[PATCH v2 3/3] fanotify: Allow audit to use the full permission event response

[Richard Guy Briggs <rgb@redhat.com>]

This patch passes the full value so that the audit function can use all
of it. The audit function was updated to log the additional information in
the AUDIT_FANOTIFY record. The following is an example of the new record
format:

type=FANOTIFY msg=audit(1600385147.372:590): resp=2 fan_type=1 fan_ctx=17

Suggested-by: Steve Grubb <sgrubb@redhat.com>
Link: https://lore.kernel.org/r/3075502.aeNJFYEL58@x2
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Link: https://lore.kernel.org/r/23c7f206a465d88cc646a944515fcc6a365f5eb2.1651174324.git.rgb@redhat.com
---
 fs/notify/fanotify/fanotify.c |  4 +++-
 include/linux/audit.h         |  8 ++++----
 kernel/auditsc.c              | 18 +++++++++++++++---
 3 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 00aff6e29bf8..bb16d9e0f31b 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -272,7 +272,9 @@ static int fanotify_get_response(struct fsnotify_group *group,
 
 	/* Check if the response should be audited */
 	if (event->response & FAN_AUDIT)
-		audit_fanotify(event->response & ~FAN_AUDIT);
+		audit_fanotify(event->response & ~FAN_AUDIT,
+			       event->extra_info_type,
+			       (char *)&event->extra_info_buf);
 
 	pr_debug("%s: group=%p event=%p about to return ret=%d\n", __func__,
 		 group, event, ret);
diff --git a/include/linux/audit.h b/include/linux/audit.h
index d06134ac6245..0897128ee43b 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -419,7 +419,7 @@ extern void __audit_log_capset(const struct cred *new, const struct cred *old);
 extern void __audit_mmap_fd(int fd, int flags);
 extern void __audit_openat2_how(struct open_how *how);
 extern void __audit_log_kern_module(char *name);
-extern void __audit_fanotify(unsigned int response);
+extern void __audit_fanotify(__u16 response, __u16 type, char *buf);
 extern void __audit_tk_injoffset(struct timespec64 offset);
 extern void __audit_ntp_log(const struct audit_ntp_data *ad);
 extern void __audit_log_nfcfg(const char *name, u8 af, unsigned int nentries,
@@ -526,10 +526,10 @@ static inline void audit_log_kern_module(char *name)
 		__audit_log_kern_module(name);
 }
 
-static inline void audit_fanotify(unsigned int response)
+static inline void audit_fanotify(__u16 response, __u16 type, char *buf)
 {
 	if (!audit_dummy_context())
-		__audit_fanotify(response);
+		__audit_fanotify(response, type, buf);
 }
 
 static inline void audit_tk_injoffset(struct timespec64 offset)
@@ -686,7 +686,7 @@ static inline void audit_log_kern_module(char *name)
 {
 }
 
-static inline void audit_fanotify(unsigned int response)
+static inline void audit_fanotify(__u16 response, __u16 type, char *buf)
 { }
 
 static inline void audit_tk_injoffset(struct timespec64 offset)
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index ea2ee1181921..afdbc416069a 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -64,6 +64,7 @@
 #include <uapi/linux/limits.h>
 #include <uapi/linux/netfilter/nf_tables.h>
 #include <uapi/linux/openat2.h> // struct open_how
+#include <uapi/linux/fanotify.h>
 
 #include "audit.h"
 
@@ -2893,10 +2894,21 @@ void __audit_log_kern_module(char *name)
 	context->type = AUDIT_KERN_MODULE;
 }
 
-void __audit_fanotify(unsigned int response)
+void __audit_fanotify(__u16 response, __u16 type, char *buf)
 {
-	audit_log(audit_context(), GFP_KERNEL,
-		AUDIT_FANOTIFY,	"resp=%u", response);
+	switch (type) {
+	case FAN_RESPONSE_INFO_AUDIT_RULE:
+		audit_log(audit_context(), GFP_KERNEL, AUDIT_FANOTIFY,
+			  "resp=%u fan_type=%u fan_ctx=%u",
+			  response, type, (__u32)*buf);
+		break;
+	case FAN_RESPONSE_INFO_AUDIT_NONE:
+	default:
+		audit_log(audit_context(), GFP_KERNEL, AUDIT_FANOTIFY,
+			  "resp=%u fan_type=%u fan_ctx=?",
+			  response, type);
+		break;
+	}
 }
 
 void __audit_tk_injoffset(struct timespec64 offset)
-- 
2.27.0