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") Reviewed-by: Jonathan McDowell noodles@meta.com Signed-off-by: Jarkko Sakkinen jarkko@kernel.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;