brendan webster - Page 7

RHEL - NFS4: Mounted/Exported as rw, user write permission denied

- by brendanmac

Hello, I have nfs4 configured between a RHEL 5.3 server (charlie) and a RHEL 5.4 client (simcom1). The machines are configured to authenticate users via kerberos by a Windows Server 2008 active directory machine called "alpha." Alpha also serves as a dns and dhcp machine for the local network. I notice that when a user logs in to a RHEL machine for the first time they are issued a unique uid to that machine; The first user to log on gets 10001. So, what I see is that users between simcom1 and charlie have different UIDs. When a user does an 'ls -la' command from within an nfs4 mount I would have thought that the usernames in the owner column would indicate 'nobody' or at least the wrong user name - since UIDs are different between the machines for each user, and not all users have logged into each machine. However, the simcom1 is able to resolve usernames in an 'ls -la' executed on files residing on charlie via nfs4 correctly. Most troubling is that users are unable to write to files across the nfs mount. The server, charlie, has the root directory exported as rw. The client, simcom1, mounts the export as rw. My configurations are shown below. My question is, how do I configure the RHEL machines to allow users to write files across nfs4 that is already mounted as read/write? [root@charlie ~]# more /etc/exports / 10.100.0.0/16(rw,no_root_squash,fsid=0) [root@charlie ~]#cat /etc/sysconfig/nfs # # Define which protocol versions mountd # will advertise. The values are "no" or "yes" # with yes being the default #MOUNTD_NFS_V1="no" #MOUNTD_NFS_V2="no" #MOUNTD_NFS_V3="no" # # # Path to remote quota server. See rquotad(8) #RQUOTAD="/usr/sbin/rpc.rquotad" # Port rquotad should listen on. #RQUOTAD_PORT=875 # Optinal options passed to rquotad #RPCRQUOTADOPTS="" # # # TCP port rpc.lockd should listen on. #LOCKD_TCPPORT=32803 # UDP port rpc.lockd should listen on. #LOCKD_UDPPORT=32769 # # # Optional arguments passed to rpc.nfsd. See rpc.nfsd(8) # Turn off v2 and v3 protocol support #RPCNFSDARGS="-N 2 -N 3" # Turn off v4 protocol support #RPCNFSDARGS="-N 4" # Number of nfs server processes to be started. # The default is 8. RPCNFSDCOUNT=8 # Stop the nfsd module from being pre-loaded #NFSD_MODULE="noload" # # # Optional arguments passed to rpc.mountd. See rpc.mountd(8) #STATDARG="" #RPCMOUNTDOPTS="" # Port rpc.mountd should listen on. #MOUNTD_PORT=892 # # # Optional arguments passed to rpc.statd. See rpc.statd(8) #RPCIDMAPDARGS="" # # Set to turn on Secure NFS mounts. SECURE_NFS="no" # Optional arguments passed to rpc.gssd. See rpc.gssd(8) #RPCGSSDARGS="-vvv" # Optional arguments passed to rpc.svcgssd. See rpc.svcgssd(8) #RPCSVCGSSDARGS="-vvv" # Don't load security modules in to the kernel #SECURE_NFS_MODS="noload" # # Don't load sunrpc module. #RPCMTAB="noload" # [root@simcom1 ~]# cat /etc/fstab --start snip-- charlie:/home /usr/local/dev/charlie nfs4 rw,nosuid, 0 0 --end snip-- [brendanmac@simcom1 /usr/local/dev/charlie/brendanmac]# touch file touch: cannot touch 'file': Permission denied [brendanmac@simcom1 /usr/local/dev/charlie/brendanmac]# su Password: [root@simcom1 /usr/local/dev/charlie/brendanmac]# touch file [root@simcom1 /usr/local/dev/charlie/brendanmac]# ls -la file -rw------- 1 root root 0 May 26 10:43 file Thank you for your assistance, Brendan

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Tracing Silex from PHP to the OS with DTrace

- by cj

In this blog post I show the full stack tracing of Brendan Gregg's php_syscolors.d script in the DTrace Toolkit. The Toolkit contains a dozen very useful PHP DTrace scripts and many more scripts for other languages and the OS. For this example, I'll trace the PHP micro framework Silex, which was the topic of the second of two talks by Dustin Whittle at a recent SF PHP Meetup. His slides are at Silex: From Micro to Full Stack. Installing DTrace and PHP The php_syscolors.d script uses some static PHP probes and some kernel probes. For Oracle Linux I discussed installing DTrace and PHP in DTrace PHP Using Oracle Linux 'playground' Pre-Built Packages. On other platforms with DTrace support, follow your standard procedures to enable DTrace and load the correct providers. The sdt and systrace providers are required in addition to fasttrap. On Oracle Linux, I loaded the DTrace modules like: # modprobe fasttrap # modprobe sdt # modprobe systrace # chmod 666 /dev/dtrace/helper Installing the DTrace Toolkit I download DTraceToolkit-0.99.tar.gz and extracted it: $ tar -zxf DTraceToolkit-0.99.tar.gz The PHP scripts are in the Php directory and examples in the Examples directory. Installing Silex I downloaded the "fat" Silex .tgz file from the download page and extracted it: $ tar -zxf silex_fat.tgz I changed the demonstration silex/web/index.php so I could use the PHP development web server: <?php // web/index.php $filename = __DIR__.preg_replace('#(\?.*)$#', '', $_SERVER['REQUEST_URI']); if (php_sapi_name() === 'cli-server' && is_file($filename)) { return false; } require_once __DIR__.'/../vendor/autoload.php'; $app = new Silex\Application(); //$app['debug'] = true; $app->get('/hello', function() { return 'Hello!'; }); $app->run(); ?> Running DTrace The php_syscolors.d script uses the -Z option to dtrace, so it can be started before PHP, i.e. when there are zero of the requested probes available to be traced. I ran DTrace like: # cd DTraceToolkit-0.99/Php # ./php_syscolors.d Next, I started the PHP developer web server in a second terminal: $ cd silex $ php -S localhost:8080 -t web web/index.php At this point, the web server is idle, waiting for requests. DTrace is idle, waiting for the probes in php_syscolors.d to be fired, at which time the action associated with each probe will run. I then loaded the demonstration page in a browser: http://localhost:8080/hello When the request was fulfilled and the simple output of "Hello" was displayed, I ^C'd php and dtrace in their terminals to stop them. DTrace output over a thousand lines long had been generated. Here is one snippet from when run() was invoked: C PID/TID DELTA(us) FILE:LINE TYPE -- NAME ... 1 4765/4765 21 Application.php:487 func -> run 1 4765/4765 29 ClassLoader.php:182 func -> loadClass 1 4765/4765 17 ClassLoader.php:198 func -> findFile 1 4765/4765 31 ":- syscall -> access 1 4765/4765 26 ":- syscall <- access 1 4765/4765 16 ClassLoader.php:198 func <- findFile 1 4765/4765 25 ":- syscall -> newlstat 1 4765/4765 15 ":- syscall <- newlstat 1 4765/4765 13 ":- syscall -> newlstat 1 4765/4765 13 ":- syscall <- newlstat 1 4765/4765 22 ":- syscall -> newlstat 1 4765/4765 14 ":- syscall <- newlstat 1 4765/4765 15 ":- syscall -> newlstat 1 4765/4765 60 ":- syscall <- newlstat 1 4765/4765 13 ":- syscall -> newlstat 1 4765/4765 13 ":- syscall <- newlstat 1 4765/4765 20 ":- syscall -> open 1 4765/4765 16 ":- syscall <- open 1 4765/4765 26 ":- syscall -> newfstat 1 4765/4765 12 ":- syscall <- newfstat 1 4765/4765 17 ":- syscall -> newfstat 1 4765/4765 12 ":- syscall <- newfstat 1 4765/4765 12 ":- syscall -> newfstat 1 4765/4765 12 ":- syscall <- newfstat 1 4765/4765 20 ":- syscall -> mmap 1 4765/4765 14 ":- syscall <- mmap 1 4765/4765 3201 ":- syscall -> mmap 1 4765/4765 27 ":- syscall <- mmap 1 4765/4765 1233 ":- syscall -> munmap 1 4765/4765 53 ":- syscall <- munmap 1 4765/4765 15 ":- syscall -> close 1 4765/4765 13 ":- syscall <- close 1 4765/4765 34 Request.php:32 func -> main 1 4765/4765 22 Request.php:32 func <- main 1 4765/4765 31 ClassLoader.php:182 func <- loadClass 1 4765/4765 33 Request.php:249 func -> createFromGlobals 1 4765/4765 29 Request.php:198 func -> __construct 1 4765/4765 24 Request.php:218 func -> initialize 1 4765/4765 26 ClassLoader.php:182 func -> loadClass 1 4765/4765 89 ClassLoader.php:198 func -> findFile 1 4765/4765 43 ":- syscall -> access ... The output shows PHP functions being called and returning (and where they are located) and which system calls the PHP functions in turn invoked. The time each line took from the previous one is displayed in the third column. The first column is the CPU number. In this example, the process was always on CPU 1 so the output is naturally ordered without requiring post-processing, or the D script requiring to be modified to display a time stamp. On a terminal, the output of php_syscolors.d is color-coded according to whether each function is a PHP or system one, hence the file name. Summary With one tool, I was able to trace the interaction of a user application with the operating system. I was able to do this to an application running "live" in a web context. The DTrace Toolkit provides a very handy repository of DTrace information. Even though the PHP scripts were created in the time frame of the original PHP DTrace PECL extension, which only had PHP function entry and return probes, the scripts provide core examples for custom investigation and resolution scripts. You can easily adapt the ideas and and create scripts using the other PHP static probes, which are listed in the PHP Manual. Because DTrace is "always on", you can take advantage of it to resolve development questions or fix production situations.

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What broke in this Javascript 1.2 snippet?

- by Rob Kelley

A friend has pointed me to his old website and says "the submit form just stopped working a while ago. I'm sure it's something simple." The form asks a child for a certain word from a book, and based on the answer, it should redirect the child to a success page or a failure page. It's using Javascript 1.2, circa 2001. You can see this form in in-action at: http://www.secrethidingplaces.com/login1.html Any idea why it's failing? The HTML does this: <script src="password.js" type="text/javascript" language="JavaScript1.2"> </script> <script type="text/javascript" language="JavaScript1.2">  </script> and then this: document.write ( '<form name="questionForm" action="javascript:checkAnswer()" method="post">' ) ; ... document.write ( '<input type="text" name="userAnswer" value="" size="90">' ) ; document.write ( '<INPUT TYPE="image" NAME="submit" SRC="stock/btn_send.gif" width="121" height="41" BORDER="0" ALT="submit">' ) ; document.write ( '\</p>' ) ; document.write ( '\</form>' ) ; I'm assuming there's something ugly in CheckAnswer from ./password.js . I can hack the form to bypass that javascript and go straight to the success page: document.write ( '<form name="questionForm" action="extra.html" method="post">' ) ; but I'd like to help my friend get his kids site working again. The CheckAnswer function is below. Is something going wrong in here? function checkAnswer () { currentAnswer = answersArray [ choiceNumber ] ; if (agt.indexOf("msie") != -1) { rawAnswer = document.questionForm.userAnswer.value ; } else { rawAnswer = document.callThis.document.questionForm.userAnswer.value ; } lcAnswer = rawAnswer.toLowerCase ( ) ; includedAnswer = lcAnswer.indexOf ( "currentAnswer" ) ; zadaAnswer = lcAnswer.indexOf ( "zada" ) ; brendanAnswer = lcAnswer.indexOf ( "brendan" ) ; nineAnswer = lcAnswer.indexOf ( "nine" ) ; thirtyAnswer = lcAnswer.indexOf ( "thirty" ) ; if ( choiceNumber == 0 ) { if ( includedAnswer == -1 && zadaAnswer == -1 && brendanAnswer == -1 ) { checked = "wrong" ; } } if ( choiceNumber == 8 ) { if ( includedAnswer == -1 && zadaAnswer == -1 && nineAnswer == -1 ) { checked = "wrong" ; } } if ( choiceNumber == 16 ) { if ( includedAnswer == -1 && zadaAnswer == -1 && thirtyAnswer == -1 ) { checked = "wrong" ; } } if ( choiceNumber != 0 && choiceNumber != 8 && choiceNumber != 16 ) { if ( includedAnswer == -1 && zadaAnswer == -1 ) { checked = "wrong" ; } } if ( checked == "wrong" ) { showWrongPage () ; } else { showRightPage () ; } } Thanks!

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