Let's be more careful to avoid overrunning the memory that backs
the bitmap array. This requires updating the synopsis of
nfsd4_decode_fattr().
Bruce points out that a server needs to be careful to return nfs_ok
when a client presents bitmap bits the server doesn't support. This
includes bits in bitmap words the server might not yet support.
The current READ* based implementation is good about that, but that
requirement hasn't been documented.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
fs/nfsd/nfs4xdr.c | 82 +++++++++++++++++++++++++++++++++++++++++------------
1 file changed, 64 insertions(+), 18 deletions(-)
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 54481804a096..9b295c810ef3 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -260,6 +260,46 @@ nfsd4_decode_bitmap(struct nfsd4_compoundargs *argp, u32 *bmval)
DECODE_TAIL;
}
+/**
+ * nfsd4_decode_bitmap4 - Decode an NFSv4 bitmap4
+ * @argp: NFSv4 compound argument structure
+ * @bmval: pointer to an array of u32's to decode into
+ * @bmlen: size of the @bmval array
+ *
+ * The server needs to return nfs_ok rather than nfserr_bad_xdr when
+ * encountering bitmaps containing bits it does not recognize. This
+ * includes bits in bitmap words past WORDn, where WORDn is the last
+ * bitmap WORD the implementation currently supports. Thus we are
+ * careful here to simply ignore bits in bitmap words that this
+ * implementation has yet to support explicitly.
+ *
+ * Return values:
+ * %nfs_ok: @bmval populated successfully
+ * %nfserr_bad_xdr: the encoded bitmap was invalid
+ */
+static __be32
+nfsd4_decode_bitmap4(struct nfsd4_compoundargs *argp, u32 *bmval, u32 bmlen)
+{
+ u32 i, count;
+ __be32 *p;
+
+ if (xdr_stream_decode_u32(argp->xdr, &count) < 0)
+ return nfserr_bad_xdr;
+ /* request sanity */
+ if (count > 1000)
+ return nfserr_bad_xdr;
+ p = xdr_inline_decode(argp->xdr, count << 2);
+ if (!p)
+ return nfserr_bad_xdr;
+ i = 0;
+ while (i < count)
+ bmval[i++] = be32_to_cpup(p++);
+ while (i < bmlen)
+ bmval[i++] = 0;
+
+ return nfs_ok;
+}
+
static __be32
nfsd4_decode_nfsace4(struct nfsd4_compoundargs *argp, struct nfs4_ace *ace)
{
@@ -352,17 +392,18 @@ nfsd4_decode_security_label(struct nfsd4_compoundargs *argp,
}
static __be32
-nfsd4_decode_fattr(struct nfsd4_compoundargs *argp, u32 *bmval,
- struct iattr *iattr, struct nfs4_acl **acl,
- struct xdr_netobj *label, int *umask)
+nfsd4_decode_fattr4(struct nfsd4_compoundargs *argp, u32 *bmval, u32 bmlen,
+ struct iattr *iattr, struct nfs4_acl **acl,
+ struct xdr_netobj *label, int *umask)
{
unsigned int starting_pos;
u32 attrlist4_count;
+ __be32 *p, status;
- DECODE_HEAD;
iattr->ia_valid = 0;
- if ((status = nfsd4_decode_bitmap(argp, bmval)))
- return status;
+ status = nfsd4_decode_bitmap4(argp, bmval, bmlen);
+ if (status)
+ return nfserr_bad_xdr;
if (bmval[0] & ~NFSD_WRITEABLE_ATTRS_WORD0
|| bmval[1] & ~NFSD_WRITEABLE_ATTRS_WORD1
@@ -490,7 +531,7 @@ nfsd4_decode_fattr(struct nfsd4_compoundargs *argp, u32 *bmval,
if (attrlist4_count != xdr_stream_pos(argp->xdr) - starting_pos)
return nfserr_bad_xdr;
- DECODE_TAIL;
+ return nfs_ok;
}
static __be32
@@ -690,9 +731,10 @@ nfsd4_decode_create(struct nfsd4_compoundargs *argp, struct nfsd4_create *create
if ((status = check_filename(create->cr_name, create->cr_namelen)))
return status;
- status = nfsd4_decode_fattr(argp, create->cr_bmval, &create->cr_iattr,
- &create->cr_acl, &create->cr_label,
- &create->cr_umask);
+ status = nfsd4_decode_fattr4(argp, create->cr_bmval,
+ ARRAY_SIZE(create->cr_bmval),
+ &create->cr_iattr, &create->cr_acl,
+ &create->cr_label, &create->cr_umask);
if (status)
goto out;
@@ -941,9 +983,10 @@ nfsd4_decode_open(struct nfsd4_compoundargs *argp, struct nfsd4_open *open)
switch (open->op_createmode) {
case NFS4_CREATE_UNCHECKED:
case NFS4_CREATE_GUARDED:
- status = nfsd4_decode_fattr(argp, open->op_bmval,
- &open->op_iattr, &open->op_acl, &open->op_label,
- &open->op_umask);
+ status = nfsd4_decode_fattr4(argp, open->op_bmval,
+ ARRAY_SIZE(open->op_bmval),
+ &open->op_iattr, &open->op_acl,
+ &open->op_label, &open->op_umask);
if (status)
goto out;
break;
@@ -956,9 +999,10 @@ nfsd4_decode_open(struct nfsd4_compoundargs *argp, struct nfsd4_open *open)
goto xdr_error;
READ_BUF(NFS4_VERIFIER_SIZE);
COPYMEM(open->op_verf.data, NFS4_VERIFIER_SIZE);
- status = nfsd4_decode_fattr(argp, open->op_bmval,
- &open->op_iattr, &open->op_acl, &open->op_label,
- &open->op_umask);
+ status = nfsd4_decode_fattr4(argp, open->op_bmval,
+ ARRAY_SIZE(open->op_bmval),
+ &open->op_iattr, &open->op_acl,
+ &open->op_label, &open->op_umask);
if (status)
goto out;
break;
@@ -1194,8 +1238,10 @@ nfsd4_decode_setattr(struct nfsd4_compoundargs *argp, struct nfsd4_setattr *seta
status = nfsd4_decode_stateid(argp, &setattr->sa_stateid);
if (status)
return status;
- return nfsd4_decode_fattr(argp, setattr->sa_bmval, &setattr->sa_iattr,
- &setattr->sa_acl, &setattr->sa_label, NULL);
+ return nfsd4_decode_fattr4(argp, setattr->sa_bmval,
+ ARRAY_SIZE(setattr->sa_bmval),
+ &setattr->sa_iattr, &setattr->sa_acl,
+ &setattr->sa_label, NULL);
}
static __be32
