audit: Make testing for a valid loginuid explicit.

commit 780a7654cee8d61819512385e778e4827db4bfbc upstream.

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.

RGB notes: In upstream, audit_rule_to_entry has been refactored out.
This is patch is already upstream in functionally the same form in
commit 780a7654cee8d61819512385e778e4827db4bfbc .  The decimal constant
was cast to unsigned to quiet GCC 4.6 32-bit architecture warnings.

Reported-By: Steve Grubb <sgrubb@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>
Backported-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/linux/audit.h b/include/linux/audit.h
index 37464c592c92819ec3305138dc57cbedf522c545..b4086cf9b7e56b493df81f8cd463956304430b9a 100644 (file)
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -390,6 +390,11 @@ 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 */

diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
index 9f096f1c0907b7056bcbe396783fdb2237724a65..9554a19d34140524c8d4eba68c10539cd48fd2ce 100644 (file)
--- a/include/uapi/linux/audit.h
+++ b/include/uapi/linux/audit.h
@@ -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). */

diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
index f9fc54bbe06faa3e845e19871d15ace3e6c5e1b3..2bf508dfec151e54a587776622a82481760119fd 100644 (file)
--- a/kernel/auditfilter.c
+++ b/kernel/auditfilter.c
@@ -345,6 +345,12 @@ static struct audit_entry *audit_rule_to_entry(struct audit_rule *rule)
                f->uid = INVALID_UID;
                f->gid = INVALID_GID;
 
+               /* Support legacy tests for a valid loginuid */
+               if ((f->type == AUDIT_LOGINUID) && (f->val == 4294967295U)) {
+                       f->type = AUDIT_LOGINUID_SET;
+                       f->val = 0;
+               }
+
                err = -EINVAL;
                if (f->op == Audit_bad)
                        goto exit_free;
@@ -352,6 +358,12 @@ static struct audit_entry *audit_rule_to_entry(struct audit_rule *rule)
                switch(f->type) {
                default:
                        goto exit_free;
+               case AUDIT_LOGINUID_SET:
+                       if ((f->val != 0) && (f->val != 1))
+                               goto exit_free;
+                       if (f->op != Audit_not_equal && f->op != Audit_equal)
+                               goto exit_free;
+                       break;
                case AUDIT_UID:
                case AUDIT_EUID:
                case AUDIT_SUID:
@@ -459,7 +471,20 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
                f->gid = INVALID_GID;
                f->lsm_str = NULL;
                f->lsm_rule = NULL;
-               switch(f->type) {
+
+               /* Support legacy tests for a valid loginuid */
+               if ((f->type == AUDIT_LOGINUID) && (f->val == 4294967295U)) {
+                       f->type = AUDIT_LOGINUID_SET;
+                       f->val = 0;
+               }
+
+               switch (f->type) {
+               case AUDIT_LOGINUID_SET:
+                       if ((f->val != 0) && (f->val != 1))
+                               goto exit_free;
+                       if (f->op != Audit_not_equal && f->op != Audit_equal)
+                               goto exit_free;
+                       break;
                case AUDIT_UID:
                case AUDIT_EUID:
                case AUDIT_SUID:
@@ -1378,6 +1403,10 @@ static int audit_filter_user_rules(struct audit_krule *rule,
                        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_SUBJ_USER:
                case AUDIT_SUBJ_ROLE:
                case AUDIT_SUBJ_TYPE:

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index a371f857a0a908a40a960511bf047d81ade471a9..c4b72b0e07cb69c862bca0a286595bbfacd56809 100644 (file)
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -742,6 +742,9 @@ 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:
@@ -2309,7 +2312,7 @@ 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))