kernel/linux.git/arch/mips/include/uapi/asm/socket.h, branch v6.18.21

af_unix: Introduce SO_INQ.

2025-07-09T01:05:25+00:00

We have an application that uses almost the same code for TCP and AF_UNIX (SOCK_STREAM). TCP can use TCP_INQ, but AF_UNIX doesn't have it and requires an extra syscall, ioctl(SIOCINQ) or getsockopt(SO_MEMINFO) as an alternative. Let's introduce the generic version of TCP_INQ. If SO_INQ is enabled, recvmsg() will put a cmsg of SCM_INQ that contains the exact value of ioctl(SIOCINQ). The cmsg is also included when msg->msg_get_inq is non-zero to make sockets io_uring-friendly. Note that SOCK_CUSTOM_SOCKOPT is flagged only for SOCK_STREAM to override setsockopt() for SOL_SOCKET. By having the flag in struct unix_sock, instead of struct sock, we can later add SO_INQ support for TCP and reuse tcp_sk(sk)->recvmsg_inq. Note also that supporting custom getsockopt() for SOL_SOCKET will need preparation for other SOCK_CUSTOM_SOCKOPT users (UDP, vsock, MPTCP). Signed-off-by: Kuniyuki Iwashima Reviewed-by: Willem de Bruijn Link: https://patch.msgid.link/20250702223606.1054680-7-kuniyu@google.com Signed-off-by: Jakub Kicinski

af_unix: Introduce SO_PASSRIGHTS.

2025-05-23T09:24:18+00:00

As long as recvmsg() or recvmmsg() is used with cmsg, it is not possible to avoid receiving file descriptors via SCM_RIGHTS. This behaviour has occasionally been flagged as problematic, as it can be (ab)used to trigger DoS during close(), for example, by passing a FUSE-controlled fd or a hung NFS fd. For instance, as noted on the uAPI Group page [0], an untrusted peer could send a file descriptor pointing to a hung NFS mount and then close it. Once the receiver calls recvmsg() with msg_control, the descriptor is automatically installed, and then the responsibility for the final close() now falls on the receiver, which may result in blocking the process for a long time. Regarding this, systemd calls cmsg_close_all() [1] after each recvmsg() to close() unwanted file descriptors sent via SCM_RIGHTS. However, this cannot work around the issue at all, because the final fput() may still occur on the receiver's side once sendmsg() with SCM_RIGHTS succeeds. Also, even filtering by LSM at recvmsg() does not work for the same reason. Thus, we need a better way to refuse SCM_RIGHTS at sendmsg(). Let's introduce SO_PASSRIGHTS to disable SCM_RIGHTS. Note that this option is enabled by default for backward compatibility. Link: https://uapi-group.org/kernel-features/#disabling-reception-of-scm_rights-for-af_unix-sockets #[0] Link: https://github.com/systemd/systemd/blob/v257.5/src/basic/fd-util.c#L612-L628 #[1] Signed-off-by: Kuniyuki Iwashima Reviewed-by: Willem de Bruijn Signed-off-by: David S. Miller

sock: Introduce SO_RCVPRIORITY socket option

2024-12-17T02:16:44+00:00

Add new socket option, SO_RCVPRIORITY, to include SO_PRIORITY in the ancillary data returned by recvmsg(). This is analogous to the existing support for SO_RCVMARK, as implemented in commit 6fd1d51cfa253 ("net: SO_RCVMARK socket option for SO_MARK with recvmsg()"). Reviewed-by: Willem de Bruijn Suggested-by: Ferenc Fejes Signed-off-by: Anna Emese Nyiri Link: https://patch.msgid.link/20241213084457.45120-5-annaemesenyiri@gmail.com Signed-off-by: Jakub Kicinski

net_tstamp: add SCM_TS_OPT_ID to provide OPT_ID in control message

2024-10-04T18:52:19+00:00

SOF_TIMESTAMPING_OPT_ID socket option flag gives a way to correlate TX timestamps and packets sent via socket. Unfortunately, there is no way to reliably predict socket timestamp ID value in case of error returned by sendmsg. For UDP sockets it's impossible because of lockless nature of UDP transmit, several threads may send packets in parallel. In case of RAW sockets MSG_MORE option makes things complicated. More details are in the conversation [1]. This patch adds new control message type to give user-space software an opportunity to control the mapping between packets and values by providing ID with each sendmsg for UDP sockets. The documentation is also added in this patch. [1] https://lore.kernel.org/netdev/CALCETrU0jB+kg0mhV6A8mrHfTE1D1pr1SD_B9Eaa9aDPfgHdtA@mail.gmail.com/ Reviewed-by: Willem de Bruijn Reviewed-by: Jason Xing Signed-off-by: Vadim Fedorenko Link: https://patch.msgid.link/20241001125716.2832769-2-vadfed@meta.com Signed-off-by: Jakub Kicinski

net: add SO_DEVMEM_DONTNEED setsockopt to release RX frags

2024-09-12T03:44:32+00:00

Add an interface for the user to notify the kernel that it is done reading the devmem dmabuf frags returned as cmsg. The kernel will drop the reference on the frags to make them available for reuse. Signed-off-by: Willem de Bruijn Signed-off-by: Kaiyuan Zhang Signed-off-by: Mina Almasry Reviewed-by: Pavel Begunkov Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20240910171458.219195-11-almasrymina@google.com Signed-off-by: Jakub Kicinski

tcp: RX path for devmem TCP

2024-09-12T03:44:32+00:00

In tcp_recvmsg_locked(), detect if the skb being received by the user is a devmem skb. In this case - if the user provided the MSG_SOCK_DEVMEM flag - pass it to tcp_recvmsg_devmem() for custom handling. tcp_recvmsg_devmem() copies any data in the skb header to the linear buffer, and returns a cmsg to the user indicating the number of bytes returned in the linear buffer. tcp_recvmsg_devmem() then loops over the unaccessible devmem skb frags, and returns to the user a cmsg_devmem indicating the location of the data in the dmabuf device memory. cmsg_devmem contains this information: 1. the offset into the dmabuf where the payload starts. 'frag_offset'. 2. the size of the frag. 'frag_size'. 3. an opaque token 'frag_token' to return to the kernel when the buffer is to be released. The pages awaiting freeing are stored in the newly added sk->sk_user_frags, and each page passed to userspace is get_page()'d. This reference is dropped once the userspace indicates that it is done reading this page. All pages are released when the socket is destroyed. Signed-off-by: Willem de Bruijn Signed-off-by: Kaiyuan Zhang Signed-off-by: Mina Almasry Reviewed-by: Pavel Begunkov Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20240910171458.219195-10-almasrymina@google.com Signed-off-by: Jakub Kicinski

net: core: add getsockopt SO_PEERPIDFD

2023-06-12T09:45:50+00:00

Add SO_PEERPIDFD which allows to get pidfd of peer socket holder pidfd. This thing is direct analog of SO_PEERCRED which allows to get plain PID. Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: Leon Romanovsky Cc: David Ahern Cc: Arnd Bergmann Cc: Kees Cook Cc: Christian Brauner Cc: Kuniyuki Iwashima Cc: Lennart Poettering Cc: Luca Boccassi Cc: Daniel Borkmann Cc: Stanislav Fomichev Cc: bpf@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: netdev@vger.kernel.org Cc: linux-arch@vger.kernel.org Reviewed-by: Christian Brauner Acked-by: Stanislav Fomichev Tested-by: Luca Boccassi Signed-off-by: Alexander Mikhalitsyn Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller

scm: add SO_PASSPIDFD and SCM_PIDFD

2023-06-12T09:45:49+00:00

Implement SCM_PIDFD, a new type of CMSG type analogical to SCM_CREDENTIALS, but it contains pidfd instead of plain pid, which allows programmers not to care about PID reuse problem. We mask SO_PASSPIDFD feature if CONFIG_UNIX is not builtin because it depends on a pidfd_prepare() API which is not exported to the kernel modules. Idea comes from UAPI kernel group: https://uapi-group.org/kernel-features/ Big thanks to Christian Brauner and Lennart Poettering for productive discussions about this. Cc: "David S. Miller" Cc: Eric Dumazet Cc: Jakub Kicinski Cc: Paolo Abeni Cc: Leon Romanovsky Cc: David Ahern Cc: Arnd Bergmann Cc: Kees Cook Cc: Christian Brauner Cc: Kuniyuki Iwashima Cc: Lennart Poettering Cc: Luca Boccassi Cc: linux-kernel@vger.kernel.org Cc: netdev@vger.kernel.org Cc: linux-arch@vger.kernel.org Tested-by: Luca Boccassi Reviewed-by: Kuniyuki Iwashima Reviewed-by: Christian Brauner Signed-off-by: Alexander Mikhalitsyn Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller

net: SO_RCVMARK socket option for SO_MARK with recvmsg()

2022-04-28T20:08:15+00:00

Adding a new socket option, SO_RCVMARK, to indicate that SO_MARK should be included in the ancillary data returned by recvmsg(). Renamed the sock_recv_ts_and_drops() function to sock_recv_cmsgs(). Signed-off-by: Erin MacNeil Reviewed-by: Eric Dumazet Reviewed-by: David Ahern Acked-by: Marc Kleine-Budde Link: https://lore.kernel.org/r/20220427200259.2564-1-lnx.erin@gmail.com Signed-off-by: Jakub Kicinski

txhash: Add socket option to control TX hash rethink behavior

2022-01-31T15:05:25+00:00

Add the SO_TXREHASH socket option to control hash rethink behavior per socket. When default mode is set, sockets disable rehash at initialization and use sysctl option when entering listen state. setsockopt() overrides default behavior. Signed-off-by: Akhmat Karakotov Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller