Re: [PATCH ghak81 RFC V1 1/5] audit: normalize loginuid read access

On 2018-05-09 11:13, Paul Moore wrote: > On Fri, May 4, 2018 at 4:54 PM, Richard Guy Briggs <rgb(a)redhat.com&gt; wrote: > > Recognizing that the loginuid is an internal audit value, use an access > > function to retrieve the audit loginuid value for the task rather than > > reaching directly into the task struct to get it. > > > > Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com&gt; > > --- > > kernel/auditsc.c | 16 ++++++++-------- > > 1 file changed, 8 insertions(+), 8 deletions(-) > > > > diff --git a/kernel/auditsc.c b/kernel/auditsc.c > > index 479c031..f3817d0 100644 > > --- a/kernel/auditsc.c > > +++ b/kernel/auditsc.c > > @@ -374,7 +374,7 @@ static int audit_field_compare(struct task_struct *tsk, > > case AUDIT_COMPARE_EGID_TO_OBJ_GID: > > return audit_compare_gid(cred->egid, name, f, ctx); > > case AUDIT_COMPARE_AUID_TO_OBJ_UID: > > - return audit_compare_uid(tsk->loginuid, name, f, ctx); > > + return audit_compare_uid(audit_get_loginuid(tsk), name, f, ctx); > > case AUDIT_COMPARE_SUID_TO_OBJ_UID: > > return audit_compare_uid(cred->suid, name, f, ctx); > > case AUDIT_COMPARE_SGID_TO_OBJ_GID: > > @@ -385,7 +385,7 @@ static int audit_field_compare(struct task_struct *tsk, > > return audit_compare_gid(cred->fsgid, name, f, ctx); > > /* uid comparisons */ > > case AUDIT_COMPARE_UID_TO_AUID: > > - return audit_uid_comparator(cred->uid, f->op, tsk->loginuid); > > + return audit_uid_comparator(cred->uid, f->op, audit_get_loginuid(tsk)); > > case AUDIT_COMPARE_UID_TO_EUID: > > return audit_uid_comparator(cred->uid, f->op, cred->euid); > > case AUDIT_COMPARE_UID_TO_SUID: > > @@ -394,11 +394,11 @@ static int audit_field_compare(struct task_struct *tsk, > > return audit_uid_comparator(cred->uid, f->op, cred->fsuid); > > /* auid comparisons */ > > case AUDIT_COMPARE_AUID_TO_EUID: > > - return audit_uid_comparator(tsk->loginuid, f->op, cred->euid); > > + return audit_uid_comparator(audit_get_loginuid(tsk), f->op, cred->euid); > > case AUDIT_COMPARE_AUID_TO_SUID: > > - return audit_uid_comparator(tsk->loginuid, f->op, cred->suid); > > + return audit_uid_comparator(audit_get_loginuid(tsk), f->op, cred->suid); > > case AUDIT_COMPARE_AUID_TO_FSUID: > > - return audit_uid_comparator(tsk->loginuid, f->op, cred->fsuid); > > + return audit_uid_comparator(audit_get_loginuid(tsk), f->op, cred->fsuid); > > /* euid comparisons */ > > case AUDIT_COMPARE_EUID_TO_SUID: > > return audit_uid_comparator(cred->euid, f->op, cred->suid); > > @@ -611,7 +611,7 @@ static int audit_filter_rules(struct task_struct *tsk, > > result = match_tree_refs(ctx, rule->tree); > > break; > > case AUDIT_LOGINUID: > > - result = audit_uid_comparator(tsk->loginuid, f->op, f->uid); > > + result = audit_uid_comparator(audit_get_loginuid(tsk), f->op, f->uid); > > break; > > case AUDIT_LOGINUID_SET: > > result = audit_comparator(audit_loginuid_set(tsk), f->op, f->val); > > @@ -2287,8 +2287,8 @@ int audit_signal_info(int sig, struct task_struct *t) > > (sig == SIGTERM || sig == SIGHUP || > > sig == SIGUSR1 || sig == SIGUSR2)) { > > audit_sig_pid = task_tgid_nr(tsk); > > - if (uid_valid(tsk->loginuid)) > > - audit_sig_uid = tsk->loginuid; > > + if (uid_valid(audit_get_loginuid(tsk))) > > + audit_sig_uid = audit_get_loginuid(tsk); > > I realize this comment is a little silly given the nature of loginuid, > but if we are going to abstract away loginuid accesses (which I think > is good), we should probably access it once, store it in a local > variable, perform the validity check on the local variable, then > commit the local variable to audit_sig_uid. I realize a TOCTOU > problem is unlikely here, but with this new layer of abstraction it > seems that some additional safety might be a good thing. Ok, I'll just assign it to where it is going and check it there, holding the audit_ctl_lock the whole time, since it should have been done anyways for all of audit_sig_{pid,uid,sid} anyways to get a consistent view from the AUDIT_SIGNAL_INFO fetch.

> > else > > audit_sig_uid = uid; > > security_task_getsecid(tsk, &audit_sig_sid); > paul moore - RGB