tpm: Unify the mismatching TPM space buffer sizes

The size of the buffers for storing context's and sessions can vary from
arch to arch as PAGE_SIZE can be anything between 4 kB and 256 kB (the
maximum for PPC64). Define a fixed buffer size set to 16 kB. This should be
enough for most use with three handles (that is how many we allow at the
moment). Parametrize the buffer size while doing this, so that it is easier
to revisit this later on if required.

Cc: [email protected]
Reported-by: Stefan Berger <[email protected]>
Fixes: 745b361e989a ("tpm: infrastructure for TPM spaces")
Reviewed-by: Jerry Snitselaar <[email protected]>
Tested-by: Stefan Berger <[email protected]>
Signed-off-by: Jarkko Sakkinen <[email protected]>

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 8c77e88012e9f185c9b526860df18458051922c3..ddaeceb7e109105297f6baf53d74138911246fed 100644 (file)
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -386,13 +386,8 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
        chip->cdev.owner = THIS_MODULE;
        chip->cdevs.owner = THIS_MODULE;
 
-       chip->work_space.context_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
-       if (!chip->work_space.context_buf) {
-               rc = -ENOMEM;
-               goto out;
-       }
-       chip->work_space.session_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
-       if (!chip->work_space.session_buf) {
+       rc = tpm2_init_space(&chip->work_space, TPM2_SPACE_BUFFER_SIZE);
+       if (rc) {
                rc = -ENOMEM;
                goto out;
        }

diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 0fbcede241ea0b5e277d571c3f6caf61f4715baf..947d1db0a5ccf756172cfb9275ed9e046d4cdd38 100644 (file)
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -59,6 +59,9 @@ enum tpm_addr {
 
 #define TPM_TAG_RQU_COMMAND 193
 
+/* TPM2 specific constants. */
+#define TPM2_SPACE_BUFFER_SIZE         16384 /* 16 kB */
+
 struct stclear_flags_t {
        __be16  tag;
        u8      deactivated;
@@ -228,7 +231,7 @@ unsigned long tpm2_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal);
 int tpm2_probe(struct tpm_chip *chip);
 int tpm2_get_cc_attrs_tbl(struct tpm_chip *chip);
 int tpm2_find_cc(struct tpm_chip *chip, u32 cc);
-int tpm2_init_space(struct tpm_space *space);
+int tpm2_init_space(struct tpm_space *space, unsigned int buf_size);
 void tpm2_del_space(struct tpm_chip *chip, struct tpm_space *space);
 void tpm2_flush_space(struct tpm_chip *chip);
 int tpm2_prepare_space(struct tpm_chip *chip, struct tpm_space *space, u8 *cmd,

diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c
index 982d341d88379aac6330fe2543f4e17650e5e7ee..784b8b3cb903f5e098d1eaac235fec69f5a5a4d6 100644 (file)
--- a/drivers/char/tpm/tpm2-space.c
+++ b/drivers/char/tpm/tpm2-space.c
@@ -38,18 +38,21 @@ static void tpm2_flush_sessions(struct tpm_chip *chip, struct tpm_space *space)
        }
 }
 
-int tpm2_init_space(struct tpm_space *space)
+int tpm2_init_space(struct tpm_space *space, unsigned int buf_size)
 {
-       space->context_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
+       space->context_buf = kzalloc(buf_size, GFP_KERNEL);
        if (!space->context_buf)
                return -ENOMEM;
 
-       space->session_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
+       space->session_buf = kzalloc(buf_size, GFP_KERNEL);
        if (space->session_buf == NULL) {
                kfree(space->context_buf);
+               /* Prevent caller getting a dangling pointer. */
+               space->context_buf = NULL;
                return -ENOMEM;
        }
 
+       space->buf_size = buf_size;
        return 0;
 }
 
@@ -311,8 +314,10 @@ 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->buf_size);
+       memcpy(chip->work_space.session_buf, space->session_buf,
+              space->buf_size);
 
        rc = tpm2_load_space(chip);
        if (rc) {
@@ -492,7 +497,7 @@ 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->buf_size,
                                       &offset);
                if (rc == -ENOENT) {
                        space->context_tbl[i] = 0;
@@ -509,9 +514,8 @@ 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->buf_size,
                                       &offset);
-
                if (rc == -ENOENT) {
                        /* handle error saving session, just forget it */
                        space->session_tbl[i] = 0;
@@ -557,8 +561,10 @@ 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->buf_size);
+       memcpy(space->session_buf, chip->work_space.session_buf,
+              space->buf_size);
 
        return 0;
 out:

diff --git a/drivers/char/tpm/tpmrm-dev.c b/drivers/char/tpm/tpmrm-dev.c
index 7a0a7051a06fc867aa35e250d8d36d7cde46968b..eef0fb06ea83223cefd9ce823607f2aad298c5ba 100644 (file)
--- a/drivers/char/tpm/tpmrm-dev.c
+++ b/drivers/char/tpm/tpmrm-dev.c
@@ -21,7 +21,7 @@ static int tpmrm_open(struct inode *inode, struct file *file)
        if (priv == NULL)
                return -ENOMEM;
 
-       rc = tpm2_init_space(&priv->space);
+       rc = tpm2_init_space(&priv->space, TPM2_SPACE_BUFFER_SIZE);
        if (rc) {
                kfree(priv);
                return -ENOMEM;

diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 03e9b184411bee44d8be375bbcaefff5f72509a2..8f4ff39f51e7db6b645ffe82b5925a1d6a9a47db 100644 (file)
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -96,6 +96,7 @@ struct tpm_space {
        u8 *context_buf;
        u32 session_tbl[3];
        u8 *session_buf;
+       u32 buf_size;
 };
 
 struct tpm_bios_log {