100 lines
3.5 KiB
Diff
100 lines
3.5 KiB
Diff
From 1ad7c482a722a7c918609390e479c9dd4f717539 Mon Sep 17 00:00:00 2001
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From: Jarkko Sakkinen <jarkko@kernel.org>
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Date: Mon, 7 Apr 2025 15:28:05 +0300
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Subject: tpm: Mask TPM RC in tpm2_start_auth_session()
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tpm2_start_auth_session() does not mask TPM RC correctly from the callers:
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[ 28.766528] tpm tpm0: A TPM error (2307) occurred start auth session
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Process TPM RCs inside tpm2_start_auth_session(), and map them to POSIX
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error codes.
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Cc: stable@vger.kernel.org # v6.10+
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Fixes: 699e3efd6c64 ("tpm: Add HMAC session start and end functions")
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Reported-by: Herbert Xu <herbert@gondor.apana.org.au>
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Closes: https://lore.kernel.org/linux-integrity/Z_NgdRHuTKP6JK--@gondor.apana.org.au/
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Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
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---
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drivers/char/tpm/tpm2-sessions.c | 20 ++++++--------------
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include/linux/tpm.h | 21 +++++++++++++++++++++
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2 files changed, 27 insertions(+), 14 deletions(-)
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--- a/drivers/char/tpm/tpm2-sessions.c
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+++ b/drivers/char/tpm/tpm2-sessions.c
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@@ -40,11 +40,6 @@
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*
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* These are the usage functions:
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*
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- * tpm2_start_auth_session() which allocates the opaque auth structure
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- * and gets a session from the TPM. This must be called before
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- * any of the following functions. The session is protected by a
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- * session_key which is derived from a random salt value
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- * encrypted to the NULL seed.
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* tpm2_end_auth_session() kills the session and frees the resources.
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* Under normal operation this function is done by
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* tpm_buf_check_hmac_response(), so this is only to be used on
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@@ -963,16 +958,13 @@ err:
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}
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/**
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- * tpm2_start_auth_session() - create a HMAC authentication session with the TPM
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- * @chip: the TPM chip structure to create the session with
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+ * tpm2_start_auth_session() - Create an a HMAC authentication session
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+ * @chip: A TPM chip
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*
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- * This function loads the NULL seed from its saved context and starts
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- * an authentication session on the null seed, fills in the
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- * @chip->auth structure to contain all the session details necessary
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- * for performing the HMAC, encrypt and decrypt operations and
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- * returns. The NULL seed is flushed before this function returns.
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+ * Loads the ephemeral key (null seed), and starts an HMAC authenticated
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+ * session. The null seed is flushed before the return.
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*
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- * Return: zero on success or actual error encountered.
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+ * Returns zero on success, or a POSIX error code.
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*/
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int tpm2_start_auth_session(struct tpm_chip *chip)
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{
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@@ -1024,7 +1016,7 @@ int tpm2_start_auth_session(struct tpm_c
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/* hash algorithm for session */
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tpm_buf_append_u16(&buf, TPM_ALG_SHA256);
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- rc = tpm_transmit_cmd(chip, &buf, 0, "start auth session");
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+ rc = tpm_to_ret(tpm_transmit_cmd(chip, &buf, 0, "StartAuthSession"));
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tpm2_flush_context(chip, null_key);
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if (rc == TPM2_RC_SUCCESS)
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--- a/include/linux/tpm.h
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+++ b/include/linux/tpm.h
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@@ -257,8 +257,29 @@ enum tpm2_return_codes {
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TPM2_RC_TESTING = 0x090A, /* RC_WARN */
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TPM2_RC_REFERENCE_H0 = 0x0910,
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TPM2_RC_RETRY = 0x0922,
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+ TPM2_RC_SESSION_MEMORY = 0x0903,
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};
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+/*
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+ * Convert a return value from tpm_transmit_cmd() to a POSIX return value. The
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+ * fallback return value is -EFAULT.
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+ */
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+static inline ssize_t tpm_to_ret(ssize_t ret)
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+{
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+ /* Already a POSIX error: */
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+ if (ret < 0)
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+ return ret;
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+
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+ switch (ret) {
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+ case TPM2_RC_SUCCESS:
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+ return 0;
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+ case TPM2_RC_SESSION_MEMORY:
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+ return -ENOMEM;
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+ default:
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+ return -EFAULT;
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+ }
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+}
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+
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enum tpm2_command_codes {
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TPM2_CC_FIRST = 0x011F,
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TPM2_CC_HIERARCHY_CONTROL = 0x0121,
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