xref: /openbmc/qemu/hw/nvme/nguid.c (revision bdc31646)
1 /*
2  *  QEMU NVMe NGUID functions
3  *
4  * Copyright 2024 Google LLC
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License as published by the
8  * Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14  * for more details.
15  */
16 
17 #include "qemu/osdep.h"
18 #include "qapi/visitor.h"
19 #include "qemu/ctype.h"
20 #include "nvme.h"
21 
22 #define NGUID_SEPARATOR '-'
23 
24 #define NGUID_VALUE_AUTO "auto"
25 
26 #define NGUID_FMT              \
27     "%02hhx%02hhx%02hhx%02hhx" \
28     "%02hhx%02hhx%02hhx%02hhx" \
29     "%02hhx%02hhx%02hhx%02hhx" \
30     "%02hhx%02hhx%02hhx%02hhx"
31 
32 #define NGUID_STR_LEN (2 * NGUID_LEN + 1)
33 
nvme_nguid_is_null(const NvmeNGUID * nguid)34 bool nvme_nguid_is_null(const NvmeNGUID *nguid)
35 {
36     static NvmeNGUID null_nguid;
37     return memcmp(nguid, &null_nguid, sizeof(NvmeNGUID)) == 0;
38 }
39 
nvme_nguid_generate(NvmeNGUID * out)40 static void nvme_nguid_generate(NvmeNGUID *out)
41 {
42     int i;
43     uint32_t x;
44 
45     QEMU_BUILD_BUG_ON((NGUID_LEN % sizeof(x)) != 0);
46 
47     for (i = 0; i < NGUID_LEN; i += sizeof(x)) {
48         x = g_random_int();
49         memcpy(&out->data[i], &x, sizeof(x));
50     }
51 }
52 
53 /*
54  * The Linux Kernel typically prints the NGUID of an NVMe namespace using the
55  * same format as the UUID. For instance:
56  *
57  * $ cat /sys/class/block/nvme0n1/nguid
58  * e9accd3b-8390-4e13-167c-f0593437f57d
59  *
60  * When there is no UUID but there is NGUID the Kernel will print the NGUID as
61  * wwid and it won't use the UUID format:
62  *
63  * $ cat /sys/class/block/nvme0n1/wwid
64  * eui.e9accd3b83904e13167cf0593437f57d
65  *
66  * The NGUID has different fields compared to the UUID, so the grouping used in
67  * the UUID format has no relation with the 3 fields of the NGUID.
68  *
69  * This implementation won't expect a strict format as the UUID one and instead
70  * it will admit any string of hexadecimal digits. Byte groups could be created
71  * using the '-' separator. The number of bytes needs to be exactly 16 and the
72  * separator '-' has to be exactly in a byte boundary. The following are
73  * examples of accepted formats for the NGUID string:
74  *
75  * nguid="e9accd3b-8390-4e13-167c-f0593437f57d"
76  * nguid="e9accd3b83904e13167cf0593437f57d"
77  * nguid="FEDCBA9876543210-ABCDEF-0123456789"
78  */
nvme_nguid_is_valid(const char * str)79 static bool nvme_nguid_is_valid(const char *str)
80 {
81     int i;
82     int digit_count = 0;
83 
84     for (i = 0; i < strlen(str); i++) {
85         const char c = str[i];
86         if (qemu_isxdigit(c)) {
87             digit_count++;
88             continue;
89         }
90         if (c == NGUID_SEPARATOR) {
91             /*
92              * We need to make sure the separator is in a byte boundary, the
93              * string does not start with the separator and they are not back to
94              * back "--".
95              */
96             if ((i > 0) && (str[i - 1] != NGUID_SEPARATOR) &&
97                 (digit_count % 2) == 0) {
98                 continue;
99             }
100         }
101         return false;
102     }
103     /*
104      * The string should have the correct byte length and not finish with the
105      * separator
106      */
107     return (digit_count == (2 * NGUID_LEN)) && (str[i - 1] != NGUID_SEPARATOR);
108 }
109 
nvme_nguid_parse(const char * str,NvmeNGUID * nguid)110 static int nvme_nguid_parse(const char *str, NvmeNGUID *nguid)
111 {
112     uint8_t *id = &nguid->data[0];
113     int ret = 0;
114     int i;
115     const char *ptr = str;
116 
117     if (!nvme_nguid_is_valid(str)) {
118         return -1;
119     }
120 
121     for (i = 0; i < NGUID_LEN; i++) {
122         ret = sscanf(ptr, "%02hhx", &id[i]);
123         if (ret != 1) {
124             return -1;
125         }
126         ptr += 2;
127         if (*ptr == NGUID_SEPARATOR) {
128             ptr++;
129         }
130     }
131 
132     return 0;
133 }
134 
135 /*
136  * When converted back to string this implementation will use a raw hex number
137  * with no separators, for instance:
138  *
139  * "e9accd3b83904e13167cf0593437f57d"
140  */
nvme_nguid_stringify(const NvmeNGUID * nguid,char * out)141 static void nvme_nguid_stringify(const NvmeNGUID *nguid, char *out)
142 {
143     const uint8_t *id = &nguid->data[0];
144     snprintf(out, NGUID_STR_LEN, NGUID_FMT,
145              id[0], id[1], id[2], id[3], id[4], id[5], id[6], id[7],
146              id[8], id[9], id[10], id[11], id[12], id[13], id[14], id[15]);
147 }
148 
get_nguid(Object * obj,Visitor * v,const char * name,void * opaque,Error ** errp)149 static void get_nguid(Object *obj, Visitor *v, const char *name, void *opaque,
150                       Error **errp)
151 {
152     Property *prop = opaque;
153     NvmeNGUID *nguid = object_field_prop_ptr(obj, prop);
154     char buffer[NGUID_STR_LEN];
155     char *p = buffer;
156 
157     nvme_nguid_stringify(nguid, buffer);
158 
159     visit_type_str(v, name, &p, errp);
160 }
161 
set_nguid(Object * obj,Visitor * v,const char * name,void * opaque,Error ** errp)162 static void set_nguid(Object *obj, Visitor *v, const char *name, void *opaque,
163                       Error **errp)
164 {
165     Property *prop = opaque;
166     NvmeNGUID *nguid = object_field_prop_ptr(obj, prop);
167     char *str;
168 
169     if (!visit_type_str(v, name, &str, errp)) {
170         return;
171     }
172 
173     if (!strcmp(str, NGUID_VALUE_AUTO)) {
174         nvme_nguid_generate(nguid);
175     } else if (nvme_nguid_parse(str, nguid) < 0) {
176         error_set_from_qdev_prop_error(errp, EINVAL, obj, name, str);
177     }
178     g_free(str);
179 }
180 
181 const PropertyInfo qdev_prop_nguid = {
182     .name  = "str",
183     .description =
184         "NGUID or \"" NGUID_VALUE_AUTO "\" for random value",
185     .get   = get_nguid,
186     .set   = set_nguid,
187 };
188