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Make setting security.capability attribute a no-op in tmpfs. #11605

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Make setting security.capability attribute a no-op in tmpfs. #11605

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5 changes: 5 additions & 0 deletions pkg/sentry/fsimpl/overlay/filesystem.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1825,6 +1825,11 @@ func (fs *filesystem) SetXattrAt(ctx context.Context, rp *vfs.ResolvingPath, opt

// Precondition: fs.renameMu must be locked.
func (fs *filesystem) setXattrLocked(ctx context.Context, d *dentry, mnt *vfs.Mount, creds *auth.Credentials, opts *vfs.SetXattrOptions) error {
if strings.HasPrefix(opts.Name, linux.XATTR_SECURITY_PREFIX) {
// TODO(b/301323819): support security extended attributes in overlayfs.
// Setting security extended attributes in overlayfs is a no-op.
return nil
}
if err := d.checkXattrPermissions(creds, opts.Name, vfs.MayWrite); err != nil {
return err
}
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5 changes: 5 additions & 0 deletions pkg/sentry/fsimpl/tmpfs/tmpfs.go
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Original file line number Diff line number Diff line change
Expand Up @@ -870,6 +870,11 @@ func (i *inode) setXattr(creds *auth.Credentials, opts *vfs.SetXattrOptions) err
if err := i.checkXattrPrefix(opts.Name); err != nil {
return err
}
if strings.HasPrefix(opts.Name, linux.XATTR_SECURITY_PREFIX) {
// TODO(b/301323819): support security extended attributes in tmpfs.
// Setting security extended attributes in tmpfs is a no-op.
return nil
}
mode := linux.FileMode(i.mode.Load())
kuid := auth.KUID(i.uid.Load())
kgid := auth.KGID(i.gid.Load())
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10 changes: 8 additions & 2 deletions test/syscalls/linux/xattr.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -111,8 +111,14 @@ TEST_F(XattrTest, SecurityCapacityXattr) {
const char* path = test_file_name_.c_str();
const char name[] = "security.capacity";
const std::string val = "";
EXPECT_THAT(lsetxattr(path, name, &val, val.size(), 0),
SyscallFailsWithErrno(EOPNOTSUPP));
if (ASSERT_NO_ERRNO_AND_VALUE(IsTmpfs(test_file_name_)) ||
ASSERT_NO_ERRNO_AND_VALUE(IsOverlayfs(test_file_name_))) {
EXPECT_THAT(lsetxattr(path, name, &val, val.size(), 0), SyscallSucceeds());
} else {
EXPECT_THAT(lsetxattr(path, name, &val, val.size(), 0),
SyscallFailsWithErrno(EOPNOTSUPP));
}

int buf = 0;
EXPECT_THAT(lgetxattr(path, name, &buf, /*size=*/128),
SyscallFailsWithErrno(AnyOf(ENODATA, EOPNOTSUPP)));
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