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audit: Make testing for a valid loginuid explicit.

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audit rule additions containing "-F auid!=4294967295" were failing
with EINVAL because of a regression caused by e1760bd.

Apparently some userland audit rule sets want to know if loginuid uid
has been set and are using a test for auid != 4294967295 to determine
that.

In practice that is a horrible way to ask if a value has been set,
because it relies on subtle implementation details and will break
every time the uid implementation in the kernel changes.

So add a clean way to test if the audit loginuid has been set, and
silently convert the old idiom to the cleaner and more comprehensible
new idiom.

Cc: <stable@vger.kernel.org> # 3.7
Reported-By: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Tested-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
This commit is contained in:
Eric W. Biederman 2013-04-09 02:22:10 -07:00 committed by Eric Paris
parent b24a30a730
commit 780a7654ce
4 changed files with 25 additions and 3 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

5
include/linux/audit.h
View file

@ -391,6 +391,11 @@ static inline void audit_ptrace(struct task_struct *t)
#define audit_signals 0
#endif /* CONFIG_AUDITSYSCALL */
static inline bool audit_loginuid_set(struct task_struct *tsk)
{
return uid_valid(audit_get_loginuid(tsk));
}
#ifdef CONFIG_AUDIT
/* These are defined in audit.c */
/* Public API */

1
include/uapi/linux/audit.h
View file

@ -246,6 +246,7 @@
#define AUDIT_OBJ_TYPE 21
#define AUDIT_OBJ_LEV_LOW 22
#define AUDIT_OBJ_LEV_HIGH 23
#define AUDIT_LOGINUID_SET 24
/* These are ONLY useful when checking
* at syscall exit time (AUDIT_AT_EXIT). */

17
kernel/auditfilter.c
View file

@ -365,7 +365,10 @@ static int audit_field_valid(struct audit_entry *entry, struct audit_field *f)
case AUDIT_DIR:
case AUDIT_FILTERKEY:
break;
/* arch is only allowed to be = or != */
case AUDIT_LOGINUID_SET:
if ((f->val != 0) && (f->val != 1))
return -EINVAL;
/* FALL THROUGH */
case AUDIT_ARCH:
if (f->op != Audit_not_equal && f->op != Audit_equal)
return -EINVAL;
@ -419,17 +422,23 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
f->lsm_str = NULL;
f->lsm_rule = NULL;
/* Support legacy tests for a valid loginuid */
if ((f->type == AUDIT_LOGINUID) && (f->val == 4294967295)) {
f->type = AUDIT_LOGINUID_SET;
f->val = 0;
}
err = audit_field_valid(entry, f);
if (err)
goto exit_free;
err = -EINVAL;
switch (f->type) {
case AUDIT_LOGINUID:
case AUDIT_UID:
case AUDIT_EUID:
case AUDIT_SUID:
case AUDIT_FSUID:
case AUDIT_LOGINUID:
case AUDIT_OBJ_UID:
f->uid = make_kuid(current_user_ns(), f->val);
if (!uid_valid(f->uid))
@ -1222,6 +1231,10 @@ static int audit_filter_user_rules(struct audit_krule *rule, int type,
result = audit_uid_comparator(audit_get_loginuid(current),
f->op, f->uid);
break;
case AUDIT_LOGINUID_SET:
result = audit_comparator(audit_loginuid_set(current),
f->op, f->val);
break;
case AUDIT_MSGTYPE:
result = audit_comparator(type, f->op, f->val);
break;

5
kernel/auditsc.c
View file

@ -613,6 +613,9 @@ static int audit_filter_rules(struct task_struct *tsk,
if (ctx)
result = audit_uid_comparator(tsk->loginuid, f->op, f->uid);
break;
case AUDIT_LOGINUID_SET:
result = audit_comparator(audit_loginuid_set(tsk), f->op, f->val);
break;
case AUDIT_SUBJ_USER:
case AUDIT_SUBJ_ROLE:
case AUDIT_SUBJ_TYPE:
@ -1970,7 +1973,7 @@ int audit_set_loginuid(kuid_t loginuid)
unsigned int sessionid;
#ifdef CONFIG_AUDIT_LOGINUID_IMMUTABLE
if (uid_valid(task->loginuid))
if (audit_loginuid_set(task))
return -EPERM;
#else /* CONFIG_AUDIT_LOGINUID_IMMUTABLE */
if (!capable(CAP_AUDIT_CONTROL))