LSM: Switch to lists of hooks

Instead of using a vector of security operations
with explicit, special case stacking of the capability
and yama hooks use lists of hooks with capability and
yama hooks included as appropriate.

The security_operations structure is no longer required.
Instead, there is a union of the function pointers that
allows all the hooks lists to use a common mechanism for
list management while retaining typing. Each module
supplies an array describing the hooks it provides instead
of a sparsely populated security_operations structure.
The description includes the element that gets put on
the hook list, avoiding the issues surrounding individual
element allocation.

The method for registering security modules is changed to
reflect the information available. The method for removing
a module, currently only used by SELinux, has also changed.
It should be generic now, however if there are potential
race conditions based on ordering of hook removal that needs
to be addressed by the calling module.

The security hooks are called from the lists and the first
failure is returned.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by:  Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <james.l.morris@oracle.com>

3 files changed, 11 insertions, 46 deletions

diff --git a/security/smack/smack.h b/security/smack/smack.h
index 262dad8..b8c1a86 100644
--- a/security/smack/smack.h
+++ b/security/smack/smack.h
@@ -276,8 +276,6 @@ extern struct mutex	smack_known_lock;
 extern struct list_head smack_known_list;
 extern struct list_head smk_netlbladdr_list;
 
-extern struct security_operations smack_ops;
-
 #define SMACK_HASH_SLOTS 16
 extern struct hlist_head smack_known_hash[SMACK_HASH_SLOTS];
 
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 4313bf4..5eae42c 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -436,17 +436,11 @@ static int smk_ptrace_rule_check(struct task_struct *tracer,
  */
 static int smack_ptrace_access_check(struct task_struct *ctp, unsigned int mode)
 {
-	int rc;
 	struct smack_known *skp;
 
-	rc = cap_ptrace_access_check(ctp, mode);
-	if (rc != 0)
-		return rc;
-
 	skp = smk_of_task_struct(ctp);
 
-	rc = smk_ptrace_rule_check(current, skp, mode, __func__);
-	return rc;
+	return smk_ptrace_rule_check(current, skp, mode, __func__);
 }
 
 /**
@@ -462,10 +456,6 @@ static int smack_ptrace_traceme(struct task_struct *ptp)
 	int rc;
 	struct smack_known *skp;
 
-	rc = cap_ptrace_traceme(ptp);
-	if (rc != 0)
-		return rc;
-
 	skp = smk_of_task(current_security());
 
 	rc = smk_ptrace_rule_check(ptp, skp, PTRACE_MODE_ATTACH, __func__);
@@ -721,10 +711,6 @@ static int smack_bprm_set_creds(struct linux_binprm *bprm)
 	struct inode_smack *isp;
 	int rc;
 
-	rc = cap_bprm_set_creds(bprm);
-	if (rc != 0)
-		return rc;
-
 	if (bprm->cred_prepared)
 		return 0;
 
@@ -779,12 +765,11 @@ static void smack_bprm_committing_creds(struct linux_binprm *bprm)
 static int smack_bprm_secureexec(struct linux_binprm *bprm)
 {
 	struct task_smack *tsp = current_security();
-	int ret = cap_bprm_secureexec(bprm);
 
-	if (!ret && (tsp->smk_task != tsp->smk_forked))
-		ret = 1;
+	if (tsp->smk_task != tsp->smk_forked)
+		return 1;
 
-	return ret;
+	return 0;
 }
 
 /*
@@ -1934,12 +1919,7 @@ static void smack_task_getsecid(struct task_struct *p, u32 *secid)
  */
 static int smack_task_setnice(struct task_struct *p, int nice)
 {
-	int rc;
-
-	rc = cap_task_setnice(p, nice);
-	if (rc == 0)
-		rc = smk_curacc_on_task(p, MAY_WRITE, __func__);
-	return rc;
+	return smk_curacc_on_task(p, MAY_WRITE, __func__);
 }
 
 /**
@@ -1951,12 +1931,7 @@ static int smack_task_setnice(struct task_struct *p, int nice)
  */
 static int smack_task_setioprio(struct task_struct *p, int ioprio)
 {
-	int rc;
-
-	rc = cap_task_setioprio(p, ioprio);
-	if (rc == 0)
-		rc = smk_curacc_on_task(p, MAY_WRITE, __func__);
-	return rc;
+	return smk_curacc_on_task(p, MAY_WRITE, __func__);
 }
 
 /**
@@ -1980,12 +1955,7 @@ static int smack_task_getioprio(struct task_struct *p)
  */
 static int smack_task_setscheduler(struct task_struct *p)
 {
-	int rc;
-
-	rc = cap_task_setscheduler(p);
-	if (rc == 0)
-		rc = smk_curacc_on_task(p, MAY_WRITE, __func__);
-	return rc;
+	return smk_curacc_on_task(p, MAY_WRITE, __func__);
 }
 
 /**
@@ -4266,9 +4236,7 @@ static int smack_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
 	return 0;
 }
 
-struct security_operations smack_ops = {
-	LSM_HOOK_INIT(name, "smack"),
-
+struct security_hook_list smack_hooks[] = {
 	LSM_HOOK_INIT(ptrace_access_check, smack_ptrace_access_check),
 	LSM_HOOK_INIT(ptrace_traceme, smack_ptrace_traceme),
 	LSM_HOOK_INIT(syslog, smack_syslog),
@@ -4451,7 +4419,7 @@ static __init int smack_init(void)
 	struct cred *cred;
 	struct task_smack *tsp;
 
-	if (!security_module_enable(&smack_ops))
+	if (!security_module_enable("smack"))
 		return 0;
 
 	smack_enabled = 1;
@@ -4481,8 +4449,7 @@ static __init int smack_init(void)
 	/*
 	 * Register with LSM
 	 */
-	if (register_security(&smack_ops))
-		panic("smack: Unable to register with kernel.\n");
+	security_add_hooks(smack_hooks, ARRAY_SIZE(smack_hooks));
 
 	return 0;
 }
diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index d968298..4aa12c8 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -2547,7 +2547,7 @@ static int __init init_smk_fs(void)
 	int err;
 	int rc;
 
-	if (!security_module_enable(&smack_ops))
+	if (!security_module_enable("smack"))
 		return 0;
 
 	err = smk_init_sysfs();