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 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) { 332ca3c148SAmir Goldstein pr_warn_ratelimited("overlayfs: 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 */ 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) 832ca3c148SAmir Goldstein return oe->numlower; 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 */ 942ca3c148SAmir Goldstein return oe->lowerstack[0].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 */ 1052ca3c148SAmir Goldstein static int ovl_connect_layer(struct dentry *dentry) 1062ca3c148SAmir Goldstein { 1072ca3c148SAmir Goldstein struct dentry *next, *parent = NULL; 1082ca3c148SAmir Goldstein int origin_layer; 1092ca3c148SAmir Goldstein int err = 0; 1102ca3c148SAmir Goldstein 1112ca3c148SAmir Goldstein if (WARN_ON(dentry == dentry->d_sb->s_root) || 1122ca3c148SAmir Goldstein WARN_ON(!ovl_dentry_lower(dentry))) 1132ca3c148SAmir Goldstein return -EIO; 1142ca3c148SAmir Goldstein 1152ca3c148SAmir Goldstein origin_layer = OVL_E(dentry)->lowerstack[0].layer->idx; 1162ca3c148SAmir Goldstein if (ovl_dentry_test_flag(OVL_E_CONNECTED, dentry)) 1172ca3c148SAmir Goldstein return origin_layer; 1182ca3c148SAmir Goldstein 1192ca3c148SAmir Goldstein /* Find the topmost origin layer connectable ancestor of @dentry */ 1202ca3c148SAmir Goldstein next = dget(dentry); 1212ca3c148SAmir Goldstein for (;;) { 1222ca3c148SAmir Goldstein parent = dget_parent(next); 1232ca3c148SAmir Goldstein if (WARN_ON(parent == next)) { 1242ca3c148SAmir Goldstein err = -EIO; 1252ca3c148SAmir Goldstein break; 1262ca3c148SAmir Goldstein } 1272ca3c148SAmir Goldstein 1282ca3c148SAmir Goldstein /* 1292ca3c148SAmir Goldstein * If @parent is not origin layer connectable, then copy up 1302ca3c148SAmir Goldstein * @next which is origin layer connectable and we are done. 1312ca3c148SAmir Goldstein */ 1322ca3c148SAmir Goldstein if (ovl_connectable_layer(parent) < origin_layer) { 1332ca3c148SAmir Goldstein err = ovl_encode_maybe_copy_up(next); 1342ca3c148SAmir Goldstein break; 1352ca3c148SAmir Goldstein } 1362ca3c148SAmir Goldstein 1372ca3c148SAmir Goldstein /* If @parent is connected or indexed we are done */ 1382ca3c148SAmir Goldstein if (ovl_dentry_test_flag(OVL_E_CONNECTED, parent) || 1392ca3c148SAmir Goldstein ovl_test_flag(OVL_INDEX, d_inode(parent))) 1402ca3c148SAmir Goldstein break; 1412ca3c148SAmir Goldstein 1422ca3c148SAmir Goldstein dput(next); 1432ca3c148SAmir Goldstein next = parent; 1442ca3c148SAmir Goldstein } 1452ca3c148SAmir Goldstein 1462ca3c148SAmir Goldstein dput(parent); 1472ca3c148SAmir Goldstein dput(next); 1482ca3c148SAmir Goldstein 1492ca3c148SAmir Goldstein if (!err) 1502ca3c148SAmir Goldstein ovl_dentry_set_flag(OVL_E_CONNECTED, dentry); 1512ca3c148SAmir Goldstein 1522ca3c148SAmir Goldstein return err ?: origin_layer; 1532ca3c148SAmir Goldstein } 1542ca3c148SAmir Goldstein 155b305e844SAmir Goldstein /* 156b305e844SAmir Goldstein * We only need to encode origin if there is a chance that the same object was 157b305e844SAmir Goldstein * encoded pre copy up and then we need to stay consistent with the same 158b305e844SAmir Goldstein * encoding also after copy up. If non-pure upper is not indexed, then it was 159b305e844SAmir Goldstein * copied up before NFS export was enabled. In that case we don't need to worry 160b305e844SAmir Goldstein * about staying consistent with pre copy up encoding and we encode an upper 161b305e844SAmir Goldstein * file handle. Overlay root dentry is a private case of non-indexed upper. 162b305e844SAmir Goldstein * 163b305e844SAmir Goldstein * The following table summarizes the different file handle encodings used for 164b305e844SAmir Goldstein * different overlay object types: 165b305e844SAmir Goldstein * 166b305e844SAmir Goldstein * Object type | Encoding 167b305e844SAmir Goldstein * -------------------------------- 168b305e844SAmir Goldstein * Pure upper | U 169b305e844SAmir Goldstein * Non-indexed upper | U 17005e1f118SAmir Goldstein * Indexed upper | L (*) 17105e1f118SAmir Goldstein * Non-upper | L (*) 172b305e844SAmir Goldstein * 173b305e844SAmir Goldstein * U = upper file handle 174b305e844SAmir Goldstein * L = lower file handle 17505e1f118SAmir Goldstein * 17605e1f118SAmir Goldstein * (*) Connecting an overlay dir from real lower dentry is not always 1772ca3c148SAmir Goldstein * possible when there are redirects in lower layers and non-indexed merge dirs. 1782ca3c148SAmir Goldstein * To mitigate those case, we may copy up the lower dir ancestor before encode 1792ca3c148SAmir Goldstein * a lower dir file handle. 1802ca3c148SAmir Goldstein * 1812ca3c148SAmir Goldstein * Return 0 for upper file handle, > 0 for lower file handle or < 0 on error. 182b305e844SAmir Goldstein */ 1832ca3c148SAmir Goldstein static int ovl_check_encode_origin(struct dentry *dentry) 184b305e844SAmir Goldstein { 18505e1f118SAmir Goldstein struct ovl_fs *ofs = dentry->d_sb->s_fs_info; 18605e1f118SAmir Goldstein 1872ca3c148SAmir Goldstein /* Upper file handle for pure upper */ 188b305e844SAmir Goldstein if (!ovl_dentry_lower(dentry)) 18905e1f118SAmir Goldstein return 0; 19005e1f118SAmir Goldstein 1912ca3c148SAmir Goldstein /* 1922ca3c148SAmir Goldstein * Upper file handle for non-indexed upper. 1932ca3c148SAmir Goldstein * 1942ca3c148SAmir Goldstein * Root is never indexed, so if there's an upper layer, encode upper for 1952ca3c148SAmir Goldstein * root. 1962ca3c148SAmir Goldstein */ 1972ca3c148SAmir Goldstein if (ovl_dentry_upper(dentry) && 1982ca3c148SAmir Goldstein !ovl_test_flag(OVL_INDEX, d_inode(dentry))) 1992ca3c148SAmir Goldstein return 0; 20005e1f118SAmir Goldstein 2012ca3c148SAmir Goldstein /* 2022ca3c148SAmir Goldstein * Decoding a merge dir, whose origin's ancestor is under a redirected 2032ca3c148SAmir Goldstein * lower dir or under a non-indexed upper is not always possible. 2042ca3c148SAmir Goldstein * ovl_connect_layer() will try to make origin's layer "connected" by 2052ca3c148SAmir Goldstein * copying up a "connectable" ancestor. 2062ca3c148SAmir Goldstein */ 2072ca3c148SAmir Goldstein if (d_is_dir(dentry) && ofs->upper_mnt) 2082ca3c148SAmir Goldstein return ovl_connect_layer(dentry); 20905e1f118SAmir Goldstein 2102ca3c148SAmir Goldstein /* Lower file handle for indexed and non-upper dir/non-dir */ 2112ca3c148SAmir Goldstein return 1; 21205e1f118SAmir Goldstein } 21305e1f118SAmir Goldstein 214cbe7fba8SAmir Goldstein static int ovl_dentry_to_fid(struct dentry *dentry, u32 *fid, int buflen) 2158ed5eec9SAmir Goldstein { 2168ed5eec9SAmir Goldstein struct ovl_fh *fh = NULL; 2172ca3c148SAmir Goldstein int err, enc_lower; 218cbe7fba8SAmir Goldstein int len; 2198ed5eec9SAmir Goldstein 22005e1f118SAmir Goldstein /* 2212ca3c148SAmir Goldstein * Check if we should encode a lower or upper file handle and maybe 2222ca3c148SAmir Goldstein * copy up an ancestor to make lower file handle connectable. 22305e1f118SAmir Goldstein */ 2242ca3c148SAmir Goldstein err = enc_lower = ovl_check_encode_origin(dentry); 2252ca3c148SAmir Goldstein if (enc_lower < 0) 22605e1f118SAmir Goldstein goto fail; 2278ed5eec9SAmir Goldstein 2282ca3c148SAmir Goldstein /* Encode an upper or lower file handle */ 2295b2cccd3SAmir Goldstein fh = ovl_encode_real_fh(enc_lower ? ovl_dentry_lower(dentry) : 2302ca3c148SAmir Goldstein ovl_dentry_upper(dentry), !enc_lower); 2319b6faee0SAmir Goldstein if (IS_ERR(fh)) 23297f024b9SDing Xiang return PTR_ERR(fh); 2338ed5eec9SAmir Goldstein 2348ed5eec9SAmir Goldstein err = -EOVERFLOW; 235cbe7fba8SAmir Goldstein len = OVL_FH_LEN(fh); 236cbe7fba8SAmir Goldstein if (len > buflen) 2378ed5eec9SAmir Goldstein goto fail; 2388ed5eec9SAmir Goldstein 239cbe7fba8SAmir Goldstein memcpy(fid, fh, len); 240cbe7fba8SAmir Goldstein err = len; 2418ed5eec9SAmir Goldstein 2428ed5eec9SAmir Goldstein out: 2438ed5eec9SAmir Goldstein kfree(fh); 2448ed5eec9SAmir Goldstein return err; 2458ed5eec9SAmir Goldstein 2468ed5eec9SAmir Goldstein fail: 2478ed5eec9SAmir Goldstein pr_warn_ratelimited("overlayfs: failed to encode file handle (%pd2, err=%i, buflen=%d, len=%d, type=%d)\n", 248cbe7fba8SAmir Goldstein dentry, err, buflen, fh ? (int)fh->fb.len : 0, 249cbe7fba8SAmir Goldstein fh ? fh->fb.type : 0); 2508ed5eec9SAmir Goldstein goto out; 2518ed5eec9SAmir Goldstein } 2528ed5eec9SAmir Goldstein 2535b2cccd3SAmir Goldstein static int ovl_encode_fh(struct inode *inode, u32 *fid, int *max_len, 2548ed5eec9SAmir Goldstein struct inode *parent) 2558ed5eec9SAmir Goldstein { 2568ed5eec9SAmir Goldstein struct dentry *dentry; 257cbe7fba8SAmir Goldstein int bytes = *max_len << 2; 2588ed5eec9SAmir Goldstein 2598ed5eec9SAmir Goldstein /* TODO: encode connectable file handles */ 2608ed5eec9SAmir Goldstein if (parent) 2618ed5eec9SAmir Goldstein return FILEID_INVALID; 2628ed5eec9SAmir Goldstein 2638ed5eec9SAmir Goldstein dentry = d_find_any_alias(inode); 2648ed5eec9SAmir Goldstein if (WARN_ON(!dentry)) 2658ed5eec9SAmir Goldstein return FILEID_INVALID; 2668ed5eec9SAmir Goldstein 267cbe7fba8SAmir Goldstein bytes = ovl_dentry_to_fid(dentry, fid, bytes); 2688ed5eec9SAmir Goldstein dput(dentry); 269cbe7fba8SAmir Goldstein if (bytes <= 0) 270cbe7fba8SAmir Goldstein return FILEID_INVALID; 271cbe7fba8SAmir Goldstein 272cbe7fba8SAmir Goldstein *max_len = bytes >> 2; 273cbe7fba8SAmir Goldstein 274cbe7fba8SAmir Goldstein return OVL_FILEID_V1; 2758ed5eec9SAmir Goldstein } 2768ed5eec9SAmir Goldstein 2778556a420SAmir Goldstein /* 278f71bd9cfSAmir Goldstein * Find or instantiate an overlay dentry from real dentries and index. 2798556a420SAmir Goldstein */ 2808556a420SAmir Goldstein static struct dentry *ovl_obtain_alias(struct super_block *sb, 281f71bd9cfSAmir Goldstein struct dentry *upper_alias, 282f71bd9cfSAmir Goldstein struct ovl_path *lowerpath, 283f71bd9cfSAmir Goldstein struct dentry *index) 2848556a420SAmir Goldstein { 285f941866fSAmir Goldstein struct dentry *lower = lowerpath ? lowerpath->dentry : NULL; 286f71bd9cfSAmir Goldstein struct dentry *upper = upper_alias ?: index; 2878556a420SAmir Goldstein struct dentry *dentry; 288f941866fSAmir Goldstein struct inode *inode; 2898556a420SAmir Goldstein struct ovl_entry *oe; 290ac6a52ebSVivek Goyal struct ovl_inode_params oip = { 291ac6a52ebSVivek Goyal .lowerpath = lowerpath, 292ac6a52ebSVivek Goyal .index = index, 293ac6a52ebSVivek Goyal .numlower = !!lower 294ac6a52ebSVivek Goyal }; 2958556a420SAmir Goldstein 296f71bd9cfSAmir Goldstein /* We get overlay directory dentries with ovl_lookup_real() */ 297f71bd9cfSAmir Goldstein if (d_is_dir(upper ?: lower)) 2988556a420SAmir Goldstein return ERR_PTR(-EIO); 2998556a420SAmir Goldstein 300ac6a52ebSVivek Goyal oip.upperdentry = dget(upper); 301ac6a52ebSVivek Goyal inode = ovl_get_inode(sb, &oip); 3028556a420SAmir Goldstein if (IS_ERR(inode)) { 3038556a420SAmir Goldstein dput(upper); 3048556a420SAmir Goldstein return ERR_CAST(inode); 3058556a420SAmir Goldstein } 3068556a420SAmir Goldstein 3079d3dfea3SVivek Goyal if (upper) 3089d3dfea3SVivek Goyal ovl_set_flag(OVL_UPPERDATA, inode); 3099d3dfea3SVivek Goyal 3108556a420SAmir Goldstein dentry = d_find_any_alias(inode); 3118556a420SAmir Goldstein if (!dentry) { 3128556a420SAmir Goldstein dentry = d_alloc_anon(inode->i_sb); 3138556a420SAmir Goldstein if (!dentry) 3148556a420SAmir Goldstein goto nomem; 315f941866fSAmir Goldstein oe = ovl_alloc_entry(lower ? 1 : 0); 3168556a420SAmir Goldstein if (!oe) 3178556a420SAmir Goldstein goto nomem; 3188556a420SAmir Goldstein 319f941866fSAmir Goldstein if (lower) { 320f941866fSAmir Goldstein oe->lowerstack->dentry = dget(lower); 321f941866fSAmir Goldstein oe->lowerstack->layer = lowerpath->layer; 322f941866fSAmir Goldstein } 3238556a420SAmir Goldstein dentry->d_fsdata = oe; 324f71bd9cfSAmir Goldstein if (upper_alias) 3258556a420SAmir Goldstein ovl_dentry_set_upper_alias(dentry); 3268556a420SAmir Goldstein } 3278556a420SAmir Goldstein 3288556a420SAmir Goldstein return d_instantiate_anon(dentry, inode); 3298556a420SAmir Goldstein 3308556a420SAmir Goldstein nomem: 3318556a420SAmir Goldstein iput(inode); 3328556a420SAmir Goldstein dput(dentry); 3338556a420SAmir Goldstein return ERR_PTR(-ENOMEM); 3348556a420SAmir Goldstein } 3358556a420SAmir Goldstein 33698892516SAmir Goldstein /* Get the upper or lower dentry in stach whose on layer @idx */ 33798892516SAmir Goldstein static struct dentry *ovl_dentry_real_at(struct dentry *dentry, int idx) 33898892516SAmir Goldstein { 33998892516SAmir Goldstein struct ovl_entry *oe = dentry->d_fsdata; 34098892516SAmir Goldstein int i; 34198892516SAmir Goldstein 34298892516SAmir Goldstein if (!idx) 34398892516SAmir Goldstein return ovl_dentry_upper(dentry); 34498892516SAmir Goldstein 34598892516SAmir Goldstein for (i = 0; i < oe->numlower; i++) { 34698892516SAmir Goldstein if (oe->lowerstack[i].layer->idx == idx) 34798892516SAmir Goldstein return oe->lowerstack[i].dentry; 34898892516SAmir Goldstein } 34998892516SAmir Goldstein 35098892516SAmir Goldstein return NULL; 35198892516SAmir Goldstein } 35298892516SAmir Goldstein 3533985b70aSAmir Goldstein /* 3543985b70aSAmir Goldstein * Lookup a child overlay dentry to get a connected overlay dentry whose real 3553985b70aSAmir Goldstein * dentry is @real. If @real is on upper layer, we lookup a child overlay 3563985b70aSAmir Goldstein * dentry with the same name as the real dentry. Otherwise, we need to consult 3573985b70aSAmir Goldstein * index for lookup. 3583985b70aSAmir Goldstein */ 3593985b70aSAmir Goldstein static struct dentry *ovl_lookup_real_one(struct dentry *connected, 3603985b70aSAmir Goldstein struct dentry *real, 3613985b70aSAmir Goldstein struct ovl_layer *layer) 3623985b70aSAmir Goldstein { 3633985b70aSAmir Goldstein struct inode *dir = d_inode(connected); 3643985b70aSAmir Goldstein struct dentry *this, *parent = NULL; 3653985b70aSAmir Goldstein struct name_snapshot name; 3663985b70aSAmir Goldstein int err; 3673985b70aSAmir Goldstein 3683985b70aSAmir Goldstein /* 3693985b70aSAmir Goldstein * Lookup child overlay dentry by real name. The dir mutex protects us 3703985b70aSAmir Goldstein * from racing with overlay rename. If the overlay dentry that is above 3713985b70aSAmir Goldstein * real has already been moved to a parent that is not under the 3723985b70aSAmir Goldstein * connected overlay dir, we return -ECHILD and restart the lookup of 3733985b70aSAmir Goldstein * connected real path from the top. 3743985b70aSAmir Goldstein */ 3753985b70aSAmir Goldstein inode_lock_nested(dir, I_MUTEX_PARENT); 3763985b70aSAmir Goldstein err = -ECHILD; 3773985b70aSAmir Goldstein parent = dget_parent(real); 37898892516SAmir Goldstein if (ovl_dentry_real_at(connected, layer->idx) != parent) 3793985b70aSAmir Goldstein goto fail; 3803985b70aSAmir Goldstein 3813985b70aSAmir Goldstein /* 3823985b70aSAmir Goldstein * We also need to take a snapshot of real dentry name to protect us 3833985b70aSAmir Goldstein * from racing with underlying layer rename. In this case, we don't 3843985b70aSAmir Goldstein * care about returning ESTALE, only from dereferencing a free name 3853985b70aSAmir Goldstein * pointer because we hold no lock on the real dentry. 3863985b70aSAmir Goldstein */ 3873985b70aSAmir Goldstein take_dentry_name_snapshot(&name, real); 388230c6402SAl Viro this = lookup_one_len(name.name.name, connected, name.name.len); 3893985b70aSAmir Goldstein err = PTR_ERR(this); 3903985b70aSAmir Goldstein if (IS_ERR(this)) { 3913985b70aSAmir Goldstein goto fail; 3923985b70aSAmir Goldstein } else if (!this || !this->d_inode) { 3933985b70aSAmir Goldstein dput(this); 3943985b70aSAmir Goldstein err = -ENOENT; 3953985b70aSAmir Goldstein goto fail; 39698892516SAmir Goldstein } else if (ovl_dentry_real_at(this, layer->idx) != real) { 3973985b70aSAmir Goldstein dput(this); 3983985b70aSAmir Goldstein err = -ESTALE; 3993985b70aSAmir Goldstein goto fail; 4003985b70aSAmir Goldstein } 4013985b70aSAmir Goldstein 4023985b70aSAmir Goldstein out: 4033985b70aSAmir Goldstein release_dentry_name_snapshot(&name); 4043985b70aSAmir Goldstein dput(parent); 4053985b70aSAmir Goldstein inode_unlock(dir); 4063985b70aSAmir Goldstein return this; 4073985b70aSAmir Goldstein 4083985b70aSAmir Goldstein fail: 4093985b70aSAmir Goldstein pr_warn_ratelimited("overlayfs: failed to lookup one by real (%pd2, layer=%d, connected=%pd2, err=%i)\n", 4103985b70aSAmir Goldstein real, layer->idx, connected, err); 4113985b70aSAmir Goldstein this = ERR_PTR(err); 4123985b70aSAmir Goldstein goto out; 4133985b70aSAmir Goldstein } 4143985b70aSAmir Goldstein 41506170154SAmir Goldstein static struct dentry *ovl_lookup_real(struct super_block *sb, 41606170154SAmir Goldstein struct dentry *real, 41706170154SAmir Goldstein struct ovl_layer *layer); 41806170154SAmir Goldstein 4193985b70aSAmir Goldstein /* 4204b91c30aSAmir Goldstein * Lookup an indexed or hashed overlay dentry by real inode. 4214b91c30aSAmir Goldstein */ 4224b91c30aSAmir Goldstein static struct dentry *ovl_lookup_real_inode(struct super_block *sb, 4234b91c30aSAmir Goldstein struct dentry *real, 4244b91c30aSAmir Goldstein struct ovl_layer *layer) 4254b91c30aSAmir Goldstein { 42606170154SAmir Goldstein struct ovl_fs *ofs = sb->s_fs_info; 42706170154SAmir Goldstein struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt }; 42806170154SAmir Goldstein struct dentry *index = NULL; 4294b91c30aSAmir Goldstein struct dentry *this = NULL; 4304b91c30aSAmir Goldstein struct inode *inode; 4314b91c30aSAmir Goldstein 43206170154SAmir Goldstein /* 43306170154SAmir Goldstein * Decoding upper dir from index is expensive, so first try to lookup 43406170154SAmir Goldstein * overlay dentry in inode/dcache. 43506170154SAmir Goldstein */ 4364b91c30aSAmir Goldstein inode = ovl_lookup_inode(sb, real, !layer->idx); 4374b91c30aSAmir Goldstein if (IS_ERR(inode)) 4384b91c30aSAmir Goldstein return ERR_CAST(inode); 4394b91c30aSAmir Goldstein if (inode) { 4404b91c30aSAmir Goldstein this = d_find_any_alias(inode); 4414b91c30aSAmir Goldstein iput(inode); 4424b91c30aSAmir Goldstein } 4434b91c30aSAmir Goldstein 44406170154SAmir Goldstein /* 44506170154SAmir Goldstein * For decoded lower dir file handle, lookup index by origin to check 44606170154SAmir Goldstein * if lower dir was copied up and and/or removed. 44706170154SAmir Goldstein */ 44806170154SAmir Goldstein if (!this && layer->idx && ofs->indexdir && !WARN_ON(!d_is_dir(real))) { 44906170154SAmir Goldstein index = ovl_lookup_index(ofs, NULL, real, false); 45006170154SAmir Goldstein if (IS_ERR(index)) 45106170154SAmir Goldstein return index; 45206170154SAmir Goldstein } 45306170154SAmir Goldstein 45406170154SAmir Goldstein /* Get connected upper overlay dir from index */ 45506170154SAmir Goldstein if (index) { 45606170154SAmir Goldstein struct dentry *upper = ovl_index_upper(ofs, index); 45706170154SAmir Goldstein 45806170154SAmir Goldstein dput(index); 45906170154SAmir Goldstein if (IS_ERR_OR_NULL(upper)) 46006170154SAmir Goldstein return upper; 46106170154SAmir Goldstein 46206170154SAmir Goldstein /* 46306170154SAmir Goldstein * ovl_lookup_real() in lower layer may call recursively once to 46406170154SAmir Goldstein * ovl_lookup_real() in upper layer. The first level call walks 46506170154SAmir Goldstein * back lower parents to the topmost indexed parent. The second 46606170154SAmir Goldstein * recursive call walks back from indexed upper to the topmost 46706170154SAmir Goldstein * connected/hashed upper parent (or up to root). 46806170154SAmir Goldstein */ 46906170154SAmir Goldstein this = ovl_lookup_real(sb, upper, &upper_layer); 47006170154SAmir Goldstein dput(upper); 47106170154SAmir Goldstein } 47206170154SAmir Goldstein 4737168179fSAmir Goldstein if (IS_ERR_OR_NULL(this)) 4747168179fSAmir Goldstein return this; 4754b91c30aSAmir Goldstein 4764b91c30aSAmir Goldstein if (WARN_ON(ovl_dentry_real_at(this, layer->idx) != real)) { 4774b91c30aSAmir Goldstein dput(this); 4784b91c30aSAmir Goldstein this = ERR_PTR(-EIO); 4794b91c30aSAmir Goldstein } 4804b91c30aSAmir Goldstein 4814b91c30aSAmir Goldstein return this; 4824b91c30aSAmir Goldstein } 4834b91c30aSAmir Goldstein 4844b91c30aSAmir Goldstein /* 4854b91c30aSAmir Goldstein * Lookup an indexed or hashed overlay dentry, whose real dentry is an 4864b91c30aSAmir Goldstein * ancestor of @real. 4874b91c30aSAmir Goldstein */ 4884b91c30aSAmir Goldstein static struct dentry *ovl_lookup_real_ancestor(struct super_block *sb, 4894b91c30aSAmir Goldstein struct dentry *real, 4904b91c30aSAmir Goldstein struct ovl_layer *layer) 4914b91c30aSAmir Goldstein { 4924b91c30aSAmir Goldstein struct dentry *next, *parent = NULL; 4934b91c30aSAmir Goldstein struct dentry *ancestor = ERR_PTR(-EIO); 4944b91c30aSAmir Goldstein 4954b91c30aSAmir Goldstein if (real == layer->mnt->mnt_root) 4964b91c30aSAmir Goldstein return dget(sb->s_root); 4974b91c30aSAmir Goldstein 4984b91c30aSAmir Goldstein /* Find the topmost indexed or hashed ancestor */ 4994b91c30aSAmir Goldstein next = dget(real); 5004b91c30aSAmir Goldstein for (;;) { 5014b91c30aSAmir Goldstein parent = dget_parent(next); 5024b91c30aSAmir Goldstein 5034b91c30aSAmir Goldstein /* 5044b91c30aSAmir Goldstein * Lookup a matching overlay dentry in inode/dentry 5054b91c30aSAmir Goldstein * cache or in index by real inode. 5064b91c30aSAmir Goldstein */ 5074b91c30aSAmir Goldstein ancestor = ovl_lookup_real_inode(sb, next, layer); 5084b91c30aSAmir Goldstein if (ancestor) 5094b91c30aSAmir Goldstein break; 5104b91c30aSAmir Goldstein 5114b91c30aSAmir Goldstein if (parent == layer->mnt->mnt_root) { 5124b91c30aSAmir Goldstein ancestor = dget(sb->s_root); 5134b91c30aSAmir Goldstein break; 5144b91c30aSAmir Goldstein } 5154b91c30aSAmir Goldstein 5164b91c30aSAmir Goldstein /* 5174b91c30aSAmir Goldstein * If @real has been moved out of the layer root directory, 5184b91c30aSAmir Goldstein * we will eventully hit the real fs root. This cannot happen 5194b91c30aSAmir Goldstein * by legit overlay rename, so we return error in that case. 5204b91c30aSAmir Goldstein */ 5214b91c30aSAmir Goldstein if (parent == next) { 5224b91c30aSAmir Goldstein ancestor = ERR_PTR(-EXDEV); 5234b91c30aSAmir Goldstein break; 5244b91c30aSAmir Goldstein } 5254b91c30aSAmir Goldstein 5264b91c30aSAmir Goldstein dput(next); 5274b91c30aSAmir Goldstein next = parent; 5284b91c30aSAmir Goldstein } 5294b91c30aSAmir Goldstein 5304b91c30aSAmir Goldstein dput(parent); 5314b91c30aSAmir Goldstein dput(next); 5324b91c30aSAmir Goldstein 5334b91c30aSAmir Goldstein return ancestor; 5344b91c30aSAmir Goldstein } 5354b91c30aSAmir Goldstein 5364b91c30aSAmir Goldstein /* 5373985b70aSAmir Goldstein * Lookup a connected overlay dentry whose real dentry is @real. 5383985b70aSAmir Goldstein * If @real is on upper layer, we lookup a child overlay dentry with the same 5393985b70aSAmir Goldstein * path the real dentry. Otherwise, we need to consult index for lookup. 5403985b70aSAmir Goldstein */ 5413985b70aSAmir Goldstein static struct dentry *ovl_lookup_real(struct super_block *sb, 5423985b70aSAmir Goldstein struct dentry *real, 5433985b70aSAmir Goldstein struct ovl_layer *layer) 5443985b70aSAmir Goldstein { 5453985b70aSAmir Goldstein struct dentry *connected; 5463985b70aSAmir Goldstein int err = 0; 5473985b70aSAmir Goldstein 5484b91c30aSAmir Goldstein connected = ovl_lookup_real_ancestor(sb, real, layer); 5494b91c30aSAmir Goldstein if (IS_ERR(connected)) 5504b91c30aSAmir Goldstein return connected; 5513985b70aSAmir Goldstein 5523985b70aSAmir Goldstein while (!err) { 5533985b70aSAmir Goldstein struct dentry *next, *this; 5543985b70aSAmir Goldstein struct dentry *parent = NULL; 55598892516SAmir Goldstein struct dentry *real_connected = ovl_dentry_real_at(connected, 55698892516SAmir Goldstein layer->idx); 5573985b70aSAmir Goldstein 5583985b70aSAmir Goldstein if (real_connected == real) 5593985b70aSAmir Goldstein break; 5603985b70aSAmir Goldstein 5613985b70aSAmir Goldstein /* Find the topmost dentry not yet connected */ 5623985b70aSAmir Goldstein next = dget(real); 5633985b70aSAmir Goldstein for (;;) { 5643985b70aSAmir Goldstein parent = dget_parent(next); 5653985b70aSAmir Goldstein 5663985b70aSAmir Goldstein if (parent == real_connected) 5673985b70aSAmir Goldstein break; 5683985b70aSAmir Goldstein 5693985b70aSAmir Goldstein /* 5703985b70aSAmir Goldstein * If real has been moved out of 'real_connected', 5713985b70aSAmir Goldstein * we will not find 'real_connected' and hit the layer 5723985b70aSAmir Goldstein * root. In that case, we need to restart connecting. 5733985b70aSAmir Goldstein * This game can go on forever in the worst case. We 5743985b70aSAmir Goldstein * may want to consider taking s_vfs_rename_mutex if 5753985b70aSAmir Goldstein * this happens more than once. 5763985b70aSAmir Goldstein */ 5773985b70aSAmir Goldstein if (parent == layer->mnt->mnt_root) { 5783985b70aSAmir Goldstein dput(connected); 5793985b70aSAmir Goldstein connected = dget(sb->s_root); 5803985b70aSAmir Goldstein break; 5813985b70aSAmir Goldstein } 5823985b70aSAmir Goldstein 5833985b70aSAmir Goldstein /* 5843985b70aSAmir Goldstein * If real file has been moved out of the layer root 5853985b70aSAmir Goldstein * directory, we will eventully hit the real fs root. 5863985b70aSAmir Goldstein * This cannot happen by legit overlay rename, so we 5873985b70aSAmir Goldstein * return error in that case. 5883985b70aSAmir Goldstein */ 5893985b70aSAmir Goldstein if (parent == next) { 5903985b70aSAmir Goldstein err = -EXDEV; 5913985b70aSAmir Goldstein break; 5923985b70aSAmir Goldstein } 5933985b70aSAmir Goldstein 5943985b70aSAmir Goldstein dput(next); 5953985b70aSAmir Goldstein next = parent; 5963985b70aSAmir Goldstein } 5973985b70aSAmir Goldstein 5983985b70aSAmir Goldstein if (!err) { 5993985b70aSAmir Goldstein this = ovl_lookup_real_one(connected, next, layer); 6003985b70aSAmir Goldstein if (IS_ERR(this)) 6013985b70aSAmir Goldstein err = PTR_ERR(this); 6023985b70aSAmir Goldstein 6033985b70aSAmir Goldstein /* 6043985b70aSAmir Goldstein * Lookup of child in overlay can fail when racing with 6053985b70aSAmir Goldstein * overlay rename of child away from 'connected' parent. 6063985b70aSAmir Goldstein * In this case, we need to restart the lookup from the 6073985b70aSAmir Goldstein * top, because we cannot trust that 'real_connected' is 6084b91c30aSAmir Goldstein * still an ancestor of 'real'. There is a good chance 6094b91c30aSAmir Goldstein * that the renamed overlay ancestor is now in cache, so 6104b91c30aSAmir Goldstein * ovl_lookup_real_ancestor() will find it and we can 6114b91c30aSAmir Goldstein * continue to connect exactly from where lookup failed. 6123985b70aSAmir Goldstein */ 6133985b70aSAmir Goldstein if (err == -ECHILD) { 6144b91c30aSAmir Goldstein this = ovl_lookup_real_ancestor(sb, real, 6154b91c30aSAmir Goldstein layer); 616b5095f24SFengguang Wu err = PTR_ERR_OR_ZERO(this); 6173985b70aSAmir Goldstein } 6183985b70aSAmir Goldstein if (!err) { 6193985b70aSAmir Goldstein dput(connected); 6203985b70aSAmir Goldstein connected = this; 6213985b70aSAmir Goldstein } 6223985b70aSAmir Goldstein } 6233985b70aSAmir Goldstein 6243985b70aSAmir Goldstein dput(parent); 6253985b70aSAmir Goldstein dput(next); 6263985b70aSAmir Goldstein } 6273985b70aSAmir Goldstein 6283985b70aSAmir Goldstein if (err) 6293985b70aSAmir Goldstein goto fail; 6303985b70aSAmir Goldstein 6313985b70aSAmir Goldstein return connected; 6323985b70aSAmir Goldstein 6333985b70aSAmir Goldstein fail: 6343985b70aSAmir Goldstein pr_warn_ratelimited("overlayfs: failed to lookup by real (%pd2, layer=%d, connected=%pd2, err=%i)\n", 6353985b70aSAmir Goldstein real, layer->idx, connected, err); 6363985b70aSAmir Goldstein dput(connected); 6373985b70aSAmir Goldstein return ERR_PTR(err); 6383985b70aSAmir Goldstein } 6393985b70aSAmir Goldstein 6403985b70aSAmir Goldstein /* 641f71bd9cfSAmir Goldstein * Get an overlay dentry from upper/lower real dentries and index. 6423985b70aSAmir Goldstein */ 6433985b70aSAmir Goldstein static struct dentry *ovl_get_dentry(struct super_block *sb, 6443985b70aSAmir Goldstein struct dentry *upper, 645f71bd9cfSAmir Goldstein struct ovl_path *lowerpath, 646f71bd9cfSAmir Goldstein struct dentry *index) 6473985b70aSAmir Goldstein { 6483985b70aSAmir Goldstein struct ovl_fs *ofs = sb->s_fs_info; 6493985b70aSAmir Goldstein struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt }; 65098892516SAmir Goldstein struct ovl_layer *layer = upper ? &upper_layer : lowerpath->layer; 651f71bd9cfSAmir Goldstein struct dentry *real = upper ?: (index ?: lowerpath->dentry); 6523985b70aSAmir Goldstein 653f941866fSAmir Goldstein /* 654f71bd9cfSAmir Goldstein * Obtain a disconnected overlay dentry from a non-dir real dentry 655f71bd9cfSAmir Goldstein * and index. 656f941866fSAmir Goldstein */ 657f71bd9cfSAmir Goldstein if (!d_is_dir(real)) 658f71bd9cfSAmir Goldstein return ovl_obtain_alias(sb, upper, lowerpath, index); 659f941866fSAmir Goldstein 6603985b70aSAmir Goldstein /* Removed empty directory? */ 66198892516SAmir Goldstein if ((real->d_flags & DCACHE_DISCONNECTED) || d_unhashed(real)) 6623985b70aSAmir Goldstein return ERR_PTR(-ENOENT); 6633985b70aSAmir Goldstein 6643985b70aSAmir Goldstein /* 66598892516SAmir Goldstein * If real dentry is connected and hashed, get a connected overlay 66698892516SAmir Goldstein * dentry whose real dentry is @real. 6673985b70aSAmir Goldstein */ 66898892516SAmir Goldstein return ovl_lookup_real(sb, real, layer); 6693985b70aSAmir Goldstein } 6703985b70aSAmir Goldstein 6718556a420SAmir Goldstein static struct dentry *ovl_upper_fh_to_d(struct super_block *sb, 6728556a420SAmir Goldstein struct ovl_fh *fh) 6738556a420SAmir Goldstein { 6748556a420SAmir Goldstein struct ovl_fs *ofs = sb->s_fs_info; 6758556a420SAmir Goldstein struct dentry *dentry; 6768556a420SAmir Goldstein struct dentry *upper; 6778556a420SAmir Goldstein 6788556a420SAmir Goldstein if (!ofs->upper_mnt) 6798556a420SAmir Goldstein return ERR_PTR(-EACCES); 6808556a420SAmir Goldstein 6818a22efa1SAmir Goldstein upper = ovl_decode_real_fh(fh, ofs->upper_mnt, true); 6828556a420SAmir Goldstein if (IS_ERR_OR_NULL(upper)) 6838556a420SAmir Goldstein return upper; 6848556a420SAmir Goldstein 685f71bd9cfSAmir Goldstein dentry = ovl_get_dentry(sb, upper, NULL, NULL); 6868556a420SAmir Goldstein dput(upper); 6878556a420SAmir Goldstein 6888556a420SAmir Goldstein return dentry; 6898556a420SAmir Goldstein } 6908556a420SAmir Goldstein 691f941866fSAmir Goldstein static struct dentry *ovl_lower_fh_to_d(struct super_block *sb, 692f941866fSAmir Goldstein struct ovl_fh *fh) 693f941866fSAmir Goldstein { 694f941866fSAmir Goldstein struct ovl_fs *ofs = sb->s_fs_info; 695f941866fSAmir Goldstein struct ovl_path origin = { }; 696f941866fSAmir Goldstein struct ovl_path *stack = &origin; 697f941866fSAmir Goldstein struct dentry *dentry = NULL; 698f71bd9cfSAmir Goldstein struct dentry *index = NULL; 6998b58924aSAmir Goldstein struct inode *inode; 700f941866fSAmir Goldstein int err; 701f941866fSAmir Goldstein 7028b58924aSAmir Goldstein /* First lookup overlay inode in inode cache by origin fh */ 7038b58924aSAmir Goldstein err = ovl_check_origin_fh(ofs, fh, false, NULL, &stack); 7048b58924aSAmir Goldstein if (err) 7058b58924aSAmir Goldstein return ERR_PTR(err); 7068b58924aSAmir Goldstein 7078b58924aSAmir Goldstein if (!d_is_dir(origin.dentry) || 7088b58924aSAmir Goldstein !(origin.dentry->d_flags & DCACHE_DISCONNECTED)) { 7098b58924aSAmir Goldstein inode = ovl_lookup_inode(sb, origin.dentry, false); 7108b58924aSAmir Goldstein err = PTR_ERR(inode); 7118b58924aSAmir Goldstein if (IS_ERR(inode)) 7128b58924aSAmir Goldstein goto out_err; 7138b58924aSAmir Goldstein if (inode) { 7148b58924aSAmir Goldstein dentry = d_find_any_alias(inode); 7158b58924aSAmir Goldstein iput(inode); 7168b58924aSAmir Goldstein if (dentry) 7178b58924aSAmir Goldstein goto out; 7188b58924aSAmir Goldstein } 7198b58924aSAmir Goldstein } 7208b58924aSAmir Goldstein 7218b58924aSAmir Goldstein /* Then lookup indexed upper/whiteout by origin fh */ 722f71bd9cfSAmir Goldstein if (ofs->indexdir) { 723f71bd9cfSAmir Goldstein index = ovl_get_index_fh(ofs, fh); 724f71bd9cfSAmir Goldstein err = PTR_ERR(index); 7259436a1a3SAmir Goldstein if (IS_ERR(index)) { 7269436a1a3SAmir Goldstein index = NULL; 7278b58924aSAmir Goldstein goto out_err; 7289436a1a3SAmir Goldstein } 729f71bd9cfSAmir Goldstein } 730f941866fSAmir Goldstein 7318b58924aSAmir Goldstein /* Then try to get a connected upper dir by index */ 7323b0bfc6eSAmir Goldstein if (index && d_is_dir(index)) { 7333b0bfc6eSAmir Goldstein struct dentry *upper = ovl_index_upper(ofs, index); 7343b0bfc6eSAmir Goldstein 7353b0bfc6eSAmir Goldstein err = PTR_ERR(upper); 7363b0bfc6eSAmir Goldstein if (IS_ERR_OR_NULL(upper)) 7373b0bfc6eSAmir Goldstein goto out_err; 7383b0bfc6eSAmir Goldstein 7393b0bfc6eSAmir Goldstein dentry = ovl_get_dentry(sb, upper, NULL, NULL); 7403b0bfc6eSAmir Goldstein dput(upper); 7413b0bfc6eSAmir Goldstein goto out; 7423b0bfc6eSAmir Goldstein } 7433b0bfc6eSAmir Goldstein 744155b8a04SAmir Goldstein /* Find origin.dentry again with ovl_acceptable() layer check */ 745155b8a04SAmir Goldstein if (d_is_dir(origin.dentry)) { 7468b58924aSAmir Goldstein dput(origin.dentry); 7478b58924aSAmir Goldstein origin.dentry = NULL; 7488a22efa1SAmir Goldstein err = ovl_check_origin_fh(ofs, fh, true, NULL, &stack); 7498b58924aSAmir Goldstein if (err) 750f71bd9cfSAmir Goldstein goto out_err; 7518b58924aSAmir Goldstein } 7528b58924aSAmir Goldstein if (index) { 753f71bd9cfSAmir Goldstein err = ovl_verify_origin(index, origin.dentry, false); 754f71bd9cfSAmir Goldstein if (err) 755f71bd9cfSAmir Goldstein goto out_err; 756f71bd9cfSAmir Goldstein } 757f71bd9cfSAmir Goldstein 758155b8a04SAmir Goldstein /* Get a connected non-upper dir or disconnected non-dir */ 759f71bd9cfSAmir Goldstein dentry = ovl_get_dentry(sb, NULL, &origin, index); 760f71bd9cfSAmir Goldstein 761f71bd9cfSAmir Goldstein out: 762f941866fSAmir Goldstein dput(origin.dentry); 763f71bd9cfSAmir Goldstein dput(index); 764f941866fSAmir Goldstein return dentry; 765f71bd9cfSAmir Goldstein 766f71bd9cfSAmir Goldstein out_err: 767f71bd9cfSAmir Goldstein dentry = ERR_PTR(err); 768f71bd9cfSAmir Goldstein goto out; 769f941866fSAmir Goldstein } 770f941866fSAmir Goldstein 771cbe7fba8SAmir Goldstein static struct ovl_fh *ovl_fid_to_fh(struct fid *fid, int buflen, int fh_type) 772cbe7fba8SAmir Goldstein { 773cbe7fba8SAmir Goldstein struct ovl_fh *fh; 774cbe7fba8SAmir Goldstein 775cbe7fba8SAmir Goldstein /* If on-wire inner fid is aligned - nothing to do */ 776cbe7fba8SAmir Goldstein if (fh_type == OVL_FILEID_V1) 777cbe7fba8SAmir Goldstein return (struct ovl_fh *)fid; 778cbe7fba8SAmir Goldstein 779cbe7fba8SAmir Goldstein if (fh_type != OVL_FILEID_V0) 780cbe7fba8SAmir Goldstein return ERR_PTR(-EINVAL); 781cbe7fba8SAmir Goldstein 782cbe7fba8SAmir Goldstein fh = kzalloc(buflen, GFP_KERNEL); 783cbe7fba8SAmir Goldstein if (!fh) 784cbe7fba8SAmir Goldstein return ERR_PTR(-ENOMEM); 785cbe7fba8SAmir Goldstein 786cbe7fba8SAmir Goldstein /* Copy unaligned inner fh into aligned buffer */ 787cbe7fba8SAmir Goldstein memcpy(&fh->fb, fid, buflen - OVL_FH_WIRE_OFFSET); 788cbe7fba8SAmir Goldstein return fh; 789cbe7fba8SAmir Goldstein } 790cbe7fba8SAmir Goldstein 7918556a420SAmir Goldstein static struct dentry *ovl_fh_to_dentry(struct super_block *sb, struct fid *fid, 7928556a420SAmir Goldstein int fh_len, int fh_type) 7938556a420SAmir Goldstein { 7948556a420SAmir Goldstein struct dentry *dentry = NULL; 795cbe7fba8SAmir Goldstein struct ovl_fh *fh = NULL; 7968556a420SAmir Goldstein int len = fh_len << 2; 7978556a420SAmir Goldstein unsigned int flags = 0; 7988556a420SAmir Goldstein int err; 7998556a420SAmir Goldstein 800cbe7fba8SAmir Goldstein fh = ovl_fid_to_fh(fid, len, fh_type); 801cbe7fba8SAmir Goldstein err = PTR_ERR(fh); 802cbe7fba8SAmir Goldstein if (IS_ERR(fh)) 8038556a420SAmir Goldstein goto out_err; 8048556a420SAmir Goldstein 8058556a420SAmir Goldstein err = ovl_check_fh_len(fh, len); 8068556a420SAmir Goldstein if (err) 8078556a420SAmir Goldstein goto out_err; 8088556a420SAmir Goldstein 809cbe7fba8SAmir Goldstein flags = fh->fb.flags; 810f941866fSAmir Goldstein dentry = (flags & OVL_FH_FLAG_PATH_UPPER) ? 811f941866fSAmir Goldstein ovl_upper_fh_to_d(sb, fh) : 812f941866fSAmir Goldstein ovl_lower_fh_to_d(sb, fh); 8138556a420SAmir Goldstein err = PTR_ERR(dentry); 8148556a420SAmir Goldstein if (IS_ERR(dentry) && err != -ESTALE) 8158556a420SAmir Goldstein goto out_err; 8168556a420SAmir Goldstein 817cbe7fba8SAmir Goldstein out: 818cbe7fba8SAmir Goldstein /* We may have needed to re-align OVL_FILEID_V0 */ 819cbe7fba8SAmir Goldstein if (!IS_ERR_OR_NULL(fh) && fh != (void *)fid) 820cbe7fba8SAmir Goldstein kfree(fh); 821cbe7fba8SAmir Goldstein 8228556a420SAmir Goldstein return dentry; 8238556a420SAmir Goldstein 8248556a420SAmir Goldstein out_err: 8258556a420SAmir Goldstein pr_warn_ratelimited("overlayfs: failed to decode file handle (len=%d, type=%d, flags=%x, err=%i)\n", 826cbe7fba8SAmir Goldstein fh_len, fh_type, flags, err); 827cbe7fba8SAmir Goldstein dentry = ERR_PTR(err); 828cbe7fba8SAmir Goldstein goto out; 8298556a420SAmir Goldstein } 8308556a420SAmir Goldstein 8313985b70aSAmir Goldstein static struct dentry *ovl_fh_to_parent(struct super_block *sb, struct fid *fid, 8323985b70aSAmir Goldstein int fh_len, int fh_type) 8333985b70aSAmir Goldstein { 8343985b70aSAmir Goldstein pr_warn_ratelimited("overlayfs: connectable file handles not supported; use 'no_subtree_check' exportfs option.\n"); 8353985b70aSAmir Goldstein return ERR_PTR(-EACCES); 8363985b70aSAmir Goldstein } 8373985b70aSAmir Goldstein 8383985b70aSAmir Goldstein static int ovl_get_name(struct dentry *parent, char *name, 8393985b70aSAmir Goldstein struct dentry *child) 8403985b70aSAmir Goldstein { 8413985b70aSAmir Goldstein /* 8423985b70aSAmir Goldstein * ovl_fh_to_dentry() returns connected dir overlay dentries and 8433985b70aSAmir Goldstein * ovl_fh_to_parent() is not implemented, so we should not get here. 8443985b70aSAmir Goldstein */ 8453985b70aSAmir Goldstein WARN_ON_ONCE(1); 8463985b70aSAmir Goldstein return -EIO; 8473985b70aSAmir Goldstein } 8483985b70aSAmir Goldstein 8493985b70aSAmir Goldstein static struct dentry *ovl_get_parent(struct dentry *dentry) 8503985b70aSAmir Goldstein { 8513985b70aSAmir Goldstein /* 8523985b70aSAmir Goldstein * ovl_fh_to_dentry() returns connected dir overlay dentries, so we 8533985b70aSAmir Goldstein * should not get here. 8543985b70aSAmir Goldstein */ 8553985b70aSAmir Goldstein WARN_ON_ONCE(1); 8563985b70aSAmir Goldstein return ERR_PTR(-EIO); 8573985b70aSAmir Goldstein } 8583985b70aSAmir Goldstein 8598ed5eec9SAmir Goldstein const struct export_operations ovl_export_operations = { 8605b2cccd3SAmir Goldstein .encode_fh = ovl_encode_fh, 8618556a420SAmir Goldstein .fh_to_dentry = ovl_fh_to_dentry, 8623985b70aSAmir Goldstein .fh_to_parent = ovl_fh_to_parent, 8633985b70aSAmir Goldstein .get_name = ovl_get_name, 8643985b70aSAmir Goldstein .get_parent = ovl_get_parent, 8658ed5eec9SAmir Goldstein }; 866