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@vger.kernel.org # v6.10+
Fixes: d0a25bb961e6 ("tpm: Add HMAC session name/handle append")
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Reviewed-by: Jonathan McDowell <noodles@meta.com>

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index be4a9c7f2e1a832bb9f2a3bbb9dbe50e9fa39202..34e3599f094f3bea5aec998f56d2a05b2ba1f33f 100644 (file)
--- 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 385014dbca39d9efd26bfd9ba6c650aa87e190dd..3f389e2f6f580b58a4e7e5754f0c8ad7fadb9c67 100644 (file)
--- 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;