From 79f2f6ad878c1f2cb9edc674c6a263ff2ef6d1fd Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Thu, 3 Sep 2020 13:31:10 -0400 Subject: [PATCH] ceph: create symlinks with encrypted and base64-encoded targets MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When creating symlinks in encrypted directories, encrypt and base64-encode the target with the new inode's key before sending to the MDS. When filling a symlinked inode, base64-decode it into a buffer that we'll keep in ci->i_symlink. When get_link is called, decrypt the buffer into a new one that will hang off i_link. Signed-off-by: Jeff Layton Reviewed-by: Xiubo Li Reviewed-and-tested-by: Luís Henriques Reviewed-by: Milind Changire Signed-off-by: Ilya Dryomov --- fs/ceph/dir.c | 54 ++++++++++++++++++++++++--- fs/ceph/inode.c | 113 ++++++++++++++++++++++++++++++++++++++++++++++++++------ 2 files changed, 150 insertions(+), 17 deletions(-) diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c index ee5c8b9..7e064c0 100644 --- a/fs/ceph/dir.c +++ b/fs/ceph/dir.c @@ -948,6 +948,43 @@ static int ceph_create(struct mnt_idmap *idmap, struct inode *dir, return ceph_mknod(idmap, dir, dentry, mode, 0); } +#if IS_ENABLED(CONFIG_FS_ENCRYPTION) +static int prep_encrypted_symlink_target(struct ceph_mds_request *req, + const char *dest) +{ + int err; + int len = strlen(dest); + struct fscrypt_str osd_link = FSTR_INIT(NULL, 0); + + err = fscrypt_prepare_symlink(req->r_parent, dest, len, PATH_MAX, + &osd_link); + if (err) + goto out; + + err = fscrypt_encrypt_symlink(req->r_new_inode, dest, len, &osd_link); + if (err) + goto out; + + req->r_path2 = kmalloc(CEPH_BASE64_CHARS(osd_link.len) + 1, GFP_KERNEL); + if (!req->r_path2) { + err = -ENOMEM; + goto out; + } + + len = ceph_base64_encode(osd_link.name, osd_link.len, req->r_path2); + req->r_path2[len] = '\0'; +out: + fscrypt_fname_free_buffer(&osd_link); + return err; +} +#else +static int prep_encrypted_symlink_target(struct ceph_mds_request *req, + const char *dest) +{ + return -EOPNOTSUPP; +} +#endif + static int ceph_symlink(struct mnt_idmap *idmap, struct inode *dir, struct dentry *dentry, const char *dest) { @@ -983,14 +1020,21 @@ static int ceph_symlink(struct mnt_idmap *idmap, struct inode *dir, goto out_req; } - req->r_path2 = kstrdup(dest, GFP_KERNEL); - if (!req->r_path2) { - err = -ENOMEM; - goto out_req; - } req->r_parent = dir; ihold(dir); + if (IS_ENCRYPTED(req->r_new_inode)) { + err = prep_encrypted_symlink_target(req, dest); + if (err) + goto out_req; + } else { + req->r_path2 = kstrdup(dest, GFP_KERNEL); + if (!req->r_path2) { + err = -ENOMEM; + goto out_req; + } + } + set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags); req->r_dentry = dget(dentry); req->r_num_caps = 2; diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c index 0c33809..5423c69 100644 --- a/fs/ceph/inode.c +++ b/fs/ceph/inode.c @@ -35,6 +35,7 @@ */ static const struct inode_operations ceph_symlink_iops; +static const struct inode_operations ceph_encrypted_symlink_iops; static void ceph_inode_work(struct work_struct *work); @@ -640,6 +641,7 @@ void ceph_free_inode(struct inode *inode) #ifdef CONFIG_FS_ENCRYPTION kfree(ci->fscrypt_auth); #endif + fscrypt_free_inode(inode); kmem_cache_free(ceph_inode_cachep, ci); } @@ -837,6 +839,34 @@ void ceph_fill_file_time(struct inode *inode, int issued, inode, time_warp_seq, ci->i_time_warp_seq); } +#if IS_ENABLED(CONFIG_FS_ENCRYPTION) +static int decode_encrypted_symlink(const char *encsym, int enclen, u8 **decsym) +{ + int declen; + u8 *sym; + + sym = kmalloc(enclen + 1, GFP_NOFS); + if (!sym) + return -ENOMEM; + + declen = ceph_base64_decode(encsym, enclen, sym); + if (declen < 0) { + pr_err("%s: can't decode symlink (%d). Content: %.*s\n", + __func__, declen, enclen, encsym); + kfree(sym); + return -EIO; + } + sym[declen + 1] = '\0'; + *decsym = sym; + return declen; +} +#else +static int decode_encrypted_symlink(const char *encsym, int symlen, u8 **decsym) +{ + return -EOPNOTSUPP; +} +#endif + /* * Populate an inode based on info from mds. May be called on new or * existing inodes. @@ -1071,26 +1101,42 @@ int ceph_fill_inode(struct inode *inode, struct page *locked_page, inode->i_fop = &ceph_file_fops; break; case S_IFLNK: - inode->i_op = &ceph_symlink_iops; if (!ci->i_symlink) { u32 symlen = iinfo->symlink_len; char *sym; spin_unlock(&ci->i_ceph_lock); - if (symlen != i_size_read(inode)) { - pr_err("%s %llx.%llx BAD symlink " - "size %lld\n", __func__, - ceph_vinop(inode), - i_size_read(inode)); + if (IS_ENCRYPTED(inode)) { + if (symlen != i_size_read(inode)) + pr_err("%s %llx.%llx BAD symlink size %lld\n", + __func__, ceph_vinop(inode), + i_size_read(inode)); + + err = decode_encrypted_symlink(iinfo->symlink, + symlen, (u8 **)&sym); + if (err < 0) { + pr_err("%s decoding encrypted symlink failed: %d\n", + __func__, err); + goto out; + } + symlen = err; i_size_write(inode, symlen); inode->i_blocks = calc_inode_blocks(symlen); - } + } else { + if (symlen != i_size_read(inode)) { + pr_err("%s %llx.%llx BAD symlink size %lld\n", + __func__, ceph_vinop(inode), + i_size_read(inode)); + i_size_write(inode, symlen); + inode->i_blocks = calc_inode_blocks(symlen); + } - err = -ENOMEM; - sym = kstrndup(iinfo->symlink, symlen, GFP_NOFS); - if (!sym) - goto out; + err = -ENOMEM; + sym = kstrndup(iinfo->symlink, symlen, GFP_NOFS); + if (!sym) + goto out; + } spin_lock(&ci->i_ceph_lock); if (!ci->i_symlink) @@ -1098,7 +1144,17 @@ int ceph_fill_inode(struct inode *inode, struct page *locked_page, else kfree(sym); /* lost a race */ } - inode->i_link = ci->i_symlink; + + if (IS_ENCRYPTED(inode)) { + /* + * Encrypted symlinks need to be decrypted before we can + * cache their targets in i_link. Don't touch it here. + */ + inode->i_op = &ceph_encrypted_symlink_iops; + } else { + inode->i_link = ci->i_symlink; + inode->i_op = &ceph_symlink_iops; + } break; case S_IFDIR: inode->i_op = &ceph_dir_iops; @@ -2126,6 +2182,32 @@ static void ceph_inode_work(struct work_struct *work) iput(inode); } +static const char *ceph_encrypted_get_link(struct dentry *dentry, + struct inode *inode, + struct delayed_call *done) +{ + struct ceph_inode_info *ci = ceph_inode(inode); + + if (!dentry) + return ERR_PTR(-ECHILD); + + return fscrypt_get_symlink(inode, ci->i_symlink, i_size_read(inode), + done); +} + +static int ceph_encrypted_symlink_getattr(struct mnt_idmap *idmap, + const struct path *path, + struct kstat *stat, u32 request_mask, + unsigned int query_flags) +{ + int ret; + + ret = ceph_getattr(idmap, path, stat, request_mask, query_flags); + if (ret) + return ret; + return fscrypt_symlink_getattr(path, stat); +} + /* * symlinks */ @@ -2136,6 +2218,13 @@ static const struct inode_operations ceph_symlink_iops = { .listxattr = ceph_listxattr, }; +static const struct inode_operations ceph_encrypted_symlink_iops = { + .get_link = ceph_encrypted_get_link, + .setattr = ceph_setattr, + .getattr = ceph_encrypted_symlink_getattr, + .listxattr = ceph_listxattr, +}; + int __ceph_setattr(struct inode *inode, struct iattr *attr, struct ceph_iattr *cia) { -- 2.7.4