diff options
Diffstat (limited to 'fs/overlayfs/namei.c')
| -rw-r--r-- | fs/overlayfs/namei.c | 138 |
1 files changed, 78 insertions, 60 deletions
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c index 0db23baf98e7..3566282a9199 100644 --- a/fs/overlayfs/namei.c +++ b/fs/overlayfs/namei.c @@ -191,16 +191,36 @@ static bool ovl_is_opaquedir(struct dentry *dentry) return ovl_check_dir_xattr(dentry, OVL_XATTR_OPAQUE); } +static struct dentry *ovl_lookup_positive_unlocked(const char *name, + struct dentry *base, int len, + bool drop_negative) +{ + struct dentry *ret = lookup_one_len_unlocked(name, base, len); + + if (!IS_ERR(ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { + if (drop_negative && ret->d_lockref.count == 1) { + spin_lock(&ret->d_lock); + /* Recheck condition under lock */ + if (d_is_negative(ret) && ret->d_lockref.count == 1) + __d_drop(ret); + spin_unlock(&ret->d_lock); + } + dput(ret); + ret = ERR_PTR(-ENOENT); + } + return ret; +} + static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d, const char *name, unsigned int namelen, size_t prelen, const char *post, - struct dentry **ret) + struct dentry **ret, bool drop_negative) { struct dentry *this; int err; bool last_element = !post[0]; - this = lookup_positive_unlocked(name, base, namelen); + this = ovl_lookup_positive_unlocked(name, base, namelen, drop_negative); if (IS_ERR(this)) { err = PTR_ERR(this); this = NULL; @@ -276,7 +296,7 @@ out_err: } static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d, - struct dentry **ret) + struct dentry **ret, bool drop_negative) { /* Counting down from the end, since the prefix can change */ size_t rem = d->name.len - 1; @@ -285,7 +305,7 @@ static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d, if (d->name.name[0] != '/') return ovl_lookup_single(base, d, d->name.name, d->name.len, - 0, "", ret); + 0, "", ret, drop_negative); while (!IS_ERR_OR_NULL(base) && d_can_lookup(base)) { const char *s = d->name.name + d->name.len - rem; @@ -298,7 +318,8 @@ static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d, return -EIO; err = ovl_lookup_single(base, d, s, thislen, - d->name.len - rem, next, &base); + d->name.len - rem, next, &base, + drop_negative); dput(dentry); if (err) return err; @@ -468,7 +489,7 @@ struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index) if (IS_ERR_OR_NULL(fh)) return ERR_CAST(fh); - upper = ovl_decode_real_fh(fh, ofs->upper_mnt, true); + upper = ovl_decode_real_fh(fh, ovl_upper_mnt(ofs), true); kfree(fh); if (IS_ERR_OR_NULL(upper)) @@ -484,12 +505,6 @@ struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index) return upper; } -/* Is this a leftover from create/whiteout of directory index entry? */ -static bool ovl_is_temp_index(struct dentry *index) -{ - return index->d_name.name[0] == '#'; -} - /* * Verify that an index entry name matches the origin file handle stored in * OVL_XATTR_ORIGIN and that origin file handle can be decoded to lower path. @@ -507,11 +522,6 @@ int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index) if (!d_inode(index)) return 0; - /* Cleanup leftover from index create/cleanup attempt */ - err = -ESTALE; - if (ovl_is_temp_index(index)) - goto fail; - err = -EINVAL; if (index->d_name.len < sizeof(struct ovl_fb)*2) goto fail; @@ -823,7 +833,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, struct dentry *this; unsigned int i; int err; - bool metacopy = false; + bool uppermetacopy = false; struct ovl_lookup_data d = { .sb = dentry->d_sb, .name = dentry->d_name, @@ -841,7 +851,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, old_cred = ovl_override_creds(dentry->d_sb); upperdir = ovl_dentry_upper(dentry->d_parent); if (upperdir) { - err = ovl_lookup_layer(upperdir, &d, &upperdentry); + err = ovl_lookup_layer(upperdir, &d, &upperdentry, true); if (err) goto out; @@ -869,7 +879,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, goto out_put_upper; if (d.metacopy) - metacopy = true; + uppermetacopy = true; } if (d.redirect) { @@ -899,13 +909,19 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, else d.last = lower.layer->idx == roe->numlower; - err = ovl_lookup_layer(lower.dentry, &d, &this); + err = ovl_lookup_layer(lower.dentry, &d, &this, false); if (err) goto out_put; if (!this) continue; + if ((uppermetacopy || d.metacopy) && !ofs->config.metacopy) { + err = -EPERM; + pr_warn_ratelimited("refusing to follow metacopy origin for (%pd2)\n", dentry); + goto out_put; + } + /* * If no origin fh is stored in upper of a merge dir, store fh * of lower dir and set upper parent "impure". @@ -940,21 +956,21 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, origin = this; } - if (d.metacopy) - metacopy = true; - /* - * Do not store intermediate metacopy dentries in chain, - * except top most lower metacopy dentry - */ if (d.metacopy && ctr) { + /* + * Do not store intermediate metacopy dentries in + * lower chain, except top most lower metacopy dentry. + * Continue the loop so that if there is an absolute + * redirect on this dentry, poe can be reset to roe. + */ dput(this); - continue; + this = NULL; + } else { + stack[ctr].dentry = this; + stack[ctr].layer = lower.layer; + ctr++; } - stack[ctr].dentry = this; - stack[ctr].layer = lower.layer; - ctr++; - /* * Following redirects can have security consequences: it's like * a symlink into the lower layer without the permission checks. @@ -982,22 +998,17 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, } } - if (metacopy) { - /* - * Found a metacopy dentry but did not find corresponding - * data dentry - */ - if (d.metacopy) { - err = -EIO; - goto out_put; - } - - err = -EPERM; - if (!ofs->config.metacopy) { - pr_warn_ratelimited("refusing to follow metacopy origin for (%pd2)\n", - dentry); - goto out_put; - } + /* + * For regular non-metacopy upper dentries, there is no lower + * path based lookup, hence ctr will be zero. If a dentry is found + * using ORIGIN xattr on upper, install it in stack. + * + * For metacopy dentry, path based lookup will find lower dentries. + * Just make sure a corresponding data dentry has been found. + */ + if (d.metacopy || (uppermetacopy && !ctr)) { + err = -EIO; + goto out_put; } else if (!d.is_dir && upperdentry && !ctr && origin_path) { if (WARN_ON(stack != NULL)) { err = -EIO; @@ -1005,25 +1016,30 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, } stack = origin_path; ctr = 1; + origin = origin_path->dentry; origin_path = NULL; } /* - * Lookup index by lower inode and verify it matches upper inode. - * We only trust dir index if we verified that lower dir matches - * origin, otherwise dir index entries may be inconsistent and we - * ignore them. + * Always lookup index if there is no-upperdentry. + * + * For the case of upperdentry, we have set origin by now if it + * needed to be set. There are basically three cases. + * + * For directories, lookup index by lower inode and verify it matches + * upper inode. We only trust dir index if we verified that lower dir + * matches origin, otherwise dir index entries may be inconsistent + * and we ignore them. + * + * For regular upper, we already set origin if upper had ORIGIN + * xattr. There is no verification though as there is no path + * based dentry lookup in lower in this case. * - * For non-dir upper metacopy dentry, we already set "origin" if we - * verified that lower matched upper origin. If upper origin was - * not present (because lower layer did not support fh encode/decode), - * or indexing is not enabled, do not set "origin" and skip looking up - * index. This case should be handled in same way as a non-dir upper - * without ORIGIN is handled. + * For metacopy upper, we set a verified origin already if index + * is enabled and if upper had an ORIGIN xattr. * - * Always lookup index of non-dir non-metacopy and non-upper. */ - if (ctr && (!upperdentry || (!d.is_dir && !metacopy))) + if (!upperdentry && ctr) origin = stack[0].dentry; if (origin && ovl_indexdir(dentry->d_sb) && @@ -1074,6 +1090,8 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, err = PTR_ERR(inode); if (IS_ERR(inode)) goto out_free_oe; + if (upperdentry && !uppermetacopy) + ovl_set_flag(OVL_UPPERDATA, inode); } ovl_dentry_update_reval(dentry, upperdentry, |