// SPDX-License-Identifier: GPL-2.0-only/* * CUSE: Character device in Userspace * * Copyright (C) 2008-2009 SUSE Linux Products GmbH * Copyright (C) 2008-2009 Tejun Heo <tj@kernel.org> * * CUSE enables character devices to be implemented from userland much * like FUSE allows filesystems. On initialization /dev/cuse is * created. By opening the file and replying to the CUSE_INIT request * userland CUSE server can create a character device. After that the * operation is very similar to FUSE. * * A CUSE instance involves the following objects. * * cuse_conn : contains fuse_conn and serves as bonding structure * channel : file handle connected to the userland CUSE server * cdev : the implemented character device * dev : generic device for cdev * * Note that 'channel' is what 'dev' is in FUSE. As CUSE deals with * devices, it's called 'channel' to reduce confusion. * * channel determines when the character device dies. When channel is * closed, everything begins to destruct. The cuse_conn is taken off * the lookup table preventing further access from cdev, cdev and * generic device are removed and the base reference of cuse_conn is * put. * * On each open, the matching cuse_conn is looked up and if found an * additional reference is taken which is released when the file is * closed. */ #define pr_fmt(fmt) "CUSE: " fmt #include <linux/fuse.h>#include <linux/cdev.h>#include <linux/device.h>#include <linux/file.h>#include <linux/fs.h>#include <linux/kdev_t.h>#include <linux/kthread.h>#include <linux/list.h>#include <linux/magic.h>#include <linux/miscdevice.h>#include <linux/mutex.h>#include <linux/slab.h>#include <linux/stat.h>#include <linux/module.h>#include <linux/uio.h>#include <linux/user_namespace.h> #include "dev.h"#include "fuse_i.h"#include "fuse_dev_i.h" #define CUSE_CONNTBL_LEN 64 struct cuse_conn { struct list_head list; /* linked on cuse_conntbl */ struct fuse_mount fm; /* Dummy mount referencing fc */ struct fuse_conn fc; /* fuse connection */ struct cdev *cdev; /* associated character device */ struct device *dev; /* device representing @cdev */ /* init parameters, set once during initialization */ bool unrestricted_ioctl;}; static DEFINE_MUTEX(cuse_lock); /* protects registration */static struct list_head cuse_conntbl[CUSE_CONNTBL_LEN];static struct class *cuse_class; static struct cuse_conn *fc_to_cc(struct fuse_conn *fc){ return container_of(fc, struct cuse_conn, fc);} static struct list_head *cuse_conntbl_head(dev_t devt){ return &cuse_conntbl[(MAJOR(devt) + MINOR(devt)) % CUSE_CONNTBL_LEN];} /************************************************************************** * CUSE frontend operations * * These are file operations for the character device. * * On open, CUSE opens a file from the FUSE mnt and stores it to * private_data of the open file. All other ops call FUSE ops on the * FUSE file. */ static ssize_t cuse_read_iter(struct kiocb *kiocb, struct iov_iter *to){ struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(kiocb); loff_t pos = 0; return fuse_direct_io(&io, to, &pos, FUSE_DIO_CUSE);} static ssize_t cuse_write_iter(struct kiocb *kiocb, struct iov_iter *from){ struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(kiocb); loff_t pos = 0; /* * No locking or generic_write_checks(), the server is * responsible for locking and sanity checks. */ return fuse_direct_io(&io, from, &pos, FUSE_DIO_WRITE | FUSE_DIO_CUSE);} static int cuse_open(struct inode *inode, struct file *file){ dev_t devt = inode->i_cdev->dev; struct cuse_conn *cc = NULL, *pos; int rc; /* look up and get the connection */ mutex_lock(&cuse_lock); list_for_each_entry(pos, cuse_conntbl_head(devt), list) if (pos->dev->devt == devt) { fuse_conn_get(&pos->fc); cc = pos; break; } mutex_unlock(&cuse_lock); /* dead? */ if (!cc) return -ENODEV; /* * Generic permission check is already done against the chrdev * file, proceed to open. */ rc = fuse_do_open(&cc->fm, 0, file, 0); if (rc) fuse_conn_put(&cc->fc); return rc;} static int cuse_release(struct inode *inode, struct file *file){ struct fuse_file *ff = file->private_data; struct fuse_mount *fm = ff->fm; fuse_sync_release(NULL, ff, file->f_flags); fuse_conn_put(fm->fc); return 0;} static long cuse_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg){ struct fuse_file *ff = file->private_data; struct cuse_conn *cc = fc_to_cc(ff->fm->fc); unsigned int flags = 0; if (cc->unrestricted_ioctl) flags |= FUSE_IOCTL_UNRESTRICTED; return fuse_do_ioctl(file, cmd, arg, flags);} static long cuse_file_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg){ struct fuse_file *ff = file->private_data; struct cuse_conn *cc = fc_to_cc(ff->fm->fc); unsigned int flags = FUSE_IOCTL_COMPAT; if (cc->unrestricted_ioctl) flags |= FUSE_IOCTL_UNRESTRICTED; return fuse_do_ioctl(file, cmd, arg, flags);} static const struct file_operations cuse_frontend_fops = { .owner = THIS_MODULE, .read_iter = cuse_read_iter, .write_iter = cuse_write_iter, .open = cuse_open, .release = cuse_release, .unlocked_ioctl = cuse_file_ioctl, .compat_ioctl = cuse_file_compat_ioctl, .poll = fuse_file_poll, .llseek = noop_llseek,}; /************************************************************************** * CUSE channel initialization and destruction */ struct cuse_devinfo { const char *name;}; /** * cuse_parse_one - parse one key=value pair * @pp: i/o parameter for the current position * @end: points to one past the end of the packed string * @keyp: out parameter for key * @valp: out parameter for value * * *@pp points to packed strings - "key0=val0\0key1=val1\0" which ends * at @end - 1. This function parses one pair and set *@keyp to the * start of the key and *@valp to the start of the value. Note that * the original string is modified such that the key string is * terminated with '\0'. *@pp is updated to point to the next string. * * RETURNS: * 1 on successful parse, 0 on EOF, -errno on failure. */static int cuse_parse_one(char **pp, char *end, char **keyp, char **valp){ char *p = *pp; char *key, *val; while (p < end && *p == '\0') p++; if (p == end) return 0; if (end[-1] != '\0') { pr_err("info not properly terminated\n"); return -EINVAL; } key = val = p; p += strlen(p); if (valp) { strsep(&val, "="); if (!val) val = key + strlen(key); key = strstrip(key); val = strstrip(val); } else key = strstrip(key); if (!strlen(key)) { pr_err("zero length info key specified\n"); return -EINVAL; } *pp = p; *keyp = key; if (valp) *valp = val; return 1;} /** * cuse_parse_devinfo - parse device info * @p: device info string * @len: length of device info string * @devinfo: out parameter for parsed device info * * Parse @p to extract device info and store it into @devinfo. String * pointed to by @p is modified by parsing and @devinfo points into * them, so @p shouldn't be freed while @devinfo is in use. * * RETURNS: * 0 on success, -errno on failure. */static int cuse_parse_devinfo(char *p, size_t len, struct cuse_devinfo *devinfo){ char *end = p + len; char *key, *val; int rc; while (true) { rc = cuse_parse_one(&p, end, &key, &val); if (rc < 0) return rc; if (!rc) break; if (strcmp(key, "DEVNAME") == 0) devinfo->name = val; else pr_warn("unknown device info \"%s\"\n", key); } if (!devinfo->name || !strlen(devinfo->name)) { pr_err("DEVNAME unspecified\n"); return -EINVAL; } return 0;} static void cuse_gendev_release(struct device *dev){ kfree(dev);} struct cuse_init_args { struct fuse_args_pages ap; struct cuse_init_in in; struct cuse_init_out out; struct folio *folio; struct fuse_folio_desc desc; struct fuse_conn *fc;}; /** * cuse_process_init_reply - finish initializing CUSE channel * * @fm: The fuse mount information containing the CUSE connection. * @args: The arguments passed to the init reply. * @error: The error code signifying if any error occurred during the process. * * This function creates the character device and sets up all the * required data structures for it. Please read the comment at the * top of this file for high level overview. */static void cuse_process_init_reply(struct fuse_args *args, int error){ struct cuse_init_args *ia = container_of(args, typeof(*ia), ap.args); struct fuse_conn *fc = ia->fc; struct fuse_args_pages *ap = &ia->ap; struct cuse_conn *cc = fc_to_cc(fc), *pos; struct cuse_init_out *arg = &ia->out; struct folio *folio = ap->folios[0]; struct cuse_devinfo devinfo = { }; struct device *dev; struct cdev *cdev; dev_t devt; int rc, i; if (error || arg->major != FUSE_KERNEL_VERSION || arg->minor < 11) goto err; fc->minor = arg->minor; fc->max_read = max_t(unsigned, arg->max_read, 4096); fc->max_write = max_t(unsigned, arg->max_write, 4096); /* parse init reply */ cc->unrestricted_ioctl = arg->flags & CUSE_UNRESTRICTED_IOCTL; rc = cuse_parse_devinfo(folio_address(folio), ap->args.out_args[1].size, &devinfo); if (rc) goto err; /* determine and reserve devt */ devt = MKDEV(arg->dev_major, arg->dev_minor); if (!MAJOR(devt)) rc = alloc_chrdev_region(&devt, MINOR(devt), 1, devinfo.name); else rc = register_chrdev_region(devt, 1, devinfo.name); if (rc) { pr_err("failed to register chrdev region\n"); goto err; } /* devt determined, create device */ rc = -ENOMEM; dev = kzalloc_obj(*dev); if (!dev) goto err_region; device_initialize(dev); dev_set_uevent_suppress(dev, 1); dev->class = cuse_class; dev->devt = devt; dev->release = cuse_gendev_release; dev_set_drvdata(dev, cc); dev_set_name(dev, "%s", devinfo.name); mutex_lock(&cuse_lock); /* make sure the device-name is unique */ for (i = 0; i < CUSE_CONNTBL_LEN; ++i) { list_for_each_entry(pos, &cuse_conntbl[i], list) if (!strcmp(dev_name(pos->dev), dev_name(dev))) goto err_unlock; } rc = device_add(dev); if (rc) goto err_unlock; /* register cdev */ rc = -ENOMEM; cdev = cdev_alloc(); if (!cdev) goto err_dev; cdev->owner = THIS_MODULE; cdev->ops = &cuse_frontend_fops; rc = cdev_add(cdev, devt, 1); if (rc) goto err_cdev; cc->dev = dev; cc->cdev = cdev; /* make the device available */ list_add(&cc->list, cuse_conntbl_head(devt)); mutex_unlock(&cuse_lock); /* announce device availability */ dev_set_uevent_suppress(dev, 0); kobject_uevent(&dev->kobj, KOBJ_ADD);out: kfree(ia); folio_put(folio); return; err_cdev: cdev_del(cdev);err_dev: device_del(dev);err_unlock: mutex_unlock(&cuse_lock); put_device(dev);err_region: unregister_chrdev_region(devt, 1);err: fuse_chan_abort(fc->chan, false); goto out;} static int cuse_send_init(struct cuse_conn *cc){ int rc; struct folio *folio; struct fuse_mount *fm = &cc->fm; struct cuse_init_args *ia; struct fuse_args_pages *ap; BUILD_BUG_ON(CUSE_INIT_INFO_MAX > PAGE_SIZE); rc = -ENOMEM; folio = folio_alloc(GFP_KERNEL | __GFP_ZERO, 0); if (!folio) goto err; ia = kzalloc_obj(*ia); if (!ia) goto err_free_folio; ap = &ia->ap; ia->in.major = FUSE_KERNEL_VERSION; ia->in.minor = FUSE_KERNEL_MINOR_VERSION; ia->in.flags |= CUSE_UNRESTRICTED_IOCTL; ap->args.opcode = CUSE_INIT; ap->args.in_numargs = 1; ap->args.in_args[0].size = sizeof(ia->in); ap->args.in_args[0].value = &ia->in; ap->args.out_numargs = 2; ap->args.out_args[0].size = sizeof(ia->out); ap->args.out_args[0].value = &ia->out; ap->args.out_args[1].size = CUSE_INIT_INFO_MAX; ap->args.out_argvar = true; ap->args.out_pages = true; ap->num_folios = 1; ap->folios = &ia->folio; ap->descs = &ia->desc; ia->folio = folio; ia->desc.length = ap->args.out_args[1].size; ia->fc = &cc->fc; ap->args.end = cuse_process_init_reply; rc = fuse_simple_background(fm, &ap->args, GFP_KERNEL); if (rc) { kfree(ia);err_free_folio: folio_put(folio); }err: return rc;} static void cuse_fc_release(struct fuse_conn *fc){ kfree(fc_to_cc(fc));} /** * cuse_channel_open - open method for /dev/cuse * @inode: inode for /dev/cuse * @file: file struct being opened * * Userland CUSE server can create a CUSE device by opening /dev/cuse * and replying to the initialization request kernel sends. This * function is responsible for handling CUSE device initialization. * Because the fd opened by this function is used during * initialization, this function only creates cuse_conn and sends * init. The rest is delegated to a kthread.Lines 1–500 of 669. Load more
// SPDX-License-Identifier: GPL-2.0-only /* * CUSE: Character device in Userspace * * Copyright (C) 2008-2009 SUSE Linux Products GmbH * Copyright (C) 2008-2009 Tejun Heo <tj@kernel.org> * * CUSE enables character devices to be implemented from userland much * like FUSE allows filesystems. On initialization /dev/cuse is * created. By opening the file and replying to the CUSE_INIT request * userland CUSE server can create a character device. After that the * operation is very similar to FUSE. * * A CUSE instance involves the following objects. * * cuse_conn : contains fuse_conn and serves as bonding structure * channel : file handle connected to the userland CUSE server * cdev : the implemented character device * dev : generic device for cdev * * Note that 'channel' is what 'dev' is in FUSE. As CUSE deals with * devices, it's called 'channel' to reduce confusion. * * channel determines when the character device dies. When channel is * closed, everything begins to destruct. The cuse_conn is taken off * the lookup table preventing further access from cdev, cdev and * generic device are removed and the base reference of cuse_conn is * put. * * On each open, the matching cuse_conn is looked up and if found an * additional reference is taken which is released when the file is * closed. */ #define pr_fmt(fmt) "CUSE: " fmt #include <linux/fuse.h> #include <linux/cdev.h> #include <linux/device.h> #include <linux/file.h> #include <linux/fs.h> #include <linux/kdev_t.h> #include <linux/kthread.h> #include <linux/list.h> #include <linux/magic.h> #include <linux/miscdevice.h> #include <linux/mutex.h> #include <linux/slab.h> #include <linux/stat.h> #include <linux/module.h> #include <linux/uio.h> #include <linux/user_namespace.h> #include "dev.h" #include "fuse_i.h" #include "fuse_dev_i.h" #define CUSE_CONNTBL_LEN 64 struct cuse_conn { struct list_head list; /* linked on cuse_conntbl */ struct fuse_mount fm; /* Dummy mount referencing fc */ struct fuse_conn fc; /* fuse connection */ struct cdev *cdev; /* associated character device */ struct device *dev; /* device representing @cdev */ /* init parameters, set once during initialization */ bool unrestricted_ioctl; }; static DEFINE_MUTEX(cuse_lock); /* protects registration */ static struct list_head cuse_conntbl[CUSE_CONNTBL_LEN]; static struct class *cuse_class; static struct cuse_conn *fc_to_cc(struct fuse_conn *fc) { return container_of(fc, struct cuse_conn, fc); } static struct list_head *cuse_conntbl_head(dev_t devt) { return &cuse_conntbl[(MAJOR(devt) + MINOR(devt)) % CUSE_CONNTBL_LEN]; } /************************************************************************** * CUSE frontend operations * * These are file operations for the character device. * * On open, CUSE opens a file from the FUSE mnt and stores it to * private_data of the open file. All other ops call FUSE ops on the * FUSE file. */ static ssize_t cuse_read_iter(struct kiocb *kiocb, struct iov_iter *to) { struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(kiocb); loff_t pos = 0; return fuse_direct_io(&io, to, &pos, FUSE_DIO_CUSE); } static ssize_t cuse_write_iter(struct kiocb *kiocb, struct iov_iter *from) { struct fuse_io_priv io = FUSE_IO_PRIV_SYNC(kiocb); loff_t pos = 0; /* * No locking or generic_write_checks(), the server is * responsible for locking and sanity checks. */ return fuse_direct_io(&io, from, &pos, FUSE_DIO_WRITE | FUSE_DIO_CUSE); } static int cuse_open(struct inode *inode, struct file *file) { dev_t devt = inode->i_cdev->dev; struct cuse_conn *cc = NULL, *pos; int rc; /* look up and get the connection */ mutex_lock(&cuse_lock); list_for_each_entry(pos, cuse_conntbl_head(devt), list) if (pos->dev->devt == devt) { fuse_conn_get(&pos->fc); cc = pos; break; } mutex_unlock(&cuse_lock); /* dead? */ if (!cc) return -ENODEV; /* * Generic permission check is already done against the chrdev * file, proceed to open. */ rc = fuse_do_open(&cc->fm, 0, file, 0); if (rc) fuse_conn_put(&cc->fc); return rc; } static int cuse_release(struct inode *inode, struct file *file) { struct fuse_file *ff = file->private_data; struct fuse_mount *fm = ff->fm; fuse_sync_release(NULL, ff, file->f_flags); fuse_conn_put(fm->fc); return 0; } static long cuse_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct fuse_file *ff = file->private_data; struct cuse_conn *cc = fc_to_cc(ff->fm->fc); unsigned int flags = 0; if (cc->unrestricted_ioctl) flags |= FUSE_IOCTL_UNRESTRICTED; return fuse_do_ioctl(file, cmd, arg, flags); } static long cuse_file_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct fuse_file *ff = file->private_data; struct cuse_conn *cc = fc_to_cc(ff->fm->fc); unsigned int flags = FUSE_IOCTL_COMPAT; if (cc->unrestricted_ioctl) flags |= FUSE_IOCTL_UNRESTRICTED; return fuse_do_ioctl(file, cmd, arg, flags); } static const struct file_operations cuse_frontend_fops = { .owner = THIS_MODULE, .read_iter = cuse_read_iter, .write_iter = cuse_write_iter, .open = cuse_open, .release = cuse_release, .unlocked_ioctl = cuse_file_ioctl, .compat_ioctl = cuse_file_compat_ioctl, .poll = fuse_file_poll, .llseek = noop_llseek, }; /************************************************************************** * CUSE channel initialization and destruction */ struct cuse_devinfo { const char *name; }; /** * cuse_parse_one - parse one key=value pair * @pp: i/o parameter for the current position * @end: points to one past the end of the packed string * @keyp: out parameter for key * @valp: out parameter for value * * *@pp points to packed strings - "key0=val0\0key1=val1\0" which ends * at @end - 1. This function parses one pair and set *@keyp to the * start of the key and *@valp to the start of the value. Note that * the original string is modified such that the key string is * terminated with '\0'. *@pp is updated to point to the next string. * * RETURNS: * 1 on successful parse, 0 on EOF, -errno on failure. */ static int cuse_parse_one(char **pp, char *end, char **keyp, char **valp) { char *p = *pp; char *key, *val; while (p < end && *p == '\0') p++; if (p == end) return 0; if (end[-1] != '\0') { pr_err("info not properly terminated\n"); return -EINVAL; } key = val = p; p += strlen(p); if (valp) { strsep(&val, "="); if (!val) val = key + strlen(key); key = strstrip(key); val = strstrip(val); } else key = strstrip(key); if (!strlen(key)) { pr_err("zero length info key specified\n"); return -EINVAL; } *pp = p; *keyp = key; if (valp) *valp = val; return 1; } /** * cuse_parse_devinfo - parse device info * @p: device info string * @len: length of device info string * @devinfo: out parameter for parsed device info * * Parse @p to extract device info and store it into @devinfo. String * pointed to by @p is modified by parsing and @devinfo points into * them, so @p shouldn't be freed while @devinfo is in use. * * RETURNS: * 0 on success, -errno on failure. */ static int cuse_parse_devinfo(char *p, size_t len, struct cuse_devinfo *devinfo) { char *end = p + len; char *key, *val; int rc; while (true) { rc = cuse_parse_one(&p, end, &key, &val); if (rc < 0) return rc; if (!rc) break; if (strcmp(key, "DEVNAME") == 0) devinfo->name = val; else pr_warn("unknown device info \"%s\"\n", key); } if (!devinfo->name || !strlen(devinfo->name)) { pr_err("DEVNAME unspecified\n"); return -EINVAL; } return 0; } static void cuse_gendev_release(struct device *dev) { kfree(dev); } struct cuse_init_args { struct fuse_args_pages ap; struct cuse_init_in in; struct cuse_init_out out; struct folio *folio; struct fuse_folio_desc desc; struct fuse_conn *fc; }; /** * cuse_process_init_reply - finish initializing CUSE channel * * @fm: The fuse mount information containing the CUSE connection. * @args: The arguments passed to the init reply. * @error: The error code signifying if any error occurred during the process. * * This function creates the character device and sets up all the * required data structures for it. Please read the comment at the * top of this file for high level overview. */ static void cuse_process_init_reply(struct fuse_args *args, int error) { struct cuse_init_args *ia = container_of(args, typeof(*ia), ap.args); struct fuse_conn *fc = ia->fc; struct fuse_args_pages *ap = &ia->ap; struct cuse_conn *cc = fc_to_cc(fc), *pos; struct cuse_init_out *arg = &ia->out; struct folio *folio = ap->folios[0]; struct cuse_devinfo devinfo = { }; struct device *dev; struct cdev *cdev; dev_t devt; int rc, i; if (error || arg->major != FUSE_KERNEL_VERSION || arg->minor < 11) goto err; fc->minor = arg->minor; fc->max_read = max_t(unsigned, arg->max_read, 4096); fc->max_write = max_t(unsigned, arg->max_write, 4096); /* parse init reply */ cc->unrestricted_ioctl = arg->flags & CUSE_UNRESTRICTED_IOCTL; rc = cuse_parse_devinfo(folio_address(folio), ap->args.out_args[1].size, &devinfo); if (rc) goto err; /* determine and reserve devt */ devt = MKDEV(arg->dev_major, arg->dev_minor); if (!MAJOR(devt)) rc = alloc_chrdev_region(&devt, MINOR(devt), 1, devinfo.name); else rc = register_chrdev_region(devt, 1, devinfo.name); if (rc) { pr_err("failed to register chrdev region\n"); goto err; } /* devt determined, create device */ rc = -ENOMEM; dev = kzalloc_obj(*dev); if (!dev) goto err_region; device_initialize(dev); dev_set_uevent_suppress(dev, 1); dev->class = cuse_class; dev->devt = devt; dev->release = cuse_gendev_release; dev_set_drvdata(dev, cc); dev_set_name(dev, "%s", devinfo.name); mutex_lock(&cuse_lock); /* make sure the device-name is unique */ for (i = 0; i < CUSE_CONNTBL_LEN; ++i) { list_for_each_entry(pos, &cuse_conntbl[i], list) if (!strcmp(dev_name(pos->dev), dev_name(dev))) goto err_unlock; } rc = device_add(dev); if (rc) goto err_unlock; /* register cdev */ rc = -ENOMEM; cdev = cdev_alloc(); if (!cdev) goto err_dev; cdev->owner = THIS_MODULE; cdev->ops = &cuse_frontend_fops; rc = cdev_add(cdev, devt, 1); if (rc) goto err_cdev; cc->dev = dev; cc->cdev = cdev; /* make the device available */ list_add(&cc->list, cuse_conntbl_head(devt)); mutex_unlock(&cuse_lock); /* announce device availability */ dev_set_uevent_suppress(dev, 0); kobject_uevent(&dev->kobj, KOBJ_ADD); out: kfree(ia); folio_put(folio); return; err_cdev: cdev_del(cdev); err_dev: device_del(dev); err_unlock: mutex_unlock(&cuse_lock); put_device(dev); err_region: unregister_chrdev_region(devt, 1); err: fuse_chan_abort(fc->chan, false); goto out; } static int cuse_send_init(struct cuse_conn *cc) { int rc; struct folio *folio; struct fuse_mount *fm = &cc->fm; struct cuse_init_args *ia; struct fuse_args_pages *ap; BUILD_BUG_ON(CUSE_INIT_INFO_MAX > PAGE_SIZE); rc = -ENOMEM; folio = folio_alloc(GFP_KERNEL | __GFP_ZERO, 0); if (!folio) goto err; ia = kzalloc_obj(*ia); if (!ia) goto err_free_folio; ap = &ia->ap; ia->in.major = FUSE_KERNEL_VERSION; ia->in.minor = FUSE_KERNEL_MINOR_VERSION; ia->in.flags |= CUSE_UNRESTRICTED_IOCTL; ap->args.opcode = CUSE_INIT; ap->args.in_numargs = 1; ap->args.in_args[0].size = sizeof(ia->in); ap->args.in_args[0].value = &ia->in; ap->args.out_numargs = 2; ap->args.out_args[0].size = sizeof(ia->out); ap->args.out_args[0].value = &ia->out; ap->args.out_args[1].size = CUSE_INIT_INFO_MAX; ap->args.out_argvar = true; ap->args.out_pages = true; ap->num_folios = 1; ap->folios = &ia->folio; ap->descs = &ia->desc; ia->folio = folio; ia->desc.length = ap->args.out_args[1].size; ia->fc = &cc->fc; ap->args.end = cuse_process_init_reply; rc = fuse_simple_background(fm, &ap->args, GFP_KERNEL); if (rc) { kfree(ia); err_free_folio: folio_put(folio); } err: return rc; } static void cuse_fc_release(struct fuse_conn *fc) { kfree(fc_to_cc(fc)); } /** * cuse_channel_open - open method for /dev/cuse * @inode: inode for /dev/cuse * @file: file struct being opened * * Userland CUSE server can create a CUSE device by opening /dev/cuse * and replying to the initialization request kernel sends. This * function is responsible for handling CUSE device initialization. * Because the fd opened by this function is used during * initialization, this function only creates cuse_conn and sends * init. The rest is delegated to a kthread.