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bcac8bff90
Switch order of operations to avoid creating a short XDR buffer:
e.g., buflen = 12, old xdrlen = 12, new xdrlen = 20.
Having a short XDR buffer leads to lxa_maxcount be a few bytes
less than what is needed to retrieve the whole list when using
a buflen as returned by a call with size = 0:
buflen = listxattr(path, NULL, 0);
buf = malloc(buflen);
buflen = listxattr(path, buf, buflen);
For a file with one attribute (name = '123456'), the first call
with size = 0 will return buflen = 12 ('user.123456\x00').
The second call with size = 12, sends LISTXATTRS with
lxa_maxcount = 12 + 8 (cookie) + 4 (array count) = 24. The
XDR buffer needs 8 (cookie) + 4 (array count) + 4 (name count)
+ 6 (name len) + 2 (padding) + 4 (eof) = 28 which is 4 bytes
shorter than the lxa_maxcount provided in the call.
Fixes: 04a5da690e ("NFSv4.2: define limits and sizes for user xattr handling")
Signed-off-by: Jorge Mora <mora@netapp.com>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
69 lines
2.4 KiB
C
69 lines
2.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (c) 2014 Anna Schumaker <Anna.Schumaker@Netapp.com>
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*/
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#ifndef __LINUX_FS_NFS_NFS4_2_H
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#define __LINUX_FS_NFS_NFS4_2_H
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#include <linux/xattr.h>
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/*
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* FIXME: four LAYOUTSTATS calls per compound at most! Do we need to support
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* more? Need to consider not to pre-alloc too much for a compound.
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*/
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#define PNFS_LAYOUTSTATS_MAXDEV (4)
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#define READ_PLUS_SCRATCH_SIZE (16)
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/* nfs4.2proc.c */
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#ifdef CONFIG_NFS_V4_2
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int nfs42_proc_allocate(struct file *, loff_t, loff_t);
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ssize_t nfs42_proc_copy(struct file *, loff_t, struct file *, loff_t, size_t,
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struct nl4_server *, nfs4_stateid *, bool);
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int nfs42_proc_deallocate(struct file *, loff_t, loff_t);
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loff_t nfs42_proc_llseek(struct file *, loff_t, int);
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int nfs42_proc_layoutstats_generic(struct nfs_server *,
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struct nfs42_layoutstat_data *);
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int nfs42_proc_clone(struct file *, struct file *, loff_t, loff_t, loff_t);
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int nfs42_proc_layouterror(struct pnfs_layout_segment *lseg,
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const struct nfs42_layout_error *errors,
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size_t n);
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int nfs42_proc_copy_notify(struct file *, struct file *,
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struct nfs42_copy_notify_res *);
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static inline bool nfs42_files_from_same_server(struct file *in,
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struct file *out)
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{
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struct nfs_client *c_in = (NFS_SERVER(file_inode(in)))->nfs_client;
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struct nfs_client *c_out = (NFS_SERVER(file_inode(out)))->nfs_client;
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return nfs4_check_serverowner_major_id(c_in->cl_serverowner,
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c_out->cl_serverowner);
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}
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ssize_t nfs42_proc_getxattr(struct inode *inode, const char *name,
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void *buf, size_t buflen);
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int nfs42_proc_setxattr(struct inode *inode, const char *name,
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const void *buf, size_t buflen, int flags);
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ssize_t nfs42_proc_listxattrs(struct inode *inode, void *buf,
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size_t buflen, u64 *cookiep, bool *eofp);
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int nfs42_proc_removexattr(struct inode *inode, const char *name);
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/*
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* Maximum XDR buffer size needed for a listxattr buffer of buflen size.
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*
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* The upper boundary is a buffer with all 1-byte sized attribute names.
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* They would be 7 bytes long in the eventual buffer ("user.x\0"), and
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* 8 bytes long XDR-encoded.
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*
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* Include the trailing eof word as well and make the result a multiple
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* of 4 bytes.
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*/
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static inline u32 nfs42_listxattr_xdrsize(u32 buflen)
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{
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u32 size = 8 * buflen / (XATTR_USER_PREFIX_LEN + 2) + 4;
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return (size + 3) & ~3;
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}
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#endif /* CONFIG_NFS_V4_2 */
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#endif /* __LINUX_FS_NFS_NFS4_2_H */
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