[Samba] SMB3 backport not working

Marco Drummer marco.drummer at outlook.com
Thu Feb 24 15:27:23 UTC 2022

I am currently trying to get a Vero 4k from osmc.tv wo work with a SMB3 share with encryption.

They are using a customized Debian 4.9 Kernel as far as I can tell, so I am not sure who is at fault here, I am discussing this with them also.

The kernel Version 4.9.113 the supplied cifs.ko is 2.09

I followed the instructions from https://wiki.samba.org/index.php/LinuxSMB3_build_backport and grabbed the linux-4.9-full-backport branch.

Compiling this leads to the first error:
fs/cifs/connect.c:2635:13: warning: implicit declaration of function 'user_key_payload'; did you mean 'user_key_payload_rcu'? [-Wimplicit-function-declaration]

which when ignored leads to the module not working:
cifs: Unknown symbol user_key_payload (err 0)

I am unsure whether it is as simple as that and why this error is present in the first place. I find it somewhat unlikely that the kernel would have a custom patch renaming this function.

Once I heed the compiler warning and change the symbol name it compiles and loads cifs.ko successfully.
However SMB3 Encryption is still not working and a mount with "vers=3.0,seal" results in the following error, while "vers=2.1" succeeds as before:

CIFS VFS: failed to connect to IPC (rc=-11)
CIFS VFS: session ffffffc052130e00 has no tcon available for a dfs referral request
CIFS VFS: cifs_mount failed w/return code = -11

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