1d2912cb1SThomas Gleixner // SPDX-License-Identifier: GPL-2.0-only
28ed5eec9SAmir Goldstein /*
38ed5eec9SAmir Goldstein * Overlayfs NFS export support.
48ed5eec9SAmir Goldstein *
58ed5eec9SAmir Goldstein * Amir Goldstein <amir73il@gmail.com>
68ed5eec9SAmir Goldstein *
78ed5eec9SAmir Goldstein * Copyright (C) 2017-2018 CTERA Networks. All Rights Reserved.
88ed5eec9SAmir Goldstein */
98ed5eec9SAmir Goldstein
108ed5eec9SAmir Goldstein #include <linux/fs.h>
118ed5eec9SAmir Goldstein #include <linux/cred.h>
128ed5eec9SAmir Goldstein #include <linux/mount.h>
138ed5eec9SAmir Goldstein #include <linux/namei.h>
148ed5eec9SAmir Goldstein #include <linux/xattr.h>
158ed5eec9SAmir Goldstein #include <linux/exportfs.h>
168ed5eec9SAmir Goldstein #include <linux/ratelimit.h>
178ed5eec9SAmir Goldstein #include "overlayfs.h"
188ed5eec9SAmir Goldstein
ovl_encode_maybe_copy_up(struct dentry * dentry)192ca3c148SAmir Goldstein static int ovl_encode_maybe_copy_up(struct dentry *dentry)
202ca3c148SAmir Goldstein {
212ca3c148SAmir Goldstein int err;
222ca3c148SAmir Goldstein
232ca3c148SAmir Goldstein if (ovl_dentry_upper(dentry))
242ca3c148SAmir Goldstein return 0;
252ca3c148SAmir Goldstein
262ca3c148SAmir Goldstein err = ovl_want_write(dentry);
272ca3c148SAmir Goldstein if (!err) {
282ca3c148SAmir Goldstein err = ovl_copy_up(dentry);
292ca3c148SAmir Goldstein ovl_drop_write(dentry);
302ca3c148SAmir Goldstein }
312ca3c148SAmir Goldstein
322ca3c148SAmir Goldstein if (err) {
331bd0a3aeSlijiazi pr_warn_ratelimited("failed to copy up on encode (%pd2, err=%i)\n",
342ca3c148SAmir Goldstein dentry, err);
352ca3c148SAmir Goldstein }
362ca3c148SAmir Goldstein
372ca3c148SAmir Goldstein return err;
382ca3c148SAmir Goldstein }
392ca3c148SAmir Goldstein
402ca3c148SAmir Goldstein /*
412ca3c148SAmir Goldstein * Before encoding a non-upper directory file handle from real layer N, we need
422ca3c148SAmir Goldstein * to check if it will be possible to reconnect an overlay dentry from the real
432ca3c148SAmir Goldstein * lower decoded dentry. This is done by following the overlay ancestry up to a
442ca3c148SAmir Goldstein * "layer N connected" ancestor and verifying that all parents along the way are
452ca3c148SAmir Goldstein * "layer N connectable". If an ancestor that is NOT "layer N connectable" is
462ca3c148SAmir Goldstein * found, we need to copy up an ancestor, which is "layer N connectable", thus
472ca3c148SAmir Goldstein * making that ancestor "layer N connected". For example:
482ca3c148SAmir Goldstein *
492ca3c148SAmir Goldstein * layer 1: /a
502ca3c148SAmir Goldstein * layer 2: /a/b/c
512ca3c148SAmir Goldstein *
522ca3c148SAmir Goldstein * The overlay dentry /a is NOT "layer 2 connectable", because if dir /a is
532ca3c148SAmir Goldstein * copied up and renamed, upper dir /a will be indexed by lower dir /a from
542ca3c148SAmir Goldstein * layer 1. The dir /a from layer 2 will never be indexed, so the algorithm (*)
552ca3c148SAmir Goldstein * in ovl_lookup_real_ancestor() will not be able to lookup a connected overlay
562ca3c148SAmir Goldstein * dentry from the connected lower dentry /a/b/c.
572ca3c148SAmir Goldstein *
582ca3c148SAmir Goldstein * To avoid this problem on decode time, we need to copy up an ancestor of
592ca3c148SAmir Goldstein * /a/b/c, which is "layer 2 connectable", on encode time. That ancestor is
602ca3c148SAmir Goldstein * /a/b. After copy up (and index) of /a/b, it will become "layer 2 connected"
612ca3c148SAmir Goldstein * and when the time comes to decode the file handle from lower dentry /a/b/c,
622ca3c148SAmir Goldstein * ovl_lookup_real_ancestor() will find the indexed ancestor /a/b and decoding
632ca3c148SAmir Goldstein * a connected overlay dentry will be accomplished.
642ca3c148SAmir Goldstein *
652ca3c148SAmir Goldstein * (*) the algorithm in ovl_lookup_real_ancestor() can be improved to lookup an
662ca3c148SAmir Goldstein * entry /a in the lower layers above layer N and find the indexed dir /a from
672ca3c148SAmir Goldstein * layer 1. If that improvement is made, then the check for "layer N connected"
682ca3c148SAmir Goldstein * will need to verify there are no redirects in lower layers above N. In the
692ca3c148SAmir Goldstein * example above, /a will be "layer 2 connectable". However, if layer 2 dir /a
702ca3c148SAmir Goldstein * is a target of a layer 1 redirect, then /a will NOT be "layer 2 connectable":
712ca3c148SAmir Goldstein *
722ca3c148SAmir Goldstein * layer 1: /A (redirect = /a)
732ca3c148SAmir Goldstein * layer 2: /a/b/c
742ca3c148SAmir Goldstein */
752ca3c148SAmir Goldstein
762ca3c148SAmir Goldstein /* Return the lowest layer for encoding a connectable file handle */
ovl_connectable_layer(struct dentry * dentry)772ca3c148SAmir Goldstein static int ovl_connectable_layer(struct dentry *dentry)
782ca3c148SAmir Goldstein {
792ca3c148SAmir Goldstein struct ovl_entry *oe = OVL_E(dentry);
802ca3c148SAmir Goldstein
812ca3c148SAmir Goldstein /* We can get overlay root from root of any layer */
822ca3c148SAmir Goldstein if (dentry == dentry->d_sb->s_root)
835522c9c7SAmir Goldstein return ovl_numlower(oe);
842ca3c148SAmir Goldstein
852ca3c148SAmir Goldstein /*
862ca3c148SAmir Goldstein * If it's an unindexed merge dir, then it's not connectable with any
872ca3c148SAmir Goldstein * lower layer
882ca3c148SAmir Goldstein */
892ca3c148SAmir Goldstein if (ovl_dentry_upper(dentry) &&
902ca3c148SAmir Goldstein !ovl_test_flag(OVL_INDEX, d_inode(dentry)))
912ca3c148SAmir Goldstein return 0;
922ca3c148SAmir Goldstein
932ca3c148SAmir Goldstein /* We can get upper/overlay path from indexed/lower dentry */
945522c9c7SAmir Goldstein return ovl_lowerstack(oe)->layer->idx;
952ca3c148SAmir Goldstein }
962ca3c148SAmir Goldstein
972ca3c148SAmir Goldstein /*
982ca3c148SAmir Goldstein * @dentry is "connected" if all ancestors up to root or a "connected" ancestor
992ca3c148SAmir Goldstein * have the same uppermost lower layer as the origin's layer. We may need to
1002ca3c148SAmir Goldstein * copy up a "connectable" ancestor to make it "connected". A "connected" dentry
1012ca3c148SAmir Goldstein * cannot become non "connected", so cache positive result in dentry flags.
1022ca3c148SAmir Goldstein *
1032ca3c148SAmir Goldstein * Return the connected origin layer or < 0 on error.
1042ca3c148SAmir Goldstein */
ovl_connect_layer(struct dentry * dentry)1052ca3c148SAmir Goldstein static int ovl_connect_layer(struct dentry *dentry)
1062ca3c148SAmir Goldstein {
1072ca3c148SAmir Goldstein struct dentry *next, *parent = NULL;
1085522c9c7SAmir Goldstein struct ovl_entry *oe = OVL_E(dentry);
1092ca3c148SAmir Goldstein int origin_layer;
1102ca3c148SAmir Goldstein int err = 0;
1112ca3c148SAmir Goldstein
1122ca3c148SAmir Goldstein if (WARN_ON(dentry == dentry->d_sb->s_root) ||
1132ca3c148SAmir Goldstein WARN_ON(!ovl_dentry_lower(dentry)))
1142ca3c148SAmir Goldstein return -EIO;
1152ca3c148SAmir Goldstein
1165522c9c7SAmir Goldstein origin_layer = ovl_lowerstack(oe)->layer->idx;
1172ca3c148SAmir Goldstein if (ovl_dentry_test_flag(OVL_E_CONNECTED, dentry))
1182ca3c148SAmir Goldstein return origin_layer;
1192ca3c148SAmir Goldstein
1202ca3c148SAmir Goldstein /* Find the topmost origin layer connectable ancestor of @dentry */
1212ca3c148SAmir Goldstein next = dget(dentry);
1222ca3c148SAmir Goldstein for (;;) {
1232ca3c148SAmir Goldstein parent = dget_parent(next);
1242ca3c148SAmir Goldstein if (WARN_ON(parent == next)) {
1252ca3c148SAmir Goldstein err = -EIO;
1262ca3c148SAmir Goldstein break;
1272ca3c148SAmir Goldstein }
1282ca3c148SAmir Goldstein
1292ca3c148SAmir Goldstein /*
1302ca3c148SAmir Goldstein * If @parent is not origin layer connectable, then copy up
1312ca3c148SAmir Goldstein * @next which is origin layer connectable and we are done.
1322ca3c148SAmir Goldstein */
1332ca3c148SAmir Goldstein if (ovl_connectable_layer(parent) < origin_layer) {
1342ca3c148SAmir Goldstein err = ovl_encode_maybe_copy_up(next);
1352ca3c148SAmir Goldstein break;
1362ca3c148SAmir Goldstein }
1372ca3c148SAmir Goldstein
1382ca3c148SAmir Goldstein /* If @parent is connected or indexed we are done */
1392ca3c148SAmir Goldstein if (ovl_dentry_test_flag(OVL_E_CONNECTED, parent) ||
1402ca3c148SAmir Goldstein ovl_test_flag(OVL_INDEX, d_inode(parent)))
1412ca3c148SAmir Goldstein break;
1422ca3c148SAmir Goldstein
1432ca3c148SAmir Goldstein dput(next);
1442ca3c148SAmir Goldstein next = parent;
1452ca3c148SAmir Goldstein }
1462ca3c148SAmir Goldstein
1472ca3c148SAmir Goldstein dput(parent);
1482ca3c148SAmir Goldstein dput(next);
1492ca3c148SAmir Goldstein
1502ca3c148SAmir Goldstein if (!err)
1512ca3c148SAmir Goldstein ovl_dentry_set_flag(OVL_E_CONNECTED, dentry);
1522ca3c148SAmir Goldstein
1532ca3c148SAmir Goldstein return err ?: origin_layer;
1542ca3c148SAmir Goldstein }
1552ca3c148SAmir Goldstein
156b305e844SAmir Goldstein /*
157b305e844SAmir Goldstein * We only need to encode origin if there is a chance that the same object was
158b305e844SAmir Goldstein * encoded pre copy up and then we need to stay consistent with the same
159b305e844SAmir Goldstein * encoding also after copy up. If non-pure upper is not indexed, then it was
160b305e844SAmir Goldstein * copied up before NFS export was enabled. In that case we don't need to worry
161b305e844SAmir Goldstein * about staying consistent with pre copy up encoding and we encode an upper
162b305e844SAmir Goldstein * file handle. Overlay root dentry is a private case of non-indexed upper.
163b305e844SAmir Goldstein *
164b305e844SAmir Goldstein * The following table summarizes the different file handle encodings used for
165b305e844SAmir Goldstein * different overlay object types:
166b305e844SAmir Goldstein *
167b305e844SAmir Goldstein * Object type | Encoding
168b305e844SAmir Goldstein * --------------------------------
169b305e844SAmir Goldstein * Pure upper | U
170b305e844SAmir Goldstein * Non-indexed upper | U
17105e1f118SAmir Goldstein * Indexed upper | L (*)
17205e1f118SAmir Goldstein * Non-upper | L (*)
173b305e844SAmir Goldstein *
174b305e844SAmir Goldstein * U = upper file handle
175b305e844SAmir Goldstein * L = lower file handle
17605e1f118SAmir Goldstein *
17716aac5adSAmir Goldstein * (*) Decoding a connected overlay dir from real lower dentry is not always
1782ca3c148SAmir Goldstein * possible when there are redirects in lower layers and non-indexed merge dirs.
1792ca3c148SAmir Goldstein * To mitigate those case, we may copy up the lower dir ancestor before encode
18016aac5adSAmir Goldstein * of a decodable file handle for non-upper dir.
1812ca3c148SAmir Goldstein *
1822ca3c148SAmir Goldstein * Return 0 for upper file handle, > 0 for lower file handle or < 0 on error.
183b305e844SAmir Goldstein */
ovl_check_encode_origin(struct dentry * dentry)1842ca3c148SAmir Goldstein static int ovl_check_encode_origin(struct dentry *dentry)
185b305e844SAmir Goldstein {
186f01d0889SAndrea Righi struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
18716aac5adSAmir Goldstein bool decodable = ofs->config.nfs_export;
18816aac5adSAmir Goldstein
18916aac5adSAmir Goldstein /* Lower file handle for non-upper non-decodable */
19016aac5adSAmir Goldstein if (!ovl_dentry_upper(dentry) && !decodable)
191*c7242a45SAmir Goldstein return 1;
19205e1f118SAmir Goldstein
1932ca3c148SAmir Goldstein /* Upper file handle for pure upper */
194b305e844SAmir Goldstein if (!ovl_dentry_lower(dentry))
19505e1f118SAmir Goldstein return 0;
19605e1f118SAmir Goldstein
1972ca3c148SAmir Goldstein /*
1982ca3c148SAmir Goldstein * Root is never indexed, so if there's an upper layer, encode upper for
1992ca3c148SAmir Goldstein * root.
2002ca3c148SAmir Goldstein */
20116aac5adSAmir Goldstein if (dentry == dentry->d_sb->s_root)
20216aac5adSAmir Goldstein return 0;
20316aac5adSAmir Goldstein
20416aac5adSAmir Goldstein /*
20516aac5adSAmir Goldstein * Upper decodable file handle for non-indexed upper.
20616aac5adSAmir Goldstein */
20716aac5adSAmir Goldstein if (ovl_dentry_upper(dentry) && decodable &&
2082ca3c148SAmir Goldstein !ovl_test_flag(OVL_INDEX, d_inode(dentry)))
2092ca3c148SAmir Goldstein return 0;
21005e1f118SAmir Goldstein
2112ca3c148SAmir Goldstein /*
2122ca3c148SAmir Goldstein * Decoding a merge dir, whose origin's ancestor is under a redirected
2132ca3c148SAmir Goldstein * lower dir or under a non-indexed upper is not always possible.
2142ca3c148SAmir Goldstein * ovl_connect_layer() will try to make origin's layer "connected" by
2152ca3c148SAmir Goldstein * copying up a "connectable" ancestor.
2162ca3c148SAmir Goldstein */
21716aac5adSAmir Goldstein if (d_is_dir(dentry) && ovl_upper_mnt(ofs) && decodable)
2182ca3c148SAmir Goldstein return ovl_connect_layer(dentry);
21905e1f118SAmir Goldstein
2202ca3c148SAmir Goldstein /* Lower file handle for indexed and non-upper dir/non-dir */
2212ca3c148SAmir Goldstein return 1;
22205e1f118SAmir Goldstein }
22305e1f118SAmir Goldstein
ovl_dentry_to_fid(struct ovl_fs * ofs,struct dentry * dentry,u32 * fid,int buflen)2241cdb0cb6SPavel Tikhomirov static int ovl_dentry_to_fid(struct ovl_fs *ofs, struct dentry *dentry,
2251cdb0cb6SPavel Tikhomirov u32 *fid, int buflen)
2268ed5eec9SAmir Goldstein {
2278ed5eec9SAmir Goldstein struct ovl_fh *fh = NULL;
2282ca3c148SAmir Goldstein int err, enc_lower;
229cbe7fba8SAmir Goldstein int len;
2308ed5eec9SAmir Goldstein
23105e1f118SAmir Goldstein /*
2322ca3c148SAmir Goldstein * Check if we should encode a lower or upper file handle and maybe
2332ca3c148SAmir Goldstein * copy up an ancestor to make lower file handle connectable.
23405e1f118SAmir Goldstein */
2352ca3c148SAmir Goldstein err = enc_lower = ovl_check_encode_origin(dentry);
2362ca3c148SAmir Goldstein if (enc_lower < 0)
23705e1f118SAmir Goldstein goto fail;
2388ed5eec9SAmir Goldstein
2392ca3c148SAmir Goldstein /* Encode an upper or lower file handle */
2401cdb0cb6SPavel Tikhomirov fh = ovl_encode_real_fh(ofs, enc_lower ? ovl_dentry_lower(dentry) :
2412ca3c148SAmir Goldstein ovl_dentry_upper(dentry), !enc_lower);
2429b6faee0SAmir Goldstein if (IS_ERR(fh))
24397f024b9SDing Xiang return PTR_ERR(fh);
2448ed5eec9SAmir Goldstein
245cbe7fba8SAmir Goldstein len = OVL_FH_LEN(fh);
246144da23bSLubos Dolezel if (len <= buflen)
247cbe7fba8SAmir Goldstein memcpy(fid, fh, len);
248cbe7fba8SAmir Goldstein err = len;
2498ed5eec9SAmir Goldstein
2508ed5eec9SAmir Goldstein out:
2518ed5eec9SAmir Goldstein kfree(fh);
2528ed5eec9SAmir Goldstein return err;
2538ed5eec9SAmir Goldstein
2548ed5eec9SAmir Goldstein fail:
255144da23bSLubos Dolezel pr_warn_ratelimited("failed to encode file handle (%pd2, err=%i)\n",
256144da23bSLubos Dolezel dentry, err);
2578ed5eec9SAmir Goldstein goto out;
2588ed5eec9SAmir Goldstein }
2598ed5eec9SAmir Goldstein
ovl_encode_fh(struct inode * inode,u32 * fid,int * max_len,struct inode * parent)2605b2cccd3SAmir Goldstein static int ovl_encode_fh(struct inode *inode, u32 *fid, int *max_len,
2618ed5eec9SAmir Goldstein struct inode *parent)
2628ed5eec9SAmir Goldstein {
2631cdb0cb6SPavel Tikhomirov struct ovl_fs *ofs = OVL_FS(inode->i_sb);
2648ed5eec9SAmir Goldstein struct dentry *dentry;
265144da23bSLubos Dolezel int bytes, buflen = *max_len << 2;
2668ed5eec9SAmir Goldstein
2678ed5eec9SAmir Goldstein /* TODO: encode connectable file handles */
2688ed5eec9SAmir Goldstein if (parent)
2698ed5eec9SAmir Goldstein return FILEID_INVALID;
2708ed5eec9SAmir Goldstein
2718ed5eec9SAmir Goldstein dentry = d_find_any_alias(inode);
272dd524b7fSJiachen Zhang if (!dentry)
2738ed5eec9SAmir Goldstein return FILEID_INVALID;
2748ed5eec9SAmir Goldstein
2751cdb0cb6SPavel Tikhomirov bytes = ovl_dentry_to_fid(ofs, dentry, fid, buflen);
2768ed5eec9SAmir Goldstein dput(dentry);
277cbe7fba8SAmir Goldstein if (bytes <= 0)
278cbe7fba8SAmir Goldstein return FILEID_INVALID;
279cbe7fba8SAmir Goldstein
280cbe7fba8SAmir Goldstein *max_len = bytes >> 2;
281144da23bSLubos Dolezel if (bytes > buflen)
282144da23bSLubos Dolezel return FILEID_INVALID;
283cbe7fba8SAmir Goldstein
284cbe7fba8SAmir Goldstein return OVL_FILEID_V1;
2858ed5eec9SAmir Goldstein }
2868ed5eec9SAmir Goldstein
2878556a420SAmir Goldstein /*
288f71bd9cfSAmir Goldstein * Find or instantiate an overlay dentry from real dentries and index.
2898556a420SAmir Goldstein */
ovl_obtain_alias(struct super_block * sb,struct dentry * upper_alias,struct ovl_path * lowerpath,struct dentry * index)2908556a420SAmir Goldstein static struct dentry *ovl_obtain_alias(struct super_block *sb,
291f71bd9cfSAmir Goldstein struct dentry *upper_alias,
292f71bd9cfSAmir Goldstein struct ovl_path *lowerpath,
293f71bd9cfSAmir Goldstein struct dentry *index)
2948556a420SAmir Goldstein {
295f941866fSAmir Goldstein struct dentry *lower = lowerpath ? lowerpath->dentry : NULL;
296f71bd9cfSAmir Goldstein struct dentry *upper = upper_alias ?: index;
2978556a420SAmir Goldstein struct dentry *dentry;
2980af950f5SAmir Goldstein struct inode *inode = NULL;
2998556a420SAmir Goldstein struct ovl_entry *oe;
300ac6a52ebSVivek Goyal struct ovl_inode_params oip = {
301ac6a52ebSVivek Goyal .index = index,
302ac6a52ebSVivek Goyal };
3038556a420SAmir Goldstein
304f71bd9cfSAmir Goldstein /* We get overlay directory dentries with ovl_lookup_real() */
305f71bd9cfSAmir Goldstein if (d_is_dir(upper ?: lower))
3068556a420SAmir Goldstein return ERR_PTR(-EIO);
3078556a420SAmir Goldstein
3080af950f5SAmir Goldstein oe = ovl_alloc_entry(!!lower);
3090af950f5SAmir Goldstein if (!oe)
3100af950f5SAmir Goldstein return ERR_PTR(-ENOMEM);
3110af950f5SAmir Goldstein
312ac6a52ebSVivek Goyal oip.upperdentry = dget(upper);
3130af950f5SAmir Goldstein if (lower) {
3140af950f5SAmir Goldstein ovl_lowerstack(oe)->dentry = dget(lower);
3150af950f5SAmir Goldstein ovl_lowerstack(oe)->layer = lowerpath->layer;
3160af950f5SAmir Goldstein }
3170af950f5SAmir Goldstein oip.oe = oe;
318ac6a52ebSVivek Goyal inode = ovl_get_inode(sb, &oip);
3198556a420SAmir Goldstein if (IS_ERR(inode)) {
3200af950f5SAmir Goldstein ovl_free_entry(oe);
3218556a420SAmir Goldstein dput(upper);
3228556a420SAmir Goldstein return ERR_CAST(inode);
3238556a420SAmir Goldstein }
3248556a420SAmir Goldstein
3259d3dfea3SVivek Goyal if (upper)
3269d3dfea3SVivek Goyal ovl_set_flag(OVL_UPPERDATA, inode);
3279d3dfea3SVivek Goyal
3288556a420SAmir Goldstein dentry = d_find_any_alias(inode);
329504f3841SAl Viro if (dentry)
330504f3841SAl Viro goto out_iput;
331504f3841SAl Viro
3328556a420SAmir Goldstein dentry = d_alloc_anon(inode->i_sb);
333504f3841SAl Viro if (unlikely(!dentry))
3348556a420SAmir Goldstein goto nomem;
3358556a420SAmir Goldstein
336f71bd9cfSAmir Goldstein if (upper_alias)
3378556a420SAmir Goldstein ovl_dentry_set_upper_alias(dentry);
338504f3841SAl Viro
3390af950f5SAmir Goldstein ovl_dentry_init_reval(dentry, upper, OVL_I_E(inode));
3408556a420SAmir Goldstein
3418556a420SAmir Goldstein return d_instantiate_anon(dentry, inode);
3428556a420SAmir Goldstein
3438556a420SAmir Goldstein nomem:
3448556a420SAmir Goldstein dput(dentry);
345504f3841SAl Viro dentry = ERR_PTR(-ENOMEM);
346504f3841SAl Viro out_iput:
347504f3841SAl Viro iput(inode);
348504f3841SAl Viro return dentry;
3498556a420SAmir Goldstein }
3508556a420SAmir Goldstein
351cdf5c9d1SJiangshan Yi /* Get the upper or lower dentry in stack whose on layer @idx */
ovl_dentry_real_at(struct dentry * dentry,int idx)35298892516SAmir Goldstein static struct dentry *ovl_dentry_real_at(struct dentry *dentry, int idx)
35398892516SAmir Goldstein {
354a6ff2bc0SAmir Goldstein struct ovl_entry *oe = OVL_E(dentry);
3555522c9c7SAmir Goldstein struct ovl_path *lowerstack = ovl_lowerstack(oe);
35698892516SAmir Goldstein int i;
35798892516SAmir Goldstein
35898892516SAmir Goldstein if (!idx)
35998892516SAmir Goldstein return ovl_dentry_upper(dentry);
36098892516SAmir Goldstein
3615522c9c7SAmir Goldstein for (i = 0; i < ovl_numlower(oe); i++) {
3625522c9c7SAmir Goldstein if (lowerstack[i].layer->idx == idx)
3635522c9c7SAmir Goldstein return lowerstack[i].dentry;
36498892516SAmir Goldstein }
36598892516SAmir Goldstein
36698892516SAmir Goldstein return NULL;
36798892516SAmir Goldstein }
36898892516SAmir Goldstein
3693985b70aSAmir Goldstein /*
3703985b70aSAmir Goldstein * Lookup a child overlay dentry to get a connected overlay dentry whose real
3713985b70aSAmir Goldstein * dentry is @real. If @real is on upper layer, we lookup a child overlay
3723985b70aSAmir Goldstein * dentry with the same name as the real dentry. Otherwise, we need to consult
3733985b70aSAmir Goldstein * index for lookup.
3743985b70aSAmir Goldstein */
ovl_lookup_real_one(struct dentry * connected,struct dentry * real,const struct ovl_layer * layer)3753985b70aSAmir Goldstein static struct dentry *ovl_lookup_real_one(struct dentry *connected,
3763985b70aSAmir Goldstein struct dentry *real,
37713464165SMiklos Szeredi const struct ovl_layer *layer)
3783985b70aSAmir Goldstein {
3793985b70aSAmir Goldstein struct inode *dir = d_inode(connected);
3803985b70aSAmir Goldstein struct dentry *this, *parent = NULL;
3813985b70aSAmir Goldstein struct name_snapshot name;
3823985b70aSAmir Goldstein int err;
3833985b70aSAmir Goldstein
3843985b70aSAmir Goldstein /*
3853985b70aSAmir Goldstein * Lookup child overlay dentry by real name. The dir mutex protects us
3863985b70aSAmir Goldstein * from racing with overlay rename. If the overlay dentry that is above
3873985b70aSAmir Goldstein * real has already been moved to a parent that is not under the
3883985b70aSAmir Goldstein * connected overlay dir, we return -ECHILD and restart the lookup of
3893985b70aSAmir Goldstein * connected real path from the top.
3903985b70aSAmir Goldstein */
3913985b70aSAmir Goldstein inode_lock_nested(dir, I_MUTEX_PARENT);
3923985b70aSAmir Goldstein err = -ECHILD;
3933985b70aSAmir Goldstein parent = dget_parent(real);
39498892516SAmir Goldstein if (ovl_dentry_real_at(connected, layer->idx) != parent)
3953985b70aSAmir Goldstein goto fail;
3963985b70aSAmir Goldstein
3973985b70aSAmir Goldstein /*
3983985b70aSAmir Goldstein * We also need to take a snapshot of real dentry name to protect us
3993985b70aSAmir Goldstein * from racing with underlying layer rename. In this case, we don't
4003985b70aSAmir Goldstein * care about returning ESTALE, only from dereferencing a free name
4013985b70aSAmir Goldstein * pointer because we hold no lock on the real dentry.
4023985b70aSAmir Goldstein */
4033985b70aSAmir Goldstein take_dentry_name_snapshot(&name, real);
404ba9ea771SChristian Brauner /*
4054609e1f1SChristian Brauner * No idmap handling here: it's an internal lookup. Could skip
4064609e1f1SChristian Brauner * permission checking altogether, but for now just use non-idmap
407ba9ea771SChristian Brauner * transformed ids.
408ba9ea771SChristian Brauner */
409230c6402SAl Viro this = lookup_one_len(name.name.name, connected, name.name.len);
410580c6104SMiklos Szeredi release_dentry_name_snapshot(&name);
4113985b70aSAmir Goldstein err = PTR_ERR(this);
4123985b70aSAmir Goldstein if (IS_ERR(this)) {
4133985b70aSAmir Goldstein goto fail;
4143985b70aSAmir Goldstein } else if (!this || !this->d_inode) {
4153985b70aSAmir Goldstein dput(this);
4163985b70aSAmir Goldstein err = -ENOENT;
4173985b70aSAmir Goldstein goto fail;
41898892516SAmir Goldstein } else if (ovl_dentry_real_at(this, layer->idx) != real) {
4193985b70aSAmir Goldstein dput(this);
4203985b70aSAmir Goldstein err = -ESTALE;
4213985b70aSAmir Goldstein goto fail;
4223985b70aSAmir Goldstein }
4233985b70aSAmir Goldstein
4243985b70aSAmir Goldstein out:
4253985b70aSAmir Goldstein dput(parent);
4263985b70aSAmir Goldstein inode_unlock(dir);
4273985b70aSAmir Goldstein return this;
4283985b70aSAmir Goldstein
4293985b70aSAmir Goldstein fail:
4301bd0a3aeSlijiazi pr_warn_ratelimited("failed to lookup one by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",
4313985b70aSAmir Goldstein real, layer->idx, connected, err);
4323985b70aSAmir Goldstein this = ERR_PTR(err);
4333985b70aSAmir Goldstein goto out;
4343985b70aSAmir Goldstein }
4353985b70aSAmir Goldstein
43606170154SAmir Goldstein static struct dentry *ovl_lookup_real(struct super_block *sb,
43706170154SAmir Goldstein struct dentry *real,
43813464165SMiklos Szeredi const struct ovl_layer *layer);
43906170154SAmir Goldstein
4403985b70aSAmir Goldstein /*
4414b91c30aSAmir Goldstein * Lookup an indexed or hashed overlay dentry by real inode.
4424b91c30aSAmir Goldstein */
ovl_lookup_real_inode(struct super_block * sb,struct dentry * real,const struct ovl_layer * layer)4434b91c30aSAmir Goldstein static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
4444b91c30aSAmir Goldstein struct dentry *real,
44513464165SMiklos Szeredi const struct ovl_layer *layer)
4464b91c30aSAmir Goldstein {
447f01d0889SAndrea Righi struct ovl_fs *ofs = OVL_FS(sb);
44806170154SAmir Goldstein struct dentry *index = NULL;
4494b91c30aSAmir Goldstein struct dentry *this = NULL;
4504b91c30aSAmir Goldstein struct inode *inode;
4514b91c30aSAmir Goldstein
45206170154SAmir Goldstein /*
45306170154SAmir Goldstein * Decoding upper dir from index is expensive, so first try to lookup
45406170154SAmir Goldstein * overlay dentry in inode/dcache.
45506170154SAmir Goldstein */
4564b91c30aSAmir Goldstein inode = ovl_lookup_inode(sb, real, !layer->idx);
4574b91c30aSAmir Goldstein if (IS_ERR(inode))
4584b91c30aSAmir Goldstein return ERR_CAST(inode);
4594b91c30aSAmir Goldstein if (inode) {
4604b91c30aSAmir Goldstein this = d_find_any_alias(inode);
4614b91c30aSAmir Goldstein iput(inode);
4624b91c30aSAmir Goldstein }
4634b91c30aSAmir Goldstein
46406170154SAmir Goldstein /*
46506170154SAmir Goldstein * For decoded lower dir file handle, lookup index by origin to check
46606170154SAmir Goldstein * if lower dir was copied up and and/or removed.
46706170154SAmir Goldstein */
46806170154SAmir Goldstein if (!this && layer->idx && ofs->indexdir && !WARN_ON(!d_is_dir(real))) {
46906170154SAmir Goldstein index = ovl_lookup_index(ofs, NULL, real, false);
47006170154SAmir Goldstein if (IS_ERR(index))
47106170154SAmir Goldstein return index;
47206170154SAmir Goldstein }
47306170154SAmir Goldstein
47406170154SAmir Goldstein /* Get connected upper overlay dir from index */
47506170154SAmir Goldstein if (index) {
4768ea28765SAmir Goldstein struct dentry *upper = ovl_index_upper(ofs, index, true);
47706170154SAmir Goldstein
47806170154SAmir Goldstein dput(index);
47906170154SAmir Goldstein if (IS_ERR_OR_NULL(upper))
48006170154SAmir Goldstein return upper;
48106170154SAmir Goldstein
48206170154SAmir Goldstein /*
48306170154SAmir Goldstein * ovl_lookup_real() in lower layer may call recursively once to
48406170154SAmir Goldstein * ovl_lookup_real() in upper layer. The first level call walks
48506170154SAmir Goldstein * back lower parents to the topmost indexed parent. The second
48606170154SAmir Goldstein * recursive call walks back from indexed upper to the topmost
48706170154SAmir Goldstein * connected/hashed upper parent (or up to root).
48806170154SAmir Goldstein */
48994375f9dSAmir Goldstein this = ovl_lookup_real(sb, upper, &ofs->layers[0]);
49006170154SAmir Goldstein dput(upper);
49106170154SAmir Goldstein }
49206170154SAmir Goldstein
4937168179fSAmir Goldstein if (IS_ERR_OR_NULL(this))
4947168179fSAmir Goldstein return this;
4954b91c30aSAmir Goldstein
496124c2de2SAmir Goldstein if (ovl_dentry_real_at(this, layer->idx) != real) {
4974b91c30aSAmir Goldstein dput(this);
4984b91c30aSAmir Goldstein this = ERR_PTR(-EIO);
4994b91c30aSAmir Goldstein }
5004b91c30aSAmir Goldstein
5014b91c30aSAmir Goldstein return this;
5024b91c30aSAmir Goldstein }
5034b91c30aSAmir Goldstein
5044b91c30aSAmir Goldstein /*
5054b91c30aSAmir Goldstein * Lookup an indexed or hashed overlay dentry, whose real dentry is an
5064b91c30aSAmir Goldstein * ancestor of @real.
5074b91c30aSAmir Goldstein */
ovl_lookup_real_ancestor(struct super_block * sb,struct dentry * real,const struct ovl_layer * layer)5084b91c30aSAmir Goldstein static struct dentry *ovl_lookup_real_ancestor(struct super_block *sb,
5094b91c30aSAmir Goldstein struct dentry *real,
51013464165SMiklos Szeredi const struct ovl_layer *layer)
5114b91c30aSAmir Goldstein {
5124b91c30aSAmir Goldstein struct dentry *next, *parent = NULL;
5134b91c30aSAmir Goldstein struct dentry *ancestor = ERR_PTR(-EIO);
5144b91c30aSAmir Goldstein
5154b91c30aSAmir Goldstein if (real == layer->mnt->mnt_root)
5164b91c30aSAmir Goldstein return dget(sb->s_root);
5174b91c30aSAmir Goldstein
5184b91c30aSAmir Goldstein /* Find the topmost indexed or hashed ancestor */
5194b91c30aSAmir Goldstein next = dget(real);
5204b91c30aSAmir Goldstein for (;;) {
5214b91c30aSAmir Goldstein parent = dget_parent(next);
5224b91c30aSAmir Goldstein
5234b91c30aSAmir Goldstein /*
5244b91c30aSAmir Goldstein * Lookup a matching overlay dentry in inode/dentry
5254b91c30aSAmir Goldstein * cache or in index by real inode.
5264b91c30aSAmir Goldstein */
5274b91c30aSAmir Goldstein ancestor = ovl_lookup_real_inode(sb, next, layer);
5284b91c30aSAmir Goldstein if (ancestor)
5294b91c30aSAmir Goldstein break;
5304b91c30aSAmir Goldstein
5314b91c30aSAmir Goldstein if (parent == layer->mnt->mnt_root) {
5324b91c30aSAmir Goldstein ancestor = dget(sb->s_root);
5334b91c30aSAmir Goldstein break;
5344b91c30aSAmir Goldstein }
5354b91c30aSAmir Goldstein
5364b91c30aSAmir Goldstein /*
5374b91c30aSAmir Goldstein * If @real has been moved out of the layer root directory,
5384b91c30aSAmir Goldstein * we will eventully hit the real fs root. This cannot happen
5394b91c30aSAmir Goldstein * by legit overlay rename, so we return error in that case.
5404b91c30aSAmir Goldstein */
5414b91c30aSAmir Goldstein if (parent == next) {
5424b91c30aSAmir Goldstein ancestor = ERR_PTR(-EXDEV);
5434b91c30aSAmir Goldstein break;
5444b91c30aSAmir Goldstein }
5454b91c30aSAmir Goldstein
5464b91c30aSAmir Goldstein dput(next);
5474b91c30aSAmir Goldstein next = parent;
5484b91c30aSAmir Goldstein }
5494b91c30aSAmir Goldstein
5504b91c30aSAmir Goldstein dput(parent);
5514b91c30aSAmir Goldstein dput(next);
5524b91c30aSAmir Goldstein
5534b91c30aSAmir Goldstein return ancestor;
5544b91c30aSAmir Goldstein }
5554b91c30aSAmir Goldstein
5564b91c30aSAmir Goldstein /*
5573985b70aSAmir Goldstein * Lookup a connected overlay dentry whose real dentry is @real.
5583985b70aSAmir Goldstein * If @real is on upper layer, we lookup a child overlay dentry with the same
5593985b70aSAmir Goldstein * path the real dentry. Otherwise, we need to consult index for lookup.
5603985b70aSAmir Goldstein */
ovl_lookup_real(struct super_block * sb,struct dentry * real,const struct ovl_layer * layer)5613985b70aSAmir Goldstein static struct dentry *ovl_lookup_real(struct super_block *sb,
5623985b70aSAmir Goldstein struct dentry *real,
56313464165SMiklos Szeredi const struct ovl_layer *layer)
5643985b70aSAmir Goldstein {
5653985b70aSAmir Goldstein struct dentry *connected;
5663985b70aSAmir Goldstein int err = 0;
5673985b70aSAmir Goldstein
5684b91c30aSAmir Goldstein connected = ovl_lookup_real_ancestor(sb, real, layer);
5694b91c30aSAmir Goldstein if (IS_ERR(connected))
5704b91c30aSAmir Goldstein return connected;
5713985b70aSAmir Goldstein
5723985b70aSAmir Goldstein while (!err) {
5733985b70aSAmir Goldstein struct dentry *next, *this;
5743985b70aSAmir Goldstein struct dentry *parent = NULL;
57598892516SAmir Goldstein struct dentry *real_connected = ovl_dentry_real_at(connected,
57698892516SAmir Goldstein layer->idx);
5773985b70aSAmir Goldstein
5783985b70aSAmir Goldstein if (real_connected == real)
5793985b70aSAmir Goldstein break;
5803985b70aSAmir Goldstein
5813985b70aSAmir Goldstein /* Find the topmost dentry not yet connected */
5823985b70aSAmir Goldstein next = dget(real);
5833985b70aSAmir Goldstein for (;;) {
5843985b70aSAmir Goldstein parent = dget_parent(next);
5853985b70aSAmir Goldstein
5863985b70aSAmir Goldstein if (parent == real_connected)
5873985b70aSAmir Goldstein break;
5883985b70aSAmir Goldstein
5893985b70aSAmir Goldstein /*
5903985b70aSAmir Goldstein * If real has been moved out of 'real_connected',
5913985b70aSAmir Goldstein * we will not find 'real_connected' and hit the layer
5923985b70aSAmir Goldstein * root. In that case, we need to restart connecting.
5933985b70aSAmir Goldstein * This game can go on forever in the worst case. We
5943985b70aSAmir Goldstein * may want to consider taking s_vfs_rename_mutex if
5953985b70aSAmir Goldstein * this happens more than once.
5963985b70aSAmir Goldstein */
5973985b70aSAmir Goldstein if (parent == layer->mnt->mnt_root) {
5983985b70aSAmir Goldstein dput(connected);
5993985b70aSAmir Goldstein connected = dget(sb->s_root);
6003985b70aSAmir Goldstein break;
6013985b70aSAmir Goldstein }
6023985b70aSAmir Goldstein
6033985b70aSAmir Goldstein /*
6043985b70aSAmir Goldstein * If real file has been moved out of the layer root
6053985b70aSAmir Goldstein * directory, we will eventully hit the real fs root.
6063985b70aSAmir Goldstein * This cannot happen by legit overlay rename, so we
6073985b70aSAmir Goldstein * return error in that case.
6083985b70aSAmir Goldstein */
6093985b70aSAmir Goldstein if (parent == next) {
6103985b70aSAmir Goldstein err = -EXDEV;
6113985b70aSAmir Goldstein break;
6123985b70aSAmir Goldstein }
6133985b70aSAmir Goldstein
6143985b70aSAmir Goldstein dput(next);
6153985b70aSAmir Goldstein next = parent;
6163985b70aSAmir Goldstein }
6173985b70aSAmir Goldstein
6183985b70aSAmir Goldstein if (!err) {
6193985b70aSAmir Goldstein this = ovl_lookup_real_one(connected, next, layer);
6203985b70aSAmir Goldstein if (IS_ERR(this))
6213985b70aSAmir Goldstein err = PTR_ERR(this);
6223985b70aSAmir Goldstein
6233985b70aSAmir Goldstein /*
6243985b70aSAmir Goldstein * Lookup of child in overlay can fail when racing with
6253985b70aSAmir Goldstein * overlay rename of child away from 'connected' parent.
6263985b70aSAmir Goldstein * In this case, we need to restart the lookup from the
6273985b70aSAmir Goldstein * top, because we cannot trust that 'real_connected' is
6284b91c30aSAmir Goldstein * still an ancestor of 'real'. There is a good chance
6294b91c30aSAmir Goldstein * that the renamed overlay ancestor is now in cache, so
6304b91c30aSAmir Goldstein * ovl_lookup_real_ancestor() will find it and we can
6314b91c30aSAmir Goldstein * continue to connect exactly from where lookup failed.
6323985b70aSAmir Goldstein */
6333985b70aSAmir Goldstein if (err == -ECHILD) {
6344b91c30aSAmir Goldstein this = ovl_lookup_real_ancestor(sb, real,
6354b91c30aSAmir Goldstein layer);
636b5095f24SFengguang Wu err = PTR_ERR_OR_ZERO(this);
6373985b70aSAmir Goldstein }
6383985b70aSAmir Goldstein if (!err) {
6393985b70aSAmir Goldstein dput(connected);
6403985b70aSAmir Goldstein connected = this;
6413985b70aSAmir Goldstein }
6423985b70aSAmir Goldstein }
6433985b70aSAmir Goldstein
6443985b70aSAmir Goldstein dput(parent);
6453985b70aSAmir Goldstein dput(next);
6463985b70aSAmir Goldstein }
6473985b70aSAmir Goldstein
6483985b70aSAmir Goldstein if (err)
6493985b70aSAmir Goldstein goto fail;
6503985b70aSAmir Goldstein
6513985b70aSAmir Goldstein return connected;
6523985b70aSAmir Goldstein
6533985b70aSAmir Goldstein fail:
6541bd0a3aeSlijiazi pr_warn_ratelimited("failed to lookup by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",
6553985b70aSAmir Goldstein real, layer->idx, connected, err);
6563985b70aSAmir Goldstein dput(connected);
6573985b70aSAmir Goldstein return ERR_PTR(err);
6583985b70aSAmir Goldstein }
6593985b70aSAmir Goldstein
6603985b70aSAmir Goldstein /*
661f71bd9cfSAmir Goldstein * Get an overlay dentry from upper/lower real dentries and index.
6623985b70aSAmir Goldstein */
ovl_get_dentry(struct super_block * sb,struct dentry * upper,struct ovl_path * lowerpath,struct dentry * index)6633985b70aSAmir Goldstein static struct dentry *ovl_get_dentry(struct super_block *sb,
6643985b70aSAmir Goldstein struct dentry *upper,
665f71bd9cfSAmir Goldstein struct ovl_path *lowerpath,
666f71bd9cfSAmir Goldstein struct dentry *index)
6673985b70aSAmir Goldstein {
668f01d0889SAndrea Righi struct ovl_fs *ofs = OVL_FS(sb);
66913464165SMiklos Szeredi const struct ovl_layer *layer = upper ? &ofs->layers[0] : lowerpath->layer;
670f71bd9cfSAmir Goldstein struct dentry *real = upper ?: (index ?: lowerpath->dentry);
6713985b70aSAmir Goldstein
672f941866fSAmir Goldstein /*
673f71bd9cfSAmir Goldstein * Obtain a disconnected overlay dentry from a non-dir real dentry
674f71bd9cfSAmir Goldstein * and index.
675f941866fSAmir Goldstein */
676f71bd9cfSAmir Goldstein if (!d_is_dir(real))
677f71bd9cfSAmir Goldstein return ovl_obtain_alias(sb, upper, lowerpath, index);
678f941866fSAmir Goldstein
6793985b70aSAmir Goldstein /* Removed empty directory? */
68098892516SAmir Goldstein if ((real->d_flags & DCACHE_DISCONNECTED) || d_unhashed(real))
6813985b70aSAmir Goldstein return ERR_PTR(-ENOENT);
6823985b70aSAmir Goldstein
6833985b70aSAmir Goldstein /*
68498892516SAmir Goldstein * If real dentry is connected and hashed, get a connected overlay
68598892516SAmir Goldstein * dentry whose real dentry is @real.
6863985b70aSAmir Goldstein */
68798892516SAmir Goldstein return ovl_lookup_real(sb, real, layer);
6883985b70aSAmir Goldstein }
6893985b70aSAmir Goldstein
ovl_upper_fh_to_d(struct super_block * sb,struct ovl_fh * fh)6908556a420SAmir Goldstein static struct dentry *ovl_upper_fh_to_d(struct super_block *sb,
6918556a420SAmir Goldstein struct ovl_fh *fh)
6928556a420SAmir Goldstein {
693f01d0889SAndrea Righi struct ovl_fs *ofs = OVL_FS(sb);
6948556a420SAmir Goldstein struct dentry *dentry;
6958556a420SAmir Goldstein struct dentry *upper;
6968556a420SAmir Goldstein
69708f4c7c8SMiklos Szeredi if (!ovl_upper_mnt(ofs))
6988556a420SAmir Goldstein return ERR_PTR(-EACCES);
6998556a420SAmir Goldstein
7001cdb0cb6SPavel Tikhomirov upper = ovl_decode_real_fh(ofs, fh, ovl_upper_mnt(ofs), true);
7018556a420SAmir Goldstein if (IS_ERR_OR_NULL(upper))
7028556a420SAmir Goldstein return upper;
7038556a420SAmir Goldstein
704f71bd9cfSAmir Goldstein dentry = ovl_get_dentry(sb, upper, NULL, NULL);
7058556a420SAmir Goldstein dput(upper);
7068556a420SAmir Goldstein
7078556a420SAmir Goldstein return dentry;
7088556a420SAmir Goldstein }
7098556a420SAmir Goldstein
ovl_lower_fh_to_d(struct super_block * sb,struct ovl_fh * fh)710f941866fSAmir Goldstein static struct dentry *ovl_lower_fh_to_d(struct super_block *sb,
711f941866fSAmir Goldstein struct ovl_fh *fh)
712f941866fSAmir Goldstein {
713f01d0889SAndrea Righi struct ovl_fs *ofs = OVL_FS(sb);
714f941866fSAmir Goldstein struct ovl_path origin = { };
715f941866fSAmir Goldstein struct ovl_path *stack = &origin;
716f941866fSAmir Goldstein struct dentry *dentry = NULL;
717f71bd9cfSAmir Goldstein struct dentry *index = NULL;
7188b58924aSAmir Goldstein struct inode *inode;
719f941866fSAmir Goldstein int err;
720f941866fSAmir Goldstein
7218b58924aSAmir Goldstein /* First lookup overlay inode in inode cache by origin fh */
7228b58924aSAmir Goldstein err = ovl_check_origin_fh(ofs, fh, false, NULL, &stack);
7238b58924aSAmir Goldstein if (err)
7248b58924aSAmir Goldstein return ERR_PTR(err);
7258b58924aSAmir Goldstein
7268b58924aSAmir Goldstein if (!d_is_dir(origin.dentry) ||
7278b58924aSAmir Goldstein !(origin.dentry->d_flags & DCACHE_DISCONNECTED)) {
7288b58924aSAmir Goldstein inode = ovl_lookup_inode(sb, origin.dentry, false);
7298b58924aSAmir Goldstein err = PTR_ERR(inode);
7308b58924aSAmir Goldstein if (IS_ERR(inode))
7318b58924aSAmir Goldstein goto out_err;
7328b58924aSAmir Goldstein if (inode) {
7338b58924aSAmir Goldstein dentry = d_find_any_alias(inode);
7348b58924aSAmir Goldstein iput(inode);
7358b58924aSAmir Goldstein if (dentry)
7368b58924aSAmir Goldstein goto out;
7378b58924aSAmir Goldstein }
7388b58924aSAmir Goldstein }
7398b58924aSAmir Goldstein
7408b58924aSAmir Goldstein /* Then lookup indexed upper/whiteout by origin fh */
741f71bd9cfSAmir Goldstein if (ofs->indexdir) {
742f71bd9cfSAmir Goldstein index = ovl_get_index_fh(ofs, fh);
743f71bd9cfSAmir Goldstein err = PTR_ERR(index);
7449436a1a3SAmir Goldstein if (IS_ERR(index)) {
7459436a1a3SAmir Goldstein index = NULL;
7468b58924aSAmir Goldstein goto out_err;
7479436a1a3SAmir Goldstein }
748f71bd9cfSAmir Goldstein }
749f941866fSAmir Goldstein
7508b58924aSAmir Goldstein /* Then try to get a connected upper dir by index */
7513b0bfc6eSAmir Goldstein if (index && d_is_dir(index)) {
7528ea28765SAmir Goldstein struct dentry *upper = ovl_index_upper(ofs, index, true);
7533b0bfc6eSAmir Goldstein
7543b0bfc6eSAmir Goldstein err = PTR_ERR(upper);
7553b0bfc6eSAmir Goldstein if (IS_ERR_OR_NULL(upper))
7563b0bfc6eSAmir Goldstein goto out_err;
7573b0bfc6eSAmir Goldstein
7583b0bfc6eSAmir Goldstein dentry = ovl_get_dentry(sb, upper, NULL, NULL);
7593b0bfc6eSAmir Goldstein dput(upper);
7603b0bfc6eSAmir Goldstein goto out;
7613b0bfc6eSAmir Goldstein }
7623b0bfc6eSAmir Goldstein
763155b8a04SAmir Goldstein /* Find origin.dentry again with ovl_acceptable() layer check */
764155b8a04SAmir Goldstein if (d_is_dir(origin.dentry)) {
7658b58924aSAmir Goldstein dput(origin.dentry);
7668b58924aSAmir Goldstein origin.dentry = NULL;
7678a22efa1SAmir Goldstein err = ovl_check_origin_fh(ofs, fh, true, NULL, &stack);
7688b58924aSAmir Goldstein if (err)
769f71bd9cfSAmir Goldstein goto out_err;
7708b58924aSAmir Goldstein }
7718b58924aSAmir Goldstein if (index) {
772610afc0bSMiklos Szeredi err = ovl_verify_origin(ofs, index, origin.dentry, false);
773f71bd9cfSAmir Goldstein if (err)
774f71bd9cfSAmir Goldstein goto out_err;
775f71bd9cfSAmir Goldstein }
776f71bd9cfSAmir Goldstein
777155b8a04SAmir Goldstein /* Get a connected non-upper dir or disconnected non-dir */
778f71bd9cfSAmir Goldstein dentry = ovl_get_dentry(sb, NULL, &origin, index);
779f71bd9cfSAmir Goldstein
780f71bd9cfSAmir Goldstein out:
781f941866fSAmir Goldstein dput(origin.dentry);
782f71bd9cfSAmir Goldstein dput(index);
783f941866fSAmir Goldstein return dentry;
784f71bd9cfSAmir Goldstein
785f71bd9cfSAmir Goldstein out_err:
786f71bd9cfSAmir Goldstein dentry = ERR_PTR(err);
787f71bd9cfSAmir Goldstein goto out;
788f941866fSAmir Goldstein }
789f941866fSAmir Goldstein
ovl_fid_to_fh(struct fid * fid,int buflen,int fh_type)790cbe7fba8SAmir Goldstein static struct ovl_fh *ovl_fid_to_fh(struct fid *fid, int buflen, int fh_type)
791cbe7fba8SAmir Goldstein {
792cbe7fba8SAmir Goldstein struct ovl_fh *fh;
793cbe7fba8SAmir Goldstein
794cbe7fba8SAmir Goldstein /* If on-wire inner fid is aligned - nothing to do */
795cbe7fba8SAmir Goldstein if (fh_type == OVL_FILEID_V1)
796cbe7fba8SAmir Goldstein return (struct ovl_fh *)fid;
797cbe7fba8SAmir Goldstein
798cbe7fba8SAmir Goldstein if (fh_type != OVL_FILEID_V0)
799cbe7fba8SAmir Goldstein return ERR_PTR(-EINVAL);
800cbe7fba8SAmir Goldstein
8019aafc1b0SDan Carpenter if (buflen <= OVL_FH_WIRE_OFFSET)
8029aafc1b0SDan Carpenter return ERR_PTR(-EINVAL);
8039aafc1b0SDan Carpenter
804cbe7fba8SAmir Goldstein fh = kzalloc(buflen, GFP_KERNEL);
805cbe7fba8SAmir Goldstein if (!fh)
806cbe7fba8SAmir Goldstein return ERR_PTR(-ENOMEM);
807cbe7fba8SAmir Goldstein
808cbe7fba8SAmir Goldstein /* Copy unaligned inner fh into aligned buffer */
809cf8aa9bfSKees Cook memcpy(fh->buf, fid, buflen - OVL_FH_WIRE_OFFSET);
810cbe7fba8SAmir Goldstein return fh;
811cbe7fba8SAmir Goldstein }
812cbe7fba8SAmir Goldstein
ovl_fh_to_dentry(struct super_block * sb,struct fid * fid,int fh_len,int fh_type)8138556a420SAmir Goldstein static struct dentry *ovl_fh_to_dentry(struct super_block *sb, struct fid *fid,
8148556a420SAmir Goldstein int fh_len, int fh_type)
8158556a420SAmir Goldstein {
8168556a420SAmir Goldstein struct dentry *dentry = NULL;
817cbe7fba8SAmir Goldstein struct ovl_fh *fh = NULL;
8188556a420SAmir Goldstein int len = fh_len << 2;
8198556a420SAmir Goldstein unsigned int flags = 0;
8208556a420SAmir Goldstein int err;
8218556a420SAmir Goldstein
822cbe7fba8SAmir Goldstein fh = ovl_fid_to_fh(fid, len, fh_type);
823cbe7fba8SAmir Goldstein err = PTR_ERR(fh);
824cbe7fba8SAmir Goldstein if (IS_ERR(fh))
8258556a420SAmir Goldstein goto out_err;
8268556a420SAmir Goldstein
8278556a420SAmir Goldstein err = ovl_check_fh_len(fh, len);
8288556a420SAmir Goldstein if (err)
8298556a420SAmir Goldstein goto out_err;
8308556a420SAmir Goldstein
831cbe7fba8SAmir Goldstein flags = fh->fb.flags;
832f941866fSAmir Goldstein dentry = (flags & OVL_FH_FLAG_PATH_UPPER) ?
833f941866fSAmir Goldstein ovl_upper_fh_to_d(sb, fh) :
834f941866fSAmir Goldstein ovl_lower_fh_to_d(sb, fh);
8358556a420SAmir Goldstein err = PTR_ERR(dentry);
8368556a420SAmir Goldstein if (IS_ERR(dentry) && err != -ESTALE)
8378556a420SAmir Goldstein goto out_err;
8388556a420SAmir Goldstein
839cbe7fba8SAmir Goldstein out:
840cbe7fba8SAmir Goldstein /* We may have needed to re-align OVL_FILEID_V0 */
841cbe7fba8SAmir Goldstein if (!IS_ERR_OR_NULL(fh) && fh != (void *)fid)
842cbe7fba8SAmir Goldstein kfree(fh);
843cbe7fba8SAmir Goldstein
8448556a420SAmir Goldstein return dentry;
8458556a420SAmir Goldstein
8468556a420SAmir Goldstein out_err:
8471bd0a3aeSlijiazi pr_warn_ratelimited("failed to decode file handle (len=%d, type=%d, flags=%x, err=%i)\n",
848cbe7fba8SAmir Goldstein fh_len, fh_type, flags, err);
849cbe7fba8SAmir Goldstein dentry = ERR_PTR(err);
850cbe7fba8SAmir Goldstein goto out;
8518556a420SAmir Goldstein }
8528556a420SAmir Goldstein
ovl_fh_to_parent(struct super_block * sb,struct fid * fid,int fh_len,int fh_type)8533985b70aSAmir Goldstein static struct dentry *ovl_fh_to_parent(struct super_block *sb, struct fid *fid,
8543985b70aSAmir Goldstein int fh_len, int fh_type)
8553985b70aSAmir Goldstein {
8561bd0a3aeSlijiazi pr_warn_ratelimited("connectable file handles not supported; use 'no_subtree_check' exportfs option.\n");
8573985b70aSAmir Goldstein return ERR_PTR(-EACCES);
8583985b70aSAmir Goldstein }
8593985b70aSAmir Goldstein
ovl_get_name(struct dentry * parent,char * name,struct dentry * child)8603985b70aSAmir Goldstein static int ovl_get_name(struct dentry *parent, char *name,
8613985b70aSAmir Goldstein struct dentry *child)
8623985b70aSAmir Goldstein {
8633985b70aSAmir Goldstein /*
8643985b70aSAmir Goldstein * ovl_fh_to_dentry() returns connected dir overlay dentries and
8653985b70aSAmir Goldstein * ovl_fh_to_parent() is not implemented, so we should not get here.
8663985b70aSAmir Goldstein */
8673985b70aSAmir Goldstein WARN_ON_ONCE(1);
8683985b70aSAmir Goldstein return -EIO;
8693985b70aSAmir Goldstein }
8703985b70aSAmir Goldstein
ovl_get_parent(struct dentry * dentry)8713985b70aSAmir Goldstein static struct dentry *ovl_get_parent(struct dentry *dentry)
8723985b70aSAmir Goldstein {
8733985b70aSAmir Goldstein /*
8743985b70aSAmir Goldstein * ovl_fh_to_dentry() returns connected dir overlay dentries, so we
8753985b70aSAmir Goldstein * should not get here.
8763985b70aSAmir Goldstein */
8773985b70aSAmir Goldstein WARN_ON_ONCE(1);
8783985b70aSAmir Goldstein return ERR_PTR(-EIO);
8793985b70aSAmir Goldstein }
8803985b70aSAmir Goldstein
8818ed5eec9SAmir Goldstein const struct export_operations ovl_export_operations = {
8825b2cccd3SAmir Goldstein .encode_fh = ovl_encode_fh,
8838556a420SAmir Goldstein .fh_to_dentry = ovl_fh_to_dentry,
8843985b70aSAmir Goldstein .fh_to_parent = ovl_fh_to_parent,
8853985b70aSAmir Goldstein .get_name = ovl_get_name,
8863985b70aSAmir Goldstein .get_parent = ovl_get_parent,
8878ed5eec9SAmir Goldstein };
88816aac5adSAmir Goldstein
88916aac5adSAmir Goldstein /* encode_fh() encodes non-decodable file handles with nfs_export=off */
89016aac5adSAmir Goldstein const struct export_operations ovl_export_fid_operations = {
89116aac5adSAmir Goldstein .encode_fh = ovl_encode_fh,
89216aac5adSAmir Goldstein };
893