smack_socket_sendmsg(9)

🌸 NAME 🌸

okay so bestie, this is smack_socket_sendmsg(9) from the Kernel API Manual — section 9, very official, very kernel — and it's literally the page for smack_socket_sendmsg: Smack check based on destination host. that's the whole vibe: Smack, sockets, destination host, we're checking it 💅

✨ SYNOPSIS ✨

int smack_socket_sendmsg (struct socket *sock , struct msghdr *msg , int size );

🎀 ARGUMENTS 🎀

• sock — the socket. like, the actual socket, bestie 🫶
• msg — the message. the thing being sent.
• size — the size of the message. literally the size, no cap.

🦋 DESCRIPTION 🦋

so the rule is: it returns 0 if the current subject can write to the destination host. that's the green flag, periodt ✅

For IPv4, this is only a question if the destination is a single label host. iykyk — that's the condition, don't forget it.

For IPv6, this is a check against the label of the port. no cap, that's what it's doing.

💜 SEE ALSO 💜

Kernel file ./security/smack/smack_lsm.c — that's home base — plus the whole squad, and yes there are so many of them, buckle up:

• smk_fetch(9), init_inode_smack(9), init_task_smack(9), smk_copy_rules(9), smk_copy_relabel(9), smk_ptrace_mode(9), smk_ptrace_rule_check(9), smack_ptrace_access_check(9), smack_ptrace_traceme(9), smack_syslog(9), smack_sb_alloc_security(9), smack_fs_context_submount(9), smack_fs_context_dup(9), smack_fs_context_parse_param(9), smack_set_mnt_opts(9), smack_sb_statfs(9), smack_bprm_creds_for_exec(9), smack_inode_alloc_security(9), smk_rule_transmutes(9), smack_inode_init_security(9), smack_inode_link(9), smack_inode_unlink(9), smack_inode_rmdir(9), smack_inode_rename(9), smack_inode_permission(9), smack_inode_setattr(9), smack_inode_getattr(9), smack_inode_xattr_skipcap(9), smack_inode_setxattr(9), smack_inode_post_setxattr(9), smack_inode_getxattr(9), smack_inode_removexattr(9), smack_inode_set_acl(9), smack_inode_get_acl(9), smack_inode_remove_acl(9), smack_inode_getsecurity(9), smack_inode_listsecurity(9), smack_inode_getlsmprop(9), smack_file_alloc_security(9), smack_file_ioctl(9), smack_file_lock(9), smack_file_fcntl(9), smack_mmap_file(9), smack_file_set_fowner(9), smack_file_send_sigiotask(9), smack_file_receive(9), smack_file_open(9), smack_cred_alloc_blank(9), smack_cred_free(9), smack_cred_prepare(9), smack_cred_transfer(9), smack_cred_getsecid(9), smack_cred_getlsmprop(9), smack_kernel_act_as(9), smack_kernel_create_files_as(9), smk_curacc_on_task(9), smack_task_setpgid(9), smack_task_getpgid(9), smack_task_getsid(9), smack_current_getlsmprop_subj(9), smack_task_getlsmprop_obj(9), smack_task_setnice(9), smack_task_setioprio(9), smack_task_getioprio(9), smack_task_setscheduler(9), smack_task_getscheduler(9), smack_task_movememory(9), smack_task_kill(9), smack_task_to_inode(9), smack_sk_alloc_security(9), smack_sk_free_security(9), smack_sk_clone_security(9), smack_ipv4host_label(9), smack_ipv6host_label(9), smack_netlbl_add(9), smack_netlbl_delete(9), smk_ipv4_check(9), smk_ipv6_check(9), smk_ipv6_port_label(9), smk_ipv6_port_check(9), smack_inode_setsecurity(9), smack_socket_post_create(9), smack_socket_socketpair(9), smack_socket_bind(9), smack_socket_connect(9), smack_flags_to_may(9), smack_msg_msg_alloc_security(9), smack_of_ipc(9), smack_ipc_alloc_security(9), smk_curacc_shm(9), smack_shm_associate(9), smack_shm_shmctl(9), smack_shm_shmat(9), smk_curacc_sem(9), smack_sem_associate(9), smack_sem_semctl(9), smack_sem_semop(9), smk_tskacc_msq(9), smk_curacc_msq(9), smack_msg_queue_associate(9), smack_msg_queue_msgctl(9), smack_msg_queue_msgsnd(9), smack_msg_queue_msgrcv(9), smack_ipc_permission(9), smack_ipc_getlsmprop(9), smack_d_instantiate(9), smack_getselfattr(9), smack_getprocattr(9), do_setattr(9), smack_setselfattr(9), smack_setprocattr(9), smack_unix_stream_connect(9), smack_unix_may_send(9), smack_from_secattr(9), smack_from_skb(9), smack_from_netlbl(9), smack_socket_sock_rcv_skb(9), smack_socket_getpeersec_stream(9), smack_socket_getpeersec_dgram(9), smack_inet_conn_request(9), smack_inet_csk_clone(9), smack_key_alloc(9), smack_key_permission(9), smack_watch_key(9), smack_post_notification(9), smack_audit_rule_init(9), smack_audit_rule_known(9), smack_audit_rule_match(9), smack_ismaclabel(9), smack_to_secctx(9), smack_secid_to_secctx(9), smack_lsmprop_to_secctx(9), smack_secctx_to_secid(9), smack_uring_override_creds(9), smack_uring_sqpoll(9), smack_uring_cmd(9), smack_init(9)

mwah 💋 — this page comes from ./security/smack, dated October 2026, and it's all about smack_socket_sendmsg(9). byeee 🫶