106 lines
4.3 KiB
C++
106 lines
4.3 KiB
C++
// Copyright (c) 2013 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef SANDBOX_LINUX_SERVICES_CREDENTIALS_H_
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#define SANDBOX_LINUX_SERVICES_CREDENTIALS_H_
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#include "build/build_config.h"
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// Link errors are tedious to track, raise a compile-time error instead.
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#if defined(OS_ANDROID)
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#error "Android is not supported."
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#endif // defined(OS_ANDROID).
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#include <string>
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#include <vector>
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#include "base/compiler_specific.h"
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#include "base/macros.h"
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#include "sandbox/linux/system_headers/capability.h"
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#include "sandbox/sandbox_export.h"
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namespace sandbox {
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// This class should be used to manipulate the current process' credentials.
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// It is currently a stub used to manipulate POSIX.1e capabilities as
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// implemented by the Linux kernel.
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class SANDBOX_EXPORT Credentials {
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public:
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// For brevity, we only expose enums for the subset of capabilities we use.
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// This can be expanded as the need arises.
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enum class Capability {
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SYS_CHROOT,
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SYS_ADMIN,
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};
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// Drop all capabilities in the effective, inheritable and permitted sets for
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// the current thread. For security reasons, since capabilities are
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// per-thread, the caller is responsible for ensuring it is single-threaded
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// when calling this API.
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// |proc_fd| must be a file descriptor to /proc/ and remains owned by
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// the caller.
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static bool DropAllCapabilities(int proc_fd) WARN_UNUSED_RESULT;
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// A similar API which assumes that it can open /proc/self/ by itself.
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static bool DropAllCapabilities() WARN_UNUSED_RESULT;
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// Sets the effective and permitted capability sets for the current thread to
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// the list of capabiltiies in |caps|. All other capability flags are cleared.
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static bool SetCapabilities(int proc_fd,
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const std::vector<Capability>& caps)
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WARN_UNUSED_RESULT;
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// Versions of the above functions which do not check that the process is
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// single-threaded. After calling these functions, capabilities of other
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// threads will not be changed. This is dangerous, do not use unless you nkow
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// what you are doing.
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static bool DropAllCapabilitiesOnCurrentThread() WARN_UNUSED_RESULT;
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static bool SetCapabilitiesOnCurrentThread(
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const std::vector<Capability>& caps) WARN_UNUSED_RESULT;
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// Returns true if the current thread has either the effective, permitted, or
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// inheritable flag set for the given capability.
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static bool HasCapability(Capability cap);
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// Return true iff there is any capability in any of the capabilities sets
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// of the current thread.
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static bool HasAnyCapability();
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// Returns whether the kernel supports CLONE_NEWUSER and whether it would be
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// possible to immediately move to a new user namespace. There is no point
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// in using this method right before calling MoveToNewUserNS(), simply call
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// MoveToNewUserNS() immediately. This method is only useful to test the
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// ability to move to a user namespace ahead of time.
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static bool CanCreateProcessInNewUserNS();
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// Move the current process to a new "user namespace" as supported by Linux
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// 3.8+ (CLONE_NEWUSER).
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// The uid map will be set-up so that the perceived uid and gid will not
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// change.
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// If this call succeeds, the current process will be granted a full set of
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// capabilities in the new namespace.
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// This will fail if the process is not mono-threaded.
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static bool MoveToNewUserNS() WARN_UNUSED_RESULT;
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// Remove the ability of the process to access the file system. File
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// descriptors which are already open prior to calling this API remain
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// available.
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// The implementation currently uses chroot(2) and requires CAP_SYS_CHROOT.
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// CAP_SYS_CHROOT can be acquired by using the MoveToNewUserNS() API.
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// |proc_fd| must be a file descriptor to /proc/ and must be the only open
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// directory file descriptor of the process.
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//
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// CRITICAL:
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// - the caller must close |proc_fd| eventually or access to the file
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// system can be recovered.
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// - DropAllCapabilities() must be called to prevent escapes.
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static bool DropFileSystemAccess(int proc_fd) WARN_UNUSED_RESULT;
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// Forks and drops capabilities in the child.
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static pid_t ForkAndDropCapabilitiesInChild();
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private:
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DISALLOW_IMPLICIT_CONSTRUCTORS(Credentials);
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};
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} // namespace sandbox.
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#endif // SANDBOX_LINUX_SERVICES_CREDENTIALS_H_
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