[PATCH] security/loadpin: Replace "kernel_read_file_str[j]" with function "kernel_read_file_id_str(j)".

Subsystems: loadpin security module, security subsystem, the rest

STALE1983d

2 messages, 2 authors, 2021-03-04 · open the first message on its own page

[PATCH] security/loadpin: Replace "kernel_read_file_str[j]" with function "kernel_read_file_id_str(j)".

From: zhaojiele <hidden>
Date: 2021-03-04 08:37:50

Actually Linux kernel already provide function "kernel_read_file_id_str()"
for secure access in "kernel_read_file.h".And, in "parse_exclude()"
function, there is no need for
"BUILD_BUG_ON(ARRAY_SIZE(kernel_read_file_str) <
ARRAY_SIZE(ignore_read_file_id))"
when access array by functon "kernel_read_file_id_str(j)".

Signed-off-by: zhaojiele <redacted>
---
 security/loadpin/loadpin.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c
index b12f7d986b1e..3e8bdcd06600 100644
--- a/security/loadpin/loadpin.c
+++ b/security/loadpin/loadpin.c
@@ -210,8 +210,6 @@ static void __init parse_exclude(void)
 	 */
 	BUILD_BUG_ON(ARRAY_SIZE(exclude_read_files) !=
 		     ARRAY_SIZE(ignore_read_file_id));
-	BUILD_BUG_ON(ARRAY_SIZE(kernel_read_file_str) <
-		     ARRAY_SIZE(ignore_read_file_id));
 
 	for (i = 0; i < ARRAY_SIZE(exclude_read_files); i++) {
 		cur = exclude_read_files[i];
@@ -221,9 +219,9 @@ static void __init parse_exclude(void)
 			continue;
 
 		for (j = 0; j < ARRAY_SIZE(ignore_read_file_id); j++) {
-			if (strcmp(cur, kernel_read_file_str[j]) == 0) {
+			if (strcmp(cur, kernel_read_file_id_str(j)) == 0) {
 				pr_info("excluding: %s\n",
-					kernel_read_file_str[j]);
+					kernel_read_file_id_str(j));
 				ignore_read_file_id[j] = 1;
 				/*
 				 * Can not break, because one read_file_str
-- 
2.25.1

Re: [PATCH] security/loadpin: Replace "kernel_read_file_str[j]" with function "kernel_read_file_id_str(j)".

From: Kees Cook <hidden>
Date: 2021-03-04 23:50:35

On Thu, Mar 04, 2021 at 08:36:38AM +0000, zhaojiele wrote:
quoted hunk
Actually Linux kernel already provide function "kernel_read_file_id_str()"
for secure access in "kernel_read_file.h".And, in "parse_exclude()"
function, there is no need for
"BUILD_BUG_ON(ARRAY_SIZE(kernel_read_file_str) <
ARRAY_SIZE(ignore_read_file_id))"
when access array by functon "kernel_read_file_id_str(j)".

Signed-off-by: zhaojiele <redacted>
---
 security/loadpin/loadpin.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c
index b12f7d986b1e..3e8bdcd06600 100644
--- a/security/loadpin/loadpin.c
+++ b/security/loadpin/loadpin.c
@@ -210,8 +210,6 @@ static void __init parse_exclude(void)
 	 */
 	BUILD_BUG_ON(ARRAY_SIZE(exclude_read_files) !=
 		     ARRAY_SIZE(ignore_read_file_id));
-	BUILD_BUG_ON(ARRAY_SIZE(kernel_read_file_str) <
-		     ARRAY_SIZE(ignore_read_file_id));
This should stay to make sure kernel_read_file_str doesn't diverge from
the other two. However, maybe it should be tightened to:

	BUILD_BUG_ON(ARRAY_SIZE(kernel_read_file_str) - 1 ==
		     ARRAY_SIZE(ignore_read_file_id));
quoted hunk
 
 	for (i = 0; i < ARRAY_SIZE(exclude_read_files); i++) {
 		cur = exclude_read_files[i];
@@ -221,9 +219,9 @@ static void __init parse_exclude(void)
 			continue;
 
 		for (j = 0; j < ARRAY_SIZE(ignore_read_file_id); j++) {
-			if (strcmp(cur, kernel_read_file_str[j]) == 0) {
+			if (strcmp(cur, kernel_read_file_id_str(j)) == 0) {
 				pr_info("excluding: %s\n",
-					kernel_read_file_str[j]);
+					kernel_read_file_id_str(j));
 				ignore_read_file_id[j] = 1;
 				/*
 				 * Can not break, because one read_file_str
I feel funny about making these into function calls when we've already
validated the index, but yeah, that would be fine. Can you send a v2
with the earlier suggestion addressed?

Thanks!

-Kees

-- 
Kees Cook
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