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