xref: /openbmc/linux/block/blk-crypto-sysfs.c (revision 5f622417)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright 2021 Google LLC
4  *
5  * sysfs support for blk-crypto.  This file contains the code which exports the
6  * crypto capabilities of devices via /sys/block/$disk/queue/crypto/.
7  */
8 
9 #include <linux/blk-crypto-profile.h>
10 
11 #include "blk-crypto-internal.h"
12 
13 struct blk_crypto_kobj {
14 	struct kobject kobj;
15 	struct blk_crypto_profile *profile;
16 };
17 
18 struct blk_crypto_attr {
19 	struct attribute attr;
20 	ssize_t (*show)(struct blk_crypto_profile *profile,
21 			struct blk_crypto_attr *attr, char *page);
22 };
23 
kobj_to_crypto_profile(struct kobject * kobj)24 static struct blk_crypto_profile *kobj_to_crypto_profile(struct kobject *kobj)
25 {
26 	return container_of(kobj, struct blk_crypto_kobj, kobj)->profile;
27 }
28 
attr_to_crypto_attr(struct attribute * attr)29 static struct blk_crypto_attr *attr_to_crypto_attr(struct attribute *attr)
30 {
31 	return container_of(attr, struct blk_crypto_attr, attr);
32 }
33 
max_dun_bits_show(struct blk_crypto_profile * profile,struct blk_crypto_attr * attr,char * page)34 static ssize_t max_dun_bits_show(struct blk_crypto_profile *profile,
35 				 struct blk_crypto_attr *attr, char *page)
36 {
37 	return sysfs_emit(page, "%u\n", 8 * profile->max_dun_bytes_supported);
38 }
39 
num_keyslots_show(struct blk_crypto_profile * profile,struct blk_crypto_attr * attr,char * page)40 static ssize_t num_keyslots_show(struct blk_crypto_profile *profile,
41 				 struct blk_crypto_attr *attr, char *page)
42 {
43 	return sysfs_emit(page, "%u\n", profile->num_slots);
44 }
45 
46 #define BLK_CRYPTO_RO_ATTR(_name) \
47 	static struct blk_crypto_attr _name##_attr = __ATTR_RO(_name)
48 
49 BLK_CRYPTO_RO_ATTR(max_dun_bits);
50 BLK_CRYPTO_RO_ATTR(num_keyslots);
51 
52 static struct attribute *blk_crypto_attrs[] = {
53 	&max_dun_bits_attr.attr,
54 	&num_keyslots_attr.attr,
55 	NULL,
56 };
57 
58 static const struct attribute_group blk_crypto_attr_group = {
59 	.attrs = blk_crypto_attrs,
60 };
61 
62 /*
63  * The encryption mode attributes.  To avoid hard-coding the list of encryption
64  * modes, these are initialized at boot time by blk_crypto_sysfs_init().
65  */
66 static struct blk_crypto_attr __blk_crypto_mode_attrs[BLK_ENCRYPTION_MODE_MAX];
67 static struct attribute *blk_crypto_mode_attrs[BLK_ENCRYPTION_MODE_MAX + 1];
68 
blk_crypto_mode_is_visible(struct kobject * kobj,struct attribute * attr,int n)69 static umode_t blk_crypto_mode_is_visible(struct kobject *kobj,
70 					  struct attribute *attr, int n)
71 {
72 	struct blk_crypto_profile *profile = kobj_to_crypto_profile(kobj);
73 	struct blk_crypto_attr *a = attr_to_crypto_attr(attr);
74 	int mode_num = a - __blk_crypto_mode_attrs;
75 
76 	if (profile->modes_supported[mode_num])
77 		return 0444;
78 	return 0;
79 }
80 
blk_crypto_mode_show(struct blk_crypto_profile * profile,struct blk_crypto_attr * attr,char * page)81 static ssize_t blk_crypto_mode_show(struct blk_crypto_profile *profile,
82 				    struct blk_crypto_attr *attr, char *page)
83 {
84 	int mode_num = attr - __blk_crypto_mode_attrs;
85 
86 	return sysfs_emit(page, "0x%x\n", profile->modes_supported[mode_num]);
87 }
88 
89 static const struct attribute_group blk_crypto_modes_attr_group = {
90 	.name = "modes",
91 	.attrs = blk_crypto_mode_attrs,
92 	.is_visible = blk_crypto_mode_is_visible,
93 };
94 
95 static const struct attribute_group *blk_crypto_attr_groups[] = {
96 	&blk_crypto_attr_group,
97 	&blk_crypto_modes_attr_group,
98 	NULL,
99 };
100 
blk_crypto_attr_show(struct kobject * kobj,struct attribute * attr,char * page)101 static ssize_t blk_crypto_attr_show(struct kobject *kobj,
102 				    struct attribute *attr, char *page)
103 {
104 	struct blk_crypto_profile *profile = kobj_to_crypto_profile(kobj);
105 	struct blk_crypto_attr *a = attr_to_crypto_attr(attr);
106 
107 	return a->show(profile, a, page);
108 }
109 
110 static const struct sysfs_ops blk_crypto_attr_ops = {
111 	.show = blk_crypto_attr_show,
112 };
113 
blk_crypto_release(struct kobject * kobj)114 static void blk_crypto_release(struct kobject *kobj)
115 {
116 	kfree(container_of(kobj, struct blk_crypto_kobj, kobj));
117 }
118 
119 static const struct kobj_type blk_crypto_ktype = {
120 	.default_groups = blk_crypto_attr_groups,
121 	.sysfs_ops	= &blk_crypto_attr_ops,
122 	.release	= blk_crypto_release,
123 };
124 
125 /*
126  * If the request_queue has a blk_crypto_profile, create the "crypto"
127  * subdirectory in sysfs (/sys/block/$disk/queue/crypto/).
128  */
blk_crypto_sysfs_register(struct gendisk * disk)129 int blk_crypto_sysfs_register(struct gendisk *disk)
130 {
131 	struct request_queue *q = disk->queue;
132 	struct blk_crypto_kobj *obj;
133 	int err;
134 
135 	if (!q->crypto_profile)
136 		return 0;
137 
138 	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
139 	if (!obj)
140 		return -ENOMEM;
141 	obj->profile = q->crypto_profile;
142 
143 	err = kobject_init_and_add(&obj->kobj, &blk_crypto_ktype,
144 				   &disk->queue_kobj, "crypto");
145 	if (err) {
146 		kobject_put(&obj->kobj);
147 		return err;
148 	}
149 	q->crypto_kobject = &obj->kobj;
150 	return 0;
151 }
152 
blk_crypto_sysfs_unregister(struct gendisk * disk)153 void blk_crypto_sysfs_unregister(struct gendisk *disk)
154 {
155 	kobject_put(disk->queue->crypto_kobject);
156 }
157 
blk_crypto_sysfs_init(void)158 static int __init blk_crypto_sysfs_init(void)
159 {
160 	int i;
161 
162 	BUILD_BUG_ON(BLK_ENCRYPTION_MODE_INVALID != 0);
163 	for (i = 1; i < BLK_ENCRYPTION_MODE_MAX; i++) {
164 		struct blk_crypto_attr *attr = &__blk_crypto_mode_attrs[i];
165 
166 		attr->attr.name = blk_crypto_modes[i].name;
167 		attr->attr.mode = 0444;
168 		attr->show = blk_crypto_mode_show;
169 		blk_crypto_mode_attrs[i - 1] = &attr->attr;
170 	}
171 	return 0;
172 }
173 subsys_initcall(blk_crypto_sysfs_init);
174