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[35.245.174.172]) by smtp.gmail.com with ESMTPSA id oo22-20020a05620a531600b00762f37b206dsm3297776qkn.81.2023.07.24.15.58.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Jul 2023 15:58:04 -0700 (PDT) Date: Mon, 24 Jul 2023 18:58:04 -0400 From: Willem de Bruijn To: Breno Leitao , asml.silence@gmail.com, axboe@kernel.dk Cc: io-uring@vger.kernel.org, netdev@vger.kernel.org, davem@davemloft.net, kuba@kernel.org, edumazet@google.com, pabeni@redhat.com, linux-kernel@vger.kernel.org, leit@meta.com Message-ID: <64bf01fc80d67_3b637629452@willemb.c.googlers.com.notmuch> In-Reply-To: <20230724142237.358769-3-leitao@debian.org> References: <20230724142237.358769-1-leitao@debian.org> <20230724142237.358769-3-leitao@debian.org> Subject: RE: [PATCH 2/4] io_uring/cmd: Introduce SOCKET_URING_OP_GETSOCKOPT Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Breno Leitao wrote: > Add support for getsockopt command (SOCKET_URING_OP_GETSOCKOPT), where > level is SOL_SOCKET. This is leveraging the sockptr_t infrastructure, > where a sockptr_t is either userspace or kernel space, and handled as > such. > > Function io_uring_cmd_getsockopt() is inspired by __sys_getsockopt(). > > Differently from the getsockopt(2), the optlen field is not a userspace > pointers. In getsockopt(2), userspace provides optlen pointer, which is > overwritten by the kernel. In this implementation, userspace passes a > u32, and the new value is returned in cqe->res. I.e., optlen is not a > pointer. > > Important to say that userspace needs to keep the pointer alive until > the CQE is completed. > > Signed-off-by: Breno Leitao > --- > include/uapi/linux/io_uring.h | 7 ++++++ > io_uring/uring_cmd.c | 43 +++++++++++++++++++++++++++++++++++ > 2 files changed, 50 insertions(+) > > diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h > index 9fc7195f25df..8152151080db 100644 > --- a/include/uapi/linux/io_uring.h > +++ b/include/uapi/linux/io_uring.h > @@ -43,6 +43,10 @@ struct io_uring_sqe { > union { > __u64 addr; /* pointer to buffer or iovecs */ > __u64 splice_off_in; > + struct { > + __u32 level; > + __u32 optname; > + }; > }; > __u32 len; /* buffer size or number of iovecs */ > union { > @@ -79,6 +83,7 @@ struct io_uring_sqe { > union { > __s32 splice_fd_in; > __u32 file_index; > + __u32 optlen; > struct { > __u16 addr_len; > __u16 __pad3[1]; > @@ -89,6 +94,7 @@ struct io_uring_sqe { > __u64 addr3; > __u64 __pad2[1]; > }; > + __u64 optval; > /* > * If the ring is initialized with IORING_SETUP_SQE128, then > * this field is used for 80 bytes of arbitrary command data > @@ -729,6 +735,7 @@ struct io_uring_recvmsg_out { > enum { > SOCKET_URING_OP_SIOCINQ = 0, > SOCKET_URING_OP_SIOCOUTQ, > + SOCKET_URING_OP_GETSOCKOPT, > }; > > #ifdef __cplusplus > diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c > index 8e7a03c1b20e..16c857cbf3b0 100644 > --- a/io_uring/uring_cmd.c > +++ b/io_uring/uring_cmd.c > @@ -166,6 +166,47 @@ int io_uring_cmd_import_fixed(u64 ubuf, unsigned long len, int rw, > } > EXPORT_SYMBOL_GPL(io_uring_cmd_import_fixed); > > +static inline int io_uring_cmd_getsockopt(struct socket *sock, > + struct io_uring_cmd *cmd) > +{ > + void __user *optval = u64_to_user_ptr(READ_ONCE(cmd->sqe->optval)); > + int optname = READ_ONCE(cmd->sqe->optname); > + int optlen = READ_ONCE(cmd->sqe->optlen); > + int level = READ_ONCE(cmd->sqe->level); > + void *koptval; > + int err; > + > + err = security_socket_getsockopt(sock, level, optname); > + if (err) > + return err; > + > + koptval = kmalloc(optlen, GFP_KERNEL); > + if (!koptval) > + return -ENOMEM; This will try to kmalloc any length that userspace passes? That is unnecessary .. > + > + err = copy_from_user(koptval, optval, optlen); > + if (err) > + goto fail; > + > + err = -EOPNOTSUPP; > + if (level == SOL_SOCKET) { > + err = sk_getsockopt(sock->sk, level, optname, > + KERNEL_SOCKPTR(koptval), > + KERNEL_SOCKPTR(&optlen)); .. sk_getsockopt defines a union of acceptable fields, which are all fairly small. I notice that BPF added BPF_CGROUP_GETSOCKOPT_MAX_OPTLEN to work around the issue of pre-allocating for the worst case. But that also needs to deal woth other getsockopt levels. > + if (err) > + goto fail; > + } > + > + err = copy_to_user(optval, koptval, optlen); > + > +fail: > + kfree(koptval); > + if (err) > + return err; > + else > + return optlen; > +} > + > int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags) > { > struct socket *sock = cmd->file->private_data; > @@ -187,6 +228,8 @@ int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags) > if (ret) > return ret; > return arg; > + case SOCKET_URING_OP_GETSOCKOPT: > + return io_uring_cmd_getsockopt(sock, cmd); > default: > return -EOPNOTSUPP; > } > -- > 2.34.1 >