io_uring/cmd: Introduce SOCKET_URING_OP_GETSOCKOPT

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.

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 <leitao@debian.org>
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Link: https://lore.kernel.org/r/20231016134750.1381153-10-leitao@debian.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 425f64eee44eda707e4c2622a5d5accf56d90f7b..dcf7272463e9a7baac40aed8102e15d60a0ce20a 100644 (file)
--- 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 {
@@ -80,6 +84,7 @@ struct io_uring_sqe {
        union {
                __s32   splice_fd_in;
                __u32   file_index;
+               __u32   optlen;
                struct {
                        __u16   addr_len;
                        __u16   __pad3[1];
@@ -90,6 +95,7 @@ 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
@@ -736,6 +742,7 @@ 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 42694c07d8fdd6bc0994ec3476062f4ff77891bd..8b045830b0d9e12df25135ad722d65e3bce72427 100644 (file)
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -214,6 +214,32 @@ 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,
+                                         unsigned int issue_flags)
+{
+       bool compat = !!(issue_flags & IO_URING_F_COMPAT);
+       int optlen, optname, level, err;
+       void __user *optval;
+
+       level = READ_ONCE(cmd->sqe->level);
+       if (level != SOL_SOCKET)
+               return -EOPNOTSUPP;
+
+       optval = u64_to_user_ptr(READ_ONCE(cmd->sqe->optval));
+       optname = READ_ONCE(cmd->sqe->optname);
+       optlen = READ_ONCE(cmd->sqe->optlen);
+
+       err = do_sock_getsockopt(sock, compat, level, optname,
+                                USER_SOCKPTR(optval),
+                                KERNEL_SOCKPTR(&optlen));
+       if (err)
+               return err;
+
+       /* On success, return optlen */
+       return optlen;
+}
+
 #if defined(CONFIG_NET)
 int io_uring_cmd_sock(struct io_uring_cmd *cmd, unsigned int issue_flags)
 {
@@ -236,6 +262,8 @@ 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, issue_flags);
        default:
                return -EOPNOTSUPP;
        }