A regression was caused by commit 780a7654cee8:
         audit: Make testing for a valid loginuid explicit.
(which in turn attempted to fix a regression caused by e1760bd)

When audit_krule_to_data() fills in the rules to get a listing, there was a
missing clause to convert back from AUDIT_LOGINUID_SET to AUDIT_LOGINUID.

This broke userspace by not returning the same information that was sent and
expected.

The rule:
        auditctl -a exit,never -F auid=-1
gives:
        auditctl -l
                LIST_RULES: exit,never f24=0 syscall=all
when it should give:
                LIST_RULES: exit,never auid=-1 (0xffffffff) syscall=all

Tag it so that it is reported the same way it was set.

Note: move the field validation call ahead of the mutation code to have it work
on the original field set.

Signed-off-by: Richard Guy Briggs <[email protected]>
---
 include/uapi/linux/audit.h |    3 +++
 kernel/auditfilter.c       |   19 +++++++++++++------
 kernel/auditsc.c           |    2 +-
 3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index 4d100c8..860df86 100644
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -274,6 +274,9 @@
 
 #define AUDIT_FILTERKEY        210
 
+/* Flag to indicate legacy AUDIT_LOGINUID unset usage */
+#define AUDIT_LOGINUID_LEGACY          0x80000000
+
 #define AUDIT_NEGATE                   0x80000000
 
 /* These are the supported operators.
diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index 40ed981..39ce3e6 100644
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -438,9 +438,13 @@ static struct audit_entry *audit_data_to_entry(struct 
audit_rule_data *data,
                f->type = data->fields[i];
                f->val = data->values[i];
 
+               err = audit_field_valid(entry, f);
+               if (err)
+                       goto exit_free;
+
                /* Support legacy tests for a valid loginuid */
                if ((f->type == AUDIT_LOGINUID) && (f->val == AUDIT_UID_UNSET)) 
{
-                       f->type = AUDIT_LOGINUID_SET;
+                       f->type = AUDIT_LOGINUID_SET | AUDIT_LOGINUID_LEGACY;
                        f->val = 0;
                }
 
@@ -457,10 +461,6 @@ static struct audit_entry *audit_data_to_entry(struct 
audit_rule_data *data,
                        rcu_read_unlock();
                }
 
-               err = audit_field_valid(entry, f);
-               if (err)
-                       goto exit_free;
-
                err = -EINVAL;
                switch (f->type) {
                case AUDIT_LOGINUID:
@@ -630,6 +630,13 @@ static struct audit_rule_data *audit_krule_to_data(struct 
audit_krule *krule)
                        data->buflen += data->values[i] =
                                audit_pack_string(&bufp, krule->filterkey);
                        break;
+               case AUDIT_LOGINUID_SET | AUDIT_LOGINUID_LEGACY:
+                       if (!f->val) {
+                               data->fields[i] = AUDIT_LOGINUID;
+                               data->values[i] = AUDIT_UID_UNSET;
+                               break;
+                       }
+                       /* fallthrough if set */
                default:
                        data->values[i] = f->val;
                }
@@ -1270,7 +1277,7 @@ static int audit_filter_user_rules(struct audit_krule 
*rule, int type,
                int result = 0;
                u32 sid;
 
-               switch (f->type) {
+               switch (f->type & ~AUDIT_LOGINUID_LEGACY) {
                case AUDIT_PID:
                        pid = task_pid_nr(current);
                        result = audit_comparator(pid, f->op, f->val);
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 8933572..ef25cbc 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -452,7 +452,7 @@ static int audit_filter_rules(struct task_struct *tsk,
                int result = 0;
                pid_t pid;
 
-               switch (f->type) {
+               switch (f->type & ~AUDIT_LOGINUID_LEGACY) {
                case AUDIT_PID:
                        pid = task_pid_nr(tsk);
                        result = audit_comparator(pid, f->op, f->val);
-- 
1.7.1

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