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Message-ID: <20251204194743.69035-3-jarkko@kernel.org>
Date: Thu, 4 Dec 2025 21:47:40 +0200
From: Jarkko Sakkinen <jarkko@...nel.org>
To: linux-integrity@...r.kernel.org
Cc: Jarkko Sakkinen <jarkko@...nel.org>,
Peter Huewe <peterhuewe@....de>,
Jason Gunthorpe <jgg@...pe.ca>,
linux-kernel@...r.kernel.org (open list),
stable@...r.kernel.org,
Jonathan McDowell <noodles@...a.com>,
James Bottomley <James.Bottomley@...senPartnership.com>,
Ard Biesheuvel <ardb@...nel.org>
Subject: [PATCH v4 2/4] tpm2-sessions: Fix tpm2_read_public range checks
tpm2_read_public() has some rudimentary range checks but the function does
not ensure that the response buffer has enough bytes for the full TPMT_HA
payload.
Re-implement the function with necessary checks and validation, and return
name and name size for all handle types back to the caller.
Cc: stable@...r.kernel.org # v6.10+
Fixes: d0a25bb961e6 ("tpm: Add HMAC session name/handle append")
Reviewed-by: Jonathan McDowell <noodles@...a.com>
Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
---
v3:
- Rename 'rc2' as 'name_size_alg'.
- It makes a lot of sense to add additional robustness in name handling
to tpm2_read_public. Thus also process handles whose handle name is
the handle itself, and return name size back to the caller.
v3:
- No changes.
v2:
- Made the fix localized instead of spread all over the place.
---
drivers/char/tpm/tpm2-cmd.c | 3 +
drivers/char/tpm/tpm2-sessions.c | 94 +++++++++++++++++---------------
2 files changed, 53 insertions(+), 44 deletions(-)
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index be4a9c7f2e1a..34e3599f094f 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -11,8 +11,11 @@
* used by the kernel internally.
*/
+#include "linux/dev_printk.h"
+#include "linux/tpm.h"
#include "tpm.h"
#include <crypto/hash_info.h>
+#include <linux/unaligned.h>
static bool disable_pcr_integrity;
module_param(disable_pcr_integrity, bool, 0444);
diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c
index 385014dbca39..3f389e2f6f58 100644
--- a/drivers/char/tpm/tpm2-sessions.c
+++ b/drivers/char/tpm/tpm2-sessions.c
@@ -163,53 +163,61 @@ static int name_size(const u8 *name)
}
}
-static int tpm2_parse_read_public(char *name, struct tpm_buf *buf)
+static int tpm2_read_public(struct tpm_chip *chip, u32 handle, void *name)
{
- struct tpm_header *head = (struct tpm_header *)buf->data;
+ u32 mso = tpm2_handle_mso(handle);
off_t offset = TPM_HEADER_SIZE;
- u32 tot_len = be32_to_cpu(head->length);
- int ret;
- u32 val;
-
- /* we're starting after the header so adjust the length */
- tot_len -= TPM_HEADER_SIZE;
-
- /* skip public */
- val = tpm_buf_read_u16(buf, &offset);
- if (val > tot_len)
- return -EINVAL;
- offset += val;
- /* name */
- val = tpm_buf_read_u16(buf, &offset);
- ret = name_size(&buf->data[offset]);
- if (ret < 0)
- return ret;
-
- if (val != ret)
- return -EINVAL;
-
- memcpy(name, &buf->data[offset], val);
- /* forget the rest */
- return 0;
-}
-
-static int tpm2_read_public(struct tpm_chip *chip, u32 handle, char *name)
-{
+ int rc, name_size_alg;
struct tpm_buf buf;
- int rc;
+
+ if (mso != TPM2_MSO_PERSISTENT && mso != TPM2_MSO_VOLATILE &&
+ mso != TPM2_MSO_NVRAM) {
+ memcpy(name, &handle, sizeof(u32));
+ return sizeof(u32);
+ }
rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_READ_PUBLIC);
if (rc)
return rc;
tpm_buf_append_u32(&buf, handle);
- rc = tpm_transmit_cmd(chip, &buf, 0, "read public");
- if (rc == TPM2_RC_SUCCESS)
- rc = tpm2_parse_read_public(name, &buf);
- tpm_buf_destroy(&buf);
+ rc = tpm_transmit_cmd(chip, &buf, 0, "TPM2_ReadPublic");
+ if (rc) {
+ tpm_buf_destroy(&buf);
+ return tpm_ret_to_err(rc);
+ }
- return rc;
+ /* Skip TPMT_PUBLIC: */
+ offset += tpm_buf_read_u16(&buf, &offset);
+
+ /*
+ * Ensure space for the length field of TPM2B_NAME and hashAlg field of
+ * TPMT_HA (the extra four bytes).
+ */
+ if (offset + 4 > tpm_buf_length(&buf)) {
+ tpm_buf_destroy(&buf);
+ return -EIO;
+ }
+
+ rc = tpm_buf_read_u16(&buf, &offset);
+ name_size_alg = name_size(&buf.data[offset]);
+
+ if (name_size_alg < 0)
+ return name_size_alg;
+
+ if (rc != name_size_alg) {
+ tpm_buf_destroy(&buf);
+ return -EIO;
+ }
+
+ if (offset + rc > tpm_buf_length(&buf)) {
+ tpm_buf_destroy(&buf);
+ return -EIO;
+ }
+
+ memcpy(name, &buf.data[offset], rc);
+ return name_size_alg;
}
#endif /* CONFIG_TCG_TPM2_HMAC */
@@ -243,6 +251,7 @@ int tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
#ifdef CONFIG_TCG_TPM2_HMAC
enum tpm2_mso_type mso = tpm2_handle_mso(handle);
struct tpm2_auth *auth;
+ u16 name_size_alg;
int slot;
int ret;
#endif
@@ -273,8 +282,10 @@ int tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
mso == TPM2_MSO_NVRAM) {
if (!name) {
ret = tpm2_read_public(chip, handle, auth->name[slot]);
- if (ret)
+ if (ret < 0)
goto err;
+
+ name_size_alg = ret;
}
} else {
if (name) {
@@ -286,13 +297,8 @@ int tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf,
}
auth->name_h[slot] = handle;
- if (name) {
- ret = name_size(name);
- if (ret < 0)
- goto err;
-
- memcpy(auth->name[slot], name, ret);
- }
+ if (name)
+ memcpy(auth->name[slot], name, name_size_alg);
#endif
return 0;
--
2.52.0
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