From f71bd9cfb692ec80236b186419bf907eb5fa348c Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Fri, 19 Jan 2018 21:36:20 +0200 Subject: ovl: decode indexed non-dir file handles Decoding an indexed non-dir file handle is similar to decoding a lower non-dir file handle, but additionally, we lookup the file handle in index dir by name to find the real upper inode. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi --- fs/overlayfs/export.c | 71 +++++++++++++++++++++++++++++++++------------------ 1 file changed, 46 insertions(+), 25 deletions(-) (limited to 'fs/overlayfs') diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c index 8c0172d9b922..f475a10eec07 100644 --- a/fs/overlayfs/export.c +++ b/fs/overlayfs/export.c @@ -163,27 +163,32 @@ static int ovl_encode_inode_fh(struct inode *inode, u32 *fid, int *max_len, } /* - * Find or instantiate an overlay dentry from real dentries. + * Find or instantiate an overlay dentry from real dentries and index. */ static struct dentry *ovl_obtain_alias(struct super_block *sb, - struct dentry *upper, - struct ovl_path *lowerpath) + struct dentry *upper_alias, + struct ovl_path *lowerpath, + struct dentry *index) { struct dentry *lower = lowerpath ? lowerpath->dentry : NULL; + struct dentry *upper = upper_alias ?: index; struct dentry *dentry; struct inode *inode; struct ovl_entry *oe; - /* TODO: obtain an indexed non-dir upper with origin */ - if (lower && (upper || d_is_dir(lower))) + /* We get overlay directory dentries with ovl_lookup_real() */ + if (d_is_dir(upper ?: lower)) return ERR_PTR(-EIO); - inode = ovl_get_inode(sb, dget(upper), lower, NULL, !!lower); + inode = ovl_get_inode(sb, dget(upper), lower, index, !!lower); if (IS_ERR(inode)) { dput(upper); return ERR_CAST(inode); } + if (index) + ovl_set_flag(OVL_INDEX, inode); + dentry = d_find_any_alias(inode); if (!dentry) { dentry = d_alloc_anon(inode->i_sb); @@ -198,7 +203,7 @@ static struct dentry *ovl_obtain_alias(struct super_block *sb, oe->lowerstack->layer = lowerpath->layer; } dentry->d_fsdata = oe; - if (upper) + if (upper_alias) ovl_dentry_set_upper_alias(dentry); } @@ -377,33 +382,28 @@ fail: } /* - * Get an overlay dentry from upper/lower real dentries. + * Get an overlay dentry from upper/lower real dentries and index. */ static struct dentry *ovl_get_dentry(struct super_block *sb, struct dentry *upper, - struct ovl_path *lowerpath) + struct ovl_path *lowerpath, + struct dentry *index) { struct ovl_fs *ofs = sb->s_fs_info; struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt }; + struct dentry *real = upper ?: (index ?: lowerpath->dentry); /* - * Obtain a disconnected overlay dentry from a disconnected non-dir - * real lower dentry. + * Obtain a disconnected overlay dentry from a non-dir real dentry + * and index. */ - if (!upper && !d_is_dir(lowerpath->dentry)) - return ovl_obtain_alias(sb, NULL, lowerpath); + if (!d_is_dir(real)) + return ovl_obtain_alias(sb, upper, lowerpath, index); /* TODO: lookup connected dir from real lower dir */ if (!upper) return ERR_PTR(-EACCES); - /* - * Obtain a disconnected overlay dentry from a non-dir real upper - * dentry. - */ - if (!d_is_dir(upper)) - return ovl_obtain_alias(sb, upper, NULL); - /* Removed empty directory? */ if ((upper->d_flags & DCACHE_DISCONNECTED) || d_unhashed(upper)) return ERR_PTR(-ENOENT); @@ -429,7 +429,7 @@ static struct dentry *ovl_upper_fh_to_d(struct super_block *sb, if (IS_ERR_OR_NULL(upper)) return upper; - dentry = ovl_get_dentry(sb, upper, NULL); + dentry = ovl_get_dentry(sb, upper, NULL, NULL); dput(upper); return dentry; @@ -442,16 +442,37 @@ static struct dentry *ovl_lower_fh_to_d(struct super_block *sb, struct ovl_path origin = { }; struct ovl_path *stack = &origin; struct dentry *dentry = NULL; + struct dentry *index = NULL; int err; + /* First lookup indexed upper by fh */ + if (ofs->indexdir) { + index = ovl_get_index_fh(ofs, fh); + err = PTR_ERR(index); + if (IS_ERR(index)) + return ERR_PTR(err); + } + + /* Then lookup origin by fh */ err = ovl_check_origin_fh(ofs, fh, NULL, &stack); - if (err) - return ERR_PTR(err); + if (err) { + goto out_err; + } else if (index) { + err = ovl_verify_origin(index, origin.dentry, false); + if (err) + goto out_err; + } - dentry = ovl_get_dentry(sb, NULL, &origin); - dput(origin.dentry); + dentry = ovl_get_dentry(sb, NULL, &origin, index); +out: + dput(origin.dentry); + dput(index); return dentry; + +out_err: + dentry = ERR_PTR(err); + goto out; } static struct dentry *ovl_fh_to_dentry(struct super_block *sb, struct fid *fid, -- cgit