1 files changed, 94 insertions, 0 deletions
diff --git a/fs/nfsd/auth.c b/fs/nfsd/auth.c
new file mode 100644
index 000000000..fdf2aad73
--- /dev/null
+++ b/fs/nfsd/auth.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de> */
+
+#include <linux/sched.h>
+#include "nfsd.h"
+#include "auth.h"
+
+int nfsexp_flags(struct svc_rqst *rqstp, struct svc_export *exp)
+{
+	struct exp_flavor_info *f;
+	struct exp_flavor_info *end = exp->ex_flavors + exp->ex_nflavors;
+
+	for (f = exp->ex_flavors; f < end; f++) {
+		if (f->pseudoflavor == rqstp->rq_cred.cr_flavor)
+			return f->flags;
+	}
+	return exp->ex_flags;
+
+}
+
+int nfsd_setuser(struct svc_rqst *rqstp, struct svc_export *exp)
+{
+	struct group_info *rqgi;
+	struct group_info *gi;
+	struct cred *new;
+	int i;
+	int flags = nfsexp_flags(rqstp, exp);
+
+	validate_process_creds();
+
+	/* discard any old override before preparing the new set */
+	revert_creds(get_cred(current_real_cred()));
+	new = prepare_creds();
+	if (!new)
+		return -ENOMEM;
+
+	new->fsuid = rqstp->rq_cred.cr_uid;
+	new->fsgid = rqstp->rq_cred.cr_gid;
+
+	rqgi = rqstp->rq_cred.cr_group_info;
+
+	if (flags & NFSEXP_ALLSQUASH) {
+		new->fsuid = exp->ex_anon_uid;
+		new->fsgid = exp->ex_anon_gid;
+		gi = groups_alloc(0);
+		if (!gi)
+			goto oom;
+	} else if (flags & NFSEXP_ROOTSQUASH) {
+		if (uid_eq(new->fsuid, GLOBAL_ROOT_UID))
+			new->fsuid = exp->ex_anon_uid;
+		if (gid_eq(new->fsgid, GLOBAL_ROOT_GID))
+			new->fsgid = exp->ex_anon_gid;
+
+		gi = groups_alloc(rqgi->ngroups);
+		if (!gi)
+			goto oom;
+
+		for (i = 0; i < rqgi->ngroups; i++) {
+			if (gid_eq(GLOBAL_ROOT_GID, rqgi->gid[i]))
+				gi->gid[i] = exp->ex_anon_gid;
+			else
+				gi->gid[i] = rqgi->gid[i];
+		}
+
+		/* Each thread allocates its own gi, no race */
+		groups_sort(gi);
+	} else {
+		gi = get_group_info(rqgi);
+	}
+
+	if (uid_eq(new->fsuid, INVALID_UID))
+		new->fsuid = exp->ex_anon_uid;
+	if (gid_eq(new->fsgid, INVALID_GID))
+		new->fsgid = exp->ex_anon_gid;
+
+	set_groups(new, gi);
+	put_group_info(gi);
+
+	if (!uid_eq(new->fsuid, GLOBAL_ROOT_UID))
+		new->cap_effective = cap_drop_nfsd_set(new->cap_effective);
+	else
+		new->cap_effective = cap_raise_nfsd_set(new->cap_effective,
+							new->cap_permitted);
+	validate_process_creds();
+	put_cred(override_creds(new));
+	put_cred(new);
+	validate_process_creds();
+	return 0;
+
+oom:
+	abort_creds(new);
+	return -ENOMEM;
+}
+