1 // SPDX-License-Identifier: GPL-2.0-only
2 /******************************************************************************
3 *******************************************************************************
4 **
5 ** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
6 ** Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
7 **
8 **
9 *******************************************************************************
10 ******************************************************************************/
11
12 /*
13 * midcomms.c
14 *
15 * This is the appallingly named "mid-level" comms layer.
16 *
17 * Its purpose is to take packets from the "real" comms layer,
18 * split them up into packets and pass them to the interested
19 * part of the locking mechanism.
20 *
21 * It also takes messages from the locking layer, formats them
22 * into packets and sends them to the comms layer.
23 */
24
25 #include "dlm_internal.h"
26 #include "lowcomms.h"
27 #include "config.h"
28 #include "lock.h"
29 #include "midcomms.h"
30
31
32 static void copy_from_cb(void *dst, const void *base, unsigned offset,
33 unsigned len, unsigned limit)
34 {
35 unsigned copy = len;
36
37 if ((copy + offset) > limit)
38 copy = limit - offset;
39 memcpy(dst, base + offset, copy);
40 len -= copy;
41 if (len)
42 memcpy(dst + copy, base, len);
43 }
44
45 /*
46 * Called from the low-level comms layer to process a buffer of
47 * commands.
48 *
49 * Only complete messages are processed here, any "spare" bytes from
50 * the end of a buffer are saved and tacked onto the front of the next
51 * message that comes in. I doubt this will happen very often but we
52 * need to be able to cope with it and I don't want the task to be waiting
53 * for packets to come in when there is useful work to be done.
54 */
55
56 int dlm_process_incoming_buffer(int nodeid, const void *base,
57 unsigned offset, unsigned len, unsigned limit)
58 {
59 union {
60 unsigned char __buf[DLM_INBUF_LEN];
61 /* this is to force proper alignment on some arches */
62 union dlm_packet p;
63 } __tmp;
64 union dlm_packet *p = &__tmp.p;
65 int ret = 0;
66 int err = 0;
67 uint16_t msglen;
68 uint32_t lockspace;
69
70 while (len > sizeof(struct dlm_header)) {
71
72 /* Copy just the header to check the total length. The
73 message may wrap around the end of the buffer back to the
74 start, so we need to use a temp buffer and copy_from_cb. */
75
76 copy_from_cb(p, base, offset, sizeof(struct dlm_header),
77 limit);
78
79 msglen = le16_to_cpu(p->header.h_length);
80 lockspace = p->header.h_lockspace;
81
82 err = -EINVAL;
83 if (msglen < sizeof(struct dlm_header))
84 break;
85 if (p->header.h_cmd == DLM_MSG) {
86 if (msglen < sizeof(struct dlm_message))
87 break;
88 } else {
89 if (msglen < sizeof(struct dlm_rcom))
90 break;
91 }
92 err = -E2BIG;
93 if (msglen > dlm_config.ci_buffer_size) {
94 log_print("message size %d from %d too big, buf len %d",
95 msglen, nodeid, len);
96 break;
97 }
98 err = 0;
99
100 /* If only part of the full message is contained in this
101 buffer, then do nothing and wait for lowcomms to call
102 us again later with more data. We return 0 meaning
103 we've consumed none of the input buffer. */
104
105 if (msglen > len)
106 break;
107
108 /* Allocate a larger temp buffer if the full message won't fit
109 in the buffer on the stack (which should work for most
110 ordinary messages). */
111
112 if (msglen > sizeof(__tmp) && p == &__tmp.p) {
113 p = kmalloc(dlm_config.ci_buffer_size, GFP_NOFS);
114 if (p == NULL)
115 return ret;
116 }
117
118 copy_from_cb(p, base, offset, msglen, limit);
119
120 BUG_ON(lockspace != p->header.h_lockspace);
121
122 ret += msglen;
123 offset += msglen;
124 offset &= (limit - 1);
125 len -= msglen;
126
127 dlm_receive_buffer(p, nodeid);
128 }
129
130 if (p != &__tmp.p)
131 kfree(p);
132
133 return err ? err : ret;
134 }
135