'tpm2_read_public' has some rudimentary range checks but does not explicitly check that both fields of TPMT_HA actually fit within the buffer size limits.

Introduce a new function 'tpm2_resolve_name' to address all the possible out-of-range issues, and in addition do handle type validation.

Cc: stable@vger.kernel.org # v6.10+ Fixes: d0a25bb961e6 ("tpm: Add HMAC session name/handle append") Signed-off-by: Jarkko Sakkinen jarkko@kernel.org --- drivers/char/tpm/tpm2-cmd.c | 95 ++++++++++++++++++++++++++++++++ drivers/char/tpm/tpm2-sessions.c | 78 +------------------------- include/linux/tpm.h | 2 + 3 files changed, 98 insertions(+), 77 deletions(-)

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index e63254135a74..d51272573004 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); @@ -769,3 +772,95 @@ int tpm2_find_cc(struct tpm_chip *chip, u32 cc)

return -1; } + +/** + * tpm2_name_size() - Resolve size of a TPMT_HA instance + * @name: Pointer to TPMT_HA structure extracted from TPM2B_NAME. + * + * Calculate size of the TPMT_HA payload of TPM2B_NAME. It is used with + * transient keys, persistent and NV indexes. + * + * Returns zero when the hash size was successfully calculated. + * Returns -EINVAL when the hash algorithm was not recognized. + */ +int tpm2_name_size(const u8 *name) +{ + u16 hash_alg = get_unaligned_be16(name); + + switch (hash_alg) { + case TPM_ALG_SHA1: + return SHA1_DIGEST_SIZE + 2; + case TPM_ALG_SHA256: + return SHA256_DIGEST_SIZE + 2; + case TPM_ALG_SHA384: + return SHA384_DIGEST_SIZE + 2; + case TPM_ALG_SHA512: + return SHA512_DIGEST_SIZE + 2; + case TPM_ALG_SM3_256: + return SM3256_DIGEST_SIZE + 2; + } + + return -EINVAL; +} + +/** + * tpm2_resolve_name - Resolve TPM object's name from the public area + * @handle: Persistent, transient or nv handle. + * + * Returns zero on success. + * Returns -EINVAL when handles are not of valid type. + * Returns -EIO if the transmission fails or response is malformed. + */ +int tpm2_resolve_name(struct tpm_chip *chip, u32 handle, void *name) +{ + u32 mso = tpm2_handle_mso(handle); + off_t offset = TPM_HEADER_SIZE; + int name_size, name_size_2; + struct tpm_buf buf; + int rc; + + if (mso != TPM2_MSO_PERSISTENT && mso != TPM2_MSO_VOLATILE && + mso != TPM2_MSO_NVRAM) + return -EINVAL; + + 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, "TPM2_ReadPublic"); + if (rc) { + tpm_buf_destroy(&buf); + return tpm_ret_to_err(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; + } + + name_size = tpm_buf_read_u16(&buf, &offset); + name_size_2 = tpm2_name_size(&buf.data[offset]); + + if (name_size != name_size_2) { + tpm_buf_destroy(&buf); + return -EIO; + } + + if (offset + name_size > tpm_buf_length(&buf)) { + tpm_buf_destroy(&buf); + return -EIO; + } + + memcpy(name, &buf.data[offset], name_size); + return 0; +} +EXPORT_SYMBOL_GPL(tpm2_resolve_name); diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c index 82b9d9096fd1..7c85333d47c4 100644 --- a/drivers/char/tpm/tpm2-sessions.c +++ b/drivers/char/tpm/tpm2-sessions.c @@ -140,82 +140,6 @@ struct tpm2_auth { u8 name[AUTH_MAX_NAMES][2 + SHA512_DIGEST_SIZE]; };

-#ifdef CONFIG_TCG_TPM2_HMAC - -/* - * Calculate size of the TPMT_HA payload of TPM2B_NAME. - */ -static int tpm2_name_size(const u8 *name) -{ - u16 hash_alg = get_unaligned_be16(name); - - switch (hash_alg) { - case TPM_ALG_SHA1: - return SHA1_DIGEST_SIZE + 2; - case TPM_ALG_SHA256: - return SHA256_DIGEST_SIZE + 2; - case TPM_ALG_SHA384: - return SHA384_DIGEST_SIZE + 2; - case TPM_ALG_SHA512: - return SHA512_DIGEST_SIZE + 2; - case TPM_ALG_SM3_256: - return SM3256_DIGEST_SIZE + 2; - } - - return -EINVAL; -} - -static int tpm2_parse_read_public(char *name, struct tpm_buf *buf) -{ - struct tpm_header *head = (struct tpm_header *)buf->data; - off_t offset = TPM_HEADER_SIZE; - u32 tot_len = be32_to_cpu(head->length); - int name_size_alg; - 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); - name_size_alg = tpm2_name_size(&buf->data[offset]); - if (name_size_alg < 0) - return name_size_alg; - - if (val != name_size_alg) - 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) -{ - struct tpm_buf buf; - int rc; - - 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); - - return rc; -} -#endif /* CONFIG_TCG_TPM2_HMAC */ - /** * tpm_buf_append_name() - add a handle area to the buffer * @chip: the TPM chip structure @@ -272,7 +196,7 @@ int tpm_buf_append_name(struct tpm_chip *chip, struct tpm_buf *buf, mso == TPM2_MSO_VOLATILE || mso == TPM2_MSO_NVRAM) { if (!name) { - ret = tpm2_read_public(chip, handle, auth->name[slot]); + ret = tpm2_resolve_name(chip, handle, auth->name[slot]); if (ret) return tpm_ret_to_err(ret); } diff --git a/include/linux/tpm.h b/include/linux/tpm.h index 1a59f0190eb3..727e6c26feeb 100644 --- a/include/linux/tpm.h +++ b/include/linux/tpm.h @@ -477,6 +477,8 @@ extern int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, extern int tpm_get_random(struct tpm_chip *chip, u8 *data, size_t max); extern struct tpm_chip *tpm_default_chip(void); void tpm2_flush_context(struct tpm_chip *chip, u32 handle); +int tpm2_name_size(const u8 *name); +int tpm2_resolve_name(struct tpm_chip *chip, u32 handle, void *name);

static inline void tpm_buf_append_empty_auth(struct tpm_buf *buf, u32 handle) {