[Bug 943] sftp will not send from a named pipe

bugzilla-daemon at bugzilla.mindrot.org bugzilla-daemon at bugzilla.mindrot.org
Wed Jun 27 01:26:46 EST 2007


Mark Fuller <azfuller at gmail.com> changed:

           What    |Removed                     |Added
             Status|RESOLVED                    |REOPENED
         Resolution|WONTFIX                     |

--- Comment #7 from Mark Fuller <azfuller at gmail.com>  2007-06-27 01:26:44 ---
I'm sorry to reopen this bug report, but you have not addressed my
concerns. The original bug (you refer to as the cause of disallowing
named pipes) said SSH should not block on named pipes. The solution was
to disallow named pipes. I am contending that this is an incorrect
resolution for two reasons (which I wish you would address):

1) It breaks the unix concept of "everything is a file."

2) SSH's importance is its security. Using named pipes are beneficial
in the most extreme implementations (such as in a DMZ) where writing
the file to disk would be too much of an exposure. In those cases a
forked process decrypts a file and serves it to the "getter" through a
named pipe. (Or, reads a named pipe to encrypt data from the

It's not that I disagree with the original bug report concerning how
SSH blocks on FIFOs. It's that I disagree with how the problem was
solved in such a sweeping manner. It should have been an option to SSH
to skip FIFOs. 

In your last response you said I can use cat/dd/stdio redirection. I
believe this will result in one of two things happening. It will either
cause blocking (true FIFO behavior, which means the sweeping
elimination of FIFOs didn't really fix anything). Or, it will allow
data to be written to disk (because it's not blocked, but then
eliminating the desired behavior described above in item #2).

If I have misunderstood how cat/dd/stdio would work, could you please
give me a working example? I would be happy to evaluate it. If it is
indeed a suitable solution perhaps you could add it to the FAQ? (The
page for reporting bugs says to check the FAQ for things that aren't
bugs at all. If this isn't a bug, then it seems like the FAQ should
address this with an example of how SSH should be used with named pipes
(to accomplish the goals outlined above). But, I'd like to review it
before you publish it because, as I said above, I think it's either
going to cause blocking (thereby calling into question the "fix" for
#856), or allow data to be written to disk (which breaks the goal of
eliminating data being written to disk).

I'm sorry to be a pest. I appreciate all the free work you do. I
wouldn't continue to pursue this matter if I didn't feel it is serious.


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