Android SELinux AVC Print Code
Introduction
Android SELinux (Security-Enhanced Linux) is a mandatory access control (MAC) system implemented in the Android operating system to provide an additional layer of security. AVC stands for Access Vector Cache and is used to log SELinux denials in the system. In this article, we will discuss how to print AVC messages in Android using code examples.
Printing AVC Messages
To print AVC messages in Android, we need to use the avc_audit_denied
function which is defined in the SELinux library. This function logs AVC denials to the kernel ring buffer and then to the audit subsystem where they can be viewed using tools like dmesg
or logcat
.
Here is a code example of how to print AVC messages in Android:
#include <selinux/avc.h>
void print_avc_message() {
char *scontext = "u:r:untrusted_app:s0";
char *tcontext = "u:r:system_server:s0";
char *tclass = "service_manager";
char *perm = "call";
avc_audit_denied(scontext, tcontext, tclass, perm, NULL);
}
In the code above, we call the avc_audit_denied
function with the source context u:r:untrusted_app:s0
, target context u:r:system_server:s0
, target class service_manager
, and permission call
. This will log an AVC denial message related to the specified access.
Sequence Diagram
Here is a sequence diagram showing the flow of printing AVC messages in Android:
sequenceDiagram
participant App
participant SELinux
participant Kernel
App->>+SELinux: avc_audit_denied()
SELinux->>+Kernel: Log AVC denial
Kernel-->>-SELinux: AVC denial logged
Conclusion
In this article, we have discussed how to print AVC messages in Android using code examples. By logging AVC denials, developers can better understand the interactions between different processes and enforce security policies in the system. SELinux AVC print code is an essential tool for debugging and securing Android applications.
By following the steps outlined in this article, developers can effectively utilize SELinux in Android and enhance the security of their applications.
Remember to always pay attention to SELinux AVC messages and act on them promptly to ensure the integrity and security of your Android system.