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