[PATCH 020 of 20] knfsd: nfsd: enforce per-flavor id squashing

[NeilBrown]

From: J. Bruce Fields <bfields@xxxxxxxxxxxxxx>

Allow root squashing to vary per-pseudoflavor, so that you can (for
example) allow root access only when sufficiently strong security is in
use.

Signed-off-by: "J. Bruce Fields" <bfields@xxxxxxxxxxxxxx>
Signed-off-by: Neil Brown <neilb@xxxxxxx>

### Diffstat output
 ./fs/nfsd/auth.c              |   18 ++++++++++++++++--
 ./include/linux/nfsd/export.h |    3 ++-
 2 files changed, 18 insertions(+), 3 deletions(-)

diff .prev/fs/nfsd/auth.c ./fs/nfsd/auth.c
--- .prev/fs/nfsd/auth.c	2007-07-10 12:18:33.000000000 +1000
+++ ./fs/nfsd/auth.c	2007-07-10 12:19:40.000000000 +1000
@@ -12,17 +12,31 @@
 
 #define	CAP_NFSD_MASK (CAP_FS_MASK|CAP_TO_MASK(CAP_SYS_RESOURCE))
 
+static 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_flavor)
+			return f->flags;
+	}
+	return exp->ex_flags;
+
+}
+
 int nfsd_setuser(struct svc_rqst *rqstp, struct svc_export *exp)
 {
 	struct svc_cred	cred = rqstp->rq_cred;
 	int i;
+	int flags = nfsexp_flags(rqstp, exp);
 	int ret;
 
-	if (exp->ex_flags & NFSEXP_ALLSQUASH) {
+	if (flags & NFSEXP_ALLSQUASH) {
 		cred.cr_uid = exp->ex_anon_uid;
 		cred.cr_gid = exp->ex_anon_gid;
 		cred.cr_group_info = groups_alloc(0);
-	} else if (exp->ex_flags & NFSEXP_ROOTSQUASH) {
+	} else if (flags & NFSEXP_ROOTSQUASH) {
 		struct group_info *gi;
 		if (!cred.cr_uid)
 			cred.cr_uid = exp->ex_anon_uid;

diff .prev/include/linux/nfsd/export.h ./include/linux/nfsd/export.h
--- .prev/include/linux/nfsd/export.h	2007-07-10 12:18:33.000000000 +1000
+++ ./include/linux/nfsd/export.h	2007-07-10 12:19:40.000000000 +1000
@@ -43,7 +43,8 @@
 #define NFSEXP_ALLFLAGS		0xFE3F
 
 /* The flags that may vary depending on security flavor: */
-#define NFSEXP_SECINFO_FLAGS	NFSEXP_READONLY
+#define NFSEXP_SECINFO_FLAGS	(NFSEXP_READONLY | NFSEXP_ROOTSQUASH \
+					| NFSEXP_ALLSQUASH)
 
 #ifdef __KERNEL__
 
-
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