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author | Amir Goldstein <amir73il@gmail.com> | 2017-07-12 13:17:16 +0200 |
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committer | Miklos Szeredi <mszeredi@redhat.com> | 2018-01-24 11:25:59 +0100 |
commit | 8ed5eec9d6c4c013aa657ebefbd10a1a0d15893d (patch) | |
tree | 634ea6f80f9212f0d81c846145a8b260f2c6d34a /fs/overlayfs/export.c | |
parent | ovl: document NFS export (diff) | |
download | linux-8ed5eec9d6c4c013aa657ebefbd10a1a0d15893d.tar.xz linux-8ed5eec9d6c4c013aa657ebefbd10a1a0d15893d.zip |
ovl: encode pure upper file handles
Encode overlay file handles as struct ovl_fh containing the file handle
encoding of the real upper inode.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/overlayfs/export.c')
-rw-r--r-- | fs/overlayfs/export.c | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c new file mode 100644 index 000000000000..67b907ca9cdc --- /dev/null +++ b/fs/overlayfs/export.c @@ -0,0 +1,98 @@ +/* + * Overlayfs NFS export support. + * + * Amir Goldstein <amir73il@gmail.com> + * + * Copyright (C) 2017-2018 CTERA Networks. All Rights Reserved. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published by + * the Free Software Foundation. + */ + +#include <linux/fs.h> +#include <linux/cred.h> +#include <linux/mount.h> +#include <linux/namei.h> +#include <linux/xattr.h> +#include <linux/exportfs.h> +#include <linux/ratelimit.h> +#include "overlayfs.h" + +static int ovl_d_to_fh(struct dentry *dentry, char *buf, int buflen) +{ + struct dentry *upper = ovl_dentry_upper(dentry); + struct dentry *origin = ovl_dentry_lower(dentry); + struct ovl_fh *fh = NULL; + int err; + + /* + * On overlay with an upper layer, overlay root inode is encoded as + * an upper file handle, because upper root dir is not indexed. + */ + if (dentry == dentry->d_sb->s_root && upper) + origin = NULL; + + err = -EACCES; + if (!upper || origin) + goto fail; + + /* TODO: encode non pure-upper by origin */ + fh = ovl_encode_fh(upper, true); + + err = -EOVERFLOW; + if (fh->len > buflen) + goto fail; + + memcpy(buf, (char *)fh, fh->len); + err = fh->len; + +out: + kfree(fh); + return err; + +fail: + pr_warn_ratelimited("overlayfs: failed to encode file handle (%pd2, err=%i, buflen=%d, len=%d, type=%d)\n", + dentry, err, buflen, fh ? (int)fh->len : 0, + fh ? fh->type : 0); + goto out; +} + +static int ovl_dentry_to_fh(struct dentry *dentry, u32 *fid, int *max_len) +{ + int res, len = *max_len << 2; + + res = ovl_d_to_fh(dentry, (char *)fid, len); + if (res <= 0) + return FILEID_INVALID; + + len = res; + + /* Round up to dwords */ + *max_len = (len + 3) >> 2; + return OVL_FILEID; +} + +static int ovl_encode_inode_fh(struct inode *inode, u32 *fid, int *max_len, + struct inode *parent) +{ + struct dentry *dentry; + int type; + + /* TODO: encode connectable file handles */ + if (parent) + return FILEID_INVALID; + + dentry = d_find_any_alias(inode); + if (WARN_ON(!dentry)) + return FILEID_INVALID; + + type = ovl_dentry_to_fh(dentry, fid, max_len); + + dput(dentry); + return type; +} + +const struct export_operations ovl_export_operations = { + .encode_fh = ovl_encode_inode_fh, +}; |