I have setup a demo "admin" website with all file permissions set to 555 for directories and 444 for files so that any "save" functionality is disabled. So far so good.
However, I noticed that the PHP touch() function is unaffected by file permissions? I am successfully running PHP touch() on directories that have no-WRITE permissions (555). Seems a bit odd. Is this intended behavior (PHP 7.2)?
I am trying to prevent touch() from being able to execute (via file permissions), but can't currently see how this is possible.
Thanks.
From the utimes(3) documentation:
The effective user ID of the process shall match the owner of the file, or has write access to the file or appropriate privileges to use this call in this manner.
So the owner can update the timestamps even without write access. You need to change the ownership of the files so they're not the same as the user running the PHP script.
If this is a problem, maybe you should use some other method to keep track of changes that the file modification times.
Related
I am using Jasperreports for generating the reports. When I am generating the new reports it will be own by root with permission of 644. So other users dont have permission to view this report.I want to change the ownership of the file or change the permission.So everyone can view or download the reports.
I tried below php functions
chmod($item, 0777);
chown($path, 'www-data');
It gives
error: dont have permission to do this
. Because its own by root and current user is www-data.
Anyone please help me,
Actually, based on what you're saying, all users have permissions to view that file. 644 means owner can read and write, and group and others can only read. If your script is getting an error reading that file, it might be because of the permissions of the directories in is path, but not the file itself.
If you could change the owner or permissions of a file owned by root like that, it would subvert the whole concept of unix file permissions. Think about it.
You can always change the user running these reports though, or add logic on the report generation side to move or change the permissions on the file as the user who owns it.
As an aside, chmod 777 is an ugly kludge used only by those who have little knowledge of unix permissions . Professionals don't do it. You should bump your understanding of unix file permissions to the next level:
https://www.tutorialspoint.com/unix/unix-file-permission.htm looks promising.
According to the manual, the owner and the supersuer have the right to do this.
And you only chage the file mod or owner, will not do. You have also to change the path.
chown
Attempts to change the owner of the file filename to user user. Only
the superuser may change the owner of a file.
Note: This function will not work on remote files as the file to be examined must be accessible via the server's filesystem.
Note: When safe mode is enabled, PHP checks whether the files or directories being operated upon have the same UID (owner) as the
script that is being executed.
chmod
Attempts to change the mode of the specified file to that given in
mode. Note: The current user is the user under which PHP runs. It is
probably not the same user you use for normal shell or FTP access. The
mode can be changed only by user who owns the file on most systems.
Note: This function will not work on remote files as the file to be
examined must be accessible via the server's filesystem.
Note: When safe mode is enabled, PHP checks whether the files or
directories you are about to operate on have the same UID (owner) as
the script that is being executed. In addition, you cannot set the
SUID, SGID and sticky bits.
It sounds perhaps hackish but if I use file_put_contents to write a .php file, what permissions does the file get? I couldn't find any documentation regarding what permissions file_put_contents sets. (Assuming the file did not exists before).
In this case this file is not written from any user input or even from the web at all.
This would typically be 644 for a user.
But it can depend on the application setting that called the function. You can modify the default creation permissions for httpd and lot's of other applications.
You said, it's not from any user input or the web. But however it's called, there will be an associated user.
It was a cms and I would like to set all my files on server to -rw-------
This will make my website working as usual? or they will not read each other, for example i have this:
require_once 'include/checksession.php';
First, you need to understand what each "segment" means.
first triad what the owner can do
second triad what the group members can do
third triad what other users can do
Your permission set (-rw-------) only has permissions on the first triad - the owner of the file - which only has read and write permissions.
read The Read permission refers to a user's capability to read the contents of the file.
write The Write permissions refer to a user's capability to write or modify a file or directory.
execute The Execute permission affects a user's capability to execute a file or view the contents of a directory.
Therefore, the owner of the group can read the contents of the file/directory, write to the file/directory, and modify the file/directory.
Under careful file/directory ownership policies, I guess this will be okay - but I wouldn't count on it. If Apache/Nginx/... doesn't have ownership of the file, your application won't work.
This being said, I'd like to raise a few questions;
Why change the permissions of all files/directories on your server?
Why set a global permission rule, and not individual to each file/directory?
What's the end-goal of this?
I'd take some consideration to Jon T's answer
Depends on whether PHP is running as your user or as as something else (Apache, nobody etc)
If it runs as your user (using suexec or something similar), then nothing else needs to read PHP files.
I'd set these to 0600, giving only your user read/write access. Set to 0400 (read-only) for things like config files.
If you have mutiple FTP users accessing your files, then you need to allow group read/write access as well. Permissions then would be 0660.
If PHP is running as another user and it's not in a chroot'd environment, change your webhost.
Also, on a side note, if your CMS requires permissions anywhere of 0777 (I'm looking at you, Joomla), use a different CMS
Is it possible to arrange file permissions/group ownership/etc in such a way that a file can be read by the function readFile() for a forced download, but it cannot be downloaded by navigating to the literal url of the file?
Maybe you could add the user that is running apache / php to the group that owns the file. And set config to read and write for owner and owner group, and no permission at all for others. (-rwxrw---- 0r 0760)
Never tested it, but it should work.
The Apache user will need read permissions. To prevent it from being navigated to, the best (and easiest) solution is to store the file outside of the web folder.
I have a file in my project folder.How i can i give file write permission using php.I used this code
chmod($file,0777);
But it giving an error
Warning: chmod() [function.chmod]: Operation not permitted
The file is created by another user.Is their any way to do this .Thanks in advance
This happens because PHP does not have rights to do the change. The user under which PHP runs is usually the web server's user and different from the user you use to add files.
You generally only do chmod on files created with PHP. To be able to do this on other files you need to change the owner (chown).
The current user is the user under
which PHP runs. It is probably not the
same user you use for normal shell or
FTP access. The mode can be changed
only by user who owns the file on most
systems.
From http://php.net/manual/en/function.chmod.php
Well - you just can't if it says you are not permitted to.
Point is - the file belongs to some user and group, most likely root:root - and you are just a user on the server. If root's the owner of that file, you can't change the permissions at all.
Notes:
$file must be a filename. If you put the handle there, the file (most likely) doesn't exists, but still.
Check if the filename is not beginning with / or something. Try different variations.
you can install php via SUEXEC or SUPHP instead of mod_php which allows to change the user as which php is executed, still this dosnt solve anything if the owner is set wrong