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audit_connect.bpf.c
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audit_connect.bpf.c
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#include "vmlinux.h"
#include <bpf/bpf_core_read.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#include "printk.bpf.h"
char LICENSE[] SEC("license") = "GPL";
#define AF_INET 2
const char program[16] = "attack_connect";
static inline bool is_program(char a[])
{
int flag = 1, i = 0;
while (a[i] != '\0' && program[i] != '\0')
{
if (a[i] != program[i])
{
flag = 0;
break;
}
i++;
}
return flag;
}
SEC("lsm/socket_connect")
int BPF_PROG(audit_connect, struct socket *sock, struct sockaddr *address, int addrlen, int ret)
{
// Satisfying "cannot override a denial" rule
if (ret != 0)
{
return ret;
}
char comm[16];
bpf_get_current_comm(comm, 16);
if (is_program(comm))
{
// Only IPv4 in this example
if (address->sa_family != AF_INET)
{
return 0;
}
// Cast the address to an IPv4 socket address
struct sockaddr_in *addr = (struct sockaddr_in *)address;
// Where do you want to go?
__u32 dest = addr->sin_addr.s_addr;
if (full_printk)
{
bpf_printk("lsm: auditing %pI4", &dest);
}
else
{
bpf_printk("lsm: auditing %d", dest);
}
}
return 0;
}