diff options
| -rw-r--r-- | pkg/sentry/loader/elf.go | 18 | ||||
| -rw-r--r-- | test/syscalls/linux/exec_binary.cc | 19 | ||||
| -rw-r--r-- | test/util/proc_util.cc | 2 |
3 files changed, 24 insertions, 15 deletions
diff --git a/pkg/sentry/loader/elf.go b/pkg/sentry/loader/elf.go index ba9c9ce12..2d9251e92 100644 --- a/pkg/sentry/loader/elf.go +++ b/pkg/sentry/loader/elf.go @@ -323,18 +323,22 @@ func mapSegment(ctx context.Context, m *mm.MemoryManager, f *fs.File, phdr *elf. return syserror.ENOEXEC } + // N.B. Linux uses vm_brk_flags to map these pages, which only + // honors the X bit, always mapping at least RW. ignoring These + // pages are not included in the final brk region. + prot := usermem.ReadWrite + if phdr.Flags&elf.PF_X == elf.PF_X { + prot.Execute = true + } + if _, err := m.MMap(ctx, memmap.MMapOpts{ Length: uint64(anonSize), Addr: anonAddr, // Fixed without Unmap will fail the mmap if something is // already at addr. - Fixed: true, - Private: true, - // N.B. Linux uses vm_brk to map these pages, ignoring - // the segment protections, instead always mapping RW. - // These pages are not included in the final brk - // region. - Perms: usermem.ReadWrite, + Fixed: true, + Private: true, + Perms: prot, MaxPerms: usermem.AnyAccess, }); err != nil { ctx.Infof("Error mapping PT_LOAD segment %v anonymous memory: %v", phdr, err) diff --git a/test/syscalls/linux/exec_binary.cc b/test/syscalls/linux/exec_binary.cc index 91b55015c..68af882bb 100644 --- a/test/syscalls/linux/exec_binary.cc +++ b/test/syscalls/linux/exec_binary.cc @@ -401,12 +401,17 @@ TEST(ElfTest, DataSegment) { }))); } -// Additonal pages beyond filesz are always RW. +// Additonal pages beyond filesz honor (only) execute protections. // -// N.B. Linux uses set_brk -> vm_brk to additional pages beyond filesz (even -// though start_brk itself will always be beyond memsz). As a result, the -// segment permissions don't apply; the mapping is always RW. +// N.B. Linux changed this in 4.11 (16e72e9b30986 "powerpc: do not make the +// entire heap executable"). Previously, extra pages were always RW. TEST(ElfTest, ExtraMemPages) { + // gVisor has the newer behavior. + if (!IsRunningOnGvisor()) { + auto version = ASSERT_NO_ERRNO_AND_VALUE(GetKernelVersion()); + SKIP_IF(version.major < 4 || (version.major == 4 && version.minor < 11)); + } + ElfBinary<64> elf = StandardElf(); // Create a standard ELF, but extend to 1.5 pages. The second page will be the @@ -415,7 +420,7 @@ TEST(ElfTest, ExtraMemPages) { decltype(elf)::ElfPhdr phdr = {}; phdr.p_type = PT_LOAD; - // RWX segment. The extra anon page will be RW anyways. + // RWX segment. The extra anon page will also be RWX. // // N.B. Linux uses clear_user to clear the end of the file-mapped page, which // respects the mapping protections. Thus if we map this RO with memsz > @@ -454,7 +459,7 @@ TEST(ElfTest, ExtraMemPages) { {0x41000, 0x42000, true, true, true, true, kPageSize, 0, 0, 0, file.path().c_str()}, // extra page from anon. - {0x42000, 0x43000, true, true, false, true, 0, 0, 0, 0, ""}, + {0x42000, 0x43000, true, true, true, true, 0, 0, 0, 0, ""}, }))); } @@ -469,7 +474,7 @@ TEST(ElfTest, AnonOnlySegment) { phdr.p_offset = 0; phdr.p_vaddr = 0x41000; phdr.p_filesz = 0; - phdr.p_memsz = kPageSize - 0xe8; + phdr.p_memsz = kPageSize; elf.phdrs.push_back(phdr); elf.UpdateOffsets(); diff --git a/test/util/proc_util.cc b/test/util/proc_util.cc index 75b24da37..34d636ba9 100644 --- a/test/util/proc_util.cc +++ b/test/util/proc_util.cc @@ -88,7 +88,7 @@ PosixErrorOr<std::vector<ProcMapsEntry>> ParseProcMaps( std::vector<ProcMapsEntry> entries; auto lines = absl::StrSplit(contents, '\n', absl::SkipEmpty()); for (const auto& l : lines) { - std::cout << "line: " << l; + std::cout << "line: " << l << std::endl; ASSIGN_OR_RETURN_ERRNO(auto entry, ParseProcMapsLine(l)); entries.push_back(entry); } |