security: Refactor declaration of LSM hooks
The information about the different types of LSM hooks is scattered
in two locations i.e. union security_list_options and
struct security_hook_heads. Rather than duplicating this information
even further for BPF_PROG_TYPE_LSM, define all the hooks with the
LSM_HOOK macro in lsm_hook_defs.h which is then used to generate all
the data structures required by the LSM framework.
The LSM hooks are defined as:
LSM_HOOK(<return_type>, <default_value>, <hook_name>, args...)
with <default_value> acccessible in security.c as:
LSM_RET_DEFAULT(<hook_name>)
Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Brendan Jackman <jackmanb@google.com>
Reviewed-by: Florent Revest <revest@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: James Morris <jamorris@linux.microsoft.com>
Link: https://lore.kernel.org/bpf/20200329004356.27286-3-kpsingh@chromium.org
diff --git a/security/security.c b/security/security.c
index 565bc9b..7fed24b 100644
--- a/security/security.c
+++ b/security/security.c
@@ -669,6 +669,25 @@
}
/*
+ * The default value of the LSM hook is defined in linux/lsm_hook_defs.h and
+ * can be accessed with:
+ *
+ * LSM_RET_DEFAULT(<hook_name>)
+ *
+ * The macros below define static constants for the default value of each
+ * LSM hook.
+ */
+#define LSM_RET_DEFAULT(NAME) (NAME##_default)
+#define DECLARE_LSM_RET_DEFAULT_void(DEFAULT, NAME)
+#define DECLARE_LSM_RET_DEFAULT_int(DEFAULT, NAME) \
+ static const int LSM_RET_DEFAULT(NAME) = (DEFAULT);
+#define LSM_HOOK(RET, DEFAULT, NAME, ...) \
+ DECLARE_LSM_RET_DEFAULT_##RET(DEFAULT, NAME)
+
+#include <linux/lsm_hook_defs.h>
+#undef LSM_HOOK
+
+/*
* Hook list operation macros.
*
* call_void_hook:
@@ -1338,16 +1357,16 @@
int rc;
if (unlikely(IS_PRIVATE(inode)))
- return -EOPNOTSUPP;
+ return LSM_RET_DEFAULT(inode_getsecurity);
/*
* Only one module will provide an attribute with a given name.
*/
hlist_for_each_entry(hp, &security_hook_heads.inode_getsecurity, list) {
rc = hp->hook.inode_getsecurity(inode, name, buffer, alloc);
- if (rc != -EOPNOTSUPP)
+ if (rc != LSM_RET_DEFAULT(inode_getsecurity))
return rc;
}
- return -EOPNOTSUPP;
+ return LSM_RET_DEFAULT(inode_getsecurity);
}
int security_inode_setsecurity(struct inode *inode, const char *name, const void *value, size_t size, int flags)
@@ -1356,17 +1375,17 @@
int rc;
if (unlikely(IS_PRIVATE(inode)))
- return -EOPNOTSUPP;
+ return LSM_RET_DEFAULT(inode_setsecurity);
/*
* Only one module will provide an attribute with a given name.
*/
hlist_for_each_entry(hp, &security_hook_heads.inode_setsecurity, list) {
rc = hp->hook.inode_setsecurity(inode, name, value, size,
flags);
- if (rc != -EOPNOTSUPP)
+ if (rc != LSM_RET_DEFAULT(inode_setsecurity))
return rc;
}
- return -EOPNOTSUPP;
+ return LSM_RET_DEFAULT(inode_setsecurity);
}
int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size)
@@ -1740,12 +1759,12 @@
unsigned long arg4, unsigned long arg5)
{
int thisrc;
- int rc = -ENOSYS;
+ int rc = LSM_RET_DEFAULT(task_prctl);
struct security_hook_list *hp;
hlist_for_each_entry(hp, &security_hook_heads.task_prctl, list) {
thisrc = hp->hook.task_prctl(option, arg2, arg3, arg4, arg5);
- if (thisrc != -ENOSYS) {
+ if (thisrc != LSM_RET_DEFAULT(task_prctl)) {
rc = thisrc;
if (thisrc != 0)
break;
@@ -1917,7 +1936,7 @@
continue;
return hp->hook.getprocattr(p, name, value);
}
- return -EINVAL;
+ return LSM_RET_DEFAULT(getprocattr);
}
int security_setprocattr(const char *lsm, const char *name, void *value,
@@ -1930,7 +1949,7 @@
continue;
return hp->hook.setprocattr(name, value, size);
}
- return -EINVAL;
+ return LSM_RET_DEFAULT(setprocattr);
}
int security_netlink_send(struct sock *sk, struct sk_buff *skb)
@@ -2315,7 +2334,7 @@
const struct flowi *fl)
{
struct security_hook_list *hp;
- int rc = 1;
+ int rc = LSM_RET_DEFAULT(xfrm_state_pol_flow_match);
/*
* Since this function is expected to return 0 or 1, the judgment