similar to: suggested fix for the sigchld race

This refactors existing code to close file descriptors in the recovery process, and also adds code to close file descriptors between the fork() and exec() of QEMU or User-Mode Linux. The reason is to avoid leaking main process file descriptors where the main process (or other libraries in the main process) are not setting O_CLOEXEC at all or not setting it atomically. Python is a particular

The last (only?) caller of guestfs_int_cmd_clear_close_files() disappeared in commit e4c396888056 ("lib/info: Remove /dev/fd hacking and pass a true filename to qemu-img info.", 2018-01-23), part of v1.37.36. Simplify the code by removing guestfs_int_cmd_clear_close_files(). Signed-off-by: Laszlo Ersek <lersek at redhat.com> --- lib/guestfs-internal.h | 1 - lib/command.c

We recently tried upgrading openssh from 2.5.2p2 to 2.9p1 and discovered that it no longer worked to feed the output from a remote command into a pipe, unless the output was short and the pipe was very fast at processing its input. Example 1: ssh remote_machine some_command | less (where "some_command" generates a lot of output) now fails after the first screenful, with a

Hello, ? I need to make many (>50) ssh connections from linux to cygwin at the same time. Using Windows 2000 Server (OpenSSH_4.3p2, OpenSSL 0.9.8b and updated cygwin) and Linux RHEL4 (OpenSSH_3.9p1, OpenSSL 0.9.7a). ? It's been difficult to optimize many simultaneous connections. Here were some issues: 1.?????? On Windows XP/Professional, Microsoft intentionally cripples the TCP/IP stack.

Yes, this is a patch against an older version of OpenSSH with other stuff anyways, BUT, it's so TRIVIAL(*), that you can see how it would apply to newer versions (which I've not tried). Here's the gist: server_loop2() has a race condition with respect to reception of SIGCHLD and checking/setting child_terminated. This patch does two things: wait_until_can_do_something() adds a 1

The original implementation utilies select(). In Linux select() typically supports up to 1024 file descriptors. This can be a problem when user tries to boot up many guests. Switching to poll() has minimum impact on existing code and has better scalibility. Up to 8192 file descriptors are supported in the current implementation. Signed-off-by: Wei Liu <wei.liu2@citrix.com> ---

It is just a wrapper around select(2). Signed-off-by: Wei Liu <wei.liu2@citrix.com> --- extras/mini-os/include/posix/poll.h | 1 + extras/mini-os/lib/sys.c | 90 ++++++++++++++++++++++++++++++++++- 2 files changed, 90 insertions(+), 1 deletion(-) create mode 100644 extras/mini-os/include/posix/poll.h diff --git a/extras/mini-os/include/posix/poll.h

From f244bcad756c4f761627557bb7f315b1d8f22fb2 Mon Sep 17 00:00:00 2001 From: Dor Laor <dor.laor@qumranet.com> Date: Thu, 20 Dec 2007 13:26:30 +0200 Subject: [PATCH] [VIRTIO-NET] Rx performance improvement The current performance are not good enough, the problem lies in qemu tap handling code that caused to pass packets one at a time and also to copy them to a temporal buffer. This patch

From f244bcad756c4f761627557bb7f315b1d8f22fb2 Mon Sep 17 00:00:00 2001 From: Dor Laor <dor.laor@qumranet.com> Date: Thu, 20 Dec 2007 13:26:30 +0200 Subject: [PATCH] [VIRTIO-NET] Rx performance improvement The current performance are not good enough, the problem lies in qemu tap handling code that caused to pass packets one at a time and also to copy them to a temporal buffer. This patch

The attached patch adds an option (off by default to preserve current behavior) to set a timeout on the select() statement that waits for input in clientloop.c. This fixes a timeout issue for me (explained below) and probably also fixes the timeouts mentioned in last month's thread "Idle time out". The patch is also available by http from:

Hi Richard, I see this patch is included into libguestfs >= 1.26.6 & libguestfs >= 1.27.24. I feel that version is too high. Now RHEL 7.0 runs libguestfs-1.22.6, RHEL 6.6 alpha and 6.5 runs libguestfs-1.20.11. Is that possible to backport this patch, in order to make this problem fixed in RHEL 7.0, 6.6, and 6.5? Thanks & Best Regards Qin Zhao (赵钦) China System and Technology Lab,

https://bugzilla.redhat.com/show_bug.cgi?id=1123007 This is version 2 of the patch which avoids incorrectly closing stderr, so we can still see debug and error messages. Rich.

Hello, In response to the timing analysis attacks presented by Dawn Song et. al. in her paper http://paris.cs.berkeley.edu/~dawnsong/ssh-timing.html we at Silicon Defense developed a patch for openssh to avoid such measures. Timing Analysis Evasion changes were developed by C. Jason Coit and Roel Jonkman of Silicon Defense. These changes cause SSH to send packets unless request not to,

From: "Richard W.M. Jones" <rjones at redhat.com> If the parent process uses a pipe (or any fd, but pipes are a particular problem), then the recovery process would hold open the file descriptor(s) of the pipe, meaning that it could not be fully closed in the parent. Because the recovery process doesn't use exec(2), this wasn't avoidable even using FD_CLOEXEC. Avoid this

As the start of work to add remote support, I'm taking a close look at the protocol layer in the library. These are some small cleanups. Rich.

during my seminar of advanced exploitation techniques (SEAT, [1]) i developed some methods to crack into system via DMA (e.g. via firewire). as part of this i developed a program that steals loaded ssh private keys from ssh-agents. i was astonished to find that the keys are not immediately removed from the agent when a timeout occurs, but only the next time the agent is queried via its socket. i

Hi all, we're suffering heavily from the "connection reset by peer" problem when running Rsync on WinNT. Great was our relief when seeing Randy's message in http://www.mail-archive.com/rsync@lists.samba.org/msg01918.html I immediately installed the full Cygwin to recompile Rsync, but since I'm far from a C guru, I'm a bit puzzled with the last 2 lines in Randy's

If running the external command fails in "argv mode" (ie. when not using the shell), then exit with either 126 or 127 as defined by POSIX. This is mostly the same as what bash does, see execute_cmd.c:shell_execve in the bash sources. Note: saving errno around perror(3) if necessary, otherwise you will see different behaviour between verbose and non-verbose mode. In non-verbose mode,

v1 was here: https://www.redhat.com/archives/libguestfs/2013-August/msg00005.html This now works, to some extent. The main problem now is that devices are named /dev/ubd[a-] which of course confuses everything. I'm thinking it may be easier to add a udev rule to rename them. Rich.

This is a User-Mode Linux backend for libguestfs. You can select it by doing: export LIBGUESTFS_BACKEND=uml export LIBGUESTFS_QEMU=/path/to/vmlinux Note we're reusing the 'qemu' variable in the handle for convenience. QEmu is not involved when using the UML backend. This almost works. UML itself crashes when the daemon tries to connect to the serial port. I suspect it's