Comment 0 for bug 1747711

file doesn't recognize modern PIE (Position Independent Executable) x86 executables as such, reporting them as “application/x-sharedlib”. Consequently, only non-PIE executables can be opened in graphical file managers such as nautilus. This may cause a minor (?) security risk if a commonly-published workaround is attempted.

Expected behaviour:

    $ echo "int main() { return 0; }" > foo.c
    $ gcc -o foo foo.c
    $ file foo
    foo: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0, BuildID[sha1]=6e7749f995a89a53f74ec29d3c16fcf3f56be90f, not stripped
    $ file --mime-type foo
    foo: application/x-executable

Actual behaviour:

    $ echo "int main() { return 0; }" > foo.c
    $ gcc -o foo foo.c
    $ file foo
    foo: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0, BuildID[sha1]=6e7749f995a89a53f74ec29d3c16fcf3f56be90f, not stripped
    $ file --mime-type foo
    foo: application/x-sharedlib

Workaround (unsafe?):

    $ echo "int main() { return 0; }" > foo.c
    $ gcc -o foo-nopie foo.c -no-pie
    $ file foo-nopie
    foo-nopie: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0, BuildID[sha1]=3eb8c581f43c19997e3c828f5a9730dbdc794470, not stripped
    $ file --mime-type foo-nopie
    foo-nopie: application/x-executable

gcc now defaults to building with PIE enabled for security reasons.

Also affects: nautilus (and likely other graphical file managers like those on Lubuntu) - because nautilus uses mime-type to determine if a file is executable, double-click to run a program no longer works.

Also noted on: Gnome Bugs - https://bugzilla.gnome.org/show_bug.cgi?id=737849 (2014) - before PIE became the default build option.

This may be an upstream issue. This may not affect architectures outside x86.*

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: file 1:5.32-1
ProcVersionSignature: Ubuntu 4.13.0-32.35-generic 4.13.13
Uname: Linux 4.13.0-32-generic x86_64
ApportVersion: 2.20.7-0ubuntu3.7
Architecture: amd64
CurrentDesktop: GNOME
Date: Tue Feb 6 11:21:20 2018
InstallationDate: Installed on 2017-05-11 (270 days ago)
InstallationMedia: Ubuntu-GNOME 17.04 "Zesty Zapus" - Release amd64 (20170412)
SourcePackage: file
UpgradeStatus: Upgraded to artful on 2017-10-21 (108 days ago)