Folks
I'm having file-access problems in Apache 2.4 under Centos 7. In
particular:
- I have a file that's readable to every user and every application,
(writeable by only one user), but my CGI scripts cannot read it.
- Some of my CGI scripts need temporary storage for some files. They
are, for example, some internal log files, tnat get cleaned up over
time, but I want to be able to look at them (as root). Where would
you suggest they be placed? I've tried /tmp/my_private_files/, and
/var/tmp/my_private_files/, but Apache fails to find even the directory.
Here's some extra information
SELINUX is disabled.
I modified my CGI script to report where in the path to
/tmp/my_private_files/temp_log.log the process failed. The Perl code I ran is:
my $x = "";
print STDERR "Trying to read /tmp/ramdisk/keys.txt\n";
for (split /\//, "/tmp/ramdisk/keys.txt") {
next unless $_;
$x .= "/$_";
print STDERR "Test $x, " , (-e $x?"exists":"does
not exist"), "\n";
}
And the output in the http error log for this virtual user,
(timestamp and other error log data stripped) was:
AH01215: Trying to read /tmp/ramdisk/keys.txt
AH01215: Test /tmp, exists
AH01215: Test /tmp/ramdisk, does not exist
AH01215: Test /tmp/ramdisk/keys.txt, does not exist
Using the "dir -l" command as root, I discover:
dir -l / | grep tmp
drwxrwxrwt. 16 root root 4096 Nov 21 08:35 tmp
dir -l /tmp | grep ramdisk
drwxrwxrwt 2 root root 140 Nov 21 08:35 ramdisk
dir -l /tmp/ramdisk | grep keys.txt
-rw-r--r-- 1 user1 user1 11829 Nov 21 08:29 keys.txt
Any suggestions?
PS: Centos 6 had no such problems, and the file locations worked just fine.
David
Jonathan Billings
2017-Nov-21 17:24 UTC
[CentOS] File access in Apache 2.4 (clarification)
On Nov 21, 2017, at 11:42, david <david at daku.org> wrote:> > Folks > > I'm having file-access problems in Apache 2.4 under Centos 7. In particular: > > - I have a file that's readable to every user and every application, (writeable by only one user), but my CGI scripts cannot read it. > > - Some of my CGI scripts need temporary storage for some files. They are, for example, some internal log files, tnat get cleaned up over time, but I want to be able to look at them (as root). Where would you suggest they be placed? I've tried /tmp/my_private_files/, and /var/tmp/my_private_files/, but Apache fails to find even the directory. > > Here's some extra information > SELINUX is disabled. > > I modified my CGI script to report where in the path to /tmp/my_private_files/temp_log.log the process failed. The Perl code I ran is: > > > my $x = ""; > print STDERR "Trying to read /tmp/ramdisk/keys.txt\n"; > for (split /\//, "/tmp/ramdisk/keys.txt") { > next unless $_; > $x .= "/$_"; > print STDERR "Test $x, " , (-e $x?"exists":"does not exist"), "\n"; > } > > And the output in the http error log for this virtual user, (timestamp and other error log data stripped) was: > > AH01215: Trying to read /tmp/ramdisk/keys.txt > AH01215: Test /tmp, exists > AH01215: Test /tmp/ramdisk, does not exist > AH01215: Test /tmp/ramdisk/keys.txt, does not exist > > Using the "dir -l" command as root, I discover: > > dir -l / | grep tmp > drwxrwxrwt. 16 root root 4096 Nov 21 08:35 tmp > > dir -l /tmp | grep ramdisk > drwxrwxrwt 2 root root 140 Nov 21 08:35 ramdisk > > dir -l /tmp/ramdisk | grep keys.txt > -rw-r--r-- 1 user1 user1 11829 Nov 21 08:29 keys.txt > > > Any suggestions? >The httpd.servicce unit in c7 has: PrivateTmp=true Which means that Apache has its own private /tmp namespace. So it?s probably working, just not where you expect. Don?t use /tmp in CGIs. (And don?t disable selinux, particularly for web apps) -- Jonathan Billings
At 09:24 AM 11/21/2017, Jonathan Billings wrote:>On Nov 21, 2017, at 11:42, david <david at daku.org> wrote: > > > > Folks > > > > I'm having file-access problems in Apache 2.4 > under Centos 7. In particular: > > > > - I have a file that's readable to every user > and every application, (writeable by only one > user), but my CGI scripts cannot read it. > > > > - Some of my CGI scripts need temporary > storage for some files. They are, for example, > some internal log files, tnat get cleaned up > over time, but I want to be able to look at > them (as root). Where would you suggest they > be placed? I've tried /tmp/my_private_files/, > and /var/tmp/my_private_files/, but Apache fails to find even the directory. > > > > Here's some extra information > > SELINUX is disabled. > > > > I modified my CGI script to report where in > the path to /tmp/my_private_files/temp_log.log > the process failed. The Perl code I ran is: > > > > > > my $x = ""; > > print STDERR "Trying to read /tmp/ramdisk/keys.txt\n"; > > for (split /\//, "/tmp/ramdisk/keys.txt") { > > next unless $_; > > $x .= "/$_"; > > print STDERR "Test $x, " , (-e $x?"exists":"does not exist"), "\n"; > > } > > > > And the output in the http error log for this > virtual user, (timestamp and other error log data stripped) was: > > > > AH01215: Trying to read /tmp/ramdisk/keys.txt > > AH01215: Test /tmp, exists > > AH01215: Test /tmp/ramdisk, does not exist > > AH01215: Test /tmp/ramdisk/keys.txt, does not exist > > > > Using the "dir -l" command as root, I discover: > > > > dir -l / | grep tmp > > drwxrwxrwt. 16 root root 4096 Nov 21 08:35 tmp > > > > dir -l /tmp | grep ramdisk > > drwxrwxrwt 2 root root 140 Nov 21 08:35 ramdisk > > > > dir -l /tmp/ramdisk | grep keys.txt > > -rw-r--r-- 1 user1 user1 11829 Nov 21 08:29 keys.txt > > > > > > Any suggestions? > > > >The httpd.servicce unit in c7 has: >PrivateTmp=true > >Which means that Apache has its own private /tmp >namespace. So it???s probably working, just not where you expect. > > >Don???t use /tmp in CGIs. > >(And don???t disable selinux, particularly for web apps) >-- >Jonathan BillingsJonathan Thanks for the advice. If you recommend NOT to use /tmp for cgi temporaries, where would you put them and how to name them? And about SELINUX, I'll consider that, but I'd like to get this working without SELINUX first. And where should I put "globally readable" files? These files need to be readable by all users (including Apache), but writeable only by one user. In the past, I've placed them in a Ram disk since I don't want them to survive a power--off, and mounted that "device" directory in /tmp/ramdisk. It was working perfectly in Centos 5, 6 and 7, with Centos 7 failing within the past week or so. I do "yum update" every night. David
On 11/21/2017 08:42 AM, david wrote:> SELINUX is disabled....> Any suggestions?Yeah, https://stopdisablingselinux.com/ Also, you *could* run "systemctl edit httpd.service" and enter two lines: [Service] PrivateTmp=false ... if you specifically need to share /tmp.? The alternative is probably to mount a new tmpfs to a new directory somewhere under /var/lib for globally shared ephemeral files.
On Tue, November 21, 2017 12:02 pm, Gordon Messmer wrote:> On 11/21/2017 08:42 AM, david wrote: >> SELINUX is disabled. > ... >> Any suggestions? > > Yeah, https://stopdisablingselinux.com/Ha-ha! I like it! Does anybody remember LIDS: https://en.wikipedia.org/wiki/Linux_Intrusion_Detection_System The name is a bit deceptive. In short, LIDS is Linux kernel patch that (roughly speaking) does the following: after boot process finishes, and all services have been started root user is demoted to user nobody ;-) You can only do administration on cold powered off system - i.e. off line. Alas, LIDS didn't make into main stream kernel. Its competitor (?) SElinux made it instead, and SElinux is child's play compared to LIDS IMHO... Every time SElinux is mentioned in one respect or another it makes my day, as I remember LIDS ;-) I hope, someone has few loughs with me here. Valeri> > Also, you *could* run "systemctl edit httpd.service" and enter two lines: > > [Service] > PrivateTmp=false > > ... if you specifically need to share /tmp.?? The alternative is probably > to mount a new tmpfs to a new directory somewhere under /var/lib for > globally shared ephemeral files. > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos >++++++++++++++++++++++++++++++++++++++++ Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247 ++++++++++++++++++++++++++++++++++++++++