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authorJarkko Sakkinen <jarkko@kernel.org>2024-04-29 23:27:56 +0300
committerJarkko Sakkinen <jarkko@kernel.org>2024-05-09 22:30:51 +0300
commitacd5eb4f50241c5e3c2e0056c0e2151295796416 (patch)
tree30354fef4cd50489d574cc302a62c85450b2b01e /drivers/char/tpm
parentd926ee92e84146ff85877b15d9ac0c7cd7c422c6 (diff)
downloadlinux-acd5eb4f50241c5e3c2e0056c0e2151295796416.tar.xz
tpm: Add tpm_buf_read_{u8,u16,u32}
Declare reader functions for the instances of struct tpm_buf. If the read goes out of boundary, TPM_BUF_BOUNDARY_ERROR is set, and subsequent read will do nothing. Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> Reviewed-by: Stefan Berger <stefanb@linux.ibm.com> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> Tested-by: Jarkko Sakkinen <jarkko@kernel.org> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Diffstat (limited to 'drivers/char/tpm')
-rw-r--r--drivers/char/tpm/tpm-buf.c79
1 files changed, 78 insertions, 1 deletions
diff --git a/drivers/char/tpm/tpm-buf.c b/drivers/char/tpm/tpm-buf.c
index d679dc1cecc7..cc14fa3fd8c2 100644
--- a/drivers/char/tpm/tpm-buf.c
+++ b/drivers/char/tpm/tpm-buf.c
@@ -108,7 +108,7 @@ void tpm_buf_append(struct tpm_buf *buf, const u8 *new_data, u16 new_length)
return;
if ((buf->length + new_length) > PAGE_SIZE) {
- WARN(1, "tpm_buf: overflow\n");
+ WARN(1, "tpm_buf: write overflow\n");
buf->flags |= TPM_BUF_OVERFLOW;
return;
}
@@ -144,3 +144,80 @@ void tpm_buf_append_u32(struct tpm_buf *buf, const u32 value)
tpm_buf_append(buf, (u8 *)&value2, 4);
}
EXPORT_SYMBOL_GPL(tpm_buf_append_u32);
+
+/**
+ * tpm_buf_read() - Read from a TPM buffer
+ * @buf: &tpm_buf instance
+ * @offset: offset within the buffer
+ * @count: the number of bytes to read
+ * @output: the output buffer
+ */
+static void tpm_buf_read(struct tpm_buf *buf, off_t *offset, size_t count, void *output)
+{
+ off_t next_offset;
+
+ /* Return silently if overflow has already happened. */
+ if (buf->flags & TPM_BUF_BOUNDARY_ERROR)
+ return;
+
+ next_offset = *offset + count;
+ if (next_offset > buf->length) {
+ WARN(1, "tpm_buf: read out of boundary\n");
+ buf->flags |= TPM_BUF_BOUNDARY_ERROR;
+ return;
+ }
+
+ memcpy(output, &buf->data[*offset], count);
+ *offset = next_offset;
+}
+
+/**
+ * tpm_buf_read_u8() - Read 8-bit word from a TPM buffer
+ * @buf: &tpm_buf instance
+ * @offset: offset within the buffer
+ *
+ * Return: next 8-bit word
+ */
+u8 tpm_buf_read_u8(struct tpm_buf *buf, off_t *offset)
+{
+ u8 value;
+
+ tpm_buf_read(buf, offset, sizeof(value), &value);
+
+ return value;
+}
+EXPORT_SYMBOL_GPL(tpm_buf_read_u8);
+
+/**
+ * tpm_buf_read_u16() - Read 16-bit word from a TPM buffer
+ * @buf: &tpm_buf instance
+ * @offset: offset within the buffer
+ *
+ * Return: next 16-bit word
+ */
+u16 tpm_buf_read_u16(struct tpm_buf *buf, off_t *offset)
+{
+ u16 value;
+
+ tpm_buf_read(buf, offset, sizeof(value), &value);
+
+ return be16_to_cpu(value);
+}
+EXPORT_SYMBOL_GPL(tpm_buf_read_u16);
+
+/**
+ * tpm_buf_read_u32() - Read 32-bit word from a TPM buffer
+ * @buf: &tpm_buf instance
+ * @offset: offset within the buffer
+ *
+ * Return: next 32-bit word
+ */
+u32 tpm_buf_read_u32(struct tpm_buf *buf, off_t *offset)
+{
+ u32 value;
+
+ tpm_buf_read(buf, offset, sizeof(value), &value);
+
+ return be32_to_cpu(value);
+}
+EXPORT_SYMBOL_GPL(tpm_buf_read_u32);