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421 lines · 10.6 KiB

1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (c) 2024-2025, NVIDIA CORPORATION & AFFILIATES
4 */
5#define pr_fmt(fmt) "fwctl: " fmt
6#include <linux/fwctl.h>
7
8#include <linux/container_of.h>
9#include <linux/fs.h>
10#include <linux/module.h>
11#include <linux/sizes.h>
12#include <linux/slab.h>
13
14#include <uapi/fwctl/fwctl.h>
15
16enum {
17 FWCTL_MAX_DEVICES = 4096,
18 MAX_RPC_LEN = SZ_2M,
19};
20static_assert(FWCTL_MAX_DEVICES < (1U << MINORBITS));
21
22static dev_t fwctl_dev;
23static DEFINE_IDA(fwctl_ida);
24static unsigned long fwctl_tainted;
25
26struct fwctl_ucmd {
27 struct fwctl_uctx *uctx;
28 void __user *ubuffer;
29 void *cmd;
30 u32 user_size;
31};
32
33static int ucmd_respond(struct fwctl_ucmd *ucmd, size_t cmd_len)
34{
35 if (copy_to_user(ucmd->ubuffer, ucmd->cmd,
36 min_t(size_t, ucmd->user_size, cmd_len)))
37 return -EFAULT;
38 return 0;
39}
40
41static int copy_to_user_zero_pad(void __user *to, const void *from,
42 size_t from_len, size_t user_len)
43{
44 size_t copy_len;
45
46 copy_len = min(from_len, user_len);
47 if (copy_to_user(to, from, copy_len))
48 return -EFAULT;
49 if (copy_len < user_len) {
50 if (clear_user(to + copy_len, user_len - copy_len))
51 return -EFAULT;
52 }
53 return 0;
54}
55
56static int fwctl_cmd_info(struct fwctl_ucmd *ucmd)
57{
58 struct fwctl_device *fwctl = ucmd->uctx->fwctl;
59 struct fwctl_info *cmd = ucmd->cmd;
60 size_t driver_info_len = 0;
61
62 if (cmd->flags)
63 return -EOPNOTSUPP;
64
65 if (!fwctl->ops->info && cmd->device_data_len) {
66 if (clear_user(u64_to_user_ptr(cmd->out_device_data),
67 cmd->device_data_len))
68 return -EFAULT;
69 } else if (cmd->device_data_len) {
70 void *driver_info __free(kfree) =
71 fwctl->ops->info(ucmd->uctx, &driver_info_len);
72 if (IS_ERR(driver_info))
73 return PTR_ERR(driver_info);
74
75 if (copy_to_user_zero_pad(u64_to_user_ptr(cmd->out_device_data),
76 driver_info, driver_info_len,
77 cmd->device_data_len))
78 return -EFAULT;
79 }
80
81 cmd->out_device_type = fwctl->ops->device_type;
82 cmd->device_data_len = driver_info_len;
83 return ucmd_respond(ucmd, sizeof(*cmd));
84}
85
86static int fwctl_cmd_rpc(struct fwctl_ucmd *ucmd)
87{
88 struct fwctl_device *fwctl = ucmd->uctx->fwctl;
89 struct fwctl_rpc *cmd = ucmd->cmd;
90 size_t out_len;
91
92 if (cmd->in_len > MAX_RPC_LEN || cmd->out_len > MAX_RPC_LEN)
93 return -EMSGSIZE;
94
95 switch (cmd->scope) {
96 case FWCTL_RPC_CONFIGURATION:
97 case FWCTL_RPC_DEBUG_READ_ONLY:
98 break;
99
100 case FWCTL_RPC_DEBUG_WRITE_FULL:
101 if (!capable(CAP_SYS_RAWIO))
102 return -EPERM;
103 fallthrough;
104 case FWCTL_RPC_DEBUG_WRITE:
105 if (!test_and_set_bit(0, &fwctl_tainted)) {
106 dev_warn(
107 &fwctl->dev,
108 "%s(%d): has requested full access to the physical device",
109 current->comm, task_pid_nr(current));
110 add_taint(TAINT_FWCTL, LOCKDEP_STILL_OK);
111 }
112 break;
113 default:
114 return -EOPNOTSUPP;
115 }
116
117 void *inbuf __free(kvfree) = kvzalloc(cmd->in_len, GFP_KERNEL_ACCOUNT);
118 if (!inbuf)
119 return -ENOMEM;
120 if (copy_from_user(inbuf, u64_to_user_ptr(cmd->in), cmd->in_len))
121 return -EFAULT;
122
123 out_len = cmd->out_len;
124 void *outbuf __free(kvfree) = fwctl->ops->fw_rpc(
125 ucmd->uctx, cmd->scope, inbuf, cmd->in_len, &out_len);
126 if (IS_ERR(outbuf))
127 return PTR_ERR(outbuf);
128 if (outbuf == inbuf) {
129 /* The driver can re-use inbuf as outbuf */
130 inbuf = NULL;
131 }
132
133 if (copy_to_user(u64_to_user_ptr(cmd->out), outbuf,
134 min(cmd->out_len, out_len)))
135 return -EFAULT;
136
137 cmd->out_len = out_len;
138 return ucmd_respond(ucmd, sizeof(*cmd));
139}
140
141/* On stack memory for the ioctl structs */
142union fwctl_ucmd_buffer {
143 struct fwctl_info info;
144 struct fwctl_rpc rpc;
145};
146
147struct fwctl_ioctl_op {
148 unsigned int size;
149 unsigned int min_size;
150 unsigned int ioctl_num;
151 int (*execute)(struct fwctl_ucmd *ucmd);
152};
153
154#define IOCTL_OP(_ioctl, _fn, _struct, _last) \
155 [_IOC_NR(_ioctl) - FWCTL_CMD_BASE] = { \
156 .size = sizeof(_struct) + \
157 BUILD_BUG_ON_ZERO(sizeof(union fwctl_ucmd_buffer) < \
158 sizeof(_struct)), \
159 .min_size = offsetofend(_struct, _last), \
160 .ioctl_num = _ioctl, \
161 .execute = _fn, \
162 }
163static const struct fwctl_ioctl_op fwctl_ioctl_ops[] = {
164 IOCTL_OP(FWCTL_INFO, fwctl_cmd_info, struct fwctl_info, out_device_data),
165 IOCTL_OP(FWCTL_RPC, fwctl_cmd_rpc, struct fwctl_rpc, out),
166};
167
168static long fwctl_fops_ioctl(struct file *filp, unsigned int cmd,
169 unsigned long arg)
170{
171 struct fwctl_uctx *uctx = filp->private_data;
172 const struct fwctl_ioctl_op *op;
173 struct fwctl_ucmd ucmd = {};
174 union fwctl_ucmd_buffer buf;
175 unsigned int nr;
176 int ret;
177
178 nr = _IOC_NR(cmd);
179 if ((nr - FWCTL_CMD_BASE) >= ARRAY_SIZE(fwctl_ioctl_ops))
180 return -ENOIOCTLCMD;
181
182 op = &fwctl_ioctl_ops[nr - FWCTL_CMD_BASE];
183 if (op->ioctl_num != cmd)
184 return -ENOIOCTLCMD;
185
186 ucmd.uctx = uctx;
187 ucmd.cmd = &buf;
188 ucmd.ubuffer = (void __user *)arg;
189 ret = get_user(ucmd.user_size, (u32 __user *)ucmd.ubuffer);
190 if (ret)
191 return ret;
192
193 if (ucmd.user_size < op->min_size)
194 return -EINVAL;
195
196 ret = copy_struct_from_user(ucmd.cmd, op->size, ucmd.ubuffer,
197 ucmd.user_size);
198 if (ret)
199 return ret;
200
201 guard(rwsem_read)(&uctx->fwctl->registration_lock);
202 if (!uctx->fwctl->ops)
203 return -ENODEV;
204 return op->execute(&ucmd);
205}
206
207static int fwctl_fops_open(struct inode *inode, struct file *filp)
208{
209 struct fwctl_device *fwctl =
210 container_of(inode->i_cdev, struct fwctl_device, cdev);
211 int ret;
212
213 guard(rwsem_read)(&fwctl->registration_lock);
214 if (!fwctl->ops)
215 return -ENODEV;
216
217 struct fwctl_uctx *uctx __free(kfree) =
218 kzalloc(fwctl->ops->uctx_size, GFP_KERNEL_ACCOUNT);
219 if (!uctx)
220 return -ENOMEM;
221
222 uctx->fwctl = fwctl;
223 ret = fwctl->ops->open_uctx(uctx);
224 if (ret)
225 return ret;
226
227 scoped_guard(mutex, &fwctl->uctx_list_lock) {
228 list_add_tail(&uctx->uctx_list_entry, &fwctl->uctx_list);
229 }
230
231 get_device(&fwctl->dev);
232 filp->private_data = no_free_ptr(uctx);
233 return 0;
234}
235
236static void fwctl_destroy_uctx(struct fwctl_uctx *uctx)
237{
238 lockdep_assert_held(&uctx->fwctl->uctx_list_lock);
239 list_del(&uctx->uctx_list_entry);
240 uctx->fwctl->ops->close_uctx(uctx);
241}
242
243static int fwctl_fops_release(struct inode *inode, struct file *filp)
244{
245 struct fwctl_uctx *uctx = filp->private_data;
246 struct fwctl_device *fwctl = uctx->fwctl;
247
248 scoped_guard(rwsem_read, &fwctl->registration_lock) {
249 /*
250 * NULL ops means fwctl_unregister() has already removed the
251 * driver and destroyed the uctx.
252 */
253 if (fwctl->ops) {
254 guard(mutex)(&fwctl->uctx_list_lock);
255 fwctl_destroy_uctx(uctx);
256 }
257 }
258
259 kfree(uctx);
260 fwctl_put(fwctl);
261 return 0;
262}
263
264static const struct file_operations fwctl_fops = {
265 .owner = THIS_MODULE,
266 .open = fwctl_fops_open,
267 .release = fwctl_fops_release,
268 .unlocked_ioctl = fwctl_fops_ioctl,
269};
270
271static void fwctl_device_release(struct device *device)
272{
273 struct fwctl_device *fwctl =
274 container_of(device, struct fwctl_device, dev);
275
276 ida_free(&fwctl_ida, fwctl->dev.devt - fwctl_dev);
277 mutex_destroy(&fwctl->uctx_list_lock);
278 kfree(fwctl);
279}
280
281static char *fwctl_devnode(const struct device *dev, umode_t *mode)
282{
283 return kasprintf(GFP_KERNEL, "fwctl/%s", dev_name(dev));
284}
285
286static struct class fwctl_class = {
287 .name = "fwctl",
288 .dev_release = fwctl_device_release,
289 .devnode = fwctl_devnode,
290};
291
292static struct fwctl_device *
293_alloc_device(struct device *parent, const struct fwctl_ops *ops, size_t size)
294{
295 struct fwctl_device *fwctl __free(kfree) = kzalloc(size, GFP_KERNEL);
296 int devnum;
297
298 if (!fwctl)
299 return NULL;
300
301 devnum = ida_alloc_max(&fwctl_ida, FWCTL_MAX_DEVICES - 1, GFP_KERNEL);
302 if (devnum < 0)
303 return NULL;
304
305 fwctl->dev.devt = fwctl_dev + devnum;
306 fwctl->dev.class = &fwctl_class;
307 fwctl->dev.parent = parent;
308
309 init_rwsem(&fwctl->registration_lock);
310 mutex_init(&fwctl->uctx_list_lock);
311 INIT_LIST_HEAD(&fwctl->uctx_list);
312
313 device_initialize(&fwctl->dev);
314 return_ptr(fwctl);
315}
316
317/* Drivers use the fwctl_alloc_device() wrapper */
318struct fwctl_device *_fwctl_alloc_device(struct device *parent,
319 const struct fwctl_ops *ops,
320 size_t size)
321{
322 struct fwctl_device *fwctl __free(fwctl) =
323 _alloc_device(parent, ops, size);
324
325 if (!fwctl)
326 return NULL;
327
328 cdev_init(&fwctl->cdev, &fwctl_fops);
329 /*
330 * The driver module is protected by fwctl_register/unregister(),
331 * unregister won't complete until we are done with the driver's module.
332 */
333 fwctl->cdev.owner = THIS_MODULE;
334
335 if (dev_set_name(&fwctl->dev, "fwctl%d", fwctl->dev.devt - fwctl_dev))
336 return NULL;
337
338 fwctl->ops = ops;
339 return_ptr(fwctl);
340}
341EXPORT_SYMBOL_NS_GPL(_fwctl_alloc_device, "FWCTL");
342
343/**
344 * fwctl_register - Register a new device to the subsystem
345 * @fwctl: Previously allocated fwctl_device
346 *
347 * On return the device is visible through sysfs and /dev, driver ops may be
348 * called.
349 */
350int fwctl_register(struct fwctl_device *fwctl)
351{
352 return cdev_device_add(&fwctl->cdev, &fwctl->dev);
353}
354EXPORT_SYMBOL_NS_GPL(fwctl_register, "FWCTL");
355
356/**
357 * fwctl_unregister - Unregister a device from the subsystem
358 * @fwctl: Previously allocated and registered fwctl_device
359 *
360 * Undoes fwctl_register(). On return no driver ops will be called. The
361 * caller must still call fwctl_put() to free the fwctl.
362 *
363 * Unregister will return even if userspace still has file descriptors open.
364 * This will call ops->close_uctx() on any open FDs and after return no driver
365 * op will be called. The FDs remain open but all fops will return -ENODEV.
366 *
367 * The design of fwctl allows this sort of disassociation of the driver from the
368 * subsystem primarily by keeping memory allocations owned by the core subsytem.
369 * The fwctl_device and fwctl_uctx can both be freed without requiring a driver
370 * callback. This allows the module to remain unlocked while FDs are open.
371 */
372void fwctl_unregister(struct fwctl_device *fwctl)
373{
374 struct fwctl_uctx *uctx;
375
376 cdev_device_del(&fwctl->cdev, &fwctl->dev);
377
378 /* Disable and free the driver's resources for any still open FDs. */
379 guard(rwsem_write)(&fwctl->registration_lock);
380 guard(mutex)(&fwctl->uctx_list_lock);
381 while ((uctx = list_first_entry_or_null(&fwctl->uctx_list,
382 struct fwctl_uctx,
383 uctx_list_entry)))
384 fwctl_destroy_uctx(uctx);
385
386 /*
387 * The driver module may unload after this returns, the op pointer will
388 * not be valid.
389 */
390 fwctl->ops = NULL;
391}
392EXPORT_SYMBOL_NS_GPL(fwctl_unregister, "FWCTL");
393
394static int __init fwctl_init(void)
395{
396 int ret;
397
398 ret = alloc_chrdev_region(&fwctl_dev, 0, FWCTL_MAX_DEVICES, "fwctl");
399 if (ret)
400 return ret;
401
402 ret = class_register(&fwctl_class);
403 if (ret)
404 goto err_chrdev;
405 return 0;
406
407err_chrdev:
408 unregister_chrdev_region(fwctl_dev, FWCTL_MAX_DEVICES);
409 return ret;
410}
411
412static void __exit fwctl_exit(void)
413{
414 class_unregister(&fwctl_class);
415 unregister_chrdev_region(fwctl_dev, FWCTL_MAX_DEVICES);
416}
417
418subsys_initcall(fwctl_init);
419module_exit(fwctl_exit);
420MODULE_DESCRIPTION("fwctl device firmware access framework");
421MODULE_LICENSE("GPL");