URL:
<https://savannah.gnu.org/bugs/?55512>
Summary: Fix blanker to work when screen is suid root
Project: GNU Screen
Submitted by: sshambar
Submitted on: Fri 18 Jan 2019 06:53:11 PM UTC
Category: Program Logic
Severity: 3 - Normal
Priority: 5 - Normal
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
Release: 4.6.2
Fixed Release: None
Planned Release: None
Work Required: None
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Details:
I found that the blankerprg setting wasn't working when screen was suid root.
I tracked the problem down to the slave PTY for the blanker not having the
permissions correctly.
I've created a patch that changes RunBlanker to use OpenDevice
(rather than OpenPTY) so that the pty permissions are setup as in ForkWindow.
I also updated the post-fork file-descriptor handling to mimic ForkWindow for
ptys (fixes some leaked descriptors).
To diagnose the problem, I modified RunBlanker to create screen.blanker
-DDEBUG files...(similar to screen.child files)
I also modified ReceiveMsg() to display MSG_ERROR when the screen is blocked
by the blanker (so errors launching the blanker are displayed).
Patch is attached.
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File Attachments:
-------------------------------------------------------
Date: Fri 18 Jan 2019 06:53:11 PM UTC Name:
Fix-blanker-to-work-when-screen-is-suid-root.patch Size: 5KiB By: sshambar
<http://savannah.gnu.org/bugs/download.php?file_id=46015>
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