When repeatedly accessing a thread credential, cache the credential

pointer in a local thread.  While this is unlikely to significantly
improve performance given modern compiler behavior, it makes the code
more readable and reduces diffs to the Mac OS X version of the same
code (which stores things in creds in the same way, but where the
cred for a thread is reached quite differently).

Discussed with: sson
MFC after:      1 month
Sponsored by:   Apple Inc.
Obtained from:	TrustedBSD Project

3 files changed, 48 insertions, 42 deletions

diff --git a/sys/security/audit/audit.c b/sys/security/audit/audit.c
index 18b69d1..4ea76c6 100644
--- a/sys/security/audit/audit.c
+++ b/sys/security/audit/audit.c
@@ -207,6 +207,7 @@ audit_record_ctor(void *mem, int size, void *arg, int flags)
 {
 	struct kaudit_record *ar;
 	struct thread *td;
+	struct ucred *cred;
 
 	KASSERT(sizeof(*ar) == size, ("audit_record_ctor: wrong size"));
 
@@ -219,15 +220,16 @@ audit_record_ctor(void *mem, int size, void *arg, int flags)
 	/*
 	 * Export the subject credential.
 	 */
-	cru2x(td->td_ucred, &ar->k_ar.ar_subj_cred);
-	ar->k_ar.ar_subj_ruid = td->td_ucred->cr_ruid;
-	ar->k_ar.ar_subj_rgid = td->td_ucred->cr_rgid;
-	ar->k_ar.ar_subj_egid = td->td_ucred->cr_groups[0];
-	ar->k_ar.ar_subj_auid = td->td_ucred->cr_audit.ai_auid;
-	ar->k_ar.ar_subj_asid = td->td_ucred->cr_audit.ai_asid;
+	cred = td->td_ucred;
+	cru2x(cred, &ar->k_ar.ar_subj_cred);
+	ar->k_ar.ar_subj_ruid = cred->cr_ruid;
+	ar->k_ar.ar_subj_rgid = cred->cr_rgid;
+	ar->k_ar.ar_subj_egid = cred->cr_groups[0];
+	ar->k_ar.ar_subj_auid = cred->cr_audit.ai_auid;
+	ar->k_ar.ar_subj_asid = cred->cr_audit.ai_asid;
 	ar->k_ar.ar_subj_pid = td->td_proc->p_pid;
-	ar->k_ar.ar_subj_amask = td->td_ucred->cr_audit.ai_mask;
-	ar->k_ar.ar_subj_term_addr = td->td_ucred->cr_audit.ai_termid;
+	ar->k_ar.ar_subj_amask = cred->cr_audit.ai_mask;
+	ar->k_ar.ar_subj_term_addr = cred->cr_audit.ai_termid;
 	return (0);
 }
 
@@ -631,6 +633,7 @@ audit_proc_coredump(struct thread *td, char *path, int errcode)
 {
 	struct kaudit_record *ar;
 	struct au_mask *aumask;
+	struct ucred *cred;
 	au_class_t class;
 	int ret, sorf;
 	char **pathp;
@@ -641,11 +644,12 @@ audit_proc_coredump(struct thread *td, char *path, int errcode)
 	/*
 	 * Make sure we are using the correct preselection mask.
 	 */
-	auid = td->td_ucred->cr_audit.ai_auid;
+	cred = td->td_ucred;
+	auid = cred->cr_audit.ai_auid;
 	if (auid == AU_DEFAUDITID)
 		aumask = &audit_nae_mask;
 	else
-		aumask = &td->td_ucred->cr_audit.ai_mask;
+		aumask = &cred->cr_audit.ai_mask;
 	/*
 	 * It's possible for coredump(9) generation to fail.  Make sure that
 	 * we handle this case correctly for preselection.
@@ -658,6 +662,7 @@ audit_proc_coredump(struct thread *td, char *path, int errcode)
 	if (au_preselect(AUE_CORE, class, aumask, sorf) == 0 &&
 	    audit_pipe_preselect(auid, AUE_CORE, class, sorf, 0) == 0)
 		return;
+
 	/*
 	 * If we are interested in seeing this audit record, allocate it.
 	 * Where possible coredump records should contain a pathname and arg32
diff --git a/sys/security/audit/audit_arg.c b/sys/security/audit/audit_arg.c
index f938881..2007041 100644
--- a/sys/security/audit/audit_arg.c
+++ b/sys/security/audit/audit_arg.c
@@ -356,6 +356,7 @@ void
 audit_arg_process(struct proc *p)
 {
 	struct kaudit_record *ar;
+	struct ucred *cred;
 
 	KASSERT(p != NULL, ("audit_arg_process: p == NULL"));
 
@@ -365,13 +366,14 @@ audit_arg_process(struct proc *p)
 	if (ar == NULL)
 		return;
 
-	ar->k_ar.ar_arg_auid = p->p_ucred->cr_audit.ai_auid;
-	ar->k_ar.ar_arg_euid = p->p_ucred->cr_uid;
-	ar->k_ar.ar_arg_egid = p->p_ucred->cr_groups[0];
-	ar->k_ar.ar_arg_ruid = p->p_ucred->cr_ruid;
-	ar->k_ar.ar_arg_rgid = p->p_ucred->cr_rgid;
-	ar->k_ar.ar_arg_asid = p->p_ucred->cr_audit.ai_asid;
-	ar->k_ar.ar_arg_termid_addr = p->p_ucred->cr_audit.ai_termid;
+	cred = p->p_ucred;
+	ar->k_ar.ar_arg_auid = cred->cr_audit.ai_auid;
+	ar->k_ar.ar_arg_euid = cred->cr_uid;
+	ar->k_ar.ar_arg_egid = cred->cr_groups[0];
+	ar->k_ar.ar_arg_ruid = cred->cr_ruid;
+	ar->k_ar.ar_arg_rgid = cred->cr_rgid;
+	ar->k_ar.ar_arg_asid = cred->cr_audit.ai_asid;
+	ar->k_ar.ar_arg_termid_addr = cred->cr_audit.ai_termid;
 	ar->k_ar.ar_arg_pid = p->p_pid;
 	ARG_SET_VALID(ar, ARG_AUID | ARG_EUID | ARG_EGID | ARG_RUID |
 	    ARG_RGID | ARG_ASID | ARG_TERMID_ADDR | ARG_PID | ARG_PROCESS);
diff --git a/sys/security/audit/audit_syscalls.c b/sys/security/audit/audit_syscalls.c
index cf88c93..83291b3 100644
--- a/sys/security/audit/audit_syscalls.c
+++ b/sys/security/audit/audit_syscalls.c
@@ -157,7 +157,7 @@ free_out:
 int
 auditon(struct thread *td, struct auditon_args *uap)
 {
-	struct ucred *newcred, *oldcred;
+	struct ucred *cred, *newcred, *oldcred;
 	int error;
 	union auditon_udata udata;
 	struct proc *tp;
@@ -321,22 +321,21 @@ auditon(struct thread *td, struct auditon_args *uap)
 			PROC_UNLOCK(tp);
 			return (error);
 		}
-		if (tp->p_ucred->cr_audit.ai_termid.at_type == AU_IPv6) {
+		cred = tp->p_ucred;
+		if (cred->cr_audit.ai_termid.at_type == AU_IPv6) {
 			PROC_UNLOCK(tp);
 			return (EINVAL);
 		}
-		udata.au_aupinfo.ap_auid =
-		    tp->p_ucred->cr_audit.ai_auid;
+		udata.au_aupinfo.ap_auid = cred->cr_audit.ai_auid;
 		udata.au_aupinfo.ap_mask.am_success =
-		    tp->p_ucred->cr_audit.ai_mask.am_success;
+		    cred->cr_audit.ai_mask.am_success;
 		udata.au_aupinfo.ap_mask.am_failure =
-		    tp->p_ucred->cr_audit.ai_mask.am_failure;
+		    cred->cr_audit.ai_mask.am_failure;
 		udata.au_aupinfo.ap_termid.machine =
-		    tp->p_ucred->cr_audit.ai_termid.at_addr[0];
+		    cred->cr_audit.ai_termid.at_addr[0];
 		udata.au_aupinfo.ap_termid.port =
-		    (dev_t)tp->p_ucred->cr_audit.ai_termid.at_port;
-		udata.au_aupinfo.ap_asid =
-		    tp->p_ucred->cr_audit.ai_asid;
+		    (dev_t)cred->cr_audit.ai_termid.at_port;
+		udata.au_aupinfo.ap_asid = cred->cr_audit.ai_asid;
 		PROC_UNLOCK(tp);
 		break;
 
@@ -381,16 +380,14 @@ auditon(struct thread *td, struct auditon_args *uap)
 			return (ESRCH);
 		if ((tp = pfind(udata.au_aupinfo_addr.ap_pid)) == NULL)
 			return (ESRCH);
-		udata.au_aupinfo_addr.ap_auid =
-		    tp->p_ucred->cr_audit.ai_auid;
+		cred = tp->p_ucred;
+		udata.au_aupinfo_addr.ap_auid = cred->cr_audit.ai_auid;
 		udata.au_aupinfo_addr.ap_mask.am_success =
-		    tp->p_ucred->cr_audit.ai_mask.am_success;
+		    cred->cr_audit.ai_mask.am_success;
 		udata.au_aupinfo_addr.ap_mask.am_failure =
-		    tp->p_ucred->cr_audit.ai_mask.am_failure;
-		udata.au_aupinfo_addr.ap_termid =
-		    tp->p_ucred->cr_audit.ai_termid;
-		udata.au_aupinfo_addr.ap_asid =
-		    tp->p_ucred->cr_audit.ai_asid;
+		    cred->cr_audit.ai_mask.am_failure;
+		udata.au_aupinfo_addr.ap_termid = cred->cr_audit.ai_termid;
+		udata.au_aupinfo_addr.ap_asid = cred->cr_audit.ai_asid;
 		PROC_UNLOCK(tp);
 		break;
 
@@ -503,21 +500,23 @@ int
 getaudit(struct thread *td, struct getaudit_args *uap)
 {
 	struct auditinfo ai;
+	struct ucred *cred;
 	int error;
 
-	if (jailed(td->td_ucred))
+	cred = td->td_ucred;
+	if (jailed(cred))
 		return (ENOSYS);
 	error = priv_check(td, PRIV_AUDIT_GETAUDIT);
 	if (error)
 		return (error);
-	if (td->td_ucred->cr_audit.ai_termid.at_type == AU_IPv6)
+	if (cred->cr_audit.ai_termid.at_type == AU_IPv6)
 		return (ERANGE);
 	bzero(&ai, sizeof(ai));
-	ai.ai_auid = td->td_ucred->cr_audit.ai_auid;
-	ai.ai_mask = td->td_ucred->cr_audit.ai_mask;
-	ai.ai_asid = td->td_ucred->cr_audit.ai_asid;
-	ai.ai_termid.machine = td->td_ucred->cr_audit.ai_termid.at_addr[0];
-	ai.ai_termid.port = td->td_ucred->cr_audit.ai_termid.at_port;
+	ai.ai_auid = cred->cr_audit.ai_auid;
+	ai.ai_mask = cred->cr_audit.ai_mask;
+	ai.ai_asid = cred->cr_audit.ai_asid;
+	ai.ai_termid.machine = cred->cr_audit.ai_termid.at_addr[0];
+	ai.ai_termid.port = cred->cr_audit.ai_termid.at_port;
 	return (copyout(&ai, uap->auditinfo, sizeof(ai)));
 }