diff options
Diffstat (limited to 'pkg/sentry/usermem/usermem.go')
| -rw-r--r-- | pkg/sentry/usermem/usermem.go | 597 |
1 files changed, 0 insertions, 597 deletions
diff --git a/pkg/sentry/usermem/usermem.go b/pkg/sentry/usermem/usermem.go deleted file mode 100644 index 7b1f312b1..000000000 --- a/pkg/sentry/usermem/usermem.go +++ /dev/null @@ -1,597 +0,0 @@ -// Copyright 2018 The gVisor Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// http://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -// Package usermem governs access to user memory. -package usermem - -import ( - "bytes" - "errors" - "io" - "strconv" - - "gvisor.dev/gvisor/pkg/binary" - "gvisor.dev/gvisor/pkg/sentry/context" - "gvisor.dev/gvisor/pkg/sentry/safemem" - "gvisor.dev/gvisor/pkg/syserror" -) - -// IO provides access to the contents of a virtual memory space. -// -// FIXME(b/38173783): Implementations of IO cannot expect ctx to contain any -// meaningful data. -type IO interface { - // CopyOut copies len(src) bytes from src to the memory mapped at addr. It - // returns the number of bytes copied. If the number of bytes copied is < - // len(src), it returns a non-nil error explaining why. - // - // Preconditions: The caller must not hold mm.MemoryManager.mappingMu or - // any following locks in the lock order. - // - // Postconditions: CopyOut does not retain src. - CopyOut(ctx context.Context, addr Addr, src []byte, opts IOOpts) (int, error) - - // CopyIn copies len(dst) bytes from the memory mapped at addr to dst. - // It returns the number of bytes copied. If the number of bytes copied is - // < len(dst), it returns a non-nil error explaining why. - // - // Preconditions: The caller must not hold mm.MemoryManager.mappingMu or - // any following locks in the lock order. - // - // Postconditions: CopyIn does not retain dst. - CopyIn(ctx context.Context, addr Addr, dst []byte, opts IOOpts) (int, error) - - // ZeroOut sets toZero bytes to 0, starting at addr. It returns the number - // of bytes zeroed. If the number of bytes zeroed is < toZero, it returns a - // non-nil error explaining why. - // - // Preconditions: The caller must not hold mm.MemoryManager.mappingMu or - // any following locks in the lock order. toZero >= 0. - ZeroOut(ctx context.Context, addr Addr, toZero int64, opts IOOpts) (int64, error) - - // CopyOutFrom copies ars.NumBytes() bytes from src to the memory mapped at - // ars. It returns the number of bytes copied, which may be less than the - // number of bytes read from src if copying fails. CopyOutFrom may return a - // partial copy without an error iff src.ReadToBlocks returns a partial - // read without an error. - // - // CopyOutFrom calls src.ReadToBlocks at most once. - // - // Preconditions: The caller must not hold mm.MemoryManager.mappingMu or - // any following locks in the lock order. src.ReadToBlocks must not block - // on mm.MemoryManager.activeMu or any preceding locks in the lock order. - CopyOutFrom(ctx context.Context, ars AddrRangeSeq, src safemem.Reader, opts IOOpts) (int64, error) - - // CopyInTo copies ars.NumBytes() bytes from the memory mapped at ars to - // dst. It returns the number of bytes copied. CopyInTo may return a - // partial copy without an error iff dst.WriteFromBlocks returns a partial - // write without an error. - // - // CopyInTo calls dst.WriteFromBlocks at most once. - // - // Preconditions: The caller must not hold mm.MemoryManager.mappingMu or - // any following locks in the lock order. dst.WriteFromBlocks must not - // block on mm.MemoryManager.activeMu or any preceding locks in the lock - // order. - CopyInTo(ctx context.Context, ars AddrRangeSeq, dst safemem.Writer, opts IOOpts) (int64, error) - - // TODO(jamieliu): The requirement that CopyOutFrom/CopyInTo call src/dst - // at most once, which is unnecessary in most cases, forces implementations - // to gather safemem.Blocks into a single slice to pass to src/dst. Add - // CopyOutFromIter/CopyInToIter, which relaxes this restriction, to avoid - // this allocation. - - // SwapUint32 atomically sets the uint32 value at addr to new and - // returns the previous value. - // - // Preconditions: The caller must not hold mm.MemoryManager.mappingMu or - // any following locks in the lock order. addr must be aligned to a 4-byte - // boundary. - SwapUint32(ctx context.Context, addr Addr, new uint32, opts IOOpts) (uint32, error) - - // CompareAndSwapUint32 atomically compares the uint32 value at addr to - // old; if they are equal, the value in memory is replaced by new. In - // either case, the previous value stored in memory is returned. - // - // Preconditions: The caller must not hold mm.MemoryManager.mappingMu or - // any following locks in the lock order. addr must be aligned to a 4-byte - // boundary. - CompareAndSwapUint32(ctx context.Context, addr Addr, old, new uint32, opts IOOpts) (uint32, error) - - // LoadUint32 atomically loads the uint32 value at addr and returns it. - // - // Preconditions: The caller must not hold mm.MemoryManager.mappingMu or - // any following locks in the lock order. addr must be aligned to a 4-byte - // boundary. - LoadUint32(ctx context.Context, addr Addr, opts IOOpts) (uint32, error) -} - -// IOOpts contains options applicable to all IO methods. -type IOOpts struct { - // If IgnorePermissions is true, application-defined memory protections set - // by mmap(2) or mprotect(2) will be ignored. (Memory protections required - // by the target of the mapping are never ignored.) - IgnorePermissions bool - - // If AddressSpaceActive is true, the IO implementation may assume that it - // has an active AddressSpace and can therefore use AddressSpace copying - // without performing activation. See mm/io.go for details. - AddressSpaceActive bool -} - -// IOReadWriter is an io.ReadWriter that reads from / writes to addresses -// starting at addr in IO. The preconditions that apply to IO.CopyIn and -// IO.CopyOut also apply to IOReadWriter.Read and IOReadWriter.Write -// respectively. -type IOReadWriter struct { - Ctx context.Context - IO IO - Addr Addr - Opts IOOpts -} - -// Read implements io.Reader.Read. -// -// Note that an address space does not have an "end of file", so Read can only -// return io.EOF if IO.CopyIn returns io.EOF. Attempts to read unmapped or -// unreadable memory, or beyond the end of the address space, should return -// EFAULT. -func (rw *IOReadWriter) Read(dst []byte) (int, error) { - n, err := rw.IO.CopyIn(rw.Ctx, rw.Addr, dst, rw.Opts) - end, ok := rw.Addr.AddLength(uint64(n)) - if ok { - rw.Addr = end - } else { - // Disallow wraparound. - rw.Addr = ^Addr(0) - if err != nil { - err = syserror.EFAULT - } - } - return n, err -} - -// Writer implements io.Writer.Write. -func (rw *IOReadWriter) Write(src []byte) (int, error) { - n, err := rw.IO.CopyOut(rw.Ctx, rw.Addr, src, rw.Opts) - end, ok := rw.Addr.AddLength(uint64(n)) - if ok { - rw.Addr = end - } else { - // Disallow wraparound. - rw.Addr = ^Addr(0) - if err != nil { - err = syserror.EFAULT - } - } - return n, err -} - -// CopyObjectOut copies a fixed-size value or slice of fixed-size values from -// src to the memory mapped at addr in uio. It returns the number of bytes -// copied. -// -// CopyObjectOut must use reflection to encode src; performance-sensitive -// clients should do encoding manually and use uio.CopyOut directly. -// -// Preconditions: As for IO.CopyOut. -func CopyObjectOut(ctx context.Context, uio IO, addr Addr, src interface{}, opts IOOpts) (int, error) { - w := &IOReadWriter{ - Ctx: ctx, - IO: uio, - Addr: addr, - Opts: opts, - } - // Allocate a byte slice the size of the object being marshaled. This - // adds an extra reflection call, but avoids needing to grow the slice - // during encoding, which can result in many heap-allocated slices. - b := make([]byte, 0, binary.Size(src)) - return w.Write(binary.Marshal(b, ByteOrder, src)) -} - -// CopyObjectIn copies a fixed-size value or slice of fixed-size values from -// the memory mapped at addr in uio to dst. It returns the number of bytes -// copied. -// -// CopyObjectIn must use reflection to decode dst; performance-sensitive -// clients should use uio.CopyIn directly and do decoding manually. -// -// Preconditions: As for IO.CopyIn. -func CopyObjectIn(ctx context.Context, uio IO, addr Addr, dst interface{}, opts IOOpts) (int, error) { - r := &IOReadWriter{ - Ctx: ctx, - IO: uio, - Addr: addr, - Opts: opts, - } - buf := make([]byte, binary.Size(dst)) - if _, err := io.ReadFull(r, buf); err != nil { - return 0, err - } - binary.Unmarshal(buf, ByteOrder, dst) - return int(r.Addr - addr), nil -} - -// CopyStringIn tuning parameters, defined outside that function for tests. -const ( - copyStringIncrement = 64 - copyStringMaxInitBufLen = 256 -) - -// CopyStringIn copies a NUL-terminated string of unknown length from the -// memory mapped at addr in uio and returns it as a string (not including the -// trailing NUL). If the length of the string, including the terminating NUL, -// would exceed maxlen, CopyStringIn returns the string truncated to maxlen and -// ENAMETOOLONG. -// -// Preconditions: As for IO.CopyFromUser. maxlen >= 0. -func CopyStringIn(ctx context.Context, uio IO, addr Addr, maxlen int, opts IOOpts) (string, error) { - initLen := maxlen - if initLen > copyStringMaxInitBufLen { - initLen = copyStringMaxInitBufLen - } - buf := make([]byte, initLen) - var done int - for done < maxlen { - // Read up to copyStringIncrement bytes at a time. - readlen := copyStringIncrement - if readlen > maxlen-done { - readlen = maxlen - done - } - end, ok := addr.AddLength(uint64(readlen)) - if !ok { - return stringFromImmutableBytes(buf[:done]), syserror.EFAULT - } - // Shorten the read to avoid crossing page boundaries, since faulting - // in a page unnecessarily is expensive. This also ensures that partial - // copies up to the end of application-mappable memory succeed. - if addr.RoundDown() != end.RoundDown() { - end = end.RoundDown() - readlen = int(end - addr) - } - // Ensure that our buffer is large enough to accommodate the read. - if done+readlen > len(buf) { - newBufLen := len(buf) * 2 - if newBufLen > maxlen { - newBufLen = maxlen - } - buf = append(buf, make([]byte, newBufLen-len(buf))...) - } - n, err := uio.CopyIn(ctx, addr, buf[done:done+readlen], opts) - // Look for the terminating zero byte, which may have occurred before - // hitting err. - if i := bytes.IndexByte(buf[done:done+n], byte(0)); i >= 0 { - return stringFromImmutableBytes(buf[:done+i]), nil - } - - done += n - if err != nil { - return stringFromImmutableBytes(buf[:done]), err - } - addr = end - } - return stringFromImmutableBytes(buf), syserror.ENAMETOOLONG -} - -// CopyOutVec copies bytes from src to the memory mapped at ars in uio. The -// maximum number of bytes copied is ars.NumBytes() or len(src), whichever is -// less. CopyOutVec returns the number of bytes copied; if this is less than -// the maximum, it returns a non-nil error explaining why. -// -// Preconditions: As for IO.CopyOut. -func CopyOutVec(ctx context.Context, uio IO, ars AddrRangeSeq, src []byte, opts IOOpts) (int, error) { - var done int - for !ars.IsEmpty() && done < len(src) { - ar := ars.Head() - cplen := len(src) - done - if Addr(cplen) >= ar.Length() { - cplen = int(ar.Length()) - } - n, err := uio.CopyOut(ctx, ar.Start, src[done:done+cplen], opts) - done += n - if err != nil { - return done, err - } - ars = ars.DropFirst(n) - } - return done, nil -} - -// CopyInVec copies bytes from the memory mapped at ars in uio to dst. The -// maximum number of bytes copied is ars.NumBytes() or len(dst), whichever is -// less. CopyInVec returns the number of bytes copied; if this is less than the -// maximum, it returns a non-nil error explaining why. -// -// Preconditions: As for IO.CopyIn. -func CopyInVec(ctx context.Context, uio IO, ars AddrRangeSeq, dst []byte, opts IOOpts) (int, error) { - var done int - for !ars.IsEmpty() && done < len(dst) { - ar := ars.Head() - cplen := len(dst) - done - if Addr(cplen) >= ar.Length() { - cplen = int(ar.Length()) - } - n, err := uio.CopyIn(ctx, ar.Start, dst[done:done+cplen], opts) - done += n - if err != nil { - return done, err - } - ars = ars.DropFirst(n) - } - return done, nil -} - -// ZeroOutVec writes zeroes to the memory mapped at ars in uio. The maximum -// number of bytes written is ars.NumBytes() or toZero, whichever is less. -// ZeroOutVec returns the number of bytes written; if this is less than the -// maximum, it returns a non-nil error explaining why. -// -// Preconditions: As for IO.ZeroOut. -func ZeroOutVec(ctx context.Context, uio IO, ars AddrRangeSeq, toZero int64, opts IOOpts) (int64, error) { - var done int64 - for !ars.IsEmpty() && done < toZero { - ar := ars.Head() - cplen := toZero - done - if Addr(cplen) >= ar.Length() { - cplen = int64(ar.Length()) - } - n, err := uio.ZeroOut(ctx, ar.Start, cplen, opts) - done += n - if err != nil { - return done, err - } - ars = ars.DropFirst64(n) - } - return done, nil -} - -func isASCIIWhitespace(b byte) bool { - // Compare Linux include/linux/ctype.h, lib/ctype.c. - // 9 => horizontal tab '\t' - // 10 => line feed '\n' - // 11 => vertical tab '\v' - // 12 => form feed '\c' - // 13 => carriage return '\r' - return b == ' ' || (b >= 9 && b <= 13) -} - -// CopyInt32StringsInVec copies up to len(dsts) whitespace-separated decimal -// strings from the memory mapped at ars in uio and converts them to int32 -// values in dsts. It returns the number of bytes read. -// -// CopyInt32StringsInVec shares the following properties with Linux's -// kernel/sysctl.c:proc_dointvec(write=1): -// -// - If any read value overflows the range of int32, or any invalid characters -// are encountered during the read, CopyInt32StringsInVec returns EINVAL. -// -// - If, upon reaching the end of ars, fewer than len(dsts) values have been -// read, CopyInt32StringsInVec returns no error if at least 1 value was read -// and EINVAL otherwise. -// -// - Trailing whitespace after the last successfully read value is counted in -// the number of bytes read. -// -// Unlike proc_dointvec(): -// -// - CopyInt32StringsInVec does not implicitly limit ars.NumBytes() to -// PageSize-1; callers that require this must do so explicitly. -// -// - CopyInt32StringsInVec returns EINVAL if ars.NumBytes() == 0. -// -// Preconditions: As for CopyInVec. -func CopyInt32StringsInVec(ctx context.Context, uio IO, ars AddrRangeSeq, dsts []int32, opts IOOpts) (int64, error) { - if len(dsts) == 0 { - return 0, nil - } - - buf := make([]byte, ars.NumBytes()) - n, cperr := CopyInVec(ctx, uio, ars, buf, opts) - buf = buf[:n] - - var i, j int - for ; j < len(dsts); j++ { - // Skip leading whitespace. - for i < len(buf) && isASCIIWhitespace(buf[i]) { - i++ - } - if i == len(buf) { - break - } - - // Find the end of the value to be parsed (next whitespace or end of string). - nextI := i + 1 - for nextI < len(buf) && !isASCIIWhitespace(buf[nextI]) { - nextI++ - } - - // Parse a single value. - val, err := strconv.ParseInt(string(buf[i:nextI]), 10, 32) - if err != nil { - return int64(i), syserror.EINVAL - } - dsts[j] = int32(val) - - i = nextI - } - - // Skip trailing whitespace. - for i < len(buf) && isASCIIWhitespace(buf[i]) { - i++ - } - - if cperr != nil { - return int64(i), cperr - } - if j == 0 { - return int64(i), syserror.EINVAL - } - return int64(i), nil -} - -// CopyInt32StringInVec is equivalent to CopyInt32StringsInVec, but copies at -// most one int32. -func CopyInt32StringInVec(ctx context.Context, uio IO, ars AddrRangeSeq, dst *int32, opts IOOpts) (int64, error) { - dsts := [1]int32{*dst} - n, err := CopyInt32StringsInVec(ctx, uio, ars, dsts[:], opts) - *dst = dsts[0] - return n, err -} - -// IOSequence holds arguments to IO methods. -type IOSequence struct { - IO IO - Addrs AddrRangeSeq - Opts IOOpts -} - -// NumBytes returns s.Addrs.NumBytes(). -// -// Note that NumBytes() may return 0 even if !s.Addrs.IsEmpty(), since -// s.Addrs may contain a non-zero number of zero-length AddrRanges. -// Many clients of -// IOSequence currently do something like: -// -// if ioseq.NumBytes() == 0 { -// return 0, nil -// } -// if f.availableBytes == 0 { -// return 0, syserror.ErrWouldBlock -// } -// return ioseq.CopyOutFrom(..., reader) -// -// In such cases, using s.Addrs.IsEmpty() will cause them to have the wrong -// behavior for zero-length I/O. However, using s.NumBytes() == 0 instead means -// that we will return success for zero-length I/O in cases where Linux would -// return EFAULT due to a failed access_ok() check, so in the long term we -// should move checks for ErrWouldBlock etc. into the body of -// reader.ReadToBlocks and use s.Addrs.IsEmpty() instead. -func (s IOSequence) NumBytes() int64 { - return s.Addrs.NumBytes() -} - -// DropFirst returns a copy of s with s.Addrs.DropFirst(n). -// -// Preconditions: As for AddrRangeSeq.DropFirst. -func (s IOSequence) DropFirst(n int) IOSequence { - return IOSequence{s.IO, s.Addrs.DropFirst(n), s.Opts} -} - -// DropFirst64 returns a copy of s with s.Addrs.DropFirst64(n). -// -// Preconditions: As for AddrRangeSeq.DropFirst64. -func (s IOSequence) DropFirst64(n int64) IOSequence { - return IOSequence{s.IO, s.Addrs.DropFirst64(n), s.Opts} -} - -// TakeFirst returns a copy of s with s.Addrs.TakeFirst(n). -// -// Preconditions: As for AddrRangeSeq.TakeFirst. -func (s IOSequence) TakeFirst(n int) IOSequence { - return IOSequence{s.IO, s.Addrs.TakeFirst(n), s.Opts} -} - -// TakeFirst64 returns a copy of s with s.Addrs.TakeFirst64(n). -// -// Preconditions: As for AddrRangeSeq.TakeFirst64. -func (s IOSequence) TakeFirst64(n int64) IOSequence { - return IOSequence{s.IO, s.Addrs.TakeFirst64(n), s.Opts} -} - -// CopyOut invokes CopyOutVec over s.Addrs. -// -// As with CopyOutVec, if s.NumBytes() < len(src), the copy will be truncated -// to s.NumBytes(), and a nil error will be returned. -// -// Preconditions: As for CopyOutVec. -func (s IOSequence) CopyOut(ctx context.Context, src []byte) (int, error) { - return CopyOutVec(ctx, s.IO, s.Addrs, src, s.Opts) -} - -// CopyIn invokes CopyInVec over s.Addrs. -// -// As with CopyInVec, if s.NumBytes() < len(dst), the copy will be truncated to -// s.NumBytes(), and a nil error will be returned. -// -// Preconditions: As for CopyInVec. -func (s IOSequence) CopyIn(ctx context.Context, dst []byte) (int, error) { - return CopyInVec(ctx, s.IO, s.Addrs, dst, s.Opts) -} - -// ZeroOut invokes ZeroOutVec over s.Addrs. -// -// As with ZeroOutVec, if s.NumBytes() < toZero, the write will be truncated -// to s.NumBytes(), and a nil error will be returned. -// -// Preconditions: As for ZeroOutVec. -func (s IOSequence) ZeroOut(ctx context.Context, toZero int64) (int64, error) { - return ZeroOutVec(ctx, s.IO, s.Addrs, toZero, s.Opts) -} - -// CopyOutFrom invokes s.CopyOutFrom over s.Addrs. -// -// Preconditions: As for IO.CopyOutFrom. -func (s IOSequence) CopyOutFrom(ctx context.Context, src safemem.Reader) (int64, error) { - return s.IO.CopyOutFrom(ctx, s.Addrs, src, s.Opts) -} - -// CopyInTo invokes s.CopyInTo over s.Addrs. -// -// Preconditions: As for IO.CopyInTo. -func (s IOSequence) CopyInTo(ctx context.Context, dst safemem.Writer) (int64, error) { - return s.IO.CopyInTo(ctx, s.Addrs, dst, s.Opts) -} - -// Reader returns an io.Reader that reads from s. Reads beyond the end of s -// return io.EOF. The preconditions that apply to s.CopyIn also apply to the -// returned io.Reader.Read. -func (s IOSequence) Reader(ctx context.Context) io.Reader { - return &ioSequenceReadWriter{ctx, s} -} - -// Writer returns an io.Writer that writes to s. Writes beyond the end of s -// return ErrEndOfIOSequence. The preconditions that apply to s.CopyOut also -// apply to the returned io.Writer.Write. -func (s IOSequence) Writer(ctx context.Context) io.Writer { - return &ioSequenceReadWriter{ctx, s} -} - -// ErrEndOfIOSequence is returned by IOSequence.Writer().Write() when -// attempting to write beyond the end of the IOSequence. -var ErrEndOfIOSequence = errors.New("write beyond end of IOSequence") - -type ioSequenceReadWriter struct { - ctx context.Context - s IOSequence -} - -// Read implements io.Reader.Read. -func (rw *ioSequenceReadWriter) Read(dst []byte) (int, error) { - n, err := rw.s.CopyIn(rw.ctx, dst) - rw.s = rw.s.DropFirst(n) - if err == nil && rw.s.NumBytes() == 0 { - err = io.EOF - } - return n, err -} - -// Write implements io.Writer.Write. -func (rw *ioSequenceReadWriter) Write(src []byte) (int, error) { - n, err := rw.s.CopyOut(rw.ctx, src) - rw.s = rw.s.DropFirst(n) - if err == nil && n < len(src) { - err = ErrEndOfIOSequence - } - return n, err -} |