// SPDX-License-Identifier: GPL-2.0

#include "vmlinux.h"
#include "bpf_tracing_net.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>

char _license[] SEC("license") = "GPL";

extern bool CONFIG_SECURITY_SELINUX __kconfig __weak;
extern bool CONFIG_SECURITY_SMACK __kconfig __weak;
extern bool CONFIG_SECURITY_APPARMOR __kconfig __weak;

#ifndef AF_PACKET
#define AF_PACKET 17
#endif

#ifndef AF_UNIX
#define AF_UNIX 1
#endif

#ifndef EPERM
#define EPERM 1
#endif

struct {
        __uint(type, BPF_MAP_TYPE_CGROUP_STORAGE);
        __type(key, __u64);
        __type(value, __u64);
} cgroup_storage SEC(".maps");

int called_socket_post_create;
int called_socket_post_create2;
int called_socket_bind;
int called_socket_bind2;
int called_socket_alloc;
int called_socket_clone;

static __always_inline int test_local_storage(void)
{
        __u64 *val;

        val = bpf_get_local_storage(&cgroup_storage, 0);
        if (!val)
                return 0;
        *val += 1;

        return 1;
}

static __always_inline int real_create(struct socket *sock, int family,
                                       int protocol)
{
        struct sock *sk;
        int prio = 123;

        /* Reject non-tx-only AF_PACKET. */
        if (family == AF_PACKET && protocol != 0)
                return 0; /* EPERM */

        sk = sock->sk;
        if (!sk)
                return 1;

        /* The rest of the sockets get default policy. */
        if (bpf_setsockopt(sk, SOL_SOCKET, SO_PRIORITY, &prio, sizeof(prio)))
                return 0; /* EPERM */

        /* Make sure bpf_getsockopt is allowed and works. */
        prio = 0;
        if (bpf_getsockopt(sk, SOL_SOCKET, SO_PRIORITY, &prio, sizeof(prio)))
                return 0; /* EPERM */
        if (prio != 123)
                return 0; /* EPERM */

        /* Can access cgroup local storage. */
        if (!test_local_storage())
                return 0; /* EPERM */

        return 1;
}

/* __cgroup_bpf_run_lsm_socket */
SEC("lsm_cgroup/socket_post_create")
int BPF_PROG(socket_post_create, struct socket *sock, int family,
             int type, int protocol, int kern)
{
        called_socket_post_create++;
        return real_create(sock, family, protocol);
}

/* __cgroup_bpf_run_lsm_socket */
SEC("lsm_cgroup/socket_post_create")
int BPF_PROG(socket_post_create2, struct socket *sock, int family,
             int type, int protocol, int kern)
{
        called_socket_post_create2++;
        return real_create(sock, family, protocol);
}

static __always_inline int real_bind(struct socket *sock,
                                     struct sockaddr *address,
                                     int addrlen)
{
        struct sockaddr_ll sa = {};
        struct sock *sk = sock->sk;

        if (!sk)
                return 1;

        if (sk->__sk_common.skc_family != AF_PACKET)
                return 1;

        if (sk->sk_kern_sock)
                return 1;

        bpf_probe_read_kernel(&sa, sizeof(sa), address);
        if (sa.sll_protocol)
                return 0; /* EPERM */

        /* Can access cgroup local storage. */
        if (!test_local_storage())
                return 0; /* EPERM */

        return 1;
}

/* __cgroup_bpf_run_lsm_socket */
SEC("lsm_cgroup/socket_bind")
int BPF_PROG(socket_bind, struct socket *sock, struct sockaddr *address,
             int addrlen)
{
        called_socket_bind++;
        return real_bind(sock, address, addrlen);
}

/* __cgroup_bpf_run_lsm_socket */
SEC("lsm_cgroup/socket_bind")
int BPF_PROG(socket_bind2, struct socket *sock, struct sockaddr *address,
             int addrlen)
{
        called_socket_bind2++;
        return real_bind(sock, address, addrlen);
}

/* __cgroup_bpf_run_lsm_current (via bpf_lsm_current_hooks) */
SEC("lsm_cgroup/sk_alloc_security")
int BPF_PROG(socket_alloc, struct sock *sk, int family, gfp_t priority)
{
        called_socket_alloc++;
        /* if already have non-bpf lsms installed, EPERM will cause memory leak of non-bpf lsms */
        if (CONFIG_SECURITY_SELINUX || CONFIG_SECURITY_SMACK || CONFIG_SECURITY_APPARMOR)
                return 1;

        if (family == AF_UNIX)
                return 0; /* EPERM */

        /* Can access cgroup local storage. */
        if (!test_local_storage())
                return 0; /* EPERM */

        return 1;
}

/* __cgroup_bpf_run_lsm_sock */
SEC("lsm_cgroup/inet_csk_clone")
int BPF_PROG(socket_clone, struct sock *newsk, const struct request_sock *req)
{
        int prio = 234;

        if (!newsk)
                return 1;

        /* Accepted request sockets get a different priority. */
        if (bpf_setsockopt(newsk, SOL_SOCKET, SO_PRIORITY, &prio, sizeof(prio)))
                return 1;

        /* Make sure bpf_getsockopt is allowed and works. */
        prio = 0;
        if (bpf_getsockopt(newsk, SOL_SOCKET, SO_PRIORITY, &prio, sizeof(prio)))
                return 1;
        if (prio != 234)
                return 1;

        /* Can access cgroup local storage. */
        if (!test_local_storage())
                return 1;

        called_socket_clone++;

        return 1;
}