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>

1 files changed, 15 insertions, 79 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 0cf105f346d4..06c9dd962c3c 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1990,12 +1990,6 @@ static int selinux_binder_transfer_file(struct task_struct *from,
 static int selinux_ptrace_access_check(struct task_struct *child,
                                      unsigned int mode)
 {
-        int rc;
-
-        rc = cap_ptrace_access_check(child, mode);
-        if (rc)
-                return rc;
-
         if (mode & PTRACE_MODE_READ) {
                 u32 sid = current_sid();
                 u32 csid = task_sid(child);
@@ -2007,25 +2001,13 @@ static int selinux_ptrace_access_check(struct task_struct *child,
 
 static int selinux_ptrace_traceme(struct task_struct *parent)
 {
-        int rc;
-
-        rc = cap_ptrace_traceme(parent);
-        if (rc)
-                return rc;
-
         return task_has_perm(parent, current, PROCESS__PTRACE);
 }
 
 static int selinux_capget(struct task_struct *target, kernel_cap_t *effective,
                           kernel_cap_t *inheritable, kernel_cap_t *permitted)
 {
-        int error;
-
-        error = current_has_perm(target, PROCESS__GETCAP);
-        if (error)
-                return error;
-
-        return cap_capget(target, effective, inheritable, permitted);
+        return current_has_perm(target, PROCESS__GETCAP);
 }
 
 static int selinux_capset(struct cred *new, const struct cred *old,
@@ -2033,13 +2015,6 @@ static int selinux_capset(struct cred *new, const struct cred *old,
                           const kernel_cap_t *inheritable,
                           const kernel_cap_t *permitted)
 {
-        int error;
-
-        error = cap_capset(new, old,
-                                      effective, inheritable, permitted);
-        if (error)
-                return error;
-
         return cred_has_perm(old, new, PROCESS__SETCAP);
 }
 
@@ -2056,12 +2031,6 @@ static int selinux_capset(struct cred *new, const struct cred *old,
 static int selinux_capable(const struct cred *cred, struct user_namespace *ns,
                            int cap, int audit)
 {
-        int rc;
-
-        rc = cap_capable(cred, ns, cap, audit);
-        if (rc)
-                return rc;
-
         return cred_has_capability(cred, cap, audit);
 }
 
@@ -2139,12 +2108,12 @@ static int selinux_vm_enough_memory(struct mm_struct *mm, long pages)
 {
         int rc, cap_sys_admin = 0;
 
-        rc = selinux_capable(current_cred(), &init_user_ns, CAP_SYS_ADMIN,
-                             SECURITY_CAP_NOAUDIT);
+        rc = cred_has_capability(current_cred(), CAP_SYS_ADMIN,
+                                        SECURITY_CAP_NOAUDIT);
         if (rc == 0)
                 cap_sys_admin = 1;
 
-        return __vm_enough_memory(mm, pages, cap_sys_admin);
+        return cap_sys_admin;
 }
 
 /* binprm security operations */
@@ -2193,10 +2162,6 @@ static int selinux_bprm_set_creds(struct linux_binprm *bprm)
         struct inode *inode = file_inode(bprm->file);
         int rc;
 
-        rc = cap_bprm_set_creds(bprm);
-        if (rc)
-                return rc;
-
         /* SELinux context only depends on initial program or script and not
          * the script interpreter */
         if (bprm->cred_prepared)
@@ -2320,7 +2285,7 @@ static int selinux_bprm_secureexec(struct linux_binprm *bprm)
                                         PROCESS__NOATSECURE, NULL);
         }
 
-        return (atsecure || cap_bprm_secureexec(bprm));
+        return !!atsecure;
 }
 
 static int match_file(const void *p, struct file *file, unsigned fd)
@@ -3132,8 +3097,11 @@ static int selinux_inode_getsecurity(const struct inode *inode, const char *name
          * and lack of permission just means that we fall back to the
          * in-core context value, not a denial.
          */
-        error = selinux_capable(current_cred(), &init_user_ns, CAP_MAC_ADMIN,
-                                SECURITY_CAP_NOAUDIT);
+        error = cap_capable(current_cred(), &init_user_ns, CAP_MAC_ADMIN,
+                            SECURITY_CAP_NOAUDIT);
+        if (!error)
+                error = cred_has_capability(current_cred(), CAP_MAC_ADMIN,
+                                            SECURITY_CAP_NOAUDIT);
         if (!error)
                 error = security_sid_to_context_force(isec->sid, &context,
                                                       &size);
@@ -3318,12 +3286,7 @@ error:
 
 static int selinux_mmap_addr(unsigned long addr)
 {
-        int rc;
-
-        /* do DAC check on address space usage */
-        rc = cap_mmap_addr(addr);
-        if (rc)
-                return rc;
+        int rc = 0;
 
         if (addr < CONFIG_LSM_MMAP_MIN_ADDR) {
                 u32 sid = current_sid();
@@ -3639,23 +3602,11 @@ static void selinux_task_getsecid(struct task_struct *p, u32 *secid)
 
 static int selinux_task_setnice(struct task_struct *p, int nice)
 {
-        int rc;
-
-        rc = cap_task_setnice(p, nice);
-        if (rc)
-                return rc;
-
         return current_has_perm(p, PROCESS__SETSCHED);
 }
 
 static int selinux_task_setioprio(struct task_struct *p, int ioprio)
 {
-        int rc;
-
-        rc = cap_task_setioprio(p, ioprio);
-        if (rc)
-                return rc;
-
         return current_has_perm(p, PROCESS__SETSCHED);
 }
 
@@ -3681,12 +3632,6 @@ static int selinux_task_setrlimit(struct task_struct *p, unsigned int resource,
 
 static int selinux_task_setscheduler(struct task_struct *p)
 {
-        int rc;
-
-        rc = cap_task_setscheduler(p);
-        if (rc)
-                return rc;
-
         return current_has_perm(p, PROCESS__SETSCHED);
 }
 
@@ -5097,12 +5042,6 @@ static unsigned int selinux_ipv6_postroute(const struct nf_hook_ops *ops,
 
 static int selinux_netlink_send(struct sock *sk, struct sk_buff *skb)
 {
-        int err;
-
-        err = cap_netlink_send(sk, skb);
-        if (err)
-                return err;
-
         return selinux_nlmsg_perm(sk, skb);
 }
 
@@ -5840,9 +5779,7 @@ static int selinux_key_getsecurity(struct key *key, char **_buffer)
 
 #endif
 
-static struct security_operations selinux_ops = {
-        LSM_HOOK_INIT(name, "selinux"),
-
+static struct security_hook_list selinux_hooks[] = {
         LSM_HOOK_INIT(binder_set_context_mgr, selinux_binder_set_context_mgr),
         LSM_HOOK_INIT(binder_transaction, selinux_binder_transaction),
         LSM_HOOK_INIT(binder_transfer_binder, selinux_binder_transfer_binder),
@@ -6055,7 +5992,7 @@ static struct security_operations selinux_ops = {
 
 static __init int selinux_init(void)
 {
-        if (!security_module_enable(&selinux_ops)) {
+        if (!security_module_enable("selinux")) {
                 selinux_enabled = 0;
                 return 0;
         }
@@ -6077,8 +6014,7 @@ static __init int selinux_init(void)
                                             0, SLAB_PANIC, NULL);
         avc_init();
 
-        if (register_security(&selinux_ops))
-                panic("SELinux: Unable to register with kernel.\n");
+        security_add_hooks(selinux_hooks, ARRAY_SIZE(selinux_hooks));
 
         if (avc_add_callback(selinux_netcache_avc_callback, AVC_CALLBACK_RESET))
                 panic("SELinux: Unable to register AVC netcache callback\n");
@@ -6206,7 +6142,7 @@ int selinux_disable(void)
         selinux_disabled = 1;
         selinux_enabled = 0;
 
-        reset_security_ops();
+        security_delete_hooks(selinux_hooks, ARRAY_SIZE(selinux_hooks));
 
         /* Try to destroy the avc node cache */
         avc_disable();