drivers/s390/char/hmcdrv_ftp.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *    HMC Drive FTP Services
   4  *
   5  *    Copyright IBM Corp. 2013
   6  *    Author(s): Ralf Hoppe (rhoppe@de.ibm.com)
   7  */
   8
   9 #define KMSG_COMPONENT "hmcdrv"
  10 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  11
  12 #include <linux/kernel.h>
  13 #include <linux/slab.h>
  14 #include <linux/uaccess.h>
  15 #include <linux/export.h>
  16
  17 #include <linux/ctype.h>
  18 #include <linux/crc16.h>
  19
  20 #include "hmcdrv_ftp.h"
  21 #include "hmcdrv_cache.h"
  22 #include "sclp_ftp.h"
  23 #include "diag_ftp.h"
  24
  25 /**
  26  * struct hmcdrv_ftp_ops - HMC drive FTP operations
  27  * @startup: startup function
  28  * @shutdown: shutdown function
  29  * @cmd: FTP transfer function
  30  */
  31 struct hmcdrv_ftp_ops {
  32         int (*startup)(void);
  33         void (*shutdown)(void);
  34         ssize_t (*transfer)(const struct hmcdrv_ftp_cmdspec *ftp,
  35                             size_t *fsize);
  36 };
  37
  38 static enum hmcdrv_ftp_cmdid hmcdrv_ftp_cmd_getid(const char *cmd, int len);
  39 static int hmcdrv_ftp_parse(char *cmd, struct hmcdrv_ftp_cmdspec *ftp);
  40
  41 static const struct hmcdrv_ftp_ops *hmcdrv_ftp_funcs; /* current operations */
  42 static DEFINE_MUTEX(hmcdrv_ftp_mutex); /* mutex for hmcdrv_ftp_funcs */
  43 static unsigned hmcdrv_ftp_refcnt; /* start/shutdown reference counter */
  44
  45 /**
  46  * hmcdrv_ftp_cmd_getid() - determine FTP command ID from a command string
  47  * @cmd: FTP command string (NOT zero-terminated)
  48  * @len: length of FTP command string in @cmd
  49  */
  50 static enum hmcdrv_ftp_cmdid hmcdrv_ftp_cmd_getid(const char *cmd, int len)
  51 {
  52         /* HMC FTP command descriptor */
  53         struct hmcdrv_ftp_cmd_desc {
  54                 const char *str;           /* command string */
  55                 enum hmcdrv_ftp_cmdid cmd; /* associated command as enum */
  56         };
  57
  58         /* Description of all HMC drive FTP commands
  59          *
  60          * Notes:
  61          * 1. Array size should be a prime number.
  62          * 2. Do not change the order of commands in table (because the
  63          *    index is determined by CRC % ARRAY_SIZE).
  64          * 3. Original command 'nlist' was renamed, else the CRC would
  65          *    collide with 'append' (see point 2).
  66          */
  67         static const struct hmcdrv_ftp_cmd_desc ftpcmds[7] = {
  68
  69                 {.str = "get", /* [0] get (CRC = 0x68eb) */
  70                  .cmd = HMCDRV_FTP_GET},
  71                 {.str = "dir", /* [1] dir (CRC = 0x6a9e) */
  72                  .cmd = HMCDRV_FTP_DIR},
  73                 {.str = "delete", /* [2] delete (CRC = 0x53ae) */
  74                  .cmd = HMCDRV_FTP_DELETE},
  75                 {.str = "nls", /* [3] nls (CRC = 0xf87c) */
  76                  .cmd = HMCDRV_FTP_NLIST},
  77                 {.str = "put", /* [4] put (CRC = 0xac56) */
  78                  .cmd = HMCDRV_FTP_PUT},
  79                 {.str = "append", /* [5] append (CRC = 0xf56e) */
  80                  .cmd = HMCDRV_FTP_APPEND},
  81                 {.str = NULL} /* [6] unused */
  82         };
  83
  84         const struct hmcdrv_ftp_cmd_desc *pdesc;
  85
  86         u16 crc = 0xffffU;
  87
  88         if (len == 0)
  89                 return HMCDRV_FTP_NOOP; /* error indiactor */
  90
  91         crc = crc16(crc, cmd, len);
  92         pdesc = ftpcmds + (crc % ARRAY_SIZE(ftpcmds));
  93         pr_debug("FTP command '%s' has CRC 0x%04x, at table pos. %lu\n",
  94                  cmd, crc, (crc % ARRAY_SIZE(ftpcmds)));
  95
  96         if (!pdesc->str || strncmp(pdesc->str, cmd, len))
  97                 return HMCDRV_FTP_NOOP;
  98
  99         pr_debug("FTP command '%s' found, with ID %d\n",
 100                  pdesc->str, pdesc->cmd);
 101
 102         return pdesc->cmd;
 103 }
 104
 105 /**
 106  * hmcdrv_ftp_parse() - HMC drive FTP command parser
 107  * @cmd: FTP command string "<cmd> <filename>"
 108  * @ftp: Pointer to FTP command specification buffer (output)
 109  *
 110  * Return: 0 on success, else a (negative) error code
 111  */
 112 static int hmcdrv_ftp_parse(char *cmd, struct hmcdrv_ftp_cmdspec *ftp)
 113 {
 114         char *start;
 115         int argc = 0;
 116
 117         ftp->id = HMCDRV_FTP_NOOP;
 118         ftp->fname = NULL;
 119
 120         while (*cmd != '\0') {
 121
 122                 while (isspace(*cmd))
 123                         ++cmd;
 124
 125                 if (*cmd == '\0')
 126                         break;
 127
 128                 start = cmd;
 129
 130                 switch (argc) {
 131                 case 0: /* 1st argument (FTP command) */
 132                         while ((*cmd != '\0') && !isspace(*cmd))
 133                                 ++cmd;
 134                         ftp->id = hmcdrv_ftp_cmd_getid(start, cmd - start);
 135                         break;
 136                 case 1: /* 2nd / last argument (rest of line) */
 137                         while ((*cmd != '\0') && !iscntrl(*cmd))
 138                                 ++cmd;
 139                         ftp->fname = start;
 140                         /* fall through */
 141                 default:
 142                         *cmd = '\0';
 143                         break;
 144                 } /* switch */
 145
 146                 ++argc;
 147         } /* while */
 148
 149         if (!ftp->fname || (ftp->id == HMCDRV_FTP_NOOP))
 150                 return -EINVAL;
 151
 152         return 0;
 153 }
 154
 155 /**
 156  * hmcdrv_ftp_do() - perform a HMC drive FTP, with data from kernel-space
 157  * @ftp: pointer to FTP command specification
 158  *
 159  * Return: number of bytes read/written or a negative error code
 160  */
 161 ssize_t hmcdrv_ftp_do(const struct hmcdrv_ftp_cmdspec *ftp)
 162 {
 163         ssize_t len;
 164
 165         mutex_lock(&hmcdrv_ftp_mutex);
 166
 167         if (hmcdrv_ftp_funcs && hmcdrv_ftp_refcnt) {
 168                 pr_debug("starting transfer, cmd %d for '%s' at %lld with %zd bytes\n",
 169                          ftp->id, ftp->fname, (long long) ftp->ofs, ftp->len);
 170                 len = hmcdrv_cache_cmd(ftp, hmcdrv_ftp_funcs->transfer);
 171         } else {
 172                 len = -ENXIO;
 173         }
 174
 175         mutex_unlock(&hmcdrv_ftp_mutex);
 176         return len;
 177 }
 178 EXPORT_SYMBOL(hmcdrv_ftp_do);
 179
 180 /**
 181  * hmcdrv_ftp_probe() - probe for the HMC drive FTP service
 182  *
 183  * Return: 0 if service is available, else an (negative) error code
 184  */
 185 int hmcdrv_ftp_probe(void)
 186 {
 187         int rc;
 188
 189         struct hmcdrv_ftp_cmdspec ftp = {
 190                 .id = HMCDRV_FTP_NOOP,
 191                 .ofs = 0,
 192                 .fname = "",
 193                 .len = PAGE_SIZE
 194         };
 195
 196         ftp.buf = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
 197
 198         if (!ftp.buf)
 199                 return -ENOMEM;
 200
 201         rc = hmcdrv_ftp_startup();
 202
 203         if (rc)
 204                 goto out;
 205
 206         rc = hmcdrv_ftp_do(&ftp);
 207         hmcdrv_ftp_shutdown();
 208
 209         switch (rc) {
 210         case -ENOENT: /* no such file/media or currently busy, */
 211         case -EBUSY:  /* but service seems to be available */
 212                 rc = 0;
 213                 break;
 214         default: /* leave 'rc' as it is for [0, -EPERM, -E...] */
 215                 if (rc > 0)
 216                         rc = 0; /* clear length (success) */
 217                 break;
 218         } /* switch */
 219 out:
 220         free_page((unsigned long) ftp.buf);
 221         return rc;
 222 }
 223 EXPORT_SYMBOL(hmcdrv_ftp_probe);
 224
 225 /**
 226  * hmcdrv_ftp_cmd() - Perform a HMC drive FTP, with data from user-space
 227  *
 228  * @cmd: FTP command string "<cmd> <filename>"
 229  * @offset: file position to read/write
 230  * @buf: user-space buffer for read/written directory/file
 231  * @len: size of @buf (read/dir) or number of bytes to write
 232  *
 233  * This function must not be called before hmcdrv_ftp_startup() was called.
 234  *
 235  * Return: number of bytes read/written or a negative error code
 236  */
 237 ssize_t hmcdrv_ftp_cmd(char __kernel *cmd, loff_t offset,
 238                        char __user *buf, size_t len)
 239 {
 240         int order;
 241
 242         struct hmcdrv_ftp_cmdspec ftp = {.len = len, .ofs = offset};
 243         ssize_t retlen = hmcdrv_ftp_parse(cmd, &ftp);
 244
 245         if (retlen)
 246                 return retlen;
 247
 248         order = get_order(ftp.len);
 249         ftp.buf = (void *) __get_free_pages(GFP_KERNEL | GFP_DMA, order);
 250
 251         if (!ftp.buf)
 252                 return -ENOMEM;
 253
 254         switch (ftp.id) {
 255         case HMCDRV_FTP_DIR:
 256         case HMCDRV_FTP_NLIST:
 257         case HMCDRV_FTP_GET:
 258                 retlen = hmcdrv_ftp_do(&ftp);
 259
 260                 if ((retlen >= 0) &&
 261                     copy_to_user(buf, ftp.buf, retlen))
 262                         retlen = -EFAULT;
 263                 break;
 264
 265         case HMCDRV_FTP_PUT:
 266         case HMCDRV_FTP_APPEND:
 267                 if (!copy_from_user(ftp.buf, buf, ftp.len))
 268                         retlen = hmcdrv_ftp_do(&ftp);
 269                 else
 270                         retlen = -EFAULT;
 271                 break;
 272
 273         case HMCDRV_FTP_DELETE:
 274                 retlen = hmcdrv_ftp_do(&ftp);
 275                 break;
 276
 277         default:
 278                 retlen = -EOPNOTSUPP;
 279                 break;
 280         }
 281
 282         free_pages((unsigned long) ftp.buf, order);
 283         return retlen;
 284 }
 285
 286 /**
 287  * hmcdrv_ftp_startup() - startup of HMC drive FTP functionality for a
 288  * dedicated (owner) instance
 289  *
 290  * Return: 0 on success, else an (negative) error code
 291  */
 292 int hmcdrv_ftp_startup(void)
 293 {
 294         static const struct hmcdrv_ftp_ops hmcdrv_ftp_zvm = {
 295                 .startup = diag_ftp_startup,
 296                 .shutdown = diag_ftp_shutdown,
 297                 .transfer = diag_ftp_cmd
 298         };
 299
 300         static const struct hmcdrv_ftp_ops hmcdrv_ftp_lpar = {
 301                 .startup = sclp_ftp_startup,
 302                 .shutdown = sclp_ftp_shutdown,
 303                 .transfer = sclp_ftp_cmd
 304         };
 305
 306         int rc = 0;
 307
 308         mutex_lock(&hmcdrv_ftp_mutex); /* block transfers while start-up */
 309
 310         if (hmcdrv_ftp_refcnt == 0) {
 311                 if (MACHINE_IS_VM)
 312                         hmcdrv_ftp_funcs = &hmcdrv_ftp_zvm;
 313                 else if (MACHINE_IS_LPAR || MACHINE_IS_KVM)
 314                         hmcdrv_ftp_funcs = &hmcdrv_ftp_lpar;
 315                 else
 316                         rc = -EOPNOTSUPP;
 317
 318                 if (hmcdrv_ftp_funcs)
 319                         rc = hmcdrv_ftp_funcs->startup();
 320         }
 321
 322         if (!rc)
 323                 ++hmcdrv_ftp_refcnt;
 324
 325         mutex_unlock(&hmcdrv_ftp_mutex);
 326         return rc;
 327 }
 328 EXPORT_SYMBOL(hmcdrv_ftp_startup);
 329
 330 /**
 331  * hmcdrv_ftp_shutdown() - shutdown of HMC drive FTP functionality for a
 332  * dedicated (owner) instance
 333  */
 334 void hmcdrv_ftp_shutdown(void)
 335 {
 336         mutex_lock(&hmcdrv_ftp_mutex);
 337         --hmcdrv_ftp_refcnt;
 338
 339         if ((hmcdrv_ftp_refcnt == 0) && hmcdrv_ftp_funcs)
 340                 hmcdrv_ftp_funcs->shutdown();
 341
 342         mutex_unlock(&hmcdrv_ftp_mutex);
 343 }
 344 EXPORT_SYMBOL(hmcdrv_ftp_shutdown);