Re: [PATCH] tpm: tpm2-space: Resize session and context buffers dynamically
From: Stefan Berger
Date: Thu Jun 25 2020 - 08:13:21 EST
On 6/25/20 12:24 AM, Jarkko Sakkinen wrote:
Re-allocate context and session buffers when needed. Scale them in page
increments so that the reallocation is only seldomly required, and thus
causes minimal stress to the system. Add a static maximum limit of four
pages for buffer sizes.
Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Suggested-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
---
Tested only for compilation.
drivers/char/tpm/tpm2-space.c | 80 ++++++++++++++++++++++++-----------
include/linux/tpm.h | 6 ++-
2 files changed, 59 insertions(+), 27 deletions(-)
diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c
index 982d341d8837..acb9e82bf9e8 100644
--- a/drivers/char/tpm/tpm2-space.c
+++ b/drivers/char/tpm/tpm2-space.c
@@ -15,6 +15,8 @@
#include <asm/unaligned.h>
#include "tpm.h"
+#define TPM2_SPACE_MAX_BUFFER_SIZE (4 * PAGE_SIZE)
PAGE_SIZE is 64k on ppc64. Rather use 4 * 4096?
Rest looks good.
+
enum tpm2_handle_types {
TPM2_HT_HMAC_SESSION = 0x02000000,
TPM2_HT_POLICY_SESSION = 0x03000000,
@@ -47,9 +49,12 @@ int tpm2_init_space(struct tpm_space *space)
space->session_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
if (space->session_buf == NULL) {
kfree(space->context_buf);
+ space->context_buf = NULL;
return -ENOMEM;
}
+ space->context_size = PAGE_SIZE;
+ space->session_size = PAGE_SIZE;
return 0;
}
@@ -116,11 +121,13 @@ static int tpm2_load_context(struct tpm_chip *chip, u8 *buf,
return 0;
}
-static int tpm2_save_context(struct tpm_chip *chip, u32 handle, u8 *buf,
- unsigned int buf_size, unsigned int *offset)
+static int tpm2_save_context(struct tpm_chip *chip, u32 handle, u8 **buf,
+ unsigned int *buf_size, unsigned int *offset)
{
- struct tpm_buf tbuf;
+ unsigned int new_buf_size;
unsigned int body_size;
+ struct tpm_buf tbuf;
+ void *new_buf;
int rc;
rc = tpm_buf_init(&tbuf, TPM2_ST_NO_SESSIONS, TPM2_CC_CONTEXT_SAVE);
@@ -131,31 +138,48 @@ static int tpm2_save_context(struct tpm_chip *chip, u32 handle, u8 *buf,
rc = tpm_transmit_cmd(chip, &tbuf, 0, NULL);
if (rc < 0) {
- dev_warn(&chip->dev, "%s: failed with a system error %d\n",
- __func__, rc);
- tpm_buf_destroy(&tbuf);
- return -EFAULT;
+ rc = -EFAULT;
+ goto err;
} else if (tpm2_rc_value(rc) == TPM2_RC_REFERENCE_H0) {
- tpm_buf_destroy(&tbuf);
- return -ENOENT;
+ rc = -ENOENT;
+ goto out;
} else if (rc) {
- dev_warn(&chip->dev, "%s: failed with a TPM error 0x%04X\n",
- __func__, rc);
- tpm_buf_destroy(&tbuf);
- return -EFAULT;
+ rc = -EFAULT;
+ goto err;
}
body_size = tpm_buf_length(&tbuf) - TPM_HEADER_SIZE;
- if ((*offset + body_size) > buf_size) {
- dev_warn(&chip->dev, "%s: out of backing storage\n", __func__);
- tpm_buf_destroy(&tbuf);
- return -ENOMEM;
+ /* We grow the buffer in page increments. */
+ new_buf_size = PFN_UP(*offset + body_size);
+
+ if (new_buf_size > TPM2_SPACE_MAX_BUFFER_SIZE) {
+ rc = -ENOMEM;
+ goto err;
}
- memcpy(&buf[*offset], &tbuf.data[TPM_HEADER_SIZE], body_size);
+ if (new_buf_size > *buf_size) {
+ new_buf = krealloc(*buf, new_buf_size, GFP_KERNEL);
+ if (!new_buf) {
+ rc = -ENOMEM;
+ goto err;
+ }
+
+ *buf = new_buf;
+ *buf_size = new_buf_size;
+ }
+
+ memcpy(*buf + *offset, &tbuf.data[TPM_HEADER_SIZE], body_size);
*offset += body_size;
+
+out:
tpm_buf_destroy(&tbuf);
- return 0;
+ return rc;
+
+err:
+ dev_warn(&chip->dev, "%s: ret=%d\n", __func__, rc);
+
+ tpm_buf_destroy(&tbuf);
+ return rc;
}
void tpm2_flush_space(struct tpm_chip *chip)
@@ -311,8 +335,10 @@ int tpm2_prepare_space(struct tpm_chip *chip, struct tpm_space *space, u8 *cmd,
sizeof(space->context_tbl));
memcpy(&chip->work_space.session_tbl, &space->session_tbl,
sizeof(space->session_tbl));
- memcpy(chip->work_space.context_buf, space->context_buf, PAGE_SIZE);
- memcpy(chip->work_space.session_buf, space->session_buf, PAGE_SIZE);
+ memcpy(chip->work_space.context_buf, space->context_buf,
+ space->context_size);
+ memcpy(chip->work_space.session_buf, space->session_buf,
+ space->session_size);
rc = tpm2_load_space(chip);
if (rc) {
@@ -492,7 +518,8 @@ static int tpm2_save_space(struct tpm_chip *chip)
continue;
rc = tpm2_save_context(chip, space->context_tbl[i],
- space->context_buf, PAGE_SIZE,
+ &space->context_buf,
+ &space->context_size,
&offset);
if (rc == -ENOENT) {
space->context_tbl[i] = 0;
@@ -509,7 +536,8 @@ static int tpm2_save_space(struct tpm_chip *chip)
continue;
rc = tpm2_save_context(chip, space->session_tbl[i],
- space->session_buf, PAGE_SIZE,
+ &space->session_buf,
+ &space->session_size,
&offset);
if (rc == -ENOENT) {
@@ -557,8 +585,10 @@ int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space,
sizeof(space->context_tbl));
memcpy(&space->session_tbl, &chip->work_space.session_tbl,
sizeof(space->session_tbl));
- memcpy(space->context_buf, chip->work_space.context_buf, PAGE_SIZE);
- memcpy(space->session_buf, chip->work_space.session_buf, PAGE_SIZE);
+ memcpy(space->context_buf, chip->work_space.context_buf,
+ space->context_size);
+ memcpy(space->session_buf, chip->work_space.session_buf,
+ space->session_size);
return 0;
out:
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 03e9b184411b..9ea39e8f7162 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -92,10 +92,12 @@ enum tpm_duration {
#define TPM_PPI_VERSION_LEN 3
struct tpm_space {
+ u8 *context_buf;
+ u8 *session_buf;
+ u32 context_size;
+ u32 session_size;
u32 context_tbl[3];
- u8 *context_buf;
u32 session_tbl[3];
- u8 *session_buf;
};
struct tpm_bios_log {