1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef SANDBOX_LINUX_SYSCALL_BROKER_BROKER_CLIENT_H_ 6 #define SANDBOX_LINUX_SYSCALL_BROKER_BROKER_CLIENT_H_ 7 8 #include "base/macros.h" 9 #include "sandbox/linux/syscall_broker/broker_channel.h" 10 #include "sandbox/linux/syscall_broker/broker_common.h" 11 12 namespace sandbox { 13 14 namespace syscall_broker { 15 16 class BrokerPolicy; 17 18 // This class can be embedded in a sandboxed process and can be 19 // used to perform certain system calls in another, presumably 20 // non-sandboxed process (which embeds BrokerHost). 21 // A key feature of this class is the ability to use some of its methods in a 22 // thread-safe and async-signal safe way. The goal is to be able to use it to 23 // replace the open() or access() system calls happening anywhere in a process 24 // (as allowed for instance by seccomp-bpf's SIGSYS mechanism). 25 class BrokerClient { 26 public: 27 // |policy| needs to match the policy used by BrokerHost. This 28 // allows to predict some of the requests which will be denied 29 // and save an IPC round trip. 30 // |ipc_channel| needs to be a suitable SOCK_SEQPACKET unix socket. 31 // |fast_check_in_client| should be set to true and 32 // |quiet_failures_for_tests| to false unless you are writing tests. 33 BrokerClient(const BrokerPolicy& policy, 34 BrokerChannel::EndPoint ipc_channel, 35 bool fast_check_in_client, 36 bool quiet_failures_for_tests); 37 ~BrokerClient(); 38 39 // Can be used in place of access(). 40 // X_OK will always return an error in practice since the broker process 41 // doesn't support execute permissions. 42 // It's similar to the access() system call and will return -errno on errors. 43 // This is async signal safe. 44 int Access(const char* pathname, int mode) const; 45 // Can be used in place of open(). 46 // The implementation only supports certain white listed flags and will 47 // return -EPERM on other flags. 48 // It's similar to the open() system call and will return -errno on errors. 49 // This is async signal safe. 50 int Open(const char* pathname, int flags) const; 51 52 // Get the file descriptor used for IPC. This is used for tests. GetIPCDescriptor()53 int GetIPCDescriptor() const { return ipc_channel_.get(); } 54 55 private: 56 const BrokerPolicy& broker_policy_; 57 const BrokerChannel::EndPoint ipc_channel_; 58 const bool fast_check_in_client_; // Whether to forward a request that we 59 // know will be denied to the broker. (Used 60 // for tests). 61 const bool quiet_failures_for_tests_; // Disable certain error message when 62 // testing for failures. 63 64 int PathAndFlagsSyscall(IPCCommand syscall_type, 65 const char* pathname, 66 int flags) const; 67 68 DISALLOW_COPY_AND_ASSIGN(BrokerClient); 69 }; 70 71 } // namespace syscall_broker 72 73 } // namespace sandbox 74 75 #endif // SANDBOX_LINUX_SYSCALL_BROKER_BROKER_CLIENT_H_ 76