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 pr_fmt(fmt) "hmcdrv: " fmt
10
11#include <linux/kernel.h>
12#include <linux/slab.h>
13#include <linux/uaccess.h>
14#include <linux/export.h>
15
16#include <linux/ctype.h>
17#include <linux/crc16.h>
18
19#include <asm/machine.h>
20
21#include "hmcdrv_ftp.h"
22#include "hmcdrv_cache.h"
23#include "sclp_ftp.h"
24#include "diag_ftp.h"
25
26/**
27 * struct hmcdrv_ftp_ops - HMC drive FTP operations
28 * @startup: startup function
29 * @shutdown: shutdown function
30 * @transfer: FTP transfer function
31 */
32struct hmcdrv_ftp_ops {
33 int (*startup)(void);
34 void (*shutdown)(void);
35 ssize_t (*transfer)(const struct hmcdrv_ftp_cmdspec *ftp,
36 size_t *fsize);
37};
38
39static enum hmcdrv_ftp_cmdid hmcdrv_ftp_cmd_getid(const char *cmd, int len);
40static int hmcdrv_ftp_parse(char *cmd, struct hmcdrv_ftp_cmdspec *ftp);
41
42static const struct hmcdrv_ftp_ops *hmcdrv_ftp_funcs; /* current operations */
43static DEFINE_MUTEX(hmcdrv_ftp_mutex); /* mutex for hmcdrv_ftp_funcs */
44static unsigned hmcdrv_ftp_refcnt; /* start/shutdown reference counter */
45
46/**
47 * hmcdrv_ftp_cmd_getid() - determine FTP command ID from a command string
48 * @cmd: FTP command string (NOT zero-terminated)
49 * @len: length of FTP command string in @cmd
50 */
51static enum hmcdrv_ftp_cmdid hmcdrv_ftp_cmd_getid(const char *cmd, int len)
52{
53 /* HMC FTP command descriptor */
54 struct hmcdrv_ftp_cmd_desc {
55 const char *str; /* command string */
56 enum hmcdrv_ftp_cmdid cmd; /* associated command as enum */
57 };
58
59 /* Description of all HMC drive FTP commands
60 *
61 * Notes:
62 * 1. Array size should be a prime number.
63 * 2. Do not change the order of commands in table (because the
64 * index is determined by CRC % ARRAY_SIZE).
65 * 3. Original command 'nlist' was renamed, else the CRC would
66 * collide with 'append' (see point 2).
67 */
68 static const struct hmcdrv_ftp_cmd_desc ftpcmds[7] = {
69
70 {.str = "get", /* [0] get (CRC = 0x68eb) */
71 .cmd = HMCDRV_FTP_GET},
72 {.str = "dir", /* [1] dir (CRC = 0x6a9e) */
73 .cmd = HMCDRV_FTP_DIR},
74 {.str = "delete", /* [2] delete (CRC = 0x53ae) */
75 .cmd = HMCDRV_FTP_DELETE},
76 {.str = "nls", /* [3] nls (CRC = 0xf87c) */
77 .cmd = HMCDRV_FTP_NLIST},
78 {.str = "put", /* [4] put (CRC = 0xac56) */
79 .cmd = HMCDRV_FTP_PUT},
80 {.str = "append", /* [5] append (CRC = 0xf56e) */
81 .cmd = HMCDRV_FTP_APPEND},
82 {.str = NULL} /* [6] unused */
83 };
84
85 const struct hmcdrv_ftp_cmd_desc *pdesc;
86
87 u16 crc = 0xffffU;
88
89 if (len == 0)
90 return HMCDRV_FTP_NOOP; /* error indiactor */
91
92 crc = crc16(crc, p: cmd, len);
93 pdesc = ftpcmds + (crc % ARRAY_SIZE(ftpcmds));
94 pr_debug("FTP command '%s' has CRC 0x%04x, at table pos. %lu\n",
95 cmd, crc, (crc % ARRAY_SIZE(ftpcmds)));
96
97 if (!pdesc->str || strncmp(pdesc->str, cmd, len))
98 return HMCDRV_FTP_NOOP;
99
100 pr_debug("FTP command '%s' found, with ID %d\n",
101 pdesc->str, pdesc->cmd);
102
103 return pdesc->cmd;
104}
105
106/**
107 * hmcdrv_ftp_parse() - HMC drive FTP command parser
108 * @cmd: FTP command string "<cmd> <filename>"
109 * @ftp: Pointer to FTP command specification buffer (output)
110 *
111 * Return: 0 on success, else a (negative) error code
112 */
113static int hmcdrv_ftp_parse(char *cmd, struct hmcdrv_ftp_cmdspec *ftp)
114{
115 char *start;
116 int argc = 0;
117
118 ftp->id = HMCDRV_FTP_NOOP;
119 ftp->fname = NULL;
120
121 while (*cmd != '\0') {
122
123 while (isspace(*cmd))
124 ++cmd;
125
126 if (*cmd == '\0')
127 break;
128
129 start = cmd;
130
131 switch (argc) {
132 case 0: /* 1st argument (FTP command) */
133 while ((*cmd != '\0') && !isspace(*cmd))
134 ++cmd;
135 ftp->id = hmcdrv_ftp_cmd_getid(cmd: start, len: cmd - start);
136 break;
137 case 1: /* 2nd / last argument (rest of line) */
138 while ((*cmd != '\0') && !iscntrl(*cmd))
139 ++cmd;
140 ftp->fname = start;
141 fallthrough;
142 default:
143 *cmd = '\0';
144 break;
145 } /* switch */
146
147 ++argc;
148 } /* while */
149
150 if (!ftp->fname || (ftp->id == HMCDRV_FTP_NOOP))
151 return -EINVAL;
152
153 return 0;
154}
155
156/**
157 * hmcdrv_ftp_do() - perform a HMC drive FTP, with data from kernel-space
158 * @ftp: pointer to FTP command specification
159 *
160 * Return: number of bytes read/written or a negative error code
161 */
162ssize_t hmcdrv_ftp_do(const struct hmcdrv_ftp_cmdspec *ftp)
163{
164 ssize_t len;
165
166 mutex_lock(&hmcdrv_ftp_mutex);
167
168 if (hmcdrv_ftp_funcs && hmcdrv_ftp_refcnt) {
169 pr_debug("starting transfer, cmd %d for '%s' at %lld with %zd bytes\n",
170 ftp->id, ftp->fname, (long long) ftp->ofs, ftp->len);
171 len = hmcdrv_cache_cmd(ftp, func: hmcdrv_ftp_funcs->transfer);
172 } else {
173 len = -ENXIO;
174 }
175
176 mutex_unlock(lock: &hmcdrv_ftp_mutex);
177 return len;
178}
179EXPORT_SYMBOL(hmcdrv_ftp_do);
180
181/**
182 * hmcdrv_ftp_probe() - probe for the HMC drive FTP service
183 *
184 * Return: 0 if service is available, else an (negative) error code
185 */
186int hmcdrv_ftp_probe(void)
187{
188 int rc;
189
190 struct hmcdrv_ftp_cmdspec ftp = {
191 .id = HMCDRV_FTP_NOOP,
192 .ofs = 0,
193 .fname = "",
194 .len = PAGE_SIZE
195 };
196
197 ftp.buf = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
198
199 if (!ftp.buf)
200 return -ENOMEM;
201
202 rc = hmcdrv_ftp_startup();
203
204 if (rc)
205 goto out;
206
207 rc = hmcdrv_ftp_do(&ftp);
208 hmcdrv_ftp_shutdown();
209
210 switch (rc) {
211 case -ENOENT: /* no such file/media or currently busy, */
212 case -EBUSY: /* but service seems to be available */
213 rc = 0;
214 break;
215 default: /* leave 'rc' as it is for [0, -EPERM, -E...] */
216 if (rc > 0)
217 rc = 0; /* clear length (success) */
218 break;
219 } /* switch */
220out:
221 free_page((unsigned long) ftp.buf);
222 return rc;
223}
224EXPORT_SYMBOL(hmcdrv_ftp_probe);
225
226/**
227 * hmcdrv_ftp_cmd() - Perform a HMC drive FTP, with data from user-space
228 *
229 * @cmd: FTP command string "<cmd> <filename>"
230 * @offset: file position to read/write
231 * @buf: user-space buffer for read/written directory/file
232 * @len: size of @buf (read/dir) or number of bytes to write
233 *
234 * This function must not be called before hmcdrv_ftp_startup() was called.
235 *
236 * Return: number of bytes read/written or a negative error code
237 */
238ssize_t hmcdrv_ftp_cmd(char __kernel *cmd, loff_t offset,
239 char __user *buf, size_t len)
240{
241 int order;
242
243 struct hmcdrv_ftp_cmdspec ftp = {.len = len, .ofs = offset};
244 ssize_t retlen = hmcdrv_ftp_parse(cmd, ftp: &ftp);
245
246 if (retlen)
247 return retlen;
248
249 order = get_order(size: ftp.len);
250 ftp.buf = (void *) __get_free_pages(GFP_KERNEL | GFP_DMA, order);
251
252 if (!ftp.buf)
253 return -ENOMEM;
254
255 switch (ftp.id) {
256 case HMCDRV_FTP_DIR:
257 case HMCDRV_FTP_NLIST:
258 case HMCDRV_FTP_GET:
259 retlen = hmcdrv_ftp_do(&ftp);
260
261 if ((retlen >= 0) &&
262 copy_to_user(to: buf, from: ftp.buf, n: retlen))
263 retlen = -EFAULT;
264 break;
265
266 case HMCDRV_FTP_PUT:
267 case HMCDRV_FTP_APPEND:
268 if (!copy_from_user(to: ftp.buf, from: buf, n: ftp.len))
269 retlen = hmcdrv_ftp_do(&ftp);
270 else
271 retlen = -EFAULT;
272 break;
273
274 case HMCDRV_FTP_DELETE:
275 retlen = hmcdrv_ftp_do(&ftp);
276 break;
277
278 default:
279 retlen = -EOPNOTSUPP;
280 break;
281 }
282
283 free_pages(addr: (unsigned long) ftp.buf, order);
284 return retlen;
285}
286
287/**
288 * hmcdrv_ftp_startup() - startup of HMC drive FTP functionality for a
289 * dedicated (owner) instance
290 *
291 * Return: 0 on success, else an (negative) error code
292 */
293int hmcdrv_ftp_startup(void)
294{
295 static const struct hmcdrv_ftp_ops hmcdrv_ftp_zvm = {
296 .startup = diag_ftp_startup,
297 .shutdown = diag_ftp_shutdown,
298 .transfer = diag_ftp_cmd
299 };
300
301 static const struct hmcdrv_ftp_ops hmcdrv_ftp_lpar = {
302 .startup = sclp_ftp_startup,
303 .shutdown = sclp_ftp_shutdown,
304 .transfer = sclp_ftp_cmd
305 };
306
307 int rc = 0;
308
309 mutex_lock(&hmcdrv_ftp_mutex); /* block transfers while start-up */
310
311 if (hmcdrv_ftp_refcnt == 0) {
312 if (machine_is_vm())
313 hmcdrv_ftp_funcs = &hmcdrv_ftp_zvm;
314 else if (machine_is_lpar() || machine_is_kvm())
315 hmcdrv_ftp_funcs = &hmcdrv_ftp_lpar;
316 else
317 rc = -EOPNOTSUPP;
318
319 if (hmcdrv_ftp_funcs)
320 rc = hmcdrv_ftp_funcs->startup();
321 }
322
323 if (!rc)
324 ++hmcdrv_ftp_refcnt;
325
326 mutex_unlock(lock: &hmcdrv_ftp_mutex);
327 return rc;
328}
329EXPORT_SYMBOL(hmcdrv_ftp_startup);
330
331/**
332 * hmcdrv_ftp_shutdown() - shutdown of HMC drive FTP functionality for a
333 * dedicated (owner) instance
334 */
335void hmcdrv_ftp_shutdown(void)
336{
337 mutex_lock(&hmcdrv_ftp_mutex);
338 --hmcdrv_ftp_refcnt;
339
340 if ((hmcdrv_ftp_refcnt == 0) && hmcdrv_ftp_funcs)
341 hmcdrv_ftp_funcs->shutdown();
342
343 mutex_unlock(lock: &hmcdrv_ftp_mutex);
344}
345EXPORT_SYMBOL(hmcdrv_ftp_shutdown);
346

source code of linux/drivers/s390/char/hmcdrv_ftp.c