ceph ->d_name race fixes

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Merge tag 'pull-ceph-d_name-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull ceph dentry->d_name fixes from Al Viro:
 "Stuff that had fallen through the cracks back in February; ceph folks
  tested that pile and said they prefer to have it go through my tree..."

* tag 'pull-ceph-d_name-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  ceph: fix a race with rename() in ceph_mdsc_build_path()
  prep for ceph_encode_encrypted_fname() fixes
  [ceph] parse_longname(): strrchr() expects NUL-terminated string

fs/ceph/caps.c

@@ -4957,24 +4957,20 @@ int ceph_encode_dentry_release(void **p, struct dentry *dentry,
 	cl = ceph_inode_to_client(dir);
 	spin_lock(&dentry->d_lock);
 	if (ret && di->lease_session && di->lease_session->s_mds == mds) {
+		int len = dentry->d_name.len;
 		doutc(cl, "%p mds%d seq %d\n",  dentry, mds,
 		      (int)di->lease_seq);
 		rel->dname_seq = cpu_to_le32(di->lease_seq);
 		__ceph_mdsc_drop_dentry_lease(dentry);
+		memcpy(*p, dentry->d_name.name, len);
 		spin_unlock(&dentry->d_lock);
 		if (IS_ENCRYPTED(dir) && fscrypt_has_encryption_key(dir)) {
-			int ret2 = ceph_encode_encrypted_fname(dir, dentry, *p);
-
-			if (ret2 < 0)
-				return ret2;
-
-			rel->dname_len = cpu_to_le32(ret2);
-			*p += ret2;
-		} else {
-			rel->dname_len = cpu_to_le32(dentry->d_name.len);
-			memcpy(*p, dentry->d_name.name, dentry->d_name.len);
-			*p += dentry->d_name.len;
+			len = ceph_encode_encrypted_dname(dir, *p, len);
+			if (len < 0)
+				return len;
 		}
+		rel->dname_len = cpu_to_le32(len);
+		*p += len;
 	} else {
 		spin_unlock(&dentry->d_lock);
 	}

fs/ceph/crypto.c

@@ -215,35 +215,31 @@ static struct inode *parse_longname(const struct inode *parent,
 	struct ceph_client *cl = ceph_inode_to_client(parent);
 	struct inode *dir = NULL;
 	struct ceph_vino vino = { .snap = CEPH_NOSNAP };
-	char *inode_number;
-	char *name_end;
-	int orig_len = *name_len;
+	char *name_end, *inode_number;
 	int ret = -EIO;
-
+	/* NUL-terminate */
+	char *str __free(kfree) = kmemdup_nul(name, *name_len, GFP_KERNEL);
+	if (!str)
+		return ERR_PTR(-ENOMEM);
 	/* Skip initial '_' */
-	name++;
-	name_end = strrchr(name, '_');
+	str++;
+	name_end = strrchr(str, '_');
 	if (!name_end) {
-		doutc(cl, "failed to parse long snapshot name: %s\n", name);
+		doutc(cl, "failed to parse long snapshot name: %s\n", str);
 		return ERR_PTR(-EIO);
 	}
-	*name_len = (name_end - name);
+	*name_len = (name_end - str);
 	if (*name_len <= 0) {
 		pr_err_client(cl, "failed to parse long snapshot name\n");
 		return ERR_PTR(-EIO);
 	}
 
 	/* Get the inode number */
-	inode_number = kmemdup_nul(name_end + 1,
-				   orig_len - *name_len - 2,
-				   GFP_KERNEL);
-	if (!inode_number)
-		return ERR_PTR(-ENOMEM);
+	inode_number = name_end + 1;
 	ret = kstrtou64(inode_number, 10, &vino.ino);
 	if (ret) {
-		doutc(cl, "failed to parse inode number: %s\n", name);
-		dir = ERR_PTR(ret);
-		goto out;
+		doutc(cl, "failed to parse inode number: %s\n", str);
+		return ERR_PTR(ret);
 	}
 
 	/* And finally the inode */
@@ -254,42 +250,29 @@ static struct inode *parse_longname(const struct inode *parent,
 		if (IS_ERR(dir))
 			doutc(cl, "can't find inode %s (%s)\n", inode_number, name);
 	}
-
-out:
-	kfree(inode_number);
 	return dir;
 }
 
-int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_name,
-				char *buf)
+int ceph_encode_encrypted_dname(struct inode *parent, char *buf, int elen)
 {
 	struct ceph_client *cl = ceph_inode_to_client(parent);
 	struct inode *dir = parent;
-	struct qstr iname;
+	char *p = buf;
 	u32 len;
-	int name_len;
-	int elen;
+	int name_len = elen;
 	int ret;
 	u8 *cryptbuf = NULL;
 
-	iname.name = d_name->name;
-	name_len = d_name->len;
-
 	/* Handle the special case of snapshot names that start with '_' */
-	if ((ceph_snap(dir) == CEPH_SNAPDIR) && (name_len > 0) &&
-	    (iname.name[0] == '_')) {
-		dir = parse_longname(parent, iname.name, &name_len);
+	if (ceph_snap(dir) == CEPH_SNAPDIR && *p == '_') {
+		dir = parse_longname(parent, p, &name_len);
 		if (IS_ERR(dir))
 			return PTR_ERR(dir);
-		iname.name++; /* skip initial '_' */
+		p++; /* skip initial '_' */
 	}
-	iname.len = name_len;
 
-	if (!fscrypt_has_encryption_key(dir)) {
-		memcpy(buf, d_name->name, d_name->len);
-		elen = d_name->len;
+	if (!fscrypt_has_encryption_key(dir))
 		goto out;
-	}
 
 	/*
 	 * Convert cleartext d_name to ciphertext. If result is longer than
@@ -297,7 +280,7 @@ int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_name,
 	 *
 	 * See: fscrypt_setup_filename
 	 */
-	if (!fscrypt_fname_encrypted_size(dir, iname.len, NAME_MAX, &len)) {
+	if (!fscrypt_fname_encrypted_size(dir, name_len, NAME_MAX, &len)) {
 		elen = -ENAMETOOLONG;
 		goto out;
 	}
@@ -310,7 +293,9 @@ int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_name,
 		goto out;
 	}
 
-	ret = fscrypt_fname_encrypt(dir, &iname, cryptbuf, len);
+	ret = fscrypt_fname_encrypt(dir,
+				    &(struct qstr)QSTR_INIT(p, name_len),
+				    cryptbuf, len);
 	if (ret) {
 		elen = ret;
 		goto out;
@@ -331,18 +316,13 @@ int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_name,
 	}
 
 	/* base64 encode the encrypted name */
-	elen = ceph_base64_encode(cryptbuf, len, buf);
-	doutc(cl, "base64-encoded ciphertext name = %.*s\n", elen, buf);
+	elen = ceph_base64_encode(cryptbuf, len, p);
+	doutc(cl, "base64-encoded ciphertext name = %.*s\n", elen, p);
 
 	/* To understand the 240 limit, see CEPH_NOHASH_NAME_MAX comments */
 	WARN_ON(elen > 240);
-	if ((elen > 0) && (dir != parent)) {
-		char tmp_buf[NAME_MAX];
-
-		elen = snprintf(tmp_buf, sizeof(tmp_buf), "_%.*s_%ld",
-				elen, buf, dir->i_ino);
-		memcpy(buf, tmp_buf, elen);
-	}
+	if (dir != parent) // leading _ is already there; append _<inum>
+		elen += 1 + sprintf(p + elen, "_%ld", dir->i_ino);
 
 out:
 	kfree(cryptbuf);
@@ -355,14 +335,6 @@ int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_name,
 	return elen;
 }
 
-int ceph_encode_encrypted_fname(struct inode *parent, struct dentry *dentry,
-				char *buf)
-{
-	WARN_ON_ONCE(!fscrypt_has_encryption_key(parent));
-
-	return ceph_encode_encrypted_dname(parent, &dentry->d_name, buf);
-}
-
 /**
  * ceph_fname_to_usr - convert a filename for userland presentation
  * @fname: ceph_fname to be converted

fs/ceph/crypto.h

@@ -102,10 +102,7 @@ int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode,
 				 struct ceph_acl_sec_ctx *as);
 void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req,
 				struct ceph_acl_sec_ctx *as);
-int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_name,
-				char *buf);
-int ceph_encode_encrypted_fname(struct inode *parent, struct dentry *dentry,
-				char *buf);
+int ceph_encode_encrypted_dname(struct inode *parent, char *buf, int len);
 
 static inline int ceph_fname_alloc_buffer(struct inode *parent,
 					  struct fscrypt_str *fname)
@@ -194,17 +191,10 @@ static inline void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req,
 {
 }
 
-static inline int ceph_encode_encrypted_dname(struct inode *parent,
-					      struct qstr *d_name, char *buf)
+static inline int ceph_encode_encrypted_dname(struct inode *parent, char *buf,
+					      int len)
 {
-	memcpy(buf, d_name->name, d_name->len);
-	return d_name->len;
-}
-
-static inline int ceph_encode_encrypted_fname(struct inode *parent,
-					      struct dentry *dentry, char *buf)
-{
-	return -EOPNOTSUPP;
+	return len;
 }
 
 static inline int ceph_fname_alloc_buffer(struct inode *parent,

fs/ceph/dir.c

@@ -423,17 +423,16 @@ static int ceph_readdir(struct file *file, struct dir_context *ctx)
 			req->r_inode_drop = CEPH_CAP_FILE_EXCL;
 		}
 		if (dfi->last_name) {
-			struct qstr d_name = { .name = dfi->last_name,
-					       .len = strlen(dfi->last_name) };
+			int len = strlen(dfi->last_name);
 
 			req->r_path2 = kzalloc(NAME_MAX + 1, GFP_KERNEL);
 			if (!req->r_path2) {
 				ceph_mdsc_put_request(req);
 				return -ENOMEM;
 			}
+			memcpy(req->r_path2, dfi->last_name, len);
 
-			err = ceph_encode_encrypted_dname(inode, &d_name,
-							  req->r_path2);
+			err = ceph_encode_encrypted_dname(inode, req->r_path2, len);
 			if (err < 0) {
 				ceph_mdsc_put_request(req);
 				return err;

fs/ceph/mds_client.c

@@ -2766,8 +2766,8 @@ char *ceph_mdsc_build_path(struct ceph_mds_client *mdsc, struct dentry *dentry,
 			}
 
 			if (fscrypt_has_encryption_key(d_inode(parent))) {
-				len = ceph_encode_encrypted_fname(d_inode(parent),
-								  cur, buf);
+				len = ceph_encode_encrypted_dname(d_inode(parent),
+								  buf, len);
 				if (len < 0) {
 					dput(parent);
 					dput(cur);