New: Can’t login as root user after upgrading to buildroot 2019.02

https://bugs.busybox.net/show_bug.cgi?id=12046

Bug ID: 12046
Summary: Can?t login as root user after upgrading to buildroot
2019.02
Product: buildroot
Version: 2019.02
Hardware: Other
OS: Linux
Status: NEW
Severity: normal
Priority: P5
Component: Other
Assignee: unassigned at buildroot.uclibc.org
Reporter: liadekel123 at gmail.com
CC: buildroot at uclibc.org
Target Milestone: ---

Hi everyone,
2 weeks ago we upgraded our buildroot version from 2018.03 to 2019.02 . Until now we were using getty in order to login, and enabled login with root user on our defconfig.

After upgrading as described above, we can?t login with root user, While with standard user we do succeed.
As I saw one of the changes between the versions was that md5 is no longer supported to hash the shadow file (same shadow file which contains our standard user details).
We did tried to change the root password without any further success.

I?ll appreciate any ideas ...
Many Thanks (:

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Carlos Santos <[email protected]> changed:

What |Removed |Added
----------------------------------------------------------------------------

             Status|NEW                         |ASSIGNED
           Assignee|unassigned at buildroot.uclibc |unixmania at gmail.com
                   |.org                        |

--- Comment #1 from Carlos Santos <[email protected]> --- Please run the following commands

    $ make savedefconfig BR2_DEFCONFIG=/tmp/bz12046.defconfig
    $ gzip /tmp/bz12046.defconfig

Then attach the resulting /tmp/bz12046.defconfig.gz file to this bug.

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Carlos Santos <[email protected]> changed:

What |Removed |Added
----------------------------------------------------------------------------

             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |NEEDINFO

--- Comment #2 from Carlos Santos <[email protected]> --- No reply from submitter after 7 days.

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--- Comment #3 from liadekel123 at gmail.com ---
Hey Carlos,
Sorry about the delay. We solved the problem...
Apparently the version of login in buildroot 2019.02 use securetty file which lists all the devices root user is allowed to login from :|

Many Thanks,
Liad

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--- Comment #4 from Carlos Santos <[email protected]> --- (In reply to liadekel123 from comment #3)

/etc/securetty is required by pam_securetty, which is part of pam-linux. It is not used by default neither by the busybox login nor by the util-linux one. What
is the contents of your /etc/pam.d/login file?

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--- Comment #5 from liadekel123 at gmail.com ---
(In reply to Carlos Santos from comment #4)
There is no pam.d in my rootfs...

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Carlos Santos <[email protected]> changed:

What |Removed |Added
----------------------------------------------------------------------------
Resolution|NEEDINFO |INVALID

--- Comment #6 from Carlos Santos <[email protected]> --- (In reply to liadekel123 from comment #5)

OK, I was able to reproduce the problem with the following defconfig:

BR2_x86_64=y
BR2_DL_DIR="$(HOME)/src"
BR2_TOOLCHAIN_EXTERNAL=y
BR2_TOOLCHAIN_EXTERNAL_DOWNLOAD=y BR2_TOOLCHAIN_EXTERNAL_URL="https://toolchains.bootlin.com/downloads/releases/toolchains/x86-64-core-i7/tarballs/x86-64-core-i7--glibc--bleeding-edge-2018.11-1.tar.bz2" BR2_TOOLCHAIN_EXTERNAL_GCC_8=y
BR2_TOOLCHAIN_EXTERNAL_HEADERS_4_14=y
BR2_TOOLCHAIN_EXTERNAL_CUSTOM_GLIBC=y
BR2_TOOLCHAIN_EXTERNAL_CXX=y
BR2_TOOLCHAIN_EXTERNAL_GDB_SERVER_COPY=y
BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_EUDEV=y
BR2_SYSTEM_DHCP="eth0"
BR2_SYSTEM_ENABLE_NLS=y
BR2_LINUX_KERNEL=y
BR2_LINUX_KERNEL_CUSTOM_VERSION=y
BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="4.19.16"
BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/qemu/x86_64/linux.config"
BR2_TARGET_ROOTFS_EXT2=y
# BR2_TARGET_ROOTFS_TAR is not set

123456789012345678901234567890123456789012345678901234567890123456789012

The problem happens with Busybox login:

- If linux-pam is NOT selected
- If /etc/securetty does not exist root can log in without restrictions
- If /etc/securetty exists then root can log in only on terminals listed
there
- If linux-pam is selected
- If pam_securetty is NOT enabled in /etc/pam.d/login then /etc/securetty is
ignored
- If pam_securetty is enabled with "auth required pam_securetty.so"
- If /etc/securetty does not exist root can log in without restrictions
- If /etc/securetty exists then can log in only on terminals listed there

Considering that by default Buildroot does NOT install a /etc/securetty file I'm keeping this bug as RESOLVED but changing the resolution reason from NEEDINFO to INVALID.

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--- Comment #7 from liadekel123 at gmail.com --- (In reply to Carlos Santos from comment #6)
But linux-pam was NOT selected in our config and still root wasn?t able to log in without the /etc/securetty file.

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