capabilities: introduce security_capable_noaudit

Exactly like security_capable except don't audit any denials.  This is for
places where the kernel may make decisions about what to do if a task has a
given capability, but which failing that capability is not a sign of a
security policy violation.  An example is checking if a task has
CAP_SYS_ADMIN to lower it's likelyhood of being killed by the oom killer.
This check is not a security violation if it is denied.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>

diff --git a/include/linux/security.h b/include/linux/security.h
index ee969ff40a26bc445776aea4af1b0807d1bb0748..caff54eee68653d95d53c077ba8094563032eeaf 100644 (file)
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1668,6 +1668,8 @@ int security_capset(struct cred *new, const struct cred *old,
                    const kernel_cap_t *permitted);
 int security_capable(const struct cred *cred, struct user_namespace *ns,
                        int cap);
+int security_capable_noaudit(const struct cred *cred, struct user_namespace *ns,
+                            int cap);
 int security_real_capable(struct task_struct *tsk, struct user_namespace *ns,
                        int cap);
 int security_real_capable_noaudit(struct task_struct *tsk,
@@ -1869,6 +1871,11 @@ static inline int security_capable(const struct cred *cred,
        return cap_capable(cred, ns, cap, SECURITY_CAP_AUDIT);
 }
 
+static inline int security_capable_noaudit(const struct cred *cred,
+                                          struct user_namespace *ns, int cap) {
+       return cap_capable(cred, ns, cap, SECURITY_CAP_NOAUDIT);
+}
+
 static inline int security_real_capable(struct task_struct *tsk, struct user_namespace *ns, int cap)
 {
        int ret;

diff --git a/security/security.c b/security/security.c
index b9e57f4fc44a43b0603544766f90aafe67500702..b7edaae77d1d2b022213c43fabbde56e5cd83add 100644 (file)
--- a/security/security.c
+++ b/security/security.c
@@ -160,6 +160,12 @@ int security_capable(const struct cred *cred, struct user_namespace *ns,
        return security_ops->capable(cred, ns, cap, SECURITY_CAP_AUDIT);
 }
 
+int security_capable_noaudit(const struct cred *cred, struct user_namespace *ns,
+                            int cap)
+{
+       return security_ops->capable(cred, ns, cap, SECURITY_CAP_NOAUDIT);
+}
+
 int security_real_capable(struct task_struct *tsk, struct user_namespace *ns,
                          int cap)
 {