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net: prevent rewrite of msg_name in sock_sendmsg()
commit86a7e0b69b
upstream. Callers of sock_sendmsg(), and similarly kernel_sendmsg(), in kernel space may observe their value of msg_name change in cases where BPF sendmsg hooks rewrite the send address. This has been confirmed to break NFS mounts running in UDP mode and has the potential to break other systems. This patch: 1) Creates a new function called __sock_sendmsg() with same logic as the old sock_sendmsg() function. 2) Replaces calls to sock_sendmsg() made by __sys_sendto() and __sys_sendmsg() with __sock_sendmsg() to avoid an unnecessary copy, as these system calls are already protected. 3) Modifies sock_sendmsg() so that it makes a copy of msg_name if present before passing it down the stack to insulate callers from changes to the send address. Link: https://lore.kernel.org/netdev/20230912013332.2048422-1-jrife@google.com/ Fixes:1cedee13d2
("bpf: Hooks for sys_sendmsg") Cc: stable@vger.kernel.org Reviewed-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Jordan Rife <jrife@google.com> Reviewed-by: Simon Horman <horms@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
34f9370ae4
commit
fc8d9630c8
1 changed files with 23 additions and 6 deletions
29
net/socket.c
29
net/socket.c
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@ -720,6 +720,14 @@ static inline int sock_sendmsg_nosec(struct socket *sock, struct msghdr *msg)
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return ret;
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return ret;
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}
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}
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static int __sock_sendmsg(struct socket *sock, struct msghdr *msg)
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{
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int err = security_socket_sendmsg(sock, msg,
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msg_data_left(msg));
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return err ?: sock_sendmsg_nosec(sock, msg);
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}
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/**
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/**
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* sock_sendmsg - send a message through @sock
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* sock_sendmsg - send a message through @sock
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* @sock: socket
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* @sock: socket
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@ -730,10 +738,19 @@ static inline int sock_sendmsg_nosec(struct socket *sock, struct msghdr *msg)
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*/
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*/
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int sock_sendmsg(struct socket *sock, struct msghdr *msg)
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int sock_sendmsg(struct socket *sock, struct msghdr *msg)
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{
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{
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int err = security_socket_sendmsg(sock, msg,
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struct sockaddr_storage *save_addr = (struct sockaddr_storage *)msg->msg_name;
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msg_data_left(msg));
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struct sockaddr_storage address;
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int ret;
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return err ?: sock_sendmsg_nosec(sock, msg);
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if (msg->msg_name) {
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memcpy(&address, msg->msg_name, msg->msg_namelen);
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msg->msg_name = &address;
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}
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ret = __sock_sendmsg(sock, msg);
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msg->msg_name = save_addr;
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return ret;
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}
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}
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EXPORT_SYMBOL(sock_sendmsg);
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EXPORT_SYMBOL(sock_sendmsg);
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@ -1110,7 +1127,7 @@ static ssize_t sock_write_iter(struct kiocb *iocb, struct iov_iter *from)
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if (sock->type == SOCK_SEQPACKET)
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if (sock->type == SOCK_SEQPACKET)
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msg.msg_flags |= MSG_EOR;
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msg.msg_flags |= MSG_EOR;
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res = sock_sendmsg(sock, &msg);
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res = __sock_sendmsg(sock, &msg);
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*from = msg.msg_iter;
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*from = msg.msg_iter;
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return res;
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return res;
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}
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}
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@ -2114,7 +2131,7 @@ int __sys_sendto(int fd, void __user *buff, size_t len, unsigned int flags,
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if (sock->file->f_flags & O_NONBLOCK)
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if (sock->file->f_flags & O_NONBLOCK)
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flags |= MSG_DONTWAIT;
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flags |= MSG_DONTWAIT;
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msg.msg_flags = flags;
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msg.msg_flags = flags;
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err = sock_sendmsg(sock, &msg);
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err = __sock_sendmsg(sock, &msg);
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out_put:
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out_put:
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fput_light(sock->file, fput_needed);
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fput_light(sock->file, fput_needed);
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@ -2479,7 +2496,7 @@ static int ____sys_sendmsg(struct socket *sock, struct msghdr *msg_sys,
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err = sock_sendmsg_nosec(sock, msg_sys);
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err = sock_sendmsg_nosec(sock, msg_sys);
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goto out_freectl;
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goto out_freectl;
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}
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}
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err = sock_sendmsg(sock, msg_sys);
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err = __sock_sendmsg(sock, msg_sys);
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/*
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/*
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* If this is sendmmsg() and sending to current destination address was
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* If this is sendmmsg() and sending to current destination address was
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* successful, remember it.
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* successful, remember it.
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