security_mptcp_add_subflow(9)

okay bestie, welcome to security_mptcp_add_subflow(9) from the Kernel API Manual — section 9, obviously 💅✨

✨ NAME ✨

security_mptcp_add_subflow — Inherit the LSM label from the MPTCP socket. Like, the subflow is literally getting the owning socket’s label energy. No cap 👑

🌸 SYNOPSIS 🌸

here’s the signature, character-for-character, do not come for me:

int security_mptcp_add_subflow (struct sock *sk , struct sock *ssk );

🎀 ARGUMENTS 🎀

• sk — the owning MPTCP socket 👑
• ssk — the new subflow 🦋

💖 DESCRIPTION 💖

okay so picture this: you’ve got an MPTCP socket, and it’s the main character. Then a new subflow shows up. This hook updates the labeling for that MPTCP subflow so it matches the one of the owning MPTCP socket. it’s giving “you are literally wearing the same label as your owner,” and honestly? iconic ✨

the important part, bestie: this hook has to be called after the socket creation and initialization via the security_socket_create and security_socket_post_create LSM hooks. not before, not in the middle — after. the order is the vibe check, and the vibe check is mandatory 🫶

🔥 RETURN 🔥

Returns 0 on success or a negative error code on failure.

that’s the whole mood: 0 = slay, negative = something went sideways 😭💀

🌈 SEE ALSO 🌈

Kernel file ./security/security.c is where the lore lives. and then there’s the extended universe — every single one of these icons, fr fr:

lsm_file_alloc(9), lsm_backing_file_alloc(9), lsm_blob_alloc(9), lsm_cred_alloc(9), lsm_inode_alloc(9), lsm_task_alloc(9), lsm_ipc_alloc(9), lsm_key_alloc(9), lsm_msg_msg_alloc(9), lsm_bdev_alloc(9), lsm_bpf_map_alloc(9), lsm_bpf_prog_alloc(9), lsm_bpf_token_alloc(9), lsm_superblock_alloc(9), lsm_fill_user_ctx(9), security_binder_set_context_mgr(9), security_binder_transaction(9), security_binder_transfer_binder(9), security_binder_transfer_file(9), security_ptrace_access_check(9), security_ptrace_traceme(9), security_capget(9), security_capset(9), security_capable(9), security_quotactl(9), security_quota_on(9), security_syslog(9), security_settime64(9), security_vm_enough_memory_mm(9), security_bprm_creds_for_exec(9), security_bprm_creds_from_file(9), security_bprm_check(9), security_bprm_committing_creds(9), security_bprm_committed_creds(9), security_fs_context_submount(9), security_fs_context_dup(9), security_fs_context_parse_param(9), security_sb_alloc(9), security_sb_delete(9), security_sb_free(9), security_free_mnt_opts(9), security_sb_eat_lsm_opts(9), security_sb_mnt_opts_compat(9), security_sb_remount(9), security_sb_kern_mount(9), security_sb_show_options(9), security_sb_statfs(9), security_sb_mount(9), security_sb_umount(9), security_sb_pivotroot(9), security_sb_set_mnt_opts(9), security_sb_clone_mnt_opts(9), security_move_mount(9), security_path_notify(9), security_inode_alloc(9), security_inode_free(9), security_dentry_init_security(9), security_dentry_create_files_as(9), security_inode_init_security(9), security_inode_init_security_anon(9), security_path_mknod(9), security_path_post_mknod(9), security_path_mkdir(9), security_path_rmdir(9), security_path_unlink(9), security_path_symlink(9), security_path_link(9), security_path_rename(9), security_path_truncate(9), security_path_chmod(9), security_path_chown(9), security_path_chroot(9), security_inode_create(9), security_inode_post_create_tmpfile(9), security_inode_link(9), security_inode_unlink(9), security_inode_symlink(9), security_inode_mkdir(9), security_inode_rmdir(9), security_inode_mknod(9), security_inode_rename(9), security_inode_readlink(9), security_inode_follow_link(9), security_inode_permission(9), security_inode_setattr(9), security_inode_post_setattr(9), security_inode_getattr(9), security_inode_setxattr(9), security_inode_set_acl(9), security_inode_post_set_acl(9), security_inode_get_acl(9), security_inode_remove_acl(9), security_inode_post_remove_acl(9), security_inode_post_setxattr(9), security_inode_getxattr(9), security_inode_listxattr(9), security_inode_removexattr(9), security_inode_post_removexattr(9), security_inode_file_setattr(9), security_inode_file_getattr(9), security_inode_need_killpriv(9), security_inode_killpriv(9), security_inode_getsecurity(9), security_inode_setsecurity(9), security_inode_listsecurity(9), security_inode_getlsmprop(9), security_inode_copy_up(9), security_inode_copy_up_xattr(9), security_inode_setintegrity(9), security_kernfs_init_security(9), security_file_permission(9), security_file_alloc(9), security_file_release(9), security_file_free(9), security_backing_file_alloc(9), security_backing_file_free(9), security_file_ioctl(9), security_file_ioctl_compat(9), security_mmap_file(9), security_mmap_backing_file(9), security_mmap_addr(9), security_file_mprotect(9), security_file_lock(9), security_file_fcntl(9), security_file_set_fowner(9), security_file_send_sigiotask(9), security_file_receive(9), security_file_open(9), security_file_post_open(9), security_file_truncate(9), security_task_alloc(9), security_task_free(9), security_cred_alloc_blank(9), security_cred_free(9), security_prepare_creds(9), security_transfer_creds(9), security_cred_getsecid(9), security_cred_getlsmprop(9), security_kernel_act_as(9), security_kernel_create_files_as(9), security_kernel_module_request(9), security_kernel_read_file(9), security_kernel_post_read_file(9), security_kernel_load_data(9), security_kernel_post_load_data(9), security_task_fix_setuid(9), security_task_fix_setgid(9), security_task_fix_setgroups(9), security_task_setpgid(9), security_task_getpgid(9), security_task_getsid(9), security_current_getlsmprop_subj(9), security_task_getlsmprop_obj(9), security_task_setnice(9), security_task_setioprio(9), security_task_getioprio(9), security_task_prlimit(9), security_task_setrlimit(9), security_task_setscheduler(9), security_task_getscheduler(9), security_task_movememory(9), security_task_kill(9), security_task_prctl(9), security_task_to_inode(9), security_create_user_ns(9), security_ipc_permission(9), security_ipc_getlsmprop(9), security_msg_msg_alloc(9), security_msg_msg_free(9), security_msg_queue_alloc(9), security_msg_queue_free(9), security_msg_queue_associate(9), security_msg_queue_msgctl(9), security_msg_queue_msgsnd(9), security_msg_queue_msgrcv(9), security_shm_alloc(9), security_shm_free(9), security_shm_associate(9), security_shm_shmctl(9), security_shm_shmat(9), security_sem_alloc(9), security_sem_free(9), security_sem_associate(9), security_sem_semctl(9), security_sem_semop(9), security_d_instantiate(9), security_getselfattr(9), security_setselfattr(9), security_getprocattr(9), security_setprocattr(9), security_ismaclabel(9), security_secid_to_secctx(9), security_lsmprop_to_secctx(9), security_secctx_to_secid(9), security_release_secctx(9), security_inode_invalidate_secctx(9), security_inode_notifysecctx(9), security_inode_setsecctx(9), security_inode_getsecctx(9), security_post_notification(9), security_watch_key(9), security_netlink_send(9), security_unix_stream_connect(9), security_unix_may_send(9), security_socket_create(9), security_socket_post_create(9), security_socket_socketpair(9), security_socket_bind(9), security_socket_connect(9), security_socket_listen(9), security_socket_accept(9), security_socket_sendmsg(9), security_socket_recvmsg(9), security_socket_getsockname(9), security_socket_getpeername(9), security_socket_getsockopt(9), security_socket_setsockopt(9), security_socket_shutdown(9), security_sock_rcv_skb(9), security_socket_getpeersec_stream(9), security_socket_getpeersec_dgram(9), lsm_sock_alloc(9), security_sk_alloc(9), security_sk_free(9), security_sk_clone(9), security_sk_classify_flow(9), security_req_classify_flow(9), security_sock_graft(9), security_inet_conn_request(9), security_inet_csk_clone(9), security_inet_conn_established(9), security_secmark_relabel_packet(9), security_secmark_refcount_inc(9), security_secmark_refcount_dec(9), security_tun_dev_alloc_security(9), security_tun_dev_free_security(9), security_tun_dev_create(9), security_tun_dev_attach_queue(9), security_tun_dev_attach(9), security_tun_dev_open(9), security_sctp_assoc_request(9), security_sctp_bind_connect(9), security_sctp_sk_clone(9), security_sctp_assoc_established(9), security_unix_find(9), security_ib_pkey_access(9), security_ib_endport_manage_subnet(9), security_ib_alloc_security(9), security_ib_free_security(9), security_xfrm_policy_alloc(9), security_xfrm_policy_clone(9), security_xfrm_policy_free(9), security_xfrm_policy_delete(9), security_xfrm_state_alloc(9), security_xfrm_state_alloc_acquire(9), security_xfrm_state_delete(9), security_xfrm_state_free(9), security_xfrm_policy_lookup(9), security_xfrm_state_pol_flow_match(9), security_xfrm_decode_session(9), security_key_alloc(9), security_key_free(9), security_key_permission(9), security_key_getsecurity(9), security_key_post_create_or_update(9), security_audit_rule_init(9), security_audit_rule_known(9), security_audit_rule_free(9), security_audit_rule_match(9), security_bpf(9), security_bpf_map(9), security_bpf_prog(9), security_bpf_map_create(9), security_bpf_prog_load(9), security_bpf_token_create(9), security_bpf_token_cmd(9), security_bpf_token_capable(9), security_bpf_map_free(9), security_bpf_prog_free(9), security_bpf_token_free(9), security_locked_down(9), security_bdev_alloc(9), security_bdev_free(9), security_bdev_setintegrity(9), security_perf_event_open(9), security_perf_event_alloc(9), security_perf_event_free(9), security_perf_event_read(9), security_perf_event_write(9), security_uring_override_creds(9), security_uring_sqpoll(9), security_uring_cmd(9), security_uring_allowed(9), security_initramfs_populated(9)

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Source/version: ./security • date: October 2026 • page: security_mptcp_add_subflow(9) — byeee bestie, go label those subflows responsibly 🫶💖