diff options
Diffstat (limited to 'pkg/sentry/loader/elf.go')
| -rw-r--r-- | pkg/sentry/loader/elf.go | 40 |
1 files changed, 27 insertions, 13 deletions
diff --git a/pkg/sentry/loader/elf.go b/pkg/sentry/loader/elf.go index 616fafa2c..98af2cc38 100644 --- a/pkg/sentry/loader/elf.go +++ b/pkg/sentry/loader/elf.go @@ -90,14 +90,23 @@ type elfInfo struct { sharedObject bool } +// fullReader interface extracts the ReadFull method from fsbridge.File so that +// client code does not need to define an entire fsbridge.File when only read +// functionality is needed. +// +// TODO(gvisor.dev/issue/1035): Once VFS2 ships, rewrite this to wrap +// vfs.FileDescription's PRead/Read instead. +type fullReader interface { + // ReadFull is the same as fsbridge.File.ReadFull. + ReadFull(ctx context.Context, dst usermem.IOSequence, offset int64) (int64, error) +} + // parseHeader parse the ELF header, verifying that this is a supported ELF // file and returning the ELF program headers. // // This is similar to elf.NewFile, except that it is more strict about what it // accepts from the ELF, and it doesn't parse unnecessary parts of the file. -// -// ctx may be nil if f does not need it. -func parseHeader(ctx context.Context, f fsbridge.File) (elfInfo, error) { +func parseHeader(ctx context.Context, f fullReader) (elfInfo, error) { // Check ident first; it will tell us the endianness of the rest of the // structs. var ident [elf.EI_NIDENT]byte @@ -185,6 +194,10 @@ func parseHeader(ctx context.Context, f fsbridge.File) (elfInfo, error) { log.Infof("Too many phdrs (%d): total size %d > %d", hdr.Phnum, totalPhdrSize, maxTotalPhdrSize) return elfInfo{}, syserror.ENOEXEC } + if int64(hdr.Phoff) < 0 || int64(hdr.Phoff+uint64(totalPhdrSize)) < 0 { + ctx.Infof("Unsupported phdr offset %d", hdr.Phoff) + return elfInfo{}, syserror.ENOEXEC + } phdrBuf := make([]byte, totalPhdrSize) _, err = f.ReadFull(ctx, usermem.BytesIOSequence(phdrBuf), int64(hdr.Phoff)) @@ -272,7 +285,7 @@ func mapSegment(ctx context.Context, m *mm.MemoryManager, f fsbridge.File, phdr } defer func() { if mopts.MappingIdentity != nil { - mopts.MappingIdentity.DecRef() + mopts.MappingIdentity.DecRef(ctx) } }() if err := f.ConfigureMMap(ctx, &mopts); err != nil { @@ -393,8 +406,7 @@ type loadedELF struct { // // It does not load the ELF interpreter, or return any auxv entries. // -// Preconditions: -// * f is an ELF file +// Preconditions: f is an ELF file. func loadParsedELF(ctx context.Context, m *mm.MemoryManager, f fsbridge.File, info elfInfo, sharedLoadOffset usermem.Addr) (loadedELF, error) { first := true var start, end usermem.Addr @@ -429,6 +441,10 @@ func loadParsedELF(ctx context.Context, m *mm.MemoryManager, f fsbridge.File, in ctx.Infof("PT_INTERP path too big: %v", phdr.Filesz) return loadedELF{}, syserror.ENOEXEC } + if int64(phdr.Off) < 0 || int64(phdr.Off+phdr.Filesz) < 0 { + ctx.Infof("Unsupported PT_INTERP offset %d", phdr.Off) + return loadedELF{}, syserror.ENOEXEC + } path := make([]byte, phdr.Filesz) _, err := f.ReadFull(ctx, usermem.BytesIOSequence(path), int64(phdr.Off)) @@ -562,8 +578,8 @@ func loadParsedELF(ctx context.Context, m *mm.MemoryManager, f fsbridge.File, in // It does not load the ELF interpreter, or return any auxv entries. // // Preconditions: -// * f is an ELF file -// * f is the first ELF loaded into m +// * f is an ELF file. +// * f is the first ELF loaded into m. func loadInitialELF(ctx context.Context, m *mm.MemoryManager, fs *cpuid.FeatureSet, f fsbridge.File) (loadedELF, arch.Context, error) { info, err := parseHeader(ctx, f) if err != nil { @@ -600,8 +616,7 @@ func loadInitialELF(ctx context.Context, m *mm.MemoryManager, fs *cpuid.FeatureS // // It does not return any auxv entries. // -// Preconditions: -// * f is an ELF file +// Preconditions: f is an ELF file. func loadInterpreterELF(ctx context.Context, m *mm.MemoryManager, f fsbridge.File, initial loadedELF) (loadedELF, error) { info, err := parseHeader(ctx, f) if err != nil { @@ -631,8 +646,7 @@ func loadInterpreterELF(ctx context.Context, m *mm.MemoryManager, f fsbridge.Fil // If loadELF returns ErrSwitchFile it should be called again with the returned // path and argv. // -// Preconditions: -// * args.File is an ELF file +// Preconditions: args.File is an ELF file. func loadELF(ctx context.Context, args LoadArgs) (loadedELF, arch.Context, error) { bin, ac, err := loadInitialELF(ctx, args.MemoryManager, args.Features, args.File) if err != nil { @@ -654,7 +668,7 @@ func loadELF(ctx context.Context, args LoadArgs) (loadedELF, arch.Context, error ctx.Infof("Error opening interpreter %s: %v", bin.interpreter, err) return loadedELF{}, nil, err } - defer intFile.DecRef() + defer intFile.DecRef(ctx) interp, err = loadInterpreterELF(ctx, args.MemoryManager, intFile, bin) if err != nil { |