[Enhancement] Implementing smb_cmd_fsctl

[sahlberg]

[Enhancement] Implementing smb_cmd_fsctl

[sahlberg]

I decided to start building something more generic we can use for DCERPC in general instead
of something that just contain pre-cooked arrays of values.

Initial wip here:
98854ef
It encodes either NDR32 or NDR64 depending on what the server prefers and can send validly
formed NetShareEnum calls for level 1 (name, type, comment) info.

I still need to add decoders and decode the blob the server returned. Which will require some thinking about how to track memory and how to handle memory allocations without leaking.
But we are getting there.

We might not just get a NetShareEnum function but simple dcerpc runtime we can use to do other kind of RPC calls with too.

[sahlberg]

Hi @amosavian
I can sure add those FCNTL functions too.
Please open a new issue for each of the ones you want and I will add them after the next release.

I will close this issue for now since we do have SMB2_IOCTL now

[amosavian]

Sorry I've found out that Failure to add signature error is not related to listing and is thrown before trying to open file srvsvc

[amosavian]

I found the issue with srvsvc on listing share names. No need to implementing fsctl, just implement a smb2_open_async() variation that open file with exactly this create request settings. Maybe by introducing a new open flag like O_PIPE.

[sahlberg]

Sounds good. Add a new flag and make sure it does not collide with any of the flags that either exist in libsmb2 already or that are in posix but not yet in libsmb2. I will build a ioctl / fcntl implementation anyway since we will need ot for thigs like detecting dfc referrals, server side copy etc. Any case, a Write+Read implementation for net share enum shoould be trivially converted to use fcntl at a later stage.

…

On Tue, May 29, 2018 at 8:19 PM, Amir Abbas Mousavian < ***@***.***> wrote: I found the issue with srvsvc on listing share names. No need to implementing fsctl, just implement a smb2_open_async() variation that open file with exactly this create request settings <https://msdn.microsoft.com/en-us/library/cc246794.aspx>. Maybe by introducing a new open flag. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#47 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAeNkE2hystIQYIGnjlDaSCYVPyPSzr3ks5t3SCtgaJpZM4UOoR-> .

[amosavian]

These are all flags and their values in Darwin

[sahlberg]

Linux goes all the way to #define __O_TMPFILE 020000000 i.e. 0x00400000 If you pick 0x80000000 it should be safe enough

…

On Tue, May 29, 2018 at 9:03 PM, Amir Abbas Mousavian < ***@***.***> wrote: In Apple, O_EXCL is highest with value equals to0x800. I don't know about Linux and Windows — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#47 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAeNkFZiQwis_HHHKOGN50SzHyaw9Wzuks5t3Sr_gaJpZM4UOoR-> .

[amosavian]

I have a better idea, why not define O_NOOVERWRITE flag?

[amosavian]

I've tested user-defined O_NOOVERWRITE flag and it fixed issue with opening file handle for srvsvc. But It seems Apple's strict implementation doesn't allow to interoperate with this pipe via READ/WRITE commands, whereas Windows and Samba does allow.

Interestingly, according to Microsoft examples on named pipes, both READ/WRITE and IOCTL can handle this, and the only difference is number of request/responses.

Indeed this is a bug is Apple's custom server implementation of SMB2 protocol.

EDIT: I can write to pipe but I get STATUS_INVALID_PARAMETER error when I try to read from pipe. I can send wireshark files if you wish.

[amosavian]

I've finally figured out what was Apple's problem. It was my fault. I had to set offset to 0 on every read and write. Now issue fixed and I can enumerate shares on Apple without IOCTL.

[sahlberg]

Nice work!

If you implement this using Create/Write/Read/Close for now,
please add this as new file lib/smb2-cmd-share-enum.c or similar, don't put it in libsmb2.c for now.

This means that your other patch to add O_NOOVERWRITE, that should go into libsmb2-private.h and not libsmb2.c.
(Having it private for now until and if we see a need to make it publicly visible)

Async code can be intimidating at first if you are not familiar with it.
If that is the case, you can implement this as a simple function that just uses the sync version of
open//write//read/close and I can refactor it later to become async.

This is exciting! Getting share enumeration working !

[amosavian]

Unfortunately I don't know C nor I do know libsmb2 internals. I did my best for a draft implementation. Please see and check it.

https://gist.github.com/amosavian/1bfc261ff33bf59684a9248ca1a82a06

Reference implementations are MSRPC.swift and listShare() function inside my project.

Meanwhile we should find a better name for O_NOOVERWRITE

[stefbon]

2018-05-31 16:50 GMT+02:00 Amir Abbas Mousavian <[email protected]>:

Unfortunately I don't know C nor I do know libsmb2 internals. I did my best for a draft implementation. Please see and check it. https://gist.github.com/amosavian/1bfc261ff33bf59684a9248ca1a82a06

Maybe you can look at the module of VLC recently added to browse and access shares of CIFS servers. See: https://github.com/videolabs/libdsm Stef

[amosavian]

Indeed I studied that lib and it helped me in initial implementation, after that I used wireshark for debuging.

I changed some parts, like encoding guid, to make the core more readable and consistant.

[sahlberg]

Correct, I have not implemented nse_enum_read_cb yet.

I need to think about how memory managment will work before I start implementing too much of it.
But it should not be too difficult to come up with something workable.

Just give me some time.

[amosavian]

That's great. There are other pipes like winreg. See here

As I see you also use write/read instead of ioctl command. 😀 However It made number of callbacks folded by two.

nse_enum_read_cb() is not implemented yet?

One more thing you must consider when enumerating enums. You must check that share type is disk. See here. You can refine result to have STYPE_DISKTREE or STYPE_SPECIAL | STYPE_DISKTREE.

The second one includes shares likeC$ in windows or user folder in macOS. Maybe you can add an argument to allow user to determine which type of shares should be enumerated?

[amosavian]

About memory management, I don't know what you exactly mean. But for internal use, you can implement a reference counting system.

[amosavian]

Hey @sahlberg,

Would you mind considering implementing FSCTL_GET_REPARSE_POINT, FSCTL_SET_REPARSE_POINT and FSCTL_DELETE_REPARSE_POINT for symbolic links as readlink() and symlink() functions after implementing FSCTL?

[thegeekyboy]

hi @sahlberg were you able to implement the server side copy feature? I was kind of in need of it :)