[Buildroot] [Bug 8276] New: package/dropbear: symlink resolution incorrect

[Buildroot] [Bug 8276] New: package/dropbear: symlink resolution incorrect

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=8276

           Summary: package/dropbear: symlink resolution incorrect
           Product: buildroot
           Version: unspecified
          Platform: All
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P5
         Component: Other
        AssignedTo: unassigned at buildroot.uclibc.org
        ReportedBy: nospam+busybox at jtang.org
                CC: buildroot at uclibc.org
   Estimated Hours: 0.0


Commit 6dc5c7ff changed how the /etc/dropbear symlink is detected, by using
readlink to resolve the target location. When using coreutils's readlink,
"readlink -f /etc/dropbear" will return /var/run/dropbear. However, if using
busybox's readlink, the same "readlink -f /etc/dropbear" returns an empty
string. I am not sure if this is a bug in the /etc/init.d/S50dropbear script,
or if busybox is not honoring the "-f" flag.

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[Buildroot] [Bug 8276] package/dropbear: symlink resolution incorrect

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=8276

Yann E. MORIN <yann.morin.1998@free.fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |yann.morin.1998 at free.fr
         AssignedTo|unassigned at buildroot.uclibc |yann.morin.1998 at free.fr
                   |.org                        |

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[Buildroot] [Bug 8276] package/dropbear: symlink resolution incorrect

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=8276

Yann E. MORIN <yann.morin.1998@free.fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED

--- Comment #1 from Yann E. MORIN <yann.morin.1998@free.fr> 2015-08-11 09:09:30 UTC ---
Hello,

I've tried to reproduce the issue, but it just works for me here.
But I've looked, and our default busybox configuration has
CONFIG_FEATURE_READLINK_FOLLOW enabled.

Did you customise your Busybox configuration?

Regards,
Yann E. MORIN.

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[Buildroot] [Bug 8276] package/dropbear: symlink resolution incorrect

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=8276

--- Comment #2 from nospam+busybox at jtang.org 2015-08-11 11:18:33 UTC ---
Yes, FEATURE_READLINK_FOLLOW is set. If it makes a difference, this is using
the raspberrypi2_defconfig, with uClibc-ng.

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[Buildroot] [Bug 8276] package/dropbear: symlink resolution incorrect

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=8276

--- Comment #3 from nospam+busybox at jtang.org 2015-08-11 22:43:00 UTC ---
I investigated this further, and it may be a difference between Busybox/uClibc
and coreutils/glibc. If the target of the symlink does not exist, in coreutils
"readlink -f" will display as much as possible. In Busybox, "readlink -f" will
result in an error, specifically ENOENT.

Test case:

ln -s /tmp/no_such_file /tmp/some_symlink


On my Debian desktop:

 $ readlink /tmp/some_symlink 
 /tmp/no_such_file
 $ readlink -f /tmp/some_symlink 
 /tmp/no_such_file


On my Raspberry Pi:

 # readlink /tmp/some_symlink
 /tmp/no_such_file
 # readlink -f /tmp/some_symlink 
 # touch /tmp/no_such_file
 # readlink -f /tmp/some_symlink 
 /tmp/no_such_file

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[Buildroot] [Bug 8276] package/dropbear: symlink resolution incorrect

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=8276

--- Comment #4 from Yann E. MORIN <yann.morin.1998@free.fr> 2015-08-17 16:02:30 UTC ---
Created attachment 6141
  --> https://bugs.busybox.net/attachment.cgi?id=6141
Fix dropbear when readling is busybox

CAre to test the attached patch and report back, please?

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[Buildroot] [Bug 8276] package/dropbear: symlink resolution incorrect

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=8276

--- Comment #5 from nospam+busybox at jtang.org 2015-08-18 02:12:52 UTC ---
Yes, this patch worked for me.

Tested-by: Jason Tang <tang@jtang.org>

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[Buildroot] [Bug 8276] package/dropbear: symlink resolution incorrect

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=8276

Thomas Petazzoni <thomas.petazzoni@free-electrons.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #6 from Thomas Petazzoni <thomas.petazzoni@free-electrons.com> 2015-08-24 20:13:23 UTC ---
Bug fixed by
http://git.buildroot.net/buildroot/commit/?id=29a0f0557984ccb299426712b71fee5abaaa2ca9.

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