1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Handling of TPM command and other buffers.
4  */
5 
6 #include <linux/tpm_command.h>
7 #include <linux/module.h>
8 #include <linux/tpm.h>
9 
10 /**
11  * tpm_buf_init() - Allocate and initialize a TPM command
12  * @buf:	A &tpm_buf
13  * @tag:	TPM_TAG_RQU_COMMAND, TPM2_ST_NO_SESSIONS or TPM2_ST_SESSIONS
14  * @ordinal:	A command ordinal
15  *
16  * Return: 0 or -ENOMEM
17  */
tpm_buf_init(struct tpm_buf * buf,u16 tag,u32 ordinal)18 int tpm_buf_init(struct tpm_buf *buf, u16 tag, u32 ordinal)
19 {
20 	buf->data = (u8 *)__get_free_page(GFP_KERNEL);
21 	if (!buf->data)
22 		return -ENOMEM;
23 
24 	tpm_buf_reset(buf, tag, ordinal);
25 	return 0;
26 }
27 EXPORT_SYMBOL_GPL(tpm_buf_init);
28 
29 /**
30  * tpm_buf_reset() - Initialize a TPM command
31  * @buf:	A &tpm_buf
32  * @tag:	TPM_TAG_RQU_COMMAND, TPM2_ST_NO_SESSIONS or TPM2_ST_SESSIONS
33  * @ordinal:	A command ordinal
34  */
tpm_buf_reset(struct tpm_buf * buf,u16 tag,u32 ordinal)35 void tpm_buf_reset(struct tpm_buf *buf, u16 tag, u32 ordinal)
36 {
37 	struct tpm_header *head = (struct tpm_header *)buf->data;
38 
39 	WARN_ON(tag != TPM_TAG_RQU_COMMAND && tag != TPM2_ST_NO_SESSIONS &&
40 		tag != TPM2_ST_SESSIONS && tag != 0);
41 
42 	buf->flags = 0;
43 	buf->length = sizeof(*head);
44 	head->tag = cpu_to_be16(tag);
45 	head->length = cpu_to_be32(sizeof(*head));
46 	head->ordinal = cpu_to_be32(ordinal);
47 	buf->handles = 0;
48 }
49 EXPORT_SYMBOL_GPL(tpm_buf_reset);
50 
51 /**
52  * tpm_buf_init_sized() - Allocate and initialize a sized (TPM2B) buffer
53  * @buf:	A @tpm_buf
54  *
55  * Return: 0 or -ENOMEM
56  */
tpm_buf_init_sized(struct tpm_buf * buf)57 int tpm_buf_init_sized(struct tpm_buf *buf)
58 {
59 	buf->data = (u8 *)__get_free_page(GFP_KERNEL);
60 	if (!buf->data)
61 		return -ENOMEM;
62 
63 	tpm_buf_reset_sized(buf);
64 	return 0;
65 }
66 EXPORT_SYMBOL_GPL(tpm_buf_init_sized);
67 
68 /**
69  * tpm_buf_reset_sized() - Initialize a sized buffer
70  * @buf:	A &tpm_buf
71  */
tpm_buf_reset_sized(struct tpm_buf * buf)72 void tpm_buf_reset_sized(struct tpm_buf *buf)
73 {
74 	buf->flags = TPM_BUF_TPM2B;
75 	buf->length = 2;
76 	buf->data[0] = 0;
77 	buf->data[1] = 0;
78 }
79 EXPORT_SYMBOL_GPL(tpm_buf_reset_sized);
80 
tpm_buf_destroy(struct tpm_buf * buf)81 void tpm_buf_destroy(struct tpm_buf *buf)
82 {
83 	free_page((unsigned long)buf->data);
84 }
85 EXPORT_SYMBOL_GPL(tpm_buf_destroy);
86 
87 /**
88  * tpm_buf_length() - Return the number of bytes consumed by the data
89  * @buf:	A &tpm_buf
90  *
91  * Return: The number of bytes consumed by the buffer
92  */
tpm_buf_length(struct tpm_buf * buf)93 u32 tpm_buf_length(struct tpm_buf *buf)
94 {
95 	return buf->length;
96 }
97 EXPORT_SYMBOL_GPL(tpm_buf_length);
98 
99 /**
100  * tpm_buf_append() - Append data to an initialized buffer
101  * @buf:	A &tpm_buf
102  * @new_data:	A data blob
103  * @new_length:	Size of the appended data
104  */
tpm_buf_append(struct tpm_buf * buf,const u8 * new_data,u16 new_length)105 void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length)
106 {
107 	/* Return silently if overflow has already happened. */
108 	if (buf->flags & TPM_BUF_OVERFLOW)
109 		return;
110 
111 	if ((buf->length + new_length) > PAGE_SIZE) {
112 		WARN(1, "tpm_buf: write overflow\n");
113 		buf->flags |= TPM_BUF_OVERFLOW;
114 		return;
115 	}
116 
117 	memcpy(&buf->data[buf->length], new_data, new_length);
118 	buf->length += new_length;
119 
120 	if (buf->flags & TPM_BUF_TPM2B)
121 		((__be16 *)buf->data)[0] = cpu_to_be16(buf->length - 2);
122 	else
123 		((struct tpm_header *)buf->data)->length = cpu_to_be32(buf->length);
124 }
125 EXPORT_SYMBOL_GPL(tpm_buf_append);
126 
tpm_buf_append_u8(struct tpm_buf * buf,const u8 value)127 void tpm_buf_append_u8(struct tpm_buf *buf, const u8 value)
128 {
129 	tpm_buf_append(buf, &value, 1);
130 }
131 EXPORT_SYMBOL_GPL(tpm_buf_append_u8);
132 
tpm_buf_append_u16(struct tpm_buf * buf,const u16 value)133 void tpm_buf_append_u16(struct tpm_buf *buf, const u16 value)
134 {
135 	__be16 value2 = cpu_to_be16(value);
136 
137 	tpm_buf_append(buf, (u8 *)&value2, 2);
138 }
139 EXPORT_SYMBOL_GPL(tpm_buf_append_u16);
140 
tpm_buf_append_u32(struct tpm_buf * buf,const u32 value)141 void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value)
142 {
143 	__be32 value2 = cpu_to_be32(value);
144 
145 	tpm_buf_append(buf, (u8 *)&value2, 4);
146 }
147 EXPORT_SYMBOL_GPL(tpm_buf_append_u32);
148 
149 /**
150  * tpm_buf_append_handle() - Add a handle
151  * @chip:	&tpm_chip instance
152  * @buf:	&tpm_buf instance
153  * @handle:	a TPM object handle
154  *
155  * Add a handle to the buffer, and increase the count tracking the number of
156  * handles in the command buffer. Works only for command buffers.
157  */
tpm_buf_append_handle(struct tpm_chip * chip,struct tpm_buf * buf,u32 handle)158 void tpm_buf_append_handle(struct tpm_chip *chip, struct tpm_buf *buf, u32 handle)
159 {
160 	if (buf->flags & TPM_BUF_TPM2B) {
161 		dev_err(&chip->dev, "Invalid buffer type (TPM2B)\n");
162 		return;
163 	}
164 
165 	tpm_buf_append_u32(buf, handle);
166 	buf->handles++;
167 }
168 
169 /**
170  * tpm_buf_read() - Read from a TPM buffer
171  * @buf:	&tpm_buf instance
172  * @offset:	offset within the buffer
173  * @count:	the number of bytes to read
174  * @output:	the output buffer
175  */
tpm_buf_read(struct tpm_buf * buf,off_t * offset,size_t count,void * output)176 static void tpm_buf_read(struct tpm_buf *buf, off_t *offset, size_t count, void *output)
177 {
178 	off_t next_offset;
179 
180 	/* Return silently if overflow has already happened. */
181 	if (buf->flags & TPM_BUF_BOUNDARY_ERROR)
182 		return;
183 
184 	next_offset = *offset + count;
185 	if (next_offset > buf->length) {
186 		WARN(1, "tpm_buf: read out of boundary\n");
187 		buf->flags |= TPM_BUF_BOUNDARY_ERROR;
188 		return;
189 	}
190 
191 	memcpy(output, &buf->data[*offset], count);
192 	*offset = next_offset;
193 }
194 
195 /**
196  * tpm_buf_read_u8() - Read 8-bit word from a TPM buffer
197  * @buf:	&tpm_buf instance
198  * @offset:	offset within the buffer
199  *
200  * Return: next 8-bit word
201  */
tpm_buf_read_u8(struct tpm_buf * buf,off_t * offset)202 u8 tpm_buf_read_u8(struct tpm_buf *buf, off_t *offset)
203 {
204 	u8 value;
205 
206 	tpm_buf_read(buf, offset, sizeof(value), &value);
207 
208 	return value;
209 }
210 EXPORT_SYMBOL_GPL(tpm_buf_read_u8);
211 
212 /**
213  * tpm_buf_read_u16() - Read 16-bit word from a TPM buffer
214  * @buf:	&tpm_buf instance
215  * @offset:	offset within the buffer
216  *
217  * Return: next 16-bit word
218  */
tpm_buf_read_u16(struct tpm_buf * buf,off_t * offset)219 u16 tpm_buf_read_u16(struct tpm_buf *buf, off_t *offset)
220 {
221 	u16 value;
222 
223 	tpm_buf_read(buf, offset, sizeof(value), &value);
224 
225 	return be16_to_cpu(value);
226 }
227 EXPORT_SYMBOL_GPL(tpm_buf_read_u16);
228 
229 /**
230  * tpm_buf_read_u32() - Read 32-bit word from a TPM buffer
231  * @buf:	&tpm_buf instance
232  * @offset:	offset within the buffer
233  *
234  * Return: next 32-bit word
235  */
tpm_buf_read_u32(struct tpm_buf * buf,off_t * offset)236 u32 tpm_buf_read_u32(struct tpm_buf *buf, off_t *offset)
237 {
238 	u32 value;
239 
240 	tpm_buf_read(buf, offset, sizeof(value), &value);
241 
242 	return be32_to_cpu(value);
243 }
244 EXPORT_SYMBOL_GPL(tpm_buf_read_u32);
245 
246 
247