net-snmp / Patches / #1350 Skip autofs entries by default

Bart Van Assche - 2019-07-24

Thanks for the patch! A modified version of this patch has been applied. Please retest.

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Ioanna Alifieraki - 2019-07-24

As mentioned in https://sourceforge.net/p/net-snmp/bugs/2968/ we're facing a similar issue in Ubuntu pacakges.
Could you please point out the commit id of modified version of this patch so I can retest?
Thanks!

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Bart Van Assche - 2019-07-24

The commit ID is as follows: cf41e6e91015 ("HOST-MIB: Skip autofs entries").

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Ioanna Alifieraki - 2019-07-24

Thanks very much for this. I retested and confirmed that the modified patch resolves the issue.

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I think it introduced regression.

snmpd 5.7.3+dfsg-1ubuntu4.2 on Ubuntu 16.04.06 LTS (before this patch) worked like this:

# snmpwalk -c putpasswordhere -v2c -On host 1.3.6.1.2.1.25.2.3.1.3
.1.3.6.1.2.1.25.2.3.1.3.1 = STRING: Physical memory
.1.3.6.1.2.1.25.2.3.1.3.3 = STRING: Virtual memory
.1.3.6.1.2.1.25.2.3.1.3.6 = STRING: Memory buffers
.1.3.6.1.2.1.25.2.3.1.3.7 = STRING: Cached memory
.1.3.6.1.2.1.25.2.3.1.3.8 = STRING: Shared memory
.1.3.6.1.2.1.25.2.3.1.3.10 = STRING: Swap space
.1.3.6.1.2.1.25.2.3.1.3.31 = STRING: /
.1.3.6.1.2.1.25.2.3.1.3.37 = STRING: /run
.1.3.6.1.2.1.25.2.3.1.3.39 = STRING: /dev/shm
.1.3.6.1.2.1.25.2.3.1.3.40 = STRING: /run/lock
.1.3.6.1.2.1.25.2.3.1.3.41 = STRING: /sys/fs/cgroup
.1.3.6.1.2.1.25.2.3.1.3.59 = STRING: /boot
.1.3.6.1.2.1.25.2.3.1.3.60 = STRING: /run/user/1002

snmp 5.7.3+dfsg-1ubuntu4.3 on Ubuntu 16.04.06 LTS (with this patch) works like this:

# snmpwalk -c putpasswordhere -v2c -On host 1.3.6.1.2.1.25.2.3.1.3
.1.3.6.1.2.1.25.2.3.1.3.1 = STRING: Physical memory
.1.3.6.1.2.1.25.2.3.1.3.3 = STRING: Virtual memory
.1.3.6.1.2.1.25.2.3.1.3.6 = STRING: Memory buffers
.1.3.6.1.2.1.25.2.3.1.3.7 = STRING: Cached memory
.1.3.6.1.2.1.25.2.3.1.3.8 = STRING: Shared memory
.1.3.6.1.2.1.25.2.3.1.3.10 = STRING: Swap space

I miss / and /boot entries ;) Both are ext filesystems, mounted via /etc/fstab, no autofs mounts.

Last edit: Lukasz Wasikowski 2019-09-06

Julian Gilbert - 2019-09-06

We see the same regression where all file sytems are missing from the above snmpwalk with:

snmp 5.7.3+dfsg-1ubuntu4.3 on Ubuntu 16.04.06 LTS
snmp 5.7.3+dfsg-1.8ubuntu3.2 on Ubuntu 18.04.3 LTS

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Eric - 2019-09-06

I filed a regression bug in launchpad:
https://bugs.launchpad.net/ubuntu/+source/net-snmp/+bug/1843036

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Eric - 2019-09-06

$ git show a0df31c18
commit a0df31c18c513a0d79f4d526b1af7fad48748e57
Author: Bart Van Assche bvanassche@acm.org
Date: Fri Jul 26 21:40:12 2019 -0700

HOST-MIB: Fix a recently introduced bug Fixes: cf41e6e91015 ("HOST-MIB: Skip autofs entries") Note: this bug was not introduced by Josef but by me.

diff --git a/agent/mibgroup/host/hrh_storage.c b/agent/mibgroup/host/hrh_storage.c
index 6f8ff6c53..c7c53922a 100644
--- a/agent/mibgroup/host/hrh_storage.c
+++ b/agent/mibgroup/host/hrh_storage.c
@@ -371,7 +371,7 @@ really_try_next:
NETSNMP_DS_AGENT_SKIPNFSINHOSTRESOURCES) &&
Check_HR_FileSys_NFS())
return NULL;
- if (Check_HR_FileSys_AutoFs())
+ if (HRFS_entry && Check_HR_FileSys_AutoFs())
return NULL;
if (store_idx <= NETSNMP_MEM_TYPE_MAX ) {
mem = (netsnmp_memory_info*)ptr;
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Eric - 2019-09-06

Disregard, the fix above is already found in Ubuntu net-snmp:

agent/mibgroup/host/hrh_storage.c

375 if (HRFS_entry && Check_HR_FileSys_AutoFs())
376 return NULL;

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Eric - 2019-09-06

I'll investigate further more and do some code inspection. Will keep you posted if I find anything.

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getfsstat doesn't seems to be in Linux
https://www.freebsd.org/cgi/man.cgi?query=getfsstat&sektion=2
https://ubuntuforums.org/showthread.php?t=1227025

Look like another method of checking the fs needs to be added for linux.

842 /* This function checks whether current file system is an AutoFs
843  * HRFS_entry must be valid prior to calling this function
844  * return 1 if AutoFs, 0 otherwise
845  */
846 int
847 Check_HR_FileSys_AutoFs(void)
848 {
849 #if HAVE_GETFSSTAT
850     if (HRFS_entry->HRFS_type != NULL &&
851 #if defined(MNTTYPE_AUTOFS)
852         !strcmp(HRFS_entry->HRFS_type, MNTTYPE_AUTOFS)
853 #else
854         !strcmp(HRFS_entry->HRFS_type, "autofs")
855 #endif
856         )
857 #endif /* HAVE_GETFSSTAT */
858         return 1;  /* AUTOFS */
859 
860     return 0; /* no AUTOFS */
861 }

Eric - 2019-09-06

and shouldn't return 1; be inside the if block ?

857 #endif /* HAVE_GETFSSTAT */ 858 return 1; /* AUTOFS */ 859 860 return 0; /* no AUTOFS */ 861 }
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Eric - 2019-09-06

buildlog:
checking for library containing getfsstat... no
checking for getfsstat... no

https://launchpadlibrarian.net/440100268/buildlog_ubuntu-bionic-amd64.net-snmp_5.7.3+dfsg-1.8ubuntu3.2_BUILDING.txt.gz

So seems the whole pre-processor block HAVE_GETFSSTAT is ignored, and the result is just this return 1.

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I haven't test (minus using gcc -E) but that should do the trick:

     if (HRFS_entry->HRFS_type != NULL &&
 #if defined(MNTTYPE_AUTOFS)
         !strcmp(HRFS_entry->HRFS_type, MNTTYPE_AUTOFS)
-#else
-        !strcmp(HRFS_entry->HRFS_type, "autofs")
 #endif
+#else /* HAVE_GETFSSTAT */
+        !strcmp(HRFS_entry->HRFS_type, "autofs")
         )
 #endif /* HAVE_GETFSSTAT */
         return 1;  /* AUTOFS */

The #else instruction never get caught otherwise:

# gcc -E #actual code
int
Check_HR_FileSys_AutoFs(void)
{
# 13 "/tmp/autofs_ORIG.c"
        return 1;

    return 0;
}

# gcc -E #with my current proposal
int
Check_HR_FileSys_AutoFs(void)
{






        !strcmp(HRFS_entry->HRFS_type, "autofs")
        )

        return 1;

    return 0;
}

Eric - 2019-09-06

The #endif IMHO is wrongly placed, so that the #else isn't doing what it is suppose to do.
Instead of being a else for HAVE_GETFSSTAT it is an ELSE for MNTTYPE_AUTOFS.

So the case where GETFSSTAT is not supported never get triggered on Linux operating system where getfsstat doesn't exist.

Last edit: Eric 2019-09-06

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Eric - 2019-09-06

If one is willing to try that test package:

sudo add-apt-repository ppa:slashd/lp1843036
sudo apt-get update

and let me know the outcome, it will be appreciated.

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Eric - 2019-09-06

after re-consideration even better :

int Check_HR_FileSys_AutoFs(void) { if (HRFS_entry->HRFS_type != NULL && #if defined(MNTTYPE_AUTOFS) !strcmp(HRFS_entry->HRFS_type, MNTTYPE_AUTOFS) #else !strcmp(HRFS_entry->HRFS_type, "autofs") #endif ) return 1; /* AUTOFS */ return 0; /* no AUTOFS */ }

We simply drop the HAVE_GETFSSTAT definition, anyway, it's good for both (GETFSSTAT system and not GETFSSTAT system) scenarios to look if the pointer is not NULL anyway.
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Eric - 2019-09-06

package to test: 5.7.3+dfsg-1.8ubuntu3.2+testpkg20190906b2

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Joe Gooch - 2019-09-06

Current ubuntu build now doesn't show ANY physical mounts.
https://bugs.launchpad.net/ubuntu/+source/net-snmp/+bug/1842924

Due to a comparison:
~~~
/ Skip AUTOFS entries /
if (entry->type == NETSNMP_FS_TYPE_AUTOFS)
continue;

Looks really innocuous until you run it through gcc -E:

if (entry->type == 7 | 0x1000 | 0x2000) continue;

~~~

At which point you realize the | is going to make this if TRUE all the time.

The attached patch puts () around the #defines.

fix_hrstorage_after_autofs.patch
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Joe Gooch - 2019-09-06

When I tested the above, I had also independently made the same change to Check_HR_FileSys_AutoFs - so that tested out fine on Ubuntu.

I can test a PPA for you if you want to roll the above patch in too.

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It's already there upstream:

$ git show 71e487212b
commit 71e487212bd65839e7454df9701524d08cf0d74f
Author: Niels Baggesen <nba@users.sourceforge.net>
Date:   Thu Jul 21 21:45:26 2016 +0200

    fsys.h: put paranthesis around macros which are expressions

diff --git a/include/net-snmp/agent/hardware/fsys.h b/include/net-snmp/agent/hardware/fsys.h
index cd7880ce7..b540a53d4 100644
--- a/include/net-snmp/agent/hardware/fsys.h
+++ b/include/net-snmp/agent/hardware/fsys.h
@@ -33,14 +33,14 @@ typedef struct netsnmp_fsys_info_s netsnmp_fsys_info;
    /*
     * Additional enumerationis - not listed in that MIB
     */
-#define NETSNMP_FS_TYPE_IGNORE    1 | _NETSNMP_FS_TYPE_LOCAL | _NETSNMP_FS_TYPE_SKIP_BIT
+#define NETSNMP_FS_TYPE_IGNORE    (1 | _NETSNMP_FS_TYPE_LOCAL | _NETSNMP_FS_TYPE_SKIP_BIT)

-#define NETSNMP_FS_TYPE_PROC      2 | _NETSNMP_FS_TYPE_LOCAL | _NETSNMP_FS_TYPE_SKIP_BIT
+#define NETSNMP_FS_TYPE_PROC      (2 | _NETSNMP_FS_TYPE_LOCAL | _NETSNMP_FS_TYPE_SKIP_BIT)

-#define NETSNMP_FS_TYPE_DEVPTS    3 | _NETSNMP_FS_TYPE_LOCAL | _NETSNMP_FS_TYPE_SKIP_BIT
-#define NETSNMP_FS_TYPE_SYSFS     4 | _NETSNMP_FS_TYPE_LOCAL | _NETSNMP_FS_TYPE_SKIP_BIT
-#define NETSNMP_FS_TYPE_TMPFS     5 | _NETSNMP_FS_TYPE_LOCAL
-#define NETSNMP_FS_TYPE_USBFS     6 | _NETSNMP_FS_TYPE_LOCAL
+#define NETSNMP_FS_TYPE_DEVPTS    (3 | _NETSNMP_FS_TYPE_LOCAL | _NETSNMP_FS_TYPE_SKIP_BIT)
+#define NETSNMP_FS_TYPE_SYSFS     (4 | _NETSNMP_FS_TYPE_LOCAL | _NETSNMP_FS_TYPE_SKIP_BIT)
+#define NETSNMP_FS_TYPE_TMPFS     (5 | _NETSNMP_FS_TYPE_LOCAL)
+#define NETSNMP_FS_TYPE_USBFS     (6 | _NETSNMP_FS_TYPE_LOCAL)

 #define NETSNMP_FS_FLAG_ACTIVE   0x01
 #define NETSNMP_FS_FLAG_REMOTE   0x02

$ git describe --contains 71e487212bd65839e7454df9701524d08cf0d74f
v5.8.pre1~7^2~14^2~15^2~22

Only thing missing upstream would be to remove the HAVE_GETFSSTAT preprocessing directive then.

Last edit: Eric 2019-09-06

Bart Van Assche - 2019-09-07

A candidate fix has been applied on the v5.8 and master branches ([bcb1a6b8afc4]). Please retest.

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Eric - 2019-09-07

Thanks Bart Van Assche !

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Eric - 2019-09-07

The Ubuntu src pkg of 'net'snmp' is in progress to be updated to include the following commit: 71e487212bd65839e7454df9701524d08cf0d74f, which fixes the problem.

To follow the progress, please follow : https://bugs.launchpad.net/ubuntu/+source/net-snmp/+bug/1843036

Thanks everyone !

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Bart Van Assche - 2019-09-17

status: open --> closed
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Skip autofs entries by default

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#1350 Skip autofs entries by default

snmpwalk -v 2c -c public test.example.com sysName

snmpwalk -v 2c -c public test.example.com hrStorage

snmpwalk -v 2c -c public test.example.com sysName

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agent/mibgroup/host/hrh_storage.c