[RFC PATCH bpf-next seccomp 06/12] lsm: New hook seccomp_extended

[YiFei Zhu <zhuyifei1999@gmail.com>]

From: YiFei Zhu <yifeifz2@illinois.edu>

This hooks takes no argument, and returns 0 if the current task is
permitted to use extended seccomp-eBPF features, or -errno if it is
not permitted.

Signed-off-by: YiFei Zhu <yifeifz2@illinois.edu>
---
 include/linux/lsm_hook_defs.h |  4 ++++
 include/linux/security.h      | 13 +++++++++++++
 security/security.c           |  8 ++++++++
 3 files changed, 25 insertions(+)

diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 61f04f7dc1a4..94e18d95e1cc 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -391,6 +391,10 @@ LSM_HOOK(int, 0, bpf_map_alloc_security, struct bpf_map *map)
 LSM_HOOK(void, LSM_RET_VOID, bpf_map_free_security, struct bpf_map *map)
 LSM_HOOK(int, 0, bpf_prog_alloc_security, struct bpf_prog_aux *aux)
 LSM_HOOK(void, LSM_RET_VOID, bpf_prog_free_security, struct bpf_prog_aux *aux)
+
+#ifdef CONFIG_SECCOMP_FILTER_EXTENDED
+LSM_HOOK(int, 0, seccomp_extended, void)
+#endif /* CONFIG_SECCOMP_FILTER_EXTENDED */
 #endif /* CONFIG_BPF_SYSCALL */
 
 LSM_HOOK(int, 0, locked_down, enum lockdown_reason what)
diff --git a/include/linux/security.h b/include/linux/security.h
index 9aeda3f9e838..8e98dd98ac90 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -1960,6 +1960,11 @@ extern int security_bpf_map_alloc(struct bpf_map *map);
 extern void security_bpf_map_free(struct bpf_map *map);
 extern int security_bpf_prog_alloc(struct bpf_prog_aux *aux);
 extern void security_bpf_prog_free(struct bpf_prog_aux *aux);
+
+#ifdef CONFIG_SECCOMP_FILTER_EXTENDED
+extern int security_seccomp_extended(void);
+#endif /* CONFIG_SECCOMP_FILTER_EXTENDED */
+
 #else
 static inline int security_bpf(int cmd, union bpf_attr *attr,
 					     unsigned int size)
@@ -1992,6 +1997,14 @@ static inline int security_bpf_prog_alloc(struct bpf_prog_aux *aux)
 
 static inline void security_bpf_prog_free(struct bpf_prog_aux *aux)
 { }
+
+#ifdef CONFIG_SECCOMP_FILTER_EXTENDED
+static inline int security_seccomp_extended(void)
+{
+	return 0;
+}
+#endif /* CONFIG_SECCOMP_FILTER_EXTENDED */
+
 #endif /* CONFIG_SECURITY */
 #endif /* CONFIG_BPF_SYSCALL */
 
diff --git a/security/security.c b/security/security.c
index 94383f83ba42..301afe76ffb2 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2553,6 +2553,14 @@ void security_bpf_prog_free(struct bpf_prog_aux *aux)
 {
 	call_void_hook(bpf_prog_free_security, aux);
 }
+
+#ifdef CONFIG_SECCOMP_FILTER_EXTENDED
+int security_seccomp_extended(void)
+{
+	return call_int_hook(seccomp_extended, 0);
+}
+#endif
+
 #endif /* CONFIG_BPF_SYSCALL */
 
 int security_locked_down(enum lockdown_reason what)
-- 
2.31.1