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@xxxxxxxxx>
---
v2 switches selinuxfs from using &selinux_state.policy_mutex to using
fsi->state->policy_mutex. selinuxfs operates on fsi->state->policy
for all policy reading or modifying operations. It only acts on
&selinux_state for checking permissions in the current context.
At present, fsi->state is always &selinux_state; this will change
when selinux namespaces are introduced.
security/selinux/hooks.c | 1 +
security/selinux/include/security.h | 1 +
security/selinux/selinuxfs.c | 26 ++++++++++----------
security/selinux/ss/services.c | 37 +++++++----------------------
4 files changed, 22 insertions(+), 43 deletions(-)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 6f30ba1a38dc..6210e98219a5 100644
--- 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 505e51264d51..bbbf7141ccdb 100644
--- 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 d1872adf0c47..29567acdda21 100644
--- 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 @@ static ssize_t sel_write_load(struct file *file, const char __user *buf,
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 e730204f060b..85cfd46836c7 100644
--- 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))
--
2.25.1
