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Date: Sat, 27 Jan 2018 18:20:27 +0200
From: Stefan Fröberg <stefan.froberg@...roprogram.com>
To: Szabolcs Nagy <nsz@...t70.net>
Cc: musl@...ts.openwall.com
Subject: Re: BUG: $ORIGIN does not seem to work

Hi


Szabolcs Nagy kirjoitti 27.01.2018 klo 13:07:
> * Stefan Fröberg <stefan.froberg@...roprogram.com> [2018-01-27 01:50:21 +0200]:
>> My ldd is just symbolic link inside musl chroot environment, to
>> /lib/ld-musl-x86_64.so.1
>> and it's symbolic link to /lib/libc.so
>>
>> Here is readelf output of that test program
>> readelf -d x
>>
>> Dynamic section at offset 0xe10 contains 24 entries:
>>   Tag        Type                         Name/Value
>>  0x0000000000000001 (NEEDED)             Shared library: [libcrypto.so.1.1]
>                                                             ^^^^^^^^^^^^^^^^
> this looks like the wrong library version
>
> if you had straced the ldd output you would have seen
> that musl tries to open lib/libcrypto.so.1.1, but you
> probably only have lib/libcrypto.so.1.0.0 based on the
> glibc ldd output below.
No, that ldd was run inside, pure, chrooted musl environment. No glibc
inside.
These are the only libcrypto* files inside that chroot environment:

 ls -lah /usr/lib/libcrypto.*
-rw-r--r--    1 0        0           5.0M Dec 17 00:24 /usr/lib/libcrypto.a
lrwxrwxrwx    1 0        0             16 Dec 17 00:24
/usr/lib/libcrypto.so -> libcrypto.so.1.1
-rwxr-xr-x    1 0        0           3.0M Jan 26 12:58
/usr/lib/libcrypto.so.1.1

Best Regards
Stefan

> at link time you need to make sure ld picks up the
> right libcrypto.
>
>>  0x0000000000000001 (NEEDED)             Shared library: [libc.so]
>>  0x000000000000000f (RPATH)              Library rpath: [$ORIGIN/lib]
>>  0x000000000000000c (INIT)               0x598
>>  0x000000000000000d (FINI)               0x812
>>  0x000000006ffffef5 (GNU_HASH)           0x220
>>  0x0000000000000005 (STRTAB)             0x390
>>  0x0000000000000006 (SYMTAB)             0x258
>>  0x000000000000000a (STRSZ)              241 (bytes)
>>  0x000000000000000b (SYMENT)             24 (bytes)
>>  0x0000000000000015 (DEBUG)              0x0
>>  0x0000000000000003 (PLTGOT)             0x201000
>>  0x0000000000000002 (PLTRELSZ)           48 (bytes)
>>  0x0000000000000014 (PLTREL)             RELA
>>  0x0000000000000017 (JMPREL)             0x568
>>  0x0000000000000007 (RELA)               0x4c0
>>  0x0000000000000008 (RELASZ)             168 (bytes)
>>  0x0000000000000009 (RELAENT)            24 (bytes)
>>  0x000000006ffffffb (FLAGS_1)            Flags: PIE
>>  0x000000006ffffffe (VERNEED)            0x4a0
>>  0x000000006fffffff (VERNEEDNUM)         1
>>  0x000000006ffffff0 (VERSYM)             0x482
>>  0x000000006ffffff9 (RELACOUNT)          2
>>  0x0000000000000000 (NULL)               0x0
>>
>> So the $ORIGIN/lib is there but for some reason ldd won't show it???
>>
>> Best Regards
>> Stefan Fröberg
>>
>> Szabolcs Nagy kirjoitti 26.01.2018 klo 16:21:
>>> * Stefan Fröberg <stefan.froberg@...roprogram.com> [2018-01-26 15:39:23 +0200]:
>>>> On glibc the following:
>>>>
>>>> gcc  -o x -Wl,-rpath='$ORIGIN/lib' x.c -L ./lib -lcrypto
>>>>
>>>> or
>>>>
>>>> gcc  -o x -Wl,-rpath,'$ORIGIN/lib' x.c -L ./lib -lcrypto
>>>>
>>>> Gives me binary with relative library path
>>>>
>>>> ldd x
>>>>     linux-vdso.so.1 (0x00007ffcb6bee000)
>>>> *    libcrypto.so.1.0.0 => /home/wizard/kal-el/lib/libcrypto.so.1.0.0
>>>> (0x00007f0bc3593000)**
>>>> *    libc.so.6 => /lib64/libc.so.6 (0x00007f0bc31e2000)
>>>>     libdl.so.2 => /lib64/libdl.so.2 (0x00007f0bc2fde000)
>>>>     libz.so.1 => /lib64/libz.so.1 (0x00007f0bc2dc7000)
>>>>     /lib64/ld-linux-x86-64.so.2 (0x00007f0bc39d2000)
>>>>
>>>> cp -rap kal-el/* batman/
>>>> ldd x
>>>>     linux-vdso.so.1 (0x00007ffdbf0b6000)
>>>> *    libcrypto.so.1.0.0 => /home/wizard/batman/lib/libcrypto.so.1.0.0
>>>> (0x00007fb682149000)**
>>>> *    libc.so.6 => /lib64/libc.so.6 (0x00007fb681d98000)
>>>>     libdl.so.2 => /lib64/libdl.so.2 (0x00007fb681b94000)
>>>>     libz.so.1 => /lib64/libz.so.1 (0x00007fb68197d000)
>>>>     /lib64/ld-linux-x86-64.so.2 (0x00007fb682588000)
>>>>
>>>>
>>>> But trying the same with musl does not seem to work?
>>>> ldd x
>>>> /lib/ld-musl-x86_64.so.1 (0x7f07372e2000)
>>>>     libc.so => /lib/ld-musl-x86_64.so.1 (0x7f07372e2000)
>>>>
>>>> and if i remove the -L ./lib from the command it uses system library
>>>> gcc  -o x -Wl,-rpath,'$ORIGIN/lib'  x.c   -lcrypto
>>>> ldd xx
>>>>     /lib/ld-musl-x86_64.so.1 (0x7fdd8618d000)
>>>>     libcrypto.so.1.1 => /usr/lib/libcrypto.so.1.1 (0x7fdd85ed7000)
>>>>     libc.so => /lib/ld-musl-x86_64.so.1 (0x7fdd8618d000)
>>>>
>>>>
>>> $ORIGIN in rpath works fine in musl
>>>
>>> you are doing something wrong
>>>
>>> but it's hard to tell what: your ldd command is looking at
>>> the wrong binary, we don't know what ldd you are using (e.g.
>>> use ld-*-musl.so.1 --list foo to make this explicit), it's
>>> not clear if the binary has $ORIGIN set up correctly since
>>> you showed a gcc command line instead of readelf -d of the
>>> generated executable, we don't know what paths have the
>>> library and what paths the ldso tried (you can check this
>>> by strace).
>>>
>>> (there are some differences between musl and glibc:
>>> e.g. glibc expands $ORIGIN in dlopen too while musl does
>>> not, however in your case musl should work)

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