex explicit
in the code rather than relying on comments.

Signed-off-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Reviewed-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 6f30ba1..6210e98 100644 (file)
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -7237,6 +7237,7 @@ static __init int selinux_init(void)
        selinux_state.checkreqprot = selinux_checkreqprot_boot;
        selinux_avc_init(&selinux_state.avc);
        mutex_init(&selinux_state.status_lock);
+       mutex_init(&selinux_state.policy_mutex);
 
        /* Set the security state for the initial task. */
        cred_init_security();

diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h
index 505e512..bbbf714 100644 (file)
--- a/security/selinux/include/security.h
+++ b/security/selinux/include/security.h
@@ -103,6 +103,7 @@ struct selinux_state {
 
        struct selinux_avc *avc;
        struct selinux_policy __rcu *policy;
+       struct mutex policy_mutex;
 } __randomize_layout;
 
 void selinux_avc_init(struct selinux_avc **avc);

diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index d1872ad..29567ac 100644 (file)
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -75,7 +75,6 @@ struct selinux_fs_info {
        unsigned long last_class_ino;
        bool policy_opened;
        struct dentry *policycap_dir;
-       struct mutex mutex;
        unsigned long last_ino;
        struct selinux_state *state;
        struct super_block *sb;
@@ -89,7 +88,6 @@ static int selinux_fs_info_create(struct super_block *sb)
        if (!fsi)
                return -ENOMEM;
 
-       mutex_init(&fsi->mutex);
        fsi->last_ino = SEL_INO_NEXT - 1;
        fsi->state = &selinux_state;
        fsi->sb = sb;
@@ -400,7 +398,7 @@ static int sel_open_policy(struct inode *inode, struct file *filp)
 
        BUG_ON(filp->private_data);
 
-       mutex_lock(&fsi->mutex);
+       mutex_lock(&fsi->state->policy_mutex);
 
        rc = avc_has_perm(&selinux_state,
                          current_sid(), SECINITSID_SECURITY,
@@ -431,11 +429,11 @@ static int sel_open_policy(struct inode *inode, struct file *filp)
 
        filp->private_data = plm;
 
-       mutex_unlock(&fsi->mutex);
+       mutex_unlock(&fsi->state->policy_mutex);
 
        return 0;
 err:
-       mutex_unlock(&fsi->mutex);
+       mutex_unlock(&fsi->state->policy_mutex);
 
        if (plm)
                vfree(plm->data);
@@ -622,7 +620,7 @@ static ssize_t sel_write_load(struct file *file, const char __user *buf,
        ssize_t length;
        void *data = NULL;
 
-       mutex_lock(&fsi->mutex);
+       mutex_lock(&fsi->state->policy_mutex);
 
        length = avc_has_perm(&selinux_state,
                              current_sid(), SECINITSID_SECURITY,
@@ -666,7 +664,7 @@ out1:
                from_kuid(&init_user_ns, audit_get_loginuid(current)),
                audit_get_sessionid(current));
 out:
-       mutex_unlock(&fsi->mutex);
+       mutex_unlock(&fsi->state->policy_mutex);
        vfree(data);
        return length;
 }
@@ -1271,7 +1269,7 @@ static ssize_t sel_read_bool(struct file *filep, char __user *buf,
        unsigned index = file_inode(filep)->i_ino & SEL_INO_MASK;
        const char *name = filep->f_path.dentry->d_name.name;
 
-       mutex_lock(&fsi->mutex);
+       mutex_lock(&fsi->state->policy_mutex);
 
        ret = -EINVAL;
        if (index >= fsi->bool_num || strcmp(name,
@@ -1290,14 +1288,14 @@ static ssize_t sel_read_bool(struct file *filep, char __user *buf,
        }
        length = scnprintf(page, PAGE_SIZE, "%d %d", cur_enforcing,
                          fsi->bool_pending_values[index]);
-       mutex_unlock(&fsi->mutex);
+       mutex_unlock(&fsi->state->policy_mutex);
        ret = simple_read_from_buffer(buf, count, ppos, page, length);
 out_free:
        free_page((unsigned long)page);
        return ret;
 
 out_unlock:
-       mutex_unlock(&fsi->mutex);
+       mutex_unlock(&fsi->state->policy_mutex);
        goto out_free;
 }
 
@@ -1322,7 +1320,7 @@ static ssize_t sel_write_bool(struct file *filep, const char __user *buf,
        if (IS_ERR(page))
                return PTR_ERR(page);
 
-       mutex_lock(&fsi->mutex);
+       mutex_lock(&fsi->state->policy_mutex);
 
        length = avc_has_perm(&selinux_state,
                              current_sid(), SECINITSID_SECURITY,
@@ -1347,7 +1345,7 @@ static ssize_t sel_write_bool(struct file *filep, const char __user *buf,
        length = count;
 
 out:
-       mutex_unlock(&fsi->mutex);
+       mutex_unlock(&fsi->state->policy_mutex);
        kfree(page);
        return length;
 }
@@ -1378,7 +1376,7 @@ static ssize_t sel_commit_bools_write(struct file *filep,
        if (IS_ERR(page))
                return PTR_ERR(page);
 
-       mutex_lock(&fsi->mutex);
+       mutex_lock(&fsi->state->policy_mutex);
 
        length = avc_has_perm(&selinux_state,
                              current_sid(), SECINITSID_SECURITY,
@@ -1400,7 +1398,7 @@ static ssize_t sel_commit_bools_write(struct file *filep,
                length = count;
 
 out:
-       mutex_unlock(&fsi->mutex);
+       mutex_unlock(&fsi->state->policy_mutex);
        kfree(page);
        return length;
 }

diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index e730204..85cfd46 100644 (file)
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -2163,13 +2163,8 @@ void selinux_policy_cancel(struct selinux_state *state,
 {
        struct selinux_policy *oldpolicy;
 
-       /*
-        * NOTE: We do not need to take the rcu read lock
-        * around the code below because other policy-modifying
-        * operations are already excluded by selinuxfs via
-        * fsi->mutex.
-        */
-       oldpolicy = rcu_dereference_check(state->policy, 1);
+       oldpolicy = rcu_dereference_protected(state->policy,
+                                       lockdep_is_held(&state->policy_mutex));
 
        sidtab_cancel_convert(oldpolicy->sidtab);
        selinux_policy_free(policy);
@@ -2192,13 +2187,8 @@ void selinux_policy_commit(struct selinux_state *state,
        struct selinux_policy *oldpolicy;
        u32 seqno;
 
-       /*
-        * NOTE: We do not need to take the rcu read lock
-        * around the code below because other policy-modifying
-        * operations are already excluded by selinuxfs via
-        * fsi->mutex.
-        */
-       oldpolicy = rcu_dereference_check(state->policy, 1);
+       oldpolicy = rcu_dereference_protected(state->policy,
+                                       lockdep_is_held(&state->policy_mutex));
 
        /* If switching between different policy types, log MLS status */
        if (oldpolicy) {
@@ -2291,13 +2281,8 @@ int security_load_policy(struct selinux_state *state, void *data, size_t len,
                return 0;
        }
 
-       /*
-        * NOTE: We do not need to take the rcu read lock
-        * around the code below because other policy-modifying
-        * operations are already excluded by selinuxfs via
-        * fsi->mutex.
-        */
-       oldpolicy = rcu_dereference_check(state->policy, 1);
+       oldpolicy = rcu_dereference_protected(state->policy,
+                                       lockdep_is_held(&state->policy_mutex));
 
        /* Preserve active boolean values from the old policy */
        rc = security_preserve_bools(oldpolicy, newpolicy);
@@ -3013,14 +2998,8 @@ int security_set_bools(struct selinux_state *state, u32 len, int *values)
        if (!selinux_initialized(state))
                return -EINVAL;
 
-       /*
-        * NOTE: We do not need to take the rcu read lock
-        * around the code below because other policy-modifying
-        * operations are already excluded by selinuxfs via
-        * fsi->mutex.
-        */
-
-       oldpolicy = rcu_dereference_check(state->policy, 1);
+       oldpolicy = rcu_dereference_protected(state->policy,
+                                       lockdep_is_held(&state->policy_mutex));
 
        /* Consistency check on number of booleans, should never fail */
        if (WARN_ON(len != oldpolicy->policydb.p_bools.nprim))