Rework the credential code to support larger values of NGROUPS and

NGROUPS_MAX, eliminate ABI dependencies on them, and raise the to 1024
and 1023 respectively.  (Previously they were equal, but under a close
reading of POSIX, NGROUPS_MAX was defined to be too large by 1 since it
is the number of supplemental groups, not total number of groups.)

The bulk of the change consists of converting the struct ucred member
cr_groups from a static array to a pointer.  Do the equivalent in
kinfo_proc.

Introduce new interfaces crcopysafe() and crsetgroups() for duplicating
a process credential before modifying it and for setting group lists
respectively.  Both interfaces take care for the details of allocating
groups array. crsetgroups() takes care of truncating the group list
to the current maximum (NGROUPS) if necessary.  In the future,
crsetgroups() may be responsible for insuring invariants such as sorting
the supplemental groups to allow groupmember() to be implemented as a
binary search.

Because we can not change struct xucred without breaking application
ABIs, we leave it alone and introduce a new XU_NGROUPS value which is
always 16 and is to be used or NGRPS as appropriate for things such as
NFS which need to use no more than 16 groups.  When feasible, truncate
the group list rather than generating an error.

Minor changes:
  - Reduce the number of hand rolled versions of groupmember().
  - Do not assign to both cr_gid and cr_groups[0].
  - Modify ipfw to cache ucreds instead of part of their contents since
    they are immutable once referenced by more than one entity.

Submitted by:	Isilon Systems (initial implementation)
X-MFC after:	never
PR:		bin/113398 kern/133867

1 files changed, 9 insertions, 3 deletions

diff --git a/sys/sys/ucred.h b/sys/sys/ucred.h
index 626b501..c7474b7 100644
--- a/sys/sys/ucred.h
+++ b/sys/sys/ucred.h
@@ -48,8 +48,7 @@ struct ucred {
 	uid_t	cr_uid;			/* effective user id */
 	uid_t	cr_ruid;		/* real user id */
 	uid_t	cr_svuid;		/* saved user id */
-	short	cr_ngroups;		/* number of groups */
-	gid_t	cr_groups[NGROUPS];	/* groups */
+	int	cr_ngroups;		/* number of groups */
 	gid_t	cr_rgid;		/* real group id */
 	gid_t	cr_svgid;		/* saved group id */
 	struct uidinfo	*cr_uidinfo;	/* per euid resource consumption */
@@ -61,11 +60,15 @@ struct ucred {
 #define	cr_endcopy	cr_label
 	struct label	*cr_label;	/* MAC label */
 	struct auditinfo_addr	cr_audit;	/* Audit properties. */
+	gid_t	*cr_groups;		/* groups */
+	int	cr_agroups;		/* Available groups */
 };
 #define	NOCRED	((struct ucred *)0)	/* no credential available */
 #define	FSCRED	((struct ucred *)-1)	/* filesystem credential */
 #endif /* _KERNEL || _WANT_UCRED */
 
+#define	XU_NGROUPS	16
+
 /*
  * This is the external representation of struct ucred.
  */
@@ -73,7 +76,7 @@ struct xucred {
 	u_int	cr_version;		/* structure layout version */
 	uid_t	cr_uid;			/* effective user id */
 	short	cr_ngroups;		/* number of groups */
-	gid_t	cr_groups[NGROUPS];	/* groups */
+	gid_t	cr_groups[XU_NGROUPS];	/* groups */
 	void	*_cr_unused1;		/* compatibility with old ucred */
 };
 #define	XUCRED_VERSION	0
@@ -82,6 +85,7 @@ struct xucred {
 #define	cr_gid cr_groups[0]
 
 #ifdef _KERNEL
+struct proc;
 struct thread;
 
 void	change_egid(struct ucred *newcred, gid_t egid);
@@ -91,6 +95,7 @@ void	change_ruid(struct ucred *newcred, struct uidinfo *ruip);
 void	change_svgid(struct ucred *newcred, gid_t svgid);
 void	change_svuid(struct ucred *newcred, uid_t svuid);
 void	crcopy(struct ucred *dest, struct ucred *src);
+struct ucred	*crcopysafe(struct proc *p, struct ucred *cr);
 struct ucred	*crdup(struct ucred *cr);
 void	cred_update_thread(struct thread *td);
 void	crfree(struct ucred *cr);
@@ -98,6 +103,7 @@ struct ucred	*crget(void);
 struct ucred	*crhold(struct ucred *cr);
 int	crshared(struct ucred *cr);
 void	cru2x(struct ucred *cr, struct xucred *xcr);
+void	crsetgroups(struct ucred *cr, int n, gid_t *groups);
 int	groupmember(gid_t gid, struct ucred *cred);
 #endif /* _KERNEL */