NFSv4: Add ACCESS operation to OPEN compound

PATCH New Weston Andros Adamson 1 participant 1 message Sep 10, 2012

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Weston Andros Adamson

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2012-09-10 18:00 UTC #0 lore raw

PATCH 1/1 NFSv4: Add ACCESS operation to OPEN compound

The OPEN operation has no way to differentiate an open for read and an open for execution - both look like read to the server. This allowed users to read files that didn't have READ access but did have EXEC access, which is obviously wrong.

This patch adds an ACCESS call to the OPEN compound to handle the difference between OPENs for reading and execution. Since we're going through the trouble of calling ACCESS, we check all possible access bits and cache the results hopefully avoiding an ACCESS call in the future.

Signed-off-by Weston Andros Adamson <[email protected]>

---
Acted on Trond's comments.

Great catch on decode_access failing - don't know how I missed that!

The only thing I can see that you may not like is using access_supported == 0 to skip the access checks instead of storing the status from the access call in opendata->o_res. It makes sense to me since only a broken server wouldn't support any access bits.

 fs/nfs/dir.c            |   16 ++++++++++++++-
 fs/nfs/nfs4proc.c       |   52 +++++++++++++++++++++++++++++++++++++++--------
 fs/nfs/nfs4xdr.c        |   16 +++++++++++----
 include/linux/nfs_fs.h  |    2 ++
 include/linux/nfs_xdr.h |    3 +++
 5 files changed, 76 insertions(+), 13 deletions(-)

fs/nfs/dir.c +15 -1

index 627f108..ce8cb92 100644
@@ -2072,7 +2072,7 @@ found:
 	nfs_access_free_entry(entry);
 }
 
-static void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set)
+void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *set)
 {
 	struct nfs_access_entry *cache = kmalloc(sizeof(*cache), GFP_KERNEL);
 	if (cache == NULL)

@@ -2098,6 +2098,20 @@ static void nfs_access_add_cache(struct inode *inode, struct nfs_access_entry *s
 		spin_unlock(&nfs_access_lru_lock);
 	}
 }
+EXPORT_SYMBOL_GPL(nfs_access_add_cache);
+
+void nfs_access_set_mask(struct nfs_access_entry *entry, u32 access_result)
+{
+	entry->mask = 0;
+	if (access_result & NFS4_ACCESS_READ)
+		entry->mask |= MAY_READ;
+	if (access_result &
+	    (NFS4_ACCESS_MODIFY | NFS4_ACCESS_EXTEND | NFS4_ACCESS_DELETE))
+		entry->mask |= MAY_WRITE;
+	if (access_result & (NFS4_ACCESS_LOOKUP|NFS4_ACCESS_EXECUTE))
+		entry->mask |= MAY_EXEC;
+}
+EXPORT_SYMBOL_GPL(nfs_access_set_mask);
 
 static int nfs_do_access(struct inode *inode, struct rpc_cred *cred, int mask)
 {

fs/nfs/nfs4proc.c +44 -8

88 lines not on this page · raw message

fs/nfs/nfs4xdr.c +12 -4

index 8dba6bd..8a9f1b8 100644
@@ -447,12 +447,14 @@ static int nfs4_stat_to_errno(int);
 				encode_sequence_maxsz + \
 				encode_putfh_maxsz + \
 				encode_open_maxsz + \
+				encode_access_maxsz + \
 				encode_getfh_maxsz + \
 				encode_getattr_maxsz)
 #define NFS4_dec_open_sz        (compound_decode_hdr_maxsz + \
 				decode_sequence_maxsz + \
 				decode_putfh_maxsz + \
 				decode_open_maxsz + \
+				decode_access_maxsz + \
 				decode_getfh_maxsz + \
 				decode_getattr_maxsz)
 #define NFS4_enc_open_confirm_sz \

@@ -467,11 +469,13 @@ static int nfs4_stat_to_errno(int);
 					encode_sequence_maxsz + \
 					encode_putfh_maxsz + \
 					encode_open_maxsz + \
+					encode_access_maxsz + \
 					encode_getattr_maxsz)
 #define NFS4_dec_open_noattr_sz	(compound_decode_hdr_maxsz + \
 					decode_sequence_maxsz + \
 					decode_putfh_maxsz + \
 					decode_open_maxsz + \
+					decode_access_maxsz + \
 					decode_getattr_maxsz)
 #define NFS4_enc_open_downgrade_sz \
 				(compound_encode_hdr_maxsz + \

@@ -2216,6 +2220,7 @@ static void nfs4_xdr_enc_open(struct rpc_rqst *req, struct xdr_stream *xdr,
 	encode_putfh(xdr, args->fh, &hdr);
 	encode_open(xdr, args, &hdr);
 	encode_getfh(xdr, &hdr);
+	encode_access(xdr, args->access, &hdr);
 	encode_getfattr_open(xdr, args->bitmask, args->open_bitmap, &hdr);
 	encode_nops(&hdr);
 }

@@ -2252,6 +2257,7 @@ static void nfs4_xdr_enc_open_noattr(struct rpc_rqst *req,
 	encode_sequence(xdr, &args->seq_args, &hdr);
 	encode_putfh(xdr, args->fh, &hdr);
 	encode_open(xdr, args, &hdr);
+	encode_access(xdr, args->access, &hdr);
 	encode_getfattr(xdr, args->bitmask, &hdr);
 	encode_nops(&hdr);
 }

@@ -4095,7 +4101,7 @@ out_overflow:
 	return -EIO;
 }
 
-static int decode_access(struct xdr_stream *xdr, struct nfs4_accessres *access)
+static int decode_access(struct xdr_stream *xdr, u32 *supported, u32 *access)
 {
 	__be32 *p;
 	uint32_t supp, acc;

@@ -4109,8 +4115,8 @@ static int decode_access(struct xdr_stream *xdr, struct nfs4_accessres *access)
 		goto out_overflow;
 	supp = be32_to_cpup(p++);
 	acc = be32_to_cpup(p);
-	access->supported = supp;
-	access->access = acc;
+	*supported = supp;
+	*access = acc;
 	return 0;
 out_overflow:
 	print_overflow_msg(__func__, xdr);

@@ -5887,7 +5893,7 @@ static int nfs4_xdr_dec_access(struct rpc_rqst *rqstp, struct xdr_stream *xdr,
 	status = decode_putfh(xdr);
 	if (status != 0)
 		goto out;
-	status = decode_access(xdr, res);
+	status = decode_access(xdr, &res->supported, &res->access);
 	if (status != 0)
 		goto out;
 	decode_getfattr(xdr, res->fattr, res->server);

@@ -6228,6 +6234,7 @@ static int nfs4_xdr_dec_open(struct rpc_rqst *rqstp, struct xdr_stream *xdr,
 	status = decode_getfh(xdr, &res->fh);
 	if (status)
 		goto out;
+	decode_access(xdr, &res->access_supported, &res->access_result);
 	decode_getfattr(xdr, res->f_attr, res->server);
 out:
 	return status;

@@ -6276,6 +6283,7 @@ static int nfs4_xdr_dec_open_noattr(struct rpc_rqst *rqstp,
 	status = decode_open(xdr, res);
 	if (status)
 		goto out;
+	decode_access(xdr, &res->access_supported, &res->access_result);
 	decode_getfattr(xdr, res->f_attr, res->server);
 out:
 	return status;

include/linux/nfs_fs.h +2 -0

index 4b03f56..3704094 100644
@@ -355,6 +355,8 @@ extern int nfs_refresh_inode(struct inode *, struct nfs_fattr *);
 extern int nfs_post_op_update_inode(struct inode *inode, struct nfs_fattr *fattr);
 extern int nfs_post_op_update_inode_force_wcc(struct inode *inode, struct nfs_fattr *fattr);
 extern int nfs_getattr(struct vfsmount *, struct dentry *, struct kstat *);
+extern void nfs_access_add_cache(struct inode *, struct nfs_access_entry *);
+extern void nfs_access_set_mask(struct nfs_access_entry *, u32);
 extern int nfs_permission(struct inode *, int);
 extern int nfs_open(struct inode *, struct file *);
 extern int nfs_release(struct inode *, struct file *);

include/linux/nfs_xdr.h +3 -0

index be9cf3c..70371aa 100644
@@ -335,6 +335,7 @@ struct nfs_openargs {
 	struct nfs_seqid *	seqid;
 	int			open_flags;
 	fmode_t			fmode;
+	u32			access;
 	__u64                   clientid;
 	struct stateowner_id	id;
 	union {

@@ -369,6 +370,8 @@ struct nfs_openres {
 	struct nfs4_string	*owner;
 	struct nfs4_string	*group_owner;
 	struct nfs4_sequence_res	seq_res;
+	__u32			access_supported;
+	__u32			access_result;
 };
 
 /*

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