tpm: dynamically allocate the allocated_banks array

This patch renames active_banks (member of tpm_chip) to allocated_banks,
stores the number of allocated PCR banks in nr_allocated_banks (new member
of tpm_chip), and replaces the static array with a pointer to a dynamically
allocated array.

tpm2_get_pcr_allocation() determines if a PCR bank is allocated by checking
the mask in the TPML_PCR_SELECTION structure returned by the TPM for
TPM2_Get_Capability(). If a bank is not allocated, the TPM returns that
bank in TPML_PCR_SELECTION, with all bits in the mask set to zero. In this
case, the bank is not included in chip->allocated_banks, to avoid that TPM
driver users unnecessarily calculate a digest for that bank.

One PCR bank with algorithm set to SHA1 is always allocated for TPM 1.x.

As a consequence of the introduction of nr_allocated_banks,
tpm_pcr_extend() does not check anymore if the algorithm stored in tpm_chip
is equal to zero.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>

5 files changed, 44 insertions, 19 deletions

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 4eb48cf6a03a..8804c9e916fd 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -266,6 +266,7 @@ static void tpm_dev_release(struct device *dev)
         kfree(chip->log.bios_event_log);
         kfree(chip->work_space.context_buf);
         kfree(chip->work_space.session_buf);
+        kfree(chip->allocated_banks);
         kfree(chip);
 }
 
diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 498809bf1bf0..2b31eff06b0e 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -318,8 +318,7 @@ EXPORT_SYMBOL_GPL(tpm_pcr_read);
 int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash)
 {
         int rc;
-        struct tpm2_digest digest_list[ARRAY_SIZE(chip->active_banks)];
-        u32 count = 0;
+        struct tpm2_digest *digest_list;
         int i;
 
         chip = tpm_find_get_ops(chip);
@@ -327,16 +326,19 @@ int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, const u8 *hash)
                 return -ENODEV;
 
         if (chip->flags & TPM_CHIP_FLAG_TPM2) {
-                memset(digest_list, 0, sizeof(digest_list));
+                digest_list = kcalloc(chip->nr_allocated_banks,
+                                      sizeof(*digest_list), GFP_KERNEL);
+                if (!digest_list)
+                        return -ENOMEM;
 
-                for (i = 0; i < ARRAY_SIZE(chip->active_banks) &&
-                            chip->active_banks[i] != TPM2_ALG_ERROR; i++) {
-                        digest_list[i].alg_id = chip->active_banks[i];
+                for (i = 0; i < chip->nr_allocated_banks; i++) {
+                        digest_list[i].alg_id = chip->allocated_banks[i];
                         memcpy(digest_list[i].digest, hash, TPM_DIGEST_SIZE);
-                        count++;
                 }
 
-                rc = tpm2_pcr_extend(chip, pcr_idx, count, digest_list);
+                rc = tpm2_pcr_extend(chip, pcr_idx, chip->nr_allocated_banks,
+                                     digest_list);
+                kfree(digest_list);
                 tpm_put_ops(chip);
                 return rc;
         }
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index 183e2b93e0fe..cd330ace6248 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -257,7 +257,8 @@ struct tpm_chip {
         const struct attribute_group *groups[3];
         unsigned int groups_cnt;
 
-        u16 active_banks[7];
+        u32 nr_allocated_banks;
+        u16 *allocated_banks;
 #ifdef CONFIG_ACPI
         acpi_handle acpi_dev_handle;
         char ppi_version[TPM_PPI_VERSION_LEN + 1];
diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c
index ec5f3693c096..e7d3228a0f37 100644
--- a/drivers/char/tpm/tpm1-cmd.c
+++ b/drivers/char/tpm/tpm1-cmd.c
@@ -696,6 +696,16 @@ int tpm1_auto_startup(struct tpm_chip *chip)
                 goto out;
         }
 
+        chip->allocated_banks = kcalloc(1, sizeof(*chip->allocated_banks),
+                                        GFP_KERNEL);
+        if (!chip->allocated_banks) {
+                rc = -ENOMEM;
+                goto out;
+        }
+
+        chip->allocated_banks[0] = TPM2_ALG_SHA1;
+        chip->nr_allocated_banks = 1;
+
         return rc;
 out:
         if (rc > 0)
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 971d46efaca5..bd20b9a61fc0 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -234,7 +234,7 @@ int tpm2_pcr_extend(struct tpm_chip *chip, u32 pcr_idx, u32 count,
         int i;
         int j;
 
-        if (count > ARRAY_SIZE(chip->active_banks))
+        if (count > chip->nr_allocated_banks)
                 return -EINVAL;
 
         rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_PCR_EXTEND);
@@ -808,8 +808,10 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
         void *marker;
         void *end;
         void *pcr_select_offset;
-        unsigned int count;
         u32 sizeof_pcr_selection;
+        u32 nr_possible_banks;
+        u32 nr_alloc_banks = 0;
+        u16 hash_alg;
         u32 rsp_len;
         int rc;
         int i = 0;
@@ -826,11 +828,14 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
         if (rc)
                 goto out;
 
-        count = be32_to_cpup(
+        nr_possible_banks = be32_to_cpup(
                 (__be32 *)&buf.data[TPM_HEADER_SIZE + 5]);
 
-        if (count > ARRAY_SIZE(chip->active_banks)) {
-                rc = -ENODEV;
+        chip->allocated_banks = kcalloc(nr_possible_banks,
+                                        sizeof(*chip->allocated_banks),
+                                        GFP_KERNEL);
+        if (!chip->allocated_banks) {
+                rc = -ENOMEM;
                 goto out;
         }
 
@@ -839,7 +844,7 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
         rsp_len = be32_to_cpup((__be32 *)&buf.data[2]);
         end = &buf.data[rsp_len];
 
-        for (i = 0; i < count; i++) {
+        for (i = 0; i < nr_possible_banks; i++) {
                 pcr_select_offset = marker +
                         offsetof(struct tpm2_pcr_selection, size_of_select);
                 if (pcr_select_offset >= end) {
@@ -848,17 +853,23 @@ static ssize_t tpm2_get_pcr_allocation(struct tpm_chip *chip)
                 }
 
                 memcpy(&pcr_selection, marker, sizeof(pcr_selection));
-                chip->active_banks[i] = be16_to_cpu(pcr_selection.hash_alg);
+                hash_alg = be16_to_cpu(pcr_selection.hash_alg);
+
+                pcr_select_offset = memchr_inv(pcr_selection.pcr_select, 0,
+                                               pcr_selection.size_of_select);
+                if (pcr_select_offset) {
+                        chip->allocated_banks[nr_alloc_banks] = hash_alg;
+                        nr_alloc_banks++;
+                }
+
                 sizeof_pcr_selection = sizeof(pcr_selection.hash_alg) +
                         sizeof(pcr_selection.size_of_select) +
                         pcr_selection.size_of_select;
                 marker = marker + sizeof_pcr_selection;
         }
 
+        chip->nr_allocated_banks = nr_alloc_banks;
 out:
-        if (i < ARRAY_SIZE(chip->active_banks))
-                chip->active_banks[i] = TPM2_ALG_ERROR;
-
         tpm_buf_destroy(&buf);
 
         return rc;