drivers/firmware/efi/capsule-loader.c

   1 /*
   2  * EFI capsule loader driver.
   3  *
   4  * Copyright 2015 Intel Corporation
   5  *
   6  * This file is part of the Linux kernel, and is made available under
   7  * the terms of the GNU General Public License version 2.
   8  */
   9
  10 #define pr_fmt(fmt) "efi: " fmt
  11
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/miscdevice.h>
  15 #include <linux/highmem.h>
  16 #include <linux/slab.h>
  17 #include <linux/mutex.h>
  18 #include <linux/efi.h>
  19
  20 #define NO_FURTHER_WRITE_ACTION -1
  21
  22 struct capsule_info {
  23         bool            header_obtained;
  24         int             reset_type;
  25         long            index;
  26         size_t          count;
  27         size_t          total_size;
  28         struct page     **pages;
  29         size_t          page_bytes_remain;
  30 };
  31
  32 /**
  33  * efi_free_all_buff_pages - free all previous allocated buffer pages
  34  * @cap_info: pointer to current instance of capsule_info structure
  35  *
  36  *      In addition to freeing buffer pages, it flags NO_FURTHER_WRITE_ACTION
  37  *      to cease processing data in subsequent write(2) calls until close(2)
  38  *      is called.
  39  **/
  40 static void efi_free_all_buff_pages(struct capsule_info *cap_info)
  41 {
  42         while (cap_info->index > 0)
  43                 __free_page(cap_info->pages[--cap_info->index]);
  44
  45         cap_info->index = NO_FURTHER_WRITE_ACTION;
  46 }
  47
  48 /**
  49  * efi_capsule_setup_info - obtain the efi capsule header in the binary and
  50  *                          setup capsule_info structure
  51  * @cap_info: pointer to current instance of capsule_info structure
  52  * @kbuff: a mapped first page buffer pointer
  53  * @hdr_bytes: the total received number of bytes for efi header
  54  **/
  55 static ssize_t efi_capsule_setup_info(struct capsule_info *cap_info,
  56                                       void *kbuff, size_t hdr_bytes)
  57 {
  58         efi_capsule_header_t *cap_hdr;
  59         size_t pages_needed;
  60         int ret;
  61         void *temp_page;
  62
  63         /* Only process data block that is larger than efi header size */
  64         if (hdr_bytes < sizeof(efi_capsule_header_t))
  65                 return 0;
  66
  67         /* Reset back to the correct offset of header */
  68         cap_hdr = kbuff - cap_info->count;
  69         pages_needed = ALIGN(cap_hdr->imagesize, PAGE_SIZE) >> PAGE_SHIFT;
  70
  71         if (pages_needed == 0) {
  72                 pr_err("%s: pages count invalid\n", __func__);
  73                 return -EINVAL;
  74         }
  75
  76         /* Check if the capsule binary supported */
  77         ret = efi_capsule_supported(cap_hdr->guid, cap_hdr->flags,
  78                                     cap_hdr->imagesize,
  79                                     &cap_info->reset_type);
  80         if (ret) {
  81                 pr_err("%s: efi_capsule_supported() failed\n",
  82                        __func__);
  83                 return ret;
  84         }
  85
  86         cap_info->total_size = cap_hdr->imagesize;
  87         temp_page = krealloc(cap_info->pages,
  88                              pages_needed * sizeof(void *),
  89                              GFP_KERNEL | __GFP_ZERO);
  90         if (!temp_page) {
  91                 pr_debug("%s: krealloc() failed\n", __func__);
  92                 return -ENOMEM;
  93         }
  94
  95         cap_info->pages = temp_page;
  96         cap_info->header_obtained = true;
  97
  98         return 0;
  99 }
 100
 101 /**
 102  * efi_capsule_submit_update - invoke the efi_capsule_update API once binary
 103  *                             upload done
 104  * @cap_info: pointer to current instance of capsule_info structure
 105  **/
 106 static ssize_t efi_capsule_submit_update(struct capsule_info *cap_info)
 107 {
 108         int ret;
 109         void *cap_hdr_temp;
 110
 111         cap_hdr_temp = kmap(cap_info->pages[0]);
 112         if (!cap_hdr_temp) {
 113                 pr_debug("%s: kmap() failed\n", __func__);
 114                 return -EFAULT;
 115         }
 116
 117         ret = efi_capsule_update(cap_hdr_temp, cap_info->pages);
 118         kunmap(cap_info->pages[0]);
 119         if (ret) {
 120                 pr_err("%s: efi_capsule_update() failed\n", __func__);
 121                 return ret;
 122         }
 123
 124         /* Indicate capsule binary uploading is done */
 125         cap_info->index = NO_FURTHER_WRITE_ACTION;
 126         pr_info("%s: Successfully upload capsule file with reboot type '%s'\n",
 127                 __func__, !cap_info->reset_type ? "RESET_COLD" :
 128                 cap_info->reset_type == 1 ? "RESET_WARM" :
 129                 "RESET_SHUTDOWN");
 130         return 0;
 131 }
 132
 133 /**
 134  * efi_capsule_write - store the capsule binary and pass it to
 135  *                     efi_capsule_update() API
 136  * @file: file pointer
 137  * @buff: buffer pointer
 138  * @count: number of bytes in @buff
 139  * @offp: not used
 140  *
 141  *      Expectation:
 142  *      - A user space tool should start at the beginning of capsule binary and
 143  *        pass data in sequentially.
 144  *      - Users should close and re-open this file note in order to upload more
 145  *        capsules.
 146  *      - After an error returned, user should close the file and restart the
 147  *        operation for the next try otherwise -EIO will be returned until the
 148  *        file is closed.
 149  *      - An EFI capsule header must be located at the beginning of capsule
 150  *        binary file and passed in as first block data of write operation.
 151  **/
 152 static ssize_t efi_capsule_write(struct file *file, const char __user *buff,
 153                                  size_t count, loff_t *offp)
 154 {
 155         int ret = 0;
 156         struct capsule_info *cap_info = file->private_data;
 157         struct page *page;
 158         void *kbuff = NULL;
 159         size_t write_byte;
 160
 161         if (count == 0)
 162                 return 0;
 163
 164         /* Return error while NO_FURTHER_WRITE_ACTION is flagged */
 165         if (cap_info->index < 0)
 166                 return -EIO;
 167
 168         /* Only alloc a new page when previous page is full */
 169         if (!cap_info->page_bytes_remain) {
 170                 page = alloc_page(GFP_KERNEL);
 171                 if (!page) {
 172                         pr_debug("%s: alloc_page() failed\n", __func__);
 173                         ret = -ENOMEM;
 174                         goto failed;
 175                 }
 176
 177                 cap_info->pages[cap_info->index++] = page;
 178                 cap_info->page_bytes_remain = PAGE_SIZE;
 179         }
 180
 181         page = cap_info->pages[cap_info->index - 1];
 182
 183         kbuff = kmap(page);
 184         if (!kbuff) {
 185                 pr_debug("%s: kmap() failed\n", __func__);
 186                 ret = -EFAULT;
 187                 goto failed;
 188         }
 189         kbuff += PAGE_SIZE - cap_info->page_bytes_remain;
 190
 191         /* Copy capsule binary data from user space to kernel space buffer */
 192         write_byte = min_t(size_t, count, cap_info->page_bytes_remain);
 193         if (copy_from_user(kbuff, buff, write_byte)) {
 194                 pr_debug("%s: copy_from_user() failed\n", __func__);
 195                 ret = -EFAULT;
 196                 goto fail_unmap;
 197         }
 198         cap_info->page_bytes_remain -= write_byte;
 199
 200         /* Setup capsule binary info structure */
 201         if (!cap_info->header_obtained) {
 202                 ret = efi_capsule_setup_info(cap_info, kbuff,
 203                                              cap_info->count + write_byte);
 204                 if (ret)
 205                         goto fail_unmap;
 206         }
 207
 208         cap_info->count += write_byte;
 209         kunmap(page);
 210
 211         /* Submit the full binary to efi_capsule_update() API */
 212         if (cap_info->header_obtained &&
 213             cap_info->count >= cap_info->total_size) {
 214                 if (cap_info->count > cap_info->total_size) {
 215                         pr_err("%s: upload size exceeded header defined size\n",
 216                                __func__);
 217                         ret = -EINVAL;
 218                         goto failed;
 219                 }
 220
 221                 ret = efi_capsule_submit_update(cap_info);
 222                 if (ret)
 223                         goto failed;
 224         }
 225
 226         return write_byte;
 227
 228 fail_unmap:
 229         kunmap(page);
 230 failed:
 231         efi_free_all_buff_pages(cap_info);
 232         return ret;
 233 }
 234
 235 /**
 236  * efi_capsule_flush - called by file close or file flush
 237  * @file: file pointer
 238  * @id: not used
 239  *
 240  *      If a capsule is being partially uploaded then calling this function
 241  *      will be treated as upload termination and will free those completed
 242  *      buffer pages and -ECANCELED will be returned.
 243  **/
 244 static int efi_capsule_flush(struct file *file, fl_owner_t id)
 245 {
 246         int ret = 0;
 247         struct capsule_info *cap_info = file->private_data;
 248
 249         if (cap_info->index > 0) {
 250                 pr_err("%s: capsule upload not complete\n", __func__);
 251                 efi_free_all_buff_pages(cap_info);
 252                 ret = -ECANCELED;
 253         }
 254
 255         return ret;
 256 }
 257
 258 /**
 259  * efi_capsule_release - called by file close
 260  * @inode: not used
 261  * @file: file pointer
 262  *
 263  *      We will not free successfully submitted pages since efi update
 264  *      requires data to be maintained across system reboot.
 265  **/
 266 static int efi_capsule_release(struct inode *inode, struct file *file)
 267 {
 268         struct capsule_info *cap_info = file->private_data;
 269
 270         kfree(cap_info->pages);
 271         kfree(file->private_data);
 272         file->private_data = NULL;
 273         return 0;
 274 }
 275
 276 /**
 277  * efi_capsule_open - called by file open
 278  * @inode: not used
 279  * @file: file pointer
 280  *
 281  *      Will allocate each capsule_info memory for each file open call.
 282  *      This provided the capability to support multiple file open feature
 283  *      where user is not needed to wait for others to finish in order to
 284  *      upload their capsule binary.
 285  **/
 286 static int efi_capsule_open(struct inode *inode, struct file *file)
 287 {
 288         struct capsule_info *cap_info;
 289
 290         cap_info = kzalloc(sizeof(*cap_info), GFP_KERNEL);
 291         if (!cap_info)
 292                 return -ENOMEM;
 293
 294         cap_info->pages = kzalloc(sizeof(void *), GFP_KERNEL);
 295         if (!cap_info->pages) {
 296                 kfree(cap_info);
 297                 return -ENOMEM;
 298         }
 299
 300         file->private_data = cap_info;
 301
 302         return 0;
 303 }
 304
 305 static const struct file_operations efi_capsule_fops = {
 306         .owner = THIS_MODULE,
 307         .open = efi_capsule_open,
 308         .write = efi_capsule_write,
 309         .flush = efi_capsule_flush,
 310         .release = efi_capsule_release,
 311         .llseek = no_llseek,
 312 };
 313
 314 static struct miscdevice efi_capsule_misc = {
 315         .minor = MISC_DYNAMIC_MINOR,
 316         .name = "efi_capsule_loader",
 317         .fops = &efi_capsule_fops,
 318 };
 319
 320 static int __init efi_capsule_loader_init(void)
 321 {
 322         int ret;
 323
 324         if (!efi_enabled(EFI_RUNTIME_SERVICES))
 325                 return -ENODEV;
 326
 327         ret = misc_register(&efi_capsule_misc);
 328         if (ret)
 329                 pr_err("%s: Failed to register misc char file note\n",
 330                        __func__);
 331
 332         return ret;
 333 }
 334 module_init(efi_capsule_loader_init);
 335
 336 static void __exit efi_capsule_loader_exit(void)
 337 {
 338         misc_deregister(&efi_capsule_misc);
 339 }
 340 module_exit(efi_capsule_loader_exit);
 341
 342 MODULE_DESCRIPTION("EFI capsule firmware binary loader");
 343 MODULE_LICENSE("GPL v2");