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createAt should return all errors from FindInode except ENOENT. 

Previously, createAt was eating all errors from FindInode except for EACCES and
proceeding with the creation. This is incorrect, as FindInode can return many
other errors (like ENAMETOOLONG) that should stop creation.

This CL changes createAt to return all errors encountered except for ENOENT,
which we can ignore because we are about to create the thing.

PiperOrigin-RevId: 245773222
Change-Id: I1b317021de70f0550fb865506f6d8147d4aebc56
This commit is contained in:
Nicolas Lacasse 2019-04-29 10:29:14 -07:00 committed by Shentubot
parent 66bca6fc22
commit 2df64cd6d2
2 changed files with 16 additions and 4 deletions
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9
pkg/sentry/syscalls/linux/sys_file.go
View File

@ -347,10 +347,9 @@ func createAt(t *kernel.Task, dirFD kdefs.FD, addr usermem.Addr, flags uint, mod
return syserror.ConvertIntr(err, kernel.ERESTARTSYS)
}
defer newFile.DecRef()
case syserror.EACCES:
// Permission denied while walking to the file.
return err
default:
case syserror.ENOENT:
// File does not exist. Proceed with creation.
// Do we have write permissions on the parent?
if err := d.Inode.CheckPermission(t, fs.PermMask{Write: true, Execute: true}); err != nil {
return err
@ -365,6 +364,8 @@ func createAt(t *kernel.Task, dirFD kdefs.FD, addr usermem.Addr, flags uint, mod
}
defer newFile.DecRef()
targetDirent = newFile.Dirent
default:
return err
}
// Success.

11
test/syscalls/linux/creat.cc
View File

@ -51,6 +51,17 @@ TEST(CreatTest, CreatTruncatesExistingFile) {
EXPECT_EQ("", new_contents);
}
TEST(CreatTest, CreatWithNameTooLong) {
// Start with a unique name, and pad it to NAME_MAX + 1;
std::string name = NewTempRelPath();
int padding = (NAME_MAX + 1) - name.size();
name.append(padding, 'x');
const std::string& path = JoinPath(GetAbsoluteTestTmpdir(), name);
// Creation should return ENAMETOOLONG.
ASSERT_THAT(creat(path.c_str(), kMode), SyscallFailsWithErrno(ENAMETOOLONG));
}
} // namespace
} // namespace testing