Recently got a dedicated server running CentOS 6.7, we have ran updates and noticed that top is only showing processes for the current user.
[myuser@server2 ~]$ top -b -n1
top - 20:19:20 up 1 day, 10:09, 3 users, load average: 0.80, 0.50, 0.41
Tasks: 11 total, 1 running, 10 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.2%us, 0.0%sy, 0.0%ni, 99.8%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 32880988k total, 26893324k used, 5987664k free, 140872k buffers
Swap: 1046520k total, 0k used, 1046520k free, 19532120k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1648 myuser 20 0 98.8m 1020 688 S 0.0 0.0 0:00.00 man
1651 myuser 20 0 103m 1184 1016 S 0.0 0.0 0:00.00 sh
1652 myuser 20 0 103m 684 500 S 0.0 0.0 0:00.00 sh
1656 myuser 20 0 103m 912 752 S 0.0 0.0 0:00.07 less
3363 myuser 20 0 100m 1708 700 S 0.0 0.0 0:00.04 sshd
3364 myuser 20 0 105m 1916 1524 S 0.0 0.0 0:00.00 bash
8337 myuser 20 0 14940 1096 880 R 0.0 0.0 0:00.00 top
30429 myuser 20 0 100m 1696 696 S 0.0 0.0 0:00.16 sshd
30430 myuser 20 0 105m 1924 1536 S 0.0 0.0 0:00.01 bash
31132 myuser 20 0 100m 1692 692 S 0.0 0.0 0:00.05 sshd
31133 myuser 20 0 105m 1928 1536 S 0.0 0.0 0:00.04 bash
However when ran with sudo i get the normal output I would expect
[myuser@server2 ~]$ sudo top -bn1
top - 20:22:08 up 1 day, 10:12, 3 users, load average: 0.36, 0.40, 0.39
Tasks: 166 total, 1 running, 165 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.2%us, 0.0%sy, 0.0%ni, 99.8%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 32880988k total, 26898188k used, 5982800k free, 141196k buffers
Swap: 1046520k total, 0k used, 1046520k free, 19532188k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
32705 otherusr 20 0 21.9g 5.8g 15m S 39.8 18.3 28:47.76 java
1 root 20 0 19280 1524 1232 S 0.0 0.0 0:00.76 init
2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd
3 root 20 0 0 0 0 S 0.0 0.0 0:00.40 ksoftirqd/0
5 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/0:0H
6 root 20 0 0 0 0 S 0.0 0.0 0:03.20 kworker/u16:0
~~~~~omitted~~~~~
I have tried running top not in batch mode and using the "u" & "U" and leaving it blank and pressing [enter], with no luck.
I'm pretty sure I'm running actual top, launching with absolute path had no impact.
$ which top
/usr/bin/top
$ file /usr/bin/top
/usr/bin/top: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.18, stripped
$ alias
alias l.='ls -d .* --color=auto'
alias ll='ls -l --color=auto'
alias ls='ls --color=auto'
alias vi='vim'
alias which='alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'
No toprc is present in /etc/
$ ls -a /etc | grep -c toprc
0
proc is mounted as follows
$ sudo cat /proc/mounts | grep proc
none /proc proc rw,relatime 0 0
none /proc/sys/fs/binfmt_misc binfmt_misc rw,relatime 0 0
$ sudo cat /etc/fstab | grep proc
proc /proc proc defaults 0 0
More details on Procs
[myuser@server2 ~]$ sudo -u otherusr ps -A
PID TTY TIME CMD
21921 pts/0 00:00:00 ps
32703 ? 00:00:00 screen
32705 pts/3 01:08:01 java
[myuser@server2 ~]$ sudo ls -l /proc/ | grep 32705
dr-xr-x--- 7 otherusr root 0 Sep 23 19:27 32705
[myuser@server2 ~]$ sudo ls -l /proc/32705/ | grep stat
-r-------- 1 otherusr root 0 Sep 23 21:54 mountstats
-r--r--r-- 1 otherusr root 0 Sep 23 19:27 stat
-r--r--r-- 1 otherusr root 0 Sep 23 19:27 statm
-r--r--r-- 1 otherusr root 0 Sep 23 19:27 status
[myuser@server2 ~]$ ls /proc/ | egrep "[0-9]{1,9}";
17363
17364
26124
26125
3363
3364
[myuser@server2 ~]$ sudo -u otheruser ls /proc/ | egrep "[0-9]{1,9}"
26132
32703
32705
[myuser@server2 ~]$ umask
0002
[root@server2 ~]# umask
0022
Any Ideas?
Best Answer
One possibility is
/proc
mounted with eitherhidepid=1
orhidepid=2
. This mount option was added in latter Linux kernels and back ported sometime around CentOS 5.9 and 6.3.Another possibility (found by the poster and added to this answer as reference information) is grsecurity which has a feature for hiding other users' processes from unprivileged users as part of it's file system hardening.