Author: mjg
Date: Wed Oct 22 01:09:07 2014
New Revision: 273444
URL: https://svnweb.freebsd.org/changeset/base/273444
Log:
Avoid crdup when possible in kern_accessat.
While here tidy up a little.
Modified:
head/sys/kern/vfs_syscalls.c
Modified: head/sys/kern/vfs_syscalls.c
==============================================================================
--- head/sys/kern/vfs_syscalls.c Wed Oct 22 01:04:16 2014
(r273443)
+++ head/sys/kern/vfs_syscalls.c Wed Oct 22 01:09:07 2014
(r273444)
@@ -2064,7 +2064,7 @@ int
kern_accessat(struct thread *td, int fd, char *path, enum uio_seg pathseg,
int flag, int amode)
{
- struct ucred *cred, *tmpcred;
+ struct ucred *cred, *usecred;
struct vnode *vp;
struct nameidata nd;
cap_rights_t rights;
@@ -2075,31 +2075,33 @@ kern_accessat(struct thread *td, int fd,
/*
* Create and modify a temporary credential instead of one that
- * is potentially shared.
+ * is potentially shared (if we need one).
*/
- if (!(flag & AT_EACCESS)) {
- cred = td->td_ucred;
- tmpcred = crdup(cred);
- tmpcred->cr_uid = cred->cr_ruid;
- tmpcred->cr_groups[0] = cred->cr_rgid;
- td->td_ucred = tmpcred;
+ cred = td->td_ucred;
+ if ((flag & AT_EACCESS) == 0 &&
+ ((cred->cr_uid != cred->cr_ruid ||
+ cred->cr_rgid != cred->cr_groups[0]))) {
+ usecred = crdup(cred);
+ usecred->cr_uid = cred->cr_ruid;
+ usecred->cr_groups[0] = cred->cr_rgid;
+ td->td_ucred = usecred;
} else
- cred = tmpcred = td->td_ucred;
+ usecred = cred;
AUDIT_ARG_VALUE(amode);
NDINIT_ATRIGHTS(&nd, LOOKUP, FOLLOW | LOCKSHARED | LOCKLEAF |
AUDITVNODE1, pathseg, path, fd, cap_rights_init(&rights, CAP_FSTAT),
td);
if ((error = namei(&nd)) != 0)
- goto out1;
+ goto out;
vp = nd.ni_vp;
- error = vn_access(vp, amode, tmpcred, td);
+ error = vn_access(vp, amode, usecred, td);
NDFREE(&nd, NDF_ONLY_PNBUF);
vput(vp);
-out1:
- if (!(flag & AT_EACCESS)) {
+out:
+ if (usecred != cred) {
td->td_ucred = cred;
- crfree(tmpcred);
+ crfree(usecred);
}
return (error);
}
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