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Sync permanent state blob upon GET_STATEBLOB cmd #1122

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Sync permanent state blob upon GET_STATEBLOB cmd #1122

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3 changes: 3 additions & 0 deletions src/swtpm/ctrlchannel.c
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Original file line number Diff line number Diff line change
Expand Up @@ -175,6 +175,9 @@ static int ctrlchannel_return_state(ptm_getstate *pgs, int fd,
if (!blobname)
res = TPM_FAIL;

if (res == 0 && blobtype == PTM_BLOB_TYPE_PERMANENT)
res = SWTPM_NVRAM_Store_Permanent();

if (res == 0 && blobtype == PTM_BLOB_TYPE_VOLATILE)
res = SWTPM_NVRAM_Store_Volatile();

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31 changes: 31 additions & 0 deletions src/swtpm/swtpm_nvstore.c
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Expand Up @@ -481,6 +481,37 @@ TPM_RESULT SWTPM_NVRAM_Store_Volatile(void)
return rc;
}

/*
* Flush libtpms's in-memory PERMANENT state to disk so that the next
* SWTPM_NVRAM_GetStateBlob(PERMANENT) returns a blob consistent with what
* libtpms is actually running. Counterpart to SWTPM_NVRAM_Store_Volatile().
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@stefanberger stefanberger May 8, 2026

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This makes sense and it shouldn't affect anything negatively. However, I was under the impression that the PERMANENT state was always stored whenever a command 'affected' it, e.g. when an NVRAM space was created or undefined etc., and therefore the latest state was always on disk. So I am a bit surprised that this is necessary and that nobody else complained about it so far.

*
* Without this, GET_STATEBLOB(PERMANENT) on the migration-out path reads a
* file that may be missing, empty, or stale relative to libtpms RAM (the
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@stefanberger stefanberger May 8, 2026

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You don't happen to have a reproducer for how we could generate a 'missing' or 'empty file' situation other than using rm intentionally, do you?

* file is only written by _plat__NvCommit() on UT_NV-class commands), and
* an empty/short-read blob then poisons the destination's state restore.
*/
TPM_RESULT SWTPM_NVRAM_Store_Permanent(void)
{
TPM_RESULT rc = 0;
char *name = TPM_PERMANENT_ALL_NAME;
uint32_t tpm_number = 0;
unsigned char *buffer = NULL;
uint32_t buflen = 0;

TPM_DEBUG(" SWTPM_Store_Permanent: Name %s\n", name);
if (rc == 0) {
rc = TPMLIB_GetState(TPMLIB_STATE_PERMANENT, &buffer, &buflen);
}
if (rc == 0 && buflen > 0) {
rc = SWTPM_NVRAM_StoreData(buffer, buflen, tpm_number, name);
}

free(buffer);

return rc;
}

static TPM_RESULT
SWTPM_NVRAM_KeyParamCheck(uint32_t keylen,
enum encryption_mode encmode)
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1 change: 1 addition & 0 deletions src/swtpm/swtpm_nvstore.h
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Expand Up @@ -69,6 +69,7 @@ TPM_RESULT SWTPM_NVRAM_DeleteName(uint32_t tpm_number,
const char *name,
TPM_BOOL mustExist);
TPM_RESULT SWTPM_NVRAM_Store_Volatile(void);
TPM_RESULT SWTPM_NVRAM_Store_Permanent(void);

TPM_RESULT SWTPM_NVRAM_Set_FileKey(const unsigned char *data,
uint32_t length,
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