net: rework recvmsg handler msg_name and msg_namelen logic

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / net / socket.c

diff --git a/net/socket.c b/net/socket.c
index 4ca1526db7562ff7a1ae189a5b51bd6487c045ed..9f7d6263f7fa77853f13b728559425187a99b02e 100644 (file)
--- a/net/socket.c
+++ b/net/socket.c
@@ -1832,8 +1832,10 @@ SYSCALL_DEFINE6(recvfrom, int, fd, void __user *, ubuf, size_t, size,
        msg.msg_iov = &iov;
        iov.iov_len = size;
        iov.iov_base = ubuf;
-       msg.msg_name = (struct sockaddr *)&address;
-       msg.msg_namelen = sizeof(address);
+       /* Save some cycles and don't copy the address if not needed */
+       msg.msg_name = addr ? (struct sockaddr *)&address : NULL;
+       /* We assume all kernel code knows the size of sockaddr_storage */
+       msg.msg_namelen = 0;
        if (sock->file->f_flags & O_NONBLOCK)
                flags |= MSG_DONTWAIT;
        err = sock_recvmsg(sock, &msg, size, flags);
@@ -1956,6 +1958,16 @@ struct used_address {
        unsigned int name_len;
 };
 
+static int copy_msghdr_from_user(struct msghdr *kmsg,
+                                struct msghdr __user *umsg)
+{
+       if (copy_from_user(kmsg, umsg, sizeof(struct msghdr)))
+               return -EFAULT;
+       if (kmsg->msg_namelen > sizeof(struct sockaddr_storage))
+               return -EINVAL;
+       return 0;
+}
+
 static int ___sys_sendmsg(struct socket *sock, struct msghdr __user *msg,
                         struct msghdr *msg_sys, unsigned int flags,
                         struct used_address *used_address)
@@ -1974,8 +1986,11 @@ static int ___sys_sendmsg(struct socket *sock, struct msghdr __user *msg,
        if (MSG_CMSG_COMPAT & flags) {
                if (get_compat_msghdr(msg_sys, msg_compat))
                        return -EFAULT;
-       } else if (copy_from_user(msg_sys, msg, sizeof(struct msghdr)))
-               return -EFAULT;
+       } else {
+               err = copy_msghdr_from_user(msg_sys, msg);
+               if (err)
+                       return err;
+       }
 
        if (msg_sys->msg_iovlen > UIO_FASTIOV) {
                err = -EMSGSIZE;
@@ -2183,8 +2198,11 @@ static int ___sys_recvmsg(struct socket *sock, struct msghdr __user *msg,
        if (MSG_CMSG_COMPAT & flags) {
                if (get_compat_msghdr(msg_sys, msg_compat))
                        return -EFAULT;
-       } else if (copy_from_user(msg_sys, msg, sizeof(struct msghdr)))
-               return -EFAULT;
+       } else {
+               err = copy_msghdr_from_user(msg_sys, msg);
+               if (err)
+                       return err;
+       }
 
        if (msg_sys->msg_iovlen > UIO_FASTIOV) {
                err = -EMSGSIZE;
@@ -2197,16 +2215,14 @@ static int ___sys_recvmsg(struct socket *sock, struct msghdr __user *msg,
                        goto out;
        }
 
-       /*
-        *      Save the user-mode address (verify_iovec will change the
-        *      kernel msghdr to use the kernel address space)
+       /* Save the user-mode address (verify_iovec will change the
+        * kernel msghdr to use the kernel address space)
         */
-
        uaddr = (__force void __user *)msg_sys->msg_name;
        uaddr_len = COMPAT_NAMELEN(msg);
-       if (MSG_CMSG_COMPAT & flags) {
+       if (MSG_CMSG_COMPAT & flags)
                err = verify_compat_iovec(msg_sys, iov, &addr, VERIFY_WRITE);
-       } else
+       else
                err = verify_iovec(msg_sys, iov, &addr, VERIFY_WRITE);
        if (err < 0)
                goto out_freeiov;
@@ -2215,6 +2231,9 @@ static int ___sys_recvmsg(struct socket *sock, struct msghdr __user *msg,
        cmsg_ptr = (unsigned long)msg_sys->msg_control;
        msg_sys->msg_flags = flags & (MSG_CMSG_CLOEXEC|MSG_CMSG_COMPAT);
 
+       /* We assume all kernel code knows the size of sockaddr_storage */
+       msg_sys->msg_namelen = 0;
+
        if (sock->file->f_flags & O_NONBLOCK)
                flags |= MSG_DONTWAIT;
        err = (nosec ? sock_recvmsg_nosec : sock_recvmsg)(sock, msg_sys,