Simplify the creation of the cancel path given the TPM's device path.
Given the path /dev/tpm0 build the path /sys/class/misc/tpm0/device/cancel.
Signed-off-by: Stefan Berger <stef...@linux.vnet.ibm.com>
---
tpm/tpm_passthrough.c | 74 +++++++++++---------------------------------------
1 file changed, 17 insertions(+), 57 deletions(-)
Index: qemu-git.pt/tpm/tpm_passthrough.c
===================================================================
--- qemu-git.pt.orig/tpm/tpm_passthrough.c
+++ qemu-git.pt/tpm/tpm_passthrough.c
@@ -336,45 +336,17 @@ static int tpm_passthrough_test_tpmdev(i
}
/*
- * Check whether the given base path, e.g., /sys/class/misc/tpm0/device,
- * is the sysfs directory of a TPM. A TPM sysfs directory should be uniquely
- * recognizable by the file entries 'pcrs' and 'cancel'.
- * Upon success 'true' is returned and the basebath buffer has '/cancel'
- * appended.
- */
-static bool tpm_passthrough_check_sysfs_cancel(char *basepath, size_t bufsz)
-{
- char path[PATH_MAX];
- struct stat statbuf;
-
- snprintf(path, sizeof(path), "%s/pcrs", basepath);
- if (stat(path, &statbuf) == -1 || !S_ISREG(statbuf.st_mode)) {
- return false;
- }
-
- snprintf(path, sizeof(path), "%s/cancel", basepath);
- if (stat(path, &statbuf) == -1 || !S_ISREG(statbuf.st_mode)) {
- return false;
- }
-
- strncpy(basepath, path, bufsz);
-
- return true;
-}
-
-/*
* Unless path or file descriptor set has been provided by user,
* determine the sysfs cancel file following kernel documentation
* in Documentation/ABI/stable/sysfs-class-tpm.
+ * From /dev/tpm0 create /sys/class/misc/tpm0/device/cancel
*/
static int tpm_passthrough_open_sysfs_cancel(TPMBackend *tb)
{
+ TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
int fd = -1;
- unsigned int idx;
- DIR *pnp_dir;
+ char *dev;
char path[PATH_MAX];
- struct dirent entry, *result;
- int len;
if (tb->cancel_path) {
fd = qemu_open(tb->cancel_path, O_WRONLY);
@@ -385,34 +357,22 @@ static int tpm_passthrough_open_sysfs_ca
return fd;
}
- snprintf(path, sizeof(path), "/sys/class/misc");
- pnp_dir = opendir(path);
- if (pnp_dir != NULL) {
- while (readdir_r(pnp_dir, &entry, &result) == 0 &&
- result != NULL) {
- /*
- * only allow /sys/class/misc/tpm%u type of paths
- */
- if (sscanf(entry.d_name, "tpm%u%n", &idx, &len) < 1 ||
- len <= strlen("tpm") ||
- len != strlen(entry.d_name)) {
- continue;
- }
-
- snprintf(path, sizeof(path), "/sys/class/misc/%s/device",
- entry.d_name);
- if (!tpm_passthrough_check_sysfs_cancel(path, sizeof(path))) {
- continue;
- }
-
+ dev = strrchr(tpm_pt->tpm_dev, '/');
+ if (dev) {
+ dev++;
+ if (snprintf(path, sizeof(path), "/sys/class/misc/%s/device/cancel",
+ dev) < sizeof(path)) {
fd = qemu_open(path, O_WRONLY);
- break;
+ if (fd >= 0) {
+ tb->cancel_path = g_strdup(path);
+ } else {
+ error_report("tpm_passthrough: Could not open TPM cancel "
+ "path %s : %s", path, strerror(errno));
+ }
}
- closedir(pnp_dir);
- }
-
- if (fd >= 0) {
- tb->cancel_path = g_strdup(path);
+ } else {
+ error_report("tpm_passthrough: Bad TPM device path %s",
+ tpm_pt->tpm_dev);
}
return fd;
