Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.
RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.

Bug 1477491

Summary: tc filter does not fail on malformed bytecode file
Product: Red Hat Enterprise Linux 7 Reporter: Jaroslav Aster <jaster>
Component: iprouteAssignee: Phil Sutter <psutter>
Status: CLOSED ERRATA QA Contact: Jaroslav Aster <jaster>
Severity: high Docs Contact:
Priority: high    
Version: 7.4-AltCC: atragler, psutter
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: iproute-4.11.0-3.el7a Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2017-11-09 11:25:03 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Attachments:
Description Flags
Regression reproducer. none

Description Jaroslav Aster 2017-08-02 09:09:49 UTC 
Description of problem:

tc filter does not fail on malformed bytecode file. It reads only first line, creates filter and ignores other line.


Version-Release number of selected component (if applicable):

iproute-4.11.0-1.el7a


How reproducible:

100%


Steps to Reproduce:

iproute-4.11.0-1.el7a

# cat /tmp/tmp.fejlMbWcco
7,40 0 0 12,21 0 4 2048,37 3 0 1500,48 0 0 14,21 0 1 66,6 0 0 262144,6 0 0 0,
12,12 13,13 0 4
blabla

# tc filter add dev TestIface parent 1:0 bpf run bytecode-file /tmp/tmp.fejlMbWcco flowid 1:13

# tc filter show dev TestIface | grep 'flowid 1:13'
filter parent 1: protocol all pref 49152 bpf handle 0x1 flowid 1:13 bytecode '7,40 0 0 12,21 0 4 2048,37 3 0 1500,48 0 0 14,21 0 1 66,6 0 0 262144,6 0 0 0'


iproute-3.10.0-87.el7

# cat /tmp/tmp.BgIfvpoxVL
7,40 0 0 12,21 0 4 2048,37 3 0 1500,48 0 0 14,21 0 1 66,6 0 0 262144,6 0 0 0,
12,12 13,13 0 4
blabla

# tc filter add dev TestIface parent 1:0 bpf run bytecode-file /tmp/tmp.BgIfvpoxVL flowid 1:13'
Real program length exceeds encoded length parameter!
Illegal "bytecode"

# tc filter show dev TestIface | grep 'flowid 1:13'
<nothing>


Actual results:

tc filter reads malformed bytecode file and creates filter instead of fails and creates nothing.


Expected results:

tc filter reports error, returns non-zero return code and creates nothing.
Comment 2 Phil Sutter 2017-08-02 13:23:33 UTC 
In fact, this is not a regression: The test case previously failed not because
of the invalid content on the second line, but because of the trailing newline
on the first one - the BPF parser never read more than a single line from the
provided bytecode file.

What has changed with the rebase is that the parser now removes any trailing
newline from that first line. This is a good thing per se, becase editors
commonly add that when editing a file (even if it contains just a single line)
anyway.

So in this particular case, the test case should be adjusted to append the
invalid bytecode part to the same line, not write a new line to the file.

Nevertheless I have submitted a patch upstream which enables the parser to
detect consecutive lines of bytecode and treat them correctly (which
implicitly also allows to split bytecode files over multiple lines):

http://marc.info/?l=linux-netdev&m=150167869213237&w=2

Cheers, Phil
Comment 3 Phil Sutter 2017-08-04 07:04:47 UTC 
Upstream accepted my patch:

commit 3da3ebfca85b8f1e8252b898453d8cb383c5c398
Author: Phil Sutter <phil>
Date:   Wed Aug 2 14:57:56 2017 +0200

    bpf: Make bytecode-file reading a little more robust
    
    bpf_parse_string() will now correctly handle:
    
    - Extraneous whitespace,
    - OPs on multiple lines and
    - overlong file names.
    
    The added feature of allowing to have OPs on multiple lines (like e.g.
    tcpdump prints them) is rather a side effect of fixing detection of
    malformed bytecode files having random content on a second line, like
    e.g.:
    
    | 4,40 0 0 12,21 0 1 2048,6 0 0 262144,6 0 0 0
    | foobar
    
    Cc: Daniel Borkmann <daniel>
    Signed-off-by: Phil Sutter <phil>
    Acked-by: Daniel Borkmann <daniel>
Comment 5 Jaroslav Aster 2017-08-28 15:03:25 UTC 
Hi Phil,

unfortunately I found a regression in the patch. It has stopped to work on correct bytecode file. See the reproducer I have attached.

iproute-4.11.0-1.el7a (old)

# cat /tmp/bytecode.txt 
7,40 0 0 12,21 0 4 2048,37 3 0 1500,48 0 0 14,21 0 1 66,6 0 0 262144,6 0 0 0,
# tc filter add dev TestIface parent 1:0 bpf run bytecode "$(cat /tmp/bytecode.txt)" flowid 1:11
# tc filter add dev TestIface parent 1:0 bpf run bytecode-file /tmp/bytecode.txt flowid 1:13


iproute-4.11.0-2.el7a (new)

# cat /tmp/bytecode.txt 
7,40 0 0 12,21 0 4 2048,37 3 0 1500,48 0 0 14,21 0 1 66,6 0 0 262144,6 0 0 0,
# tc filter add dev TestIface parent 1:0 bpf run bytecode "$(cat /tmp/bytecode.txt)" flowid 1:11
# tc filter add dev TestIface parent 1:0 bpf run bytecode-file /tmp/bytecode.txt flowid 1:13
Real program length exceeds encoded length parameter!
Comment 6 Jaroslav Aster 2017-08-28 15:04:14 UTC 
Created attachment 1319118 [details]
Regression reproducer.
Comment 7 Phil Sutter 2017-08-29 15:15:21 UTC 
Bug found, seems to happen on certain architectures only. Fix submitted upstream:
https://marc.info/?l=linux-netdev&m=150401943515102&w=2
Comment 10 errata-xmlrpc 2017-11-09 11:25:03 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHEA-2017:3172