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 */
31struct 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
38static enum hmcdrv_ftp_cmdid hmcdrv_ftp_cmd_getid(const char *cmd, int len);
39static int hmcdrv_ftp_parse(char *cmd, struct hmcdrv_ftp_cmdspec *ftp);
40
41static const struct hmcdrv_ftp_ops *hmcdrv_ftp_funcs; /* current operations */
42static DEFINE_MUTEX(hmcdrv_ftp_mutex); /* mutex for hmcdrv_ftp_funcs */
43static 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 */
50static 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 */
112static 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 */
161ssize_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}
178EXPORT_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 */
185int 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 */
219out:
220	free_page((unsigned long) ftp.buf);
221	return rc;
222}
223EXPORT_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 */
237ssize_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 */
292int 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}
328EXPORT_SYMBOL(hmcdrv_ftp_startup);
329
330/**
331 * hmcdrv_ftp_shutdown() - shutdown of HMC drive FTP functionality for a
332 * dedicated (owner) instance
333 */
334void 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}
344EXPORT_SYMBOL(hmcdrv_ftp_shutdown);
345