um: generalize os_rcv_fd

Change os_rcv_fd() to os_rcv_fd_msg() that can more generally
receive any number of FDs in any kind of message.

Link: https://patch.msgid.link/20240702192118.40b78b2bfe4e.Ic6ec12d72630e5bcae1e597d6bd5c6f29f441563@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/arch/um/drivers/port_kern.c b/arch/um/drivers/port_kern.c
index c52b3ff3c092cff658866a9d2e9a9c832575b974..a4508470df78e79790d9375f44506cf65ca1a683 100644 (file)
--- a/arch/um/drivers/port_kern.c
+++ b/arch/um/drivers/port_kern.c
@@ -45,15 +45,17 @@ struct connection {
 static irqreturn_t pipe_interrupt(int irq, void *data)
 {
        struct connection *conn = data;
-       int fd;
+       int n_fds = 1, fd = -1;
+       ssize_t ret;
 
-       fd = os_rcv_fd(conn->socket[0], &conn->helper_pid);
-       if (fd < 0) {
-               if (fd == -EAGAIN)
+       ret = os_rcv_fd_msg(conn->socket[0], &fd, n_fds, &conn->helper_pid,
+                           sizeof(conn->helper_pid));
+       if (ret != sizeof(conn->helper_pid)) {
+               if (ret == -EAGAIN)
                        return IRQ_NONE;
 
-               printk(KERN_ERR "pipe_interrupt : os_rcv_fd returned %d\n",
-                      -fd);
+               printk(KERN_ERR "pipe_interrupt : os_rcv_fd_msg returned %zd\n",
+                      ret);
                os_close_file(conn->fd);
        }
 

diff --git a/arch/um/drivers/xterm.c b/arch/um/drivers/xterm.c
index 6918de5e295665354d802bc51149ac2ad1f07e1c..e4316c7981e80229d5363c3aa29bac52c071db2c 100644 (file)
--- a/arch/um/drivers/xterm.c
+++ b/arch/um/drivers/xterm.c
@@ -156,7 +156,7 @@ static int xterm_open(int input, int output, int primary, void *d,
        new = xterm_fd(fd, &data->helper_pid);
        if (new < 0) {
                err = new;
-               printk(UM_KERN_ERR "xterm_open : os_rcv_fd failed, err = %d\n",
+               printk(UM_KERN_ERR "xterm_open : xterm_fd failed, err = %d\n",
                       -err);
                goto out_kill;
        }

diff --git a/arch/um/drivers/xterm_kern.c b/arch/um/drivers/xterm_kern.c
index 8011e51993d5c4e815d7145d00a1edeb2d8b5fde..3971252cb1a676d5a74976187adc702b5c567ed7 100644 (file)
--- a/arch/um/drivers/xterm_kern.c
+++ b/arch/um/drivers/xterm_kern.c
@@ -21,12 +21,19 @@ struct xterm_wait {
 static irqreturn_t xterm_interrupt(int irq, void *data)
 {
        struct xterm_wait *xterm = data;
-       int fd;
+       int fd = -1, n_fds = 1;
+       ssize_t ret;
 
-       fd = os_rcv_fd(xterm->fd, &xterm->pid);
-       if (fd == -EAGAIN)
+       ret = os_rcv_fd_msg(xterm->fd, &fd, n_fds,
+                           &xterm->pid, sizeof(xterm->pid));
+       if (ret == -EAGAIN)
                return IRQ_NONE;
 
+       if (ret < 0)
+               fd = ret;
+       else if (ret != sizeof(xterm->pid))
+               fd = -EMSGSIZE;
+
        xterm->new_fd = fd;
        complete(&xterm->ready);
 

diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index 6516ff5a0eccb6472e259f978b64fdc9d715870d..fc4091c127c89fa7c0d1c22a4a80cf12bf92f30a 100644 (file)
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -165,7 +165,8 @@ extern int os_create_unix_socket(const char *file, int len, int close_on_exec);
 extern int os_shutdown_socket(int fd, int r, int w);
 extern int os_dup_file(int fd);
 extern void os_close_file(int fd);
-extern int os_rcv_fd(int fd, int *helper_pid_out);
+ssize_t os_rcv_fd_msg(int fd, int *fds, unsigned int n_fds,
+                     void *data, size_t data_len);
 extern int os_connect_socket(const char *name);
 extern int os_file_type(char *file);
 extern int os_file_mode(const char *file, struct openflags *mode_out);

diff --git a/arch/um/kernel/ksyms.c b/arch/um/kernel/ksyms.c
index 3a85bde3e1734311141f36c3fbca0fe81987bc82..f2fb77da08cff0be3f34d4d34a9b6e58cbb04562 100644 (file)
--- a/arch/um/kernel/ksyms.c
+++ b/arch/um/kernel/ksyms.c
@@ -33,7 +33,7 @@ EXPORT_SYMBOL(os_shutdown_socket);
 EXPORT_SYMBOL(os_create_unix_socket);
 EXPORT_SYMBOL(os_connect_socket);
 EXPORT_SYMBOL(os_accept_connection);
-EXPORT_SYMBOL(os_rcv_fd);
+EXPORT_SYMBOL(os_rcv_fd_msg);
 EXPORT_SYMBOL(run_helper);
 EXPORT_SYMBOL(os_major);
 EXPORT_SYMBOL(os_minor);

diff --git a/arch/um/os-Linux/file.c b/arch/um/os-Linux/file.c
index abf8676b834c76e361b873c7e7a3bbfae512562a..6d3c7391094624830300003c4751dc2849defc4b 100644 (file)
--- a/arch/um/os-Linux/file.c
+++ b/arch/um/os-Linux/file.c
@@ -512,44 +512,47 @@ int os_shutdown_socket(int fd, int r, int w)
        return 0;
 }
 
-int os_rcv_fd(int fd, int *helper_pid_out)
+/**
+ * os_rcv_fd_msg - receive message with (optional) FDs
+ * @fd: the FD to receive from
+ * @fds: the array for FDs to write to
+ * @n_fds: number of FDs to receive (@fds array size)
+ * @data: the message buffer
+ * @data_len: the size of the message to receive
+ *
+ * Receive a message with FDs.
+ *
+ * Returns: the size of the received message, or an error code
+ */
+ssize_t os_rcv_fd_msg(int fd, int *fds, unsigned int n_fds,
+                     void *data, size_t data_len)
 {
-       int new, n;
-       char buf[CMSG_SPACE(sizeof(new))];
-       struct msghdr msg;
+       char buf[CMSG_SPACE(sizeof(*fds) * n_fds)];
        struct cmsghdr *cmsg;
-       struct iovec iov;
-
-       msg.msg_name = NULL;
-       msg.msg_namelen = 0;
-       iov = ((struct iovec) { .iov_base  = helper_pid_out,
-                               .iov_len   = sizeof(*helper_pid_out) });
-       msg.msg_iov = &iov;
-       msg.msg_iovlen = 1;
-       msg.msg_control = buf;
-       msg.msg_controllen = sizeof(buf);
-       msg.msg_flags = 0;
+       struct iovec iov = {
+               .iov_base = data,
+               .iov_len = data_len,
+       };
+       struct msghdr msg = {
+               .msg_iov = &iov,
+               .msg_iovlen = 1,
+               .msg_control = buf,
+               .msg_controllen = sizeof(buf),
+       };
+       int n;
 
        n = recvmsg(fd, &msg, 0);
        if (n < 0)
                return -errno;
-       else if (n != iov.iov_len)
-               *helper_pid_out = -1;
 
        cmsg = CMSG_FIRSTHDR(&msg);
-       if (cmsg == NULL) {
-               printk(UM_KERN_ERR "rcv_fd didn't receive anything, "
-                      "error = %d\n", errno);
-               return -1;
-       }
-       if ((cmsg->cmsg_level != SOL_SOCKET) ||
-           (cmsg->cmsg_type != SCM_RIGHTS)) {
-               printk(UM_KERN_ERR "rcv_fd didn't receive a descriptor\n");
-               return -1;
-       }
+       if (!cmsg ||
+           cmsg->cmsg_level != SOL_SOCKET ||
+           cmsg->cmsg_type != SCM_RIGHTS)
+               return n;
 
-       new = ((int *) CMSG_DATA(cmsg))[0];
-       return new;
+       memcpy(fds, CMSG_DATA(cmsg), cmsg->cmsg_len);
+       return n;
 }
 
 int os_create_unix_socket(const char *file, int len, int close_on_exec)