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I'm working on some software that uses libsodium for cryptography…in Java. It has worked fine for me on both macOS 10.11/10.12 and Ubuntu Server 16.04. When I try to run my software on an Amazon EC2 Instance with Amazon Linux (uname -a returns Linux ip-$IPADDR 4.4.19-29.55.amzn1.x86_64 #1 SMP Mon Aug 29 23:29:40 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux) I get this error:

java.lang.UnsatisfiedLinkError: /home/ec2-user/myproject/target/classes/linux-x86-64/libsodiumjni.so: /usr/lib64/libc.so: invalid ELF header

Turns out libc.so is an ASCII file on this machine: 

/* GNU ld script
   Use the shared library, but some functions are only in
   the static library, so try that secondarily.  */
OUTPUT_FORMAT(elf64-x86-64)
GROUP ( /lib64/libc.so.6 /usr/lib64/libc_nonshared.a  AS_NEEDED ( /lib64/ld-linux-x86-64.so.2 ) )

I tried running my code with argument -Djava.library.path=/lib64/:…:$NORMALLIBRARYPATH to hopefully get the loader to try /lib64/libc.so.6 instead but it didn't work.

The section of code that causes libsodiumjni.so to be loaded is: 

import com.sun.jna.Native;

…

File libraryFile = Native.extractFromResourcePath(libraryName);
System.load(libraryFile.getAbsolutePath());

Inside of my project, the directory structure includes the library files in paths that JNA's Native class understands: 

src/main/resources
├── darwin
│   └── libsodiumjni.dylib
└── linux-x86-64
    └── libsodiumjni.so

On a lark I deleted the ASCII libc.so and replaced it with a symlink to /lib64/libc-2.17.so and got a slightly different error: 

java.lang.UnsatisfiedLinkError: /home/ec2-user/myproject/target/classes/linux-x86-64/libsodiumjni.so: /lib64/libc.so.6: version `LIBC' not found (required by /home/ec2-user/myproject/target/classes/linux-x86-64/libsodiumjni.so

I'm really unsure what to do about this. I'd really like to continue using libsodium (through libsodium-jni) but I'm hitting a wall here. Might have to switch to a different library since many-platform compatibility is important for this project.

jacobwil
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1 Answers1

1

I managed to fix my problem.

Put broadly, the steps I followed were:
1. Recompile the JNI library shim using libsodiumjni.so/libsodiumjni.jnilib on the machine in question.
2. Compile and install the corresponding version of libsodium on the machine, placing it at /usr/local/lib/libsodium.so.18
3. Update /etc/ld.so.conf by adding a new line /usr/local/lib
4. Run sudo ldconfig

Now my tool works!

jacobwil
  • 31
  • 3