imsm: reading of UEFI variables needs an update

Content of EFI variable is stored in "data" file. Moreover size of data
provided by given variable can be initially validated by reading value of
"size" file.
Function read_efi_variable() has been introduced to simplify the code.

Signed-off-by: Przemyslaw Czarnowski <przemyslaw.hawrylewicz.czarnowski@intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 45 insertions, 17 deletions

diff --git a/platform-intel.c b/platform-intel.c
index fe6785c..cb6c7dc 100644
--- a/platform-intel.c
+++ b/platform-intel.c
@@ -357,13 +357,52 @@ int populated_efi[SYS_DEV_MAX] = { 0, 0 };
 
 static struct imsm_orom imsm_efi[SYS_DEV_MAX];
 
-const struct imsm_orom *find_imsm_efi(enum sys_dev_type hba_id)
+int read_efi_variable(void *buffer, ssize_t buf_size, char *variable_name, struct efi_guid guid)
 {
-	int dfd=-1;
 	char path[PATH_MAX];
 	char buf[GUID_STR_MAX];
-	int n;
+	int dfd;
+	ssize_t n, var_data_len;
+
+	snprintf(path, PATH_MAX, "%s/%s-%s/size", SYS_EFI_VAR_PATH, variable_name, guid_str(buf, guid));
+
+	dprintf("EFI VAR: path=%s\n", path);
+	/* get size of variable data */
+	dfd = open(path, O_RDONLY);
+	if (dfd < 0)
+		return 1;
+
+	n = read(dfd, &buf, sizeof(buf));
+	close(dfd);
+	if (n < 0)
+		return 1;
+	buf[n] = '\0';
+
+	errno = 0;
+	var_data_len = strtoul(buf, NULL, 16);
+	if ((errno == ERANGE && (var_data_len == LONG_MAX))
+            || (errno != 0 && var_data_len == 0))
+		return 1;
 
+	/* get data */
+	snprintf(path, PATH_MAX, "%s/%s-%s/data", SYS_EFI_VAR_PATH, variable_name, guid_str(buf, guid));
+
+	dprintf("EFI VAR: path=%s\n", path);
+	dfd = open(path, O_RDONLY);
+	if (dfd < 0)
+		return 1;
+
+	n = read(dfd, buffer, buf_size);
+	close(dfd);
+	if (n != var_data_len || n < buf_size) {
+		return 1;
+	}
+
+	return 0;
+}
+
+const struct imsm_orom *find_imsm_efi(enum sys_dev_type hba_id)
+{
 	if (hba_id >= SYS_DEV_MAX)
 		return NULL;
 
@@ -383,25 +422,14 @@ const struct imsm_orom *find_imsm_efi(enum sys_dev_type hba_id)
 		return imsm_platform_test(hba_id, &populated_efi[hba_id], &imsm_efi[hba_id]);
 	}
 	/* OROM test is set, return that there is no EFI capabilities */
-	if (check_env("IMSM_TEST_OROM")) {
+	if (check_env("IMSM_TEST_OROM"))
 		return NULL;
-	}
-	if (hba_id == SYS_DEV_SAS)
-		snprintf(path, PATH_MAX, "%s/%s-%s", SYS_EFI_VAR_PATH, SCU_PROP, guid_str(buf, VENDOR_GUID));
-	else
-		snprintf(path, PATH_MAX, "%s/%s-%s", SYS_EFI_VAR_PATH, AHCI_PROP, guid_str(buf, VENDOR_GUID));
 
-	dprintf("EFI VAR: path=%s\n", path);
-	dfd = open(path, O_RDONLY);
-	if (dfd < 0) {
+	if (read_efi_variable(&imsm_efi[hba_id], sizeof(imsm_efi[0]), hba_id == SYS_DEV_SAS ? SCU_PROP : AHCI_PROP, VENDOR_GUID)) {
 		populated_efi[hba_id] = 0;
 		return NULL;
 	}
-	n = read(dfd, &imsm_efi[hba_id], sizeof(imsm_efi[0]));
-	close(dfd);
-	if (n  <  (int) (sizeof(imsm_efi[0]))) {
-		return NULL;
-	}
+
 	populated_efi[hba_id] = 1;
 	return &imsm_efi[hba_id];
 }