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vfs: return EOPNOTSUPP for FICLONE/FICLONERANGE/FIDEDUPERANGE #12853

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Merged
copybara-service merged 1 commit into from
Apr 3, 2026
Merged

vfs: return EOPNOTSUPP for FICLONE/FICLONERANGE/FIDEDUPERANGE #12853

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7 changes: 7 additions & 0 deletions pkg/abi/linux/ioctl.go
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Original file line number Diff line number Diff line change
Expand Up @@ -189,6 +189,13 @@ const (
KCOV_MODE_TRACE_CMP = 3
)

// File clone/dedup ioctls from include/uapi/linux/fs.h.
var (
FICLONE = IOW(0x94, 9, 4)
FICLONERANGE = IOW(0x94, 13, 32)
FIDEDUPERANGE = IOWR(0x94, 54, 24)
)

// FUSE_DEV_IOC_CLONE from include/uapi/linux/fuse.h.
var (
FUSE_DEV_IOC_CLONE = IOR(229, 0, 4)
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6 changes: 6 additions & 0 deletions pkg/sentry/vfs/file_description_impl_util.go
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Expand Up @@ -145,6 +145,12 @@ func (FileDescriptionDefaultImpl) ConfigureMMap(ctx context.Context, opts *memma
// Ioctl implements FileDescriptionImpl.Ioctl analogously to
// file_operations::unlocked_ioctl == NULL in Linux.
func (FileDescriptionDefaultImpl) Ioctl(ctx context.Context, uio usermem.IO, sysno uintptr, args arch.SyscallArguments) (uintptr, error) {
// Return EOPNOTSUPP for reflink ioctls when the filesystem
// does not support remap_file_range, matching Linux behavior.
switch args[1].Uint() {
case linux.FICLONE, linux.FICLONERANGE, linux.FIDEDUPERANGE:
return 0, linuxerr.EOPNOTSUPP
}
return 0, linuxerr.ENOTTY
}

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1 change: 1 addition & 0 deletions test/syscalls/linux/BUILD
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Original file line number Diff line number Diff line change
Expand Up @@ -1138,6 +1138,7 @@ cc_binary(
"//test/util:file_descriptor",
"//test/util:signal_util",
"//test/util:socket_util",
"//test/util:temp_path",
"//test/util:test_main",
"//test/util:test_util",
],
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49 changes: 49 additions & 0 deletions test/syscalls/linux/ioctl.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@
#include <net/if.h>
#include <netdb.h>
#include <signal.h>
#include <linux/fs.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/types.h>
Expand All @@ -29,6 +30,7 @@
#include "test/syscalls/linux/unix_domain_socket_test_util.h"
#include "test/util/file_descriptor.h"
#include "test/util/signal_util.h"
#include "test/util/temp_path.h"
#include "test/util/socket_util.h"
#include "test/util/test_util.h"

Expand Down Expand Up @@ -422,6 +424,53 @@ std::vector<SocketKind> IoctlSocketTypes() {
INSTANTIATE_TEST_SUITE_P(IoctlTest, IoctlTestSIOCGIFCONF,
::testing::ValuesIn(IoctlSocketTypes()));

// FICLONE/FICLONERANGE/FIDEDUPERANGE should return EOPNOTSUPP on
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@ayushr2 ayushr2 Apr 2, 2026

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These tests will fail when run on Linux. IMO syscall test is not required for this change. We primarliy use them to compare gVisor <-> Linux compatibility.

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@tanyifeng tanyifeng Apr 3, 2026

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You're right — I realized that on filesystems that support reflink, these ioctls would succeed instead of returning EOPNOTSUPP, so the tests could indeed fail on native Linux depending on the filesystem. I've send a follow-up pr #12863 to remove these test cases. Thanks for catching this!

// filesystems that do not support reflink (e.g. tmpfs).
TEST_F(IoctlTest, FicloneReturnsEopnotsupp) {
auto src = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
auto dst = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
const FileDescriptor src_fd =
ASSERT_NO_ERRNO_AND_VALUE(Open(src.path(), O_RDONLY));
const FileDescriptor dst_fd =
ASSERT_NO_ERRNO_AND_VALUE(Open(dst.path(), O_WRONLY));

EXPECT_THAT(ioctl(dst_fd.get(), FICLONE, src_fd.get()),
SyscallFailsWithErrno(EOPNOTSUPP));
}

TEST_F(IoctlTest, FiclonerangeReturnsEopnotsupp) {
auto src = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
auto dst = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
const FileDescriptor src_fd =
ASSERT_NO_ERRNO_AND_VALUE(Open(src.path(), O_RDONLY));
const FileDescriptor dst_fd =
ASSERT_NO_ERRNO_AND_VALUE(Open(dst.path(), O_WRONLY));

struct file_clone_range range = {};
range.src_fd = src_fd.get();
EXPECT_THAT(ioctl(dst_fd.get(), FICLONERANGE, &range),
SyscallFailsWithErrno(EOPNOTSUPP));
}

TEST_F(IoctlTest, FideduperangeReturnsEopnotsupp) {
auto src = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
auto dst = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
const FileDescriptor src_fd =
ASSERT_NO_ERRNO_AND_VALUE(Open(src.path(), O_RDONLY));
const FileDescriptor dst_fd =
ASSERT_NO_ERRNO_AND_VALUE(Open(dst.path(), O_RDWR));

struct file_dedupe_range *range = static_cast<struct file_dedupe_range *>(
calloc(1, sizeof(*range) + sizeof(struct file_dedupe_range_info)));
ASSERT_NE(range, nullptr);
range->src_length = 0;
range->dest_count = 1;
range->info[0].dest_fd = dst_fd.get();
EXPECT_THAT(ioctl(src_fd.get(), FIDEDUPERANGE, range),
SyscallFailsWithErrno(EOPNOTSUPP));
free(range);
}

} // namespace

TEST_F(IoctlTest, FIOGETOWNSucceeds) {
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