diff options
Diffstat (limited to 'pkg/sentry/platform/platform.go')
| -rw-r--r-- | pkg/sentry/platform/platform.go | 119 |
1 files changed, 71 insertions, 48 deletions
diff --git a/pkg/sentry/platform/platform.go b/pkg/sentry/platform/platform.go index ec22dbf87..ba031516a 100644 --- a/pkg/sentry/platform/platform.go +++ b/pkg/sentry/platform/platform.go @@ -22,10 +22,11 @@ import ( "os" "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/seccomp" "gvisor.dev/gvisor/pkg/sentry/arch" - "gvisor.dev/gvisor/pkg/sentry/safemem" - "gvisor.dev/gvisor/pkg/sentry/usermem" + "gvisor.dev/gvisor/pkg/sentry/memmap" + "gvisor.dev/gvisor/pkg/usermem" ) // Platform provides abstractions for execution contexts (Context, @@ -114,6 +115,17 @@ func (NoCPUPreemptionDetection) PreemptAllCPUs() error { panic("This platform does not support CPU preemption detection") } +// MemoryManager represents an abstraction above the platform address space +// which manages memory mappings and their contents. +type MemoryManager interface { + //usermem.IO provides access to the contents of a virtual memory space. + usermem.IO + // MMap establishes a memory mapping. + MMap(ctx context.Context, opts memmap.MMapOpts) (usermem.Addr, error) + // AddressSpace returns the AddressSpace bound to mm. + AddressSpace() AddressSpace +} + // Context represents the execution context for a single thread. type Context interface { // Switch resumes execution of the thread specified by the arch.Context @@ -143,11 +155,43 @@ type Context interface { // concurrent call to Switch(). // // - ErrContextCPUPreempted: See the definition of that error for details. - Switch(as AddressSpace, ac arch.Context, cpu int32) (*arch.SignalInfo, usermem.AccessType, error) + Switch(ctx context.Context, mm MemoryManager, ac arch.Context, cpu int32) (*arch.SignalInfo, usermem.AccessType, error) + + // PullFullState() pulls a full state of the application thread. + // + // A platform can support lazy loading/restoring of a thread state + // which includes registers and a floating point state. + // + // For example, when the Sentry handles a system call, it may have only + // syscall arguments without other registers and a floating point + // state. And in this case, if the Sentry will need to construct a + // signal frame to call a signal handler, it will need to call + // PullFullState() to load all registers and FPU state. + // + // Preconditions: The caller must be running on the task goroutine. + PullFullState(as AddressSpace, ac arch.Context) + + // FullStateChanged() indicates that a thread state has been changed by + // the Sentry. This happens in case of the rt_sigreturn, execve, etc. + // + // First, it indicates that the Sentry has the full state of the thread + // and PullFullState() has to do nothing if it is called after + // FullStateChanged(). + // + // Second, it forces restoring the full state of the application + // thread. A platform can support lazy loading/restoring of a thread + // state. This means that if the Sentry has not changed a thread state, + // the platform may not restore it. + // + // Preconditions: The caller must be running on the task goroutine. + FullStateChanged() // Interrupt interrupts a concurrent call to Switch(), causing it to return // ErrContextInterrupt. Interrupt() + + // Release() releases any resources associated with this context. + Release() } var ( @@ -204,7 +248,7 @@ type AddressSpace interface { // Preconditions: addr and fr must be page-aligned. fr.Length() > 0. // at.Any() == true. At least one reference must be held on all pages in // fr, and must continue to be held as long as pages are mapped. - MapFile(addr usermem.Addr, f File, fr FileRange, at usermem.AccessType, precommit bool) error + MapFile(addr usermem.Addr, f memmap.File, fr memmap.FileRange, at usermem.AccessType, precommit bool) error // Unmap unmaps the given range. // @@ -215,6 +259,13 @@ type AddressSpace interface { // must be acquired via platform.NewAddressSpace(). Release() + // PreFork() is called before creating a copy of AddressSpace. This + // guarantees that this address space will be in a consistent state. + PreFork() + + // PostFork() is called after creating a copy of AddressSpace. + PostFork() + // AddressSpaceIO methods are supported iff the associated platform's // Platform.SupportsAddressSpaceIO() == true. AddressSpaces for which this // does not hold may panic if AddressSpaceIO methods are invoked. @@ -307,56 +358,28 @@ func (f SegmentationFault) Error() string { return fmt.Sprintf("segmentation fault at %#x", f.Addr) } -// File represents a host file that may be mapped into an AddressSpace. -type File interface { - // All pages in a File are reference-counted. - - // IncRef increments the reference count on all pages in fr. - // - // Preconditions: fr.Start and fr.End must be page-aligned. fr.Length() > - // 0. At least one reference must be held on all pages in fr. (The File - // interface does not provide a way to acquire an initial reference; - // implementors may define mechanisms for doing so.) - IncRef(fr FileRange) - - // DecRef decrements the reference count on all pages in fr. - // - // Preconditions: fr.Start and fr.End must be page-aligned. fr.Length() > - // 0. At least one reference must be held on all pages in fr. - DecRef(fr FileRange) - - // MapInternal returns a mapping of the given file offsets in the invoking - // process' address space for reading and writing. - // - // Note that fr.Start and fr.End need not be page-aligned. - // - // Preconditions: fr.Length() > 0. At least one reference must be held on - // all pages in fr. - // - // Postconditions: The returned mapping is valid as long as at least one - // reference is held on the mapped pages. - MapInternal(fr FileRange, at usermem.AccessType) (safemem.BlockSeq, error) - - // FD returns the file descriptor represented by the File. - // - // The only permitted operation on the returned file descriptor is to map - // pages from it consistent with the requirements of AddressSpace.MapFile. - FD() int -} - -// FileRange represents a range of uint64 offsets into a File. -// -// type FileRange <generated using go_generics> - -// String implements fmt.Stringer.String. -func (fr FileRange) String() string { - return fmt.Sprintf("[%#x, %#x)", fr.Start, fr.End) +// Requirements is used to specify platform specific requirements. +type Requirements struct { + // RequiresCurrentPIDNS indicates that the sandbox has to be started in the + // current pid namespace. + RequiresCurrentPIDNS bool + // RequiresCapSysPtrace indicates that the sandbox has to be started with + // the CAP_SYS_PTRACE capability. + RequiresCapSysPtrace bool } // Constructor represents a platform type. type Constructor interface { + // New returns a new platform instance. + // + // Arguments: + // + // * deviceFile - the device file (e.g. /dev/kvm for the KVM platform). New(deviceFile *os.File) (Platform, error) OpenDevice() (*os.File, error) + + // Requirements returns platform specific requirements. + Requirements() Requirements } // platforms contains all available platform types. |