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Most of the ioctls to net protocols operates directly on userspace argument (arg). Usually doing get_user()/put_user() directly in the ioctl callback. This is not flexible, because it is hard to reuse these functions without passing userspace buffers. Change the "struct proto" ioctls to avoid touching userspace memory and operate on kernel buffers, i.e., all protocol's ioctl callbacks is adapted to operate on a kernel memory other than on userspace (so, no more {put,get}_user() and friends being called in the ioctl callback). This changes the "struct proto" ioctl format in the following way: int (*ioctl)(struct sock *sk, int cmd, - unsigned long arg); + int *karg); (Important to say that this patch does not touch the "struct proto_ops" protocols) So, the "karg" argument, which is passed to the ioctl callback, is a pointer allocated to kernel space memory (inside a function wrapper). This buffer (karg) may contain input argument (copied from userspace in a prep function) and it might return a value/buffer, which is copied back to userspace if necessary. There is not one-size-fits-all format (that is I am using 'may' above), but basically, there are three type of ioctls: 1) Do not read from userspace, returns a result to userspace 2) Read an input parameter from userspace, and does not return anything to userspace 3) Read an input from userspace, and return a buffer to userspace. The default case (1) (where no input parameter is given, and an "int" is returned to userspace) encompasses more than 90% of the cases, but there are two other exceptions. Here is a list of exceptions: * Protocol RAW: * cmd = SIOCGETVIFCNT: * input and output = struct sioc_vif_req * cmd = SIOCGETSGCNT * input and output = struct sioc_sg_req * Explanation: for the SIOCGETVIFCNT case, userspace passes the input argument, which is struct sioc_vif_req. Then the callback populates the struct, which is copied back to userspace. * Protocol RAW6: * cmd = SIOCGETMIFCNT_IN6 * input and output = struct sioc_mif_req6 * cmd = SIOCGETSGCNT_IN6 * input and output = struct sioc_sg_req6 * Protocol PHONET: * cmd == SIOCPNADDRESOURCE | SIOCPNDELRESOURCE * input int (4 bytes) * Nothing is copied back to userspace. For the exception cases, functions sock_sk_ioctl_inout() will copy the userspace input, and copy it back to kernel space. The wrapper that prepare the buffer and put the buffer back to user is sk_ioctl(), so, instead of calling sk->sk_prot->ioctl(), the callee now calls sk_ioctl(), which will handle all cases. Signed-off-by: Breno Leitao <leitao@debian.org> Reviewed-by: Willem de Bruijn <willemb@google.com> Reviewed-by: David Ahern <dsahern@kernel.org> Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com> Link: https://lore.kernel.org/r/20230609152800.830401-1-leitao@debian.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
197 lines
4.0 KiB
C
197 lines
4.0 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* File: datagram.c
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*
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* Datagram (ISI) Phonet sockets
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*
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* Copyright (C) 2008 Nokia Corporation.
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*
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* Authors: Sakari Ailus <sakari.ailus@nokia.com>
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* Rémi Denis-Courmont
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/socket.h>
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#include <asm/ioctls.h>
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#include <net/sock.h>
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#include <linux/phonet.h>
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#include <linux/export.h>
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#include <net/phonet/phonet.h>
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static int pn_backlog_rcv(struct sock *sk, struct sk_buff *skb);
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/* associated socket ceases to exist */
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static void pn_sock_close(struct sock *sk, long timeout)
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{
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sk_common_release(sk);
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}
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static int pn_ioctl(struct sock *sk, int cmd, int *karg)
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{
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struct sk_buff *skb;
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switch (cmd) {
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case SIOCINQ:
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lock_sock(sk);
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skb = skb_peek(&sk->sk_receive_queue);
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*karg = skb ? skb->len : 0;
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release_sock(sk);
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return 0;
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case SIOCPNADDRESOURCE:
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case SIOCPNDELRESOURCE: {
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u32 res = *karg;
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if (res >= 256)
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return -EINVAL;
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if (cmd == SIOCPNADDRESOURCE)
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return pn_sock_bind_res(sk, res);
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else
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return pn_sock_unbind_res(sk, res);
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}
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}
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return -ENOIOCTLCMD;
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}
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/* Destroy socket. All references are gone. */
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static void pn_destruct(struct sock *sk)
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{
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skb_queue_purge(&sk->sk_receive_queue);
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}
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static int pn_init(struct sock *sk)
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{
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sk->sk_destruct = pn_destruct;
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return 0;
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}
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static int pn_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
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{
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DECLARE_SOCKADDR(struct sockaddr_pn *, target, msg->msg_name);
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struct sk_buff *skb;
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int err;
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if (msg->msg_flags & ~(MSG_DONTWAIT|MSG_EOR|MSG_NOSIGNAL|
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MSG_CMSG_COMPAT))
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return -EOPNOTSUPP;
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if (target == NULL)
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return -EDESTADDRREQ;
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if (msg->msg_namelen < sizeof(struct sockaddr_pn))
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return -EINVAL;
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if (target->spn_family != AF_PHONET)
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return -EAFNOSUPPORT;
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skb = sock_alloc_send_skb(sk, MAX_PHONET_HEADER + len,
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msg->msg_flags & MSG_DONTWAIT, &err);
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if (skb == NULL)
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return err;
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skb_reserve(skb, MAX_PHONET_HEADER);
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err = memcpy_from_msg((void *)skb_put(skb, len), msg, len);
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if (err < 0) {
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kfree_skb(skb);
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return err;
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}
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/*
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* Fill in the Phonet header and
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* finally pass the packet forwards.
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*/
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err = pn_skb_send(sk, skb, target);
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/* If ok, return len. */
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return (err >= 0) ? len : err;
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}
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static int pn_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
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int flags, int *addr_len)
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{
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struct sk_buff *skb = NULL;
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struct sockaddr_pn sa;
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int rval = -EOPNOTSUPP;
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int copylen;
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if (flags & ~(MSG_PEEK|MSG_TRUNC|MSG_DONTWAIT|MSG_NOSIGNAL|
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MSG_CMSG_COMPAT))
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goto out_nofree;
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skb = skb_recv_datagram(sk, flags, &rval);
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if (skb == NULL)
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goto out_nofree;
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pn_skb_get_src_sockaddr(skb, &sa);
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copylen = skb->len;
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if (len < copylen) {
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msg->msg_flags |= MSG_TRUNC;
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copylen = len;
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}
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rval = skb_copy_datagram_msg(skb, 0, msg, copylen);
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if (rval) {
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rval = -EFAULT;
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goto out;
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}
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rval = (flags & MSG_TRUNC) ? skb->len : copylen;
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if (msg->msg_name != NULL) {
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__sockaddr_check_size(sizeof(sa));
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memcpy(msg->msg_name, &sa, sizeof(sa));
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*addr_len = sizeof(sa);
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}
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out:
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skb_free_datagram(sk, skb);
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out_nofree:
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return rval;
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}
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/* Queue an skb for a sock. */
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static int pn_backlog_rcv(struct sock *sk, struct sk_buff *skb)
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{
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int err = sock_queue_rcv_skb(sk, skb);
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if (err < 0)
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kfree_skb(skb);
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return err ? NET_RX_DROP : NET_RX_SUCCESS;
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}
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/* Module registration */
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static struct proto pn_proto = {
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.close = pn_sock_close,
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.ioctl = pn_ioctl,
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.init = pn_init,
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.sendmsg = pn_sendmsg,
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.recvmsg = pn_recvmsg,
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.backlog_rcv = pn_backlog_rcv,
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.hash = pn_sock_hash,
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.unhash = pn_sock_unhash,
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.get_port = pn_sock_get_port,
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.obj_size = sizeof(struct pn_sock),
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.owner = THIS_MODULE,
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.name = "PHONET",
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};
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static const struct phonet_protocol pn_dgram_proto = {
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.ops = &phonet_dgram_ops,
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.prot = &pn_proto,
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.sock_type = SOCK_DGRAM,
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};
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int __init isi_register(void)
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{
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return phonet_proto_register(PN_PROTO_PHONET, &pn_dgram_proto);
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}
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void __exit isi_unregister(void)
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{
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phonet_proto_unregister(PN_PROTO_PHONET, &pn_dgram_proto);
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}
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