Bug 656014
| Summary: | nscd host caching does not respect DNS TTLs | ||||||
|---|---|---|---|---|---|---|---|
| Product: | Red Hat Enterprise Linux 6 | Reporter: | Matt Savona <matt.savona> | ||||
| Component: | glibc | Assignee: | Andreas Schwab <schwab> | ||||
| Status: | CLOSED ERRATA | QA Contact: | qe-baseos-tools-bugs | ||||
| Severity: | medium | Docs Contact: | |||||
| Priority: | low | ||||||
| Version: | 6.0 | CC: | bugzilla, fweimer, juanino, mfranc, mrkfact, pmuller | ||||
| Target Milestone: | rc | ||||||
| Target Release: | --- | ||||||
| Hardware: | x86_64 | ||||||
| OS: | Unspecified | ||||||
| Whiteboard: | |||||||
| Fixed In Version: | glibc-2.12-1.15.el6 | Doc Type: | Bug Fix | ||||
| Doc Text: | Story Points: | --- | |||||
| Clone Of: | |||||||
| : | 929035 (view as bug list) | Environment: | |||||
| Last Closed: | 2011-05-19 13:16:13 UTC | Type: | --- | ||||
| Regression: | --- | Mount Type: | --- | ||||
| Documentation: | --- | CRM: | |||||
| Verified Versions: | Category: | --- | |||||
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |||||
| Cloudforms Team: | --- | Target Upstream Version: | |||||
| Embargoed: | |||||||
| Bug Depends On: | |||||||
| Bug Blocks: | 929035, 962903 | ||||||
| Attachments: |
|
||||||
Please enable full debug level and attach the nscd log. Created attachment 462322 [details]
nscd.log - debug 9
Will the fix referenced here in glibc-2.12-1.15.el6 for RHEL6 be backported for RHEL5 as well? An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on therefore solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHBA-2011-0584.html |
Description of problem: --------------------------------------------------------------------- When nscd is enabled and a lookup is performed for a DNS record with a TTL of 0, nscd proceeds to cache the result when it should not. This behavior is seen via lookups initiated by getaddrinfo when it should not. Version-Release number of selected component (if applicable): --------------------------------------------------------------------- Tested against RHEL5 and RHEL6, up to versions: glibc-2.12-1.7.el6.x86_64 nscd-2.12-1.7.el6.x86_64 How reproducible: --------------------------------------------------------------------- 100% Steps to Reproduce (hostnames and IPs masked): --------------------------------------------------------------------- # DNS RECORD IS: ;; ANSWER SECTION: nfs.appliance.company.com. 0 IN A 1.1.1.55 (where the returned IP may vary based on specific conditions determined by the NFS appliance) # WITH NSCD ENABLED: /etc/init.d/nscd start /etc/init.d/nscd reload ltrace -f getent ahosts nfs.appliance.company.com 2>&1 | egrep "getaddrinfo|STREAM" | grep -v printf getaddrinfo("nfs.appliance.company.com", NULL, 0x7fff65794a90, 0x7fff65794b08) = 0 1.1.1.56 STREAM nfs.appliance.company.com # [ run this as many times as you want, same result ] # WITH NSCD DISABLED: /etc/init.d/nscd stop ltrace -f getent ahosts nfs.appliance.company.com 2>&1 | egrep "getaddrinfo|STREAM" | grep -v printf getaddrinfo("nfs.appliance.company.com", NULL, 0x7ffff521eb80, 0x7ffff521ebf8) = 0 1.1.1.56 STREAM nfs.appliance.company.com ltrace -f getent ahosts nfs.appliance.company.com 2>&1 | egrep "getaddrinfo|STREAM" | grep -v printf getaddrinfo("nfs.appliance.company.com", NULL, 0x7fffb80836b0, 0x7fffb8083728) = 0 1.1.1.53 STREAM nfs.appliance.company.com ltrace -f getent ahosts nfs.appliance.company.com 2>&1 | egrep "getaddrinfo|STREAM" | grep -v printf getaddrinfo("nfs.appliance.company.com", NULL, 0x7fff9d6aa5e0, 0x7fff9d6aa658) = 0 1.1.1.57 STREAM nfs.appliance.company.com # [ run this as many times as you want, different results ] Expected results: --------------------------------------------------------------------- For DNS records with a TTL of 0, the results with NSCD enabled should be identical to the results seen with NSCD disabled. Additional info: --------------------------------------------------------------------- References regarding expected nscd and getaddrinfo behavior here: http://udrepper.livejournal.com/16362.html http://sourceware.org/bugzilla/show_bug.cgi?id=4428