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 * @transfer: 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 */
hmcdrv_ftp_cmd_getid(const char * cmd,int len)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 */
hmcdrv_ftp_parse(char * cmd,struct hmcdrv_ftp_cmdspec * ftp)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 fallthrough;
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 */
hmcdrv_ftp_do(const struct hmcdrv_ftp_cmdspec * ftp)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 */
hmcdrv_ftp_probe(void)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 */
hmcdrv_ftp_cmd(char __kernel * cmd,loff_t offset,char __user * buf,size_t len)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 */
hmcdrv_ftp_startup(void)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 */
hmcdrv_ftp_shutdown(void)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);
345