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, 33 insertions, 8 deletions

diff --git a/security/commoncap.c b/security/commoncap.c
index f2875cd..d103f5a4 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -12,7 +12,7 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
-#include <linux/security.h>
+#include <linux/lsm_hooks.h>
 #include <linux/file.h>
 #include <linux/mm.h>
 #include <linux/mman.h>
@@ -53,11 +53,6 @@ static void warn_setuid_and_fcaps_mixed(const char *fname)
 	}
 }
 
-int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
-{
-	return 0;
-}
-
 /**
  * cap_capable - Determine whether a task has a particular effective capability
  * @cred: The credentials to use
@@ -941,7 +936,7 @@ int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
  * @pages: The size of the mapping
  *
  * Determine whether the allocation of a new virtual mapping by the current
- * task is permitted, returning 0 if permission is granted, -ve if not.
+ * task is permitted, returning 1 if permission is granted, 0 if not.
  */
 int cap_vm_enough_memory(struct mm_struct *mm, long pages)
 {
@@ -950,7 +945,7 @@ int cap_vm_enough_memory(struct mm_struct *mm, long pages)
 	if (cap_capable(current_cred(), &init_user_ns, CAP_SYS_ADMIN,
 			SECURITY_CAP_NOAUDIT) == 0)
 		cap_sys_admin = 1;
-	return __vm_enough_memory(mm, pages, cap_sys_admin);
+	return cap_sys_admin;
 }
 
 /*
@@ -981,3 +976,33 @@ int cap_mmap_file(struct file *file, unsigned long reqprot,
 {
 	return 0;
 }
+
+#ifdef CONFIG_SECURITY
+
+struct security_hook_list capability_hooks[] = {
+	LSM_HOOK_INIT(capable, cap_capable),
+	LSM_HOOK_INIT(settime, cap_settime),
+	LSM_HOOK_INIT(ptrace_access_check, cap_ptrace_access_check),
+	LSM_HOOK_INIT(ptrace_traceme, cap_ptrace_traceme),
+	LSM_HOOK_INIT(capget, cap_capget),
+	LSM_HOOK_INIT(capset, cap_capset),
+	LSM_HOOK_INIT(bprm_set_creds, cap_bprm_set_creds),
+	LSM_HOOK_INIT(bprm_secureexec, cap_bprm_secureexec),
+	LSM_HOOK_INIT(inode_need_killpriv, cap_inode_need_killpriv),
+	LSM_HOOK_INIT(inode_killpriv, cap_inode_killpriv),
+	LSM_HOOK_INIT(mmap_addr, cap_mmap_addr),
+	LSM_HOOK_INIT(mmap_file, cap_mmap_file),
+	LSM_HOOK_INIT(task_fix_setuid, cap_task_fix_setuid),
+	LSM_HOOK_INIT(task_prctl, cap_task_prctl),
+	LSM_HOOK_INIT(task_setscheduler, cap_task_setscheduler),
+	LSM_HOOK_INIT(task_setioprio, cap_task_setioprio),
+	LSM_HOOK_INIT(task_setnice, cap_task_setnice),
+	LSM_HOOK_INIT(vm_enough_memory, cap_vm_enough_memory),
+};
+
+void __init capability_add_hooks(void)
+{
+	security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks));
+}
+
+#endif /* CONFIG_SECURITY */