Discussion:
[PATCH V2] audit: remove arch_f pointer from struct audit_krule
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Richard Guy Briggs
2018-02-16 11:42:36 UTC
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In the process of trying to track down a potential bug altering the
registered arch for a syscall rule, I propose this simplification of
struct audit_krule that removes an unnecessary member.

The arch_f pointer was added to the struct audit_krule in commit:
e54dc2431d740a79a6bd013babade99d71b1714f ("audit signal recipients")

This is only used on addition and deletion of rules which isn't time
critical and the arch field is the first field if it is present at all,
easily found iterating over the field type. This isn't worth the
additional complexity and storage. Delete the field.

Passes audit-testsuite.
Signed-off-by: Richard Guy Briggs <***@redhat.com>
---
include/linux/audit.h | 1 -
kernel/auditfilter.c | 12 ++++++++----
2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/include/linux/audit.h b/include/linux/audit.h
index af410d9..64a3b0e 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -58,7 +58,6 @@ struct audit_krule {
u32 field_count;
char *filterkey; /* ties events to rules */
struct audit_field *fields;
- struct audit_field *arch_f; /* quick access to arch field */
struct audit_field *inode_f; /* quick access to an inode field */
struct audit_watch *watch; /* associated watch */
struct audit_tree *tree; /* associated watched tree */
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index 739a6d2..a39090d 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -220,7 +220,14 @@ static inline int audit_match_class_bits(int class, u32 *mask)

static int audit_match_signal(struct audit_entry *entry)
{
- struct audit_field *arch = entry->rule.arch_f;
+ int i;
+ struct audit_field *arch = NULL;
+
+ for (i = 0; i < entry->rule.field_count; i++)
+ if (entry->rule.fields[i].type == AUDIT_ARCH) {
+ arch = &entry->rule.fields[i];
+ break;
+ }

if (!arch) {
/* When arch is unspecified, we must check both masks on biarch
@@ -496,9 +503,6 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
if (!gid_valid(f->gid))
goto exit_free;
break;
- case AUDIT_ARCH:
- entry->rule.arch_f = f;
- break;
case AUDIT_SUBJ_USER:
case AUDIT_SUBJ_ROLE:
case AUDIT_SUBJ_TYPE:
--
1.8.3.1
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