Temporary Directory Security (sticky bit)

Race condition is a vulnerability in computing where multiple processes or threads access and manipulate the same resource concurrently, leading to unpredictable and unintended results. In other words, the outcome of an operation is dependent on the timing of the operations, which can lead to inconsistent or incorrect results.

The sticky bit is a permission bit in Unix-based operating systems that can be set on a directory to allow only the owner of a file or directory to delete or rename the file. When the sticky bit is set, it prevents other users from deleting or renaming files they do not own, even if they have write permission on the directory.

Setting the sticky bit on a directory can help prevent race conditions where multiple users are attempting to delete or rename files in the directory at the same time. By allowing only the owner of the file to delete or rename it, the sticky bit ensures that conflicting operations do not occur.

To set the sticky bit on a directory, you can use the following command:

 

To set the sticky bit on a directory, you can use the following command:

chmod +t directory_name

For example, to set the sticky bit on a directory named "mydir", you can use the following command:

 

chmod +t mydir

 

Once set, the sticky bit is indicated by a "t" in the directory's permissions, like this:

drwxrwxrwt 2 user group 4096 Feb 20 10:45 mydir

 

In this example, the "t" in the permissions indicates that the sticky bit is set on the directory "mydir".

 

The sticky bit is a permission bit that can be set on a file or directory in Unix-like operating systems, including Ubuntu. When the sticky bit is set on a directory, only the owner of the file, the owner of the directory, or the root user can delete or rename files in that directory. Other users can still read and write files in the directory, but they cannot modify or remove them.

Here is a table with the explanation of the sticky bit and some examples of how it can be used in Ubuntu 18:

PermissionExplanation

---	No permission
r--	Read permission
-w-	Write permission
--x	Execute permission
s--	Setuid permission
-s-	Setgid permission
--t	Sticky bit

Examples:

• Setting the sticky bit on a directory:This will set the sticky bit on the directory, which means that only the owner of the file, the owner of the directory, or the root user can delete or rename files in that directory.

 chmod +t /path/to/directory

• Setting the sticky bit on a file:This will set the sticky bit on the file, which means that only the owner of the file, the owner of the directory, or the root user can delete or rename the file.

$ chmod +t /path/to/file

• Checking the permissions of a file or directory:This will show the permissions of the file, including whether the sticky bit is set or not.

$ ls -l /path/to/file

• Removing the sticky bit from a file or directory:This will remove the sticky bit from the file or directory, allowing any user to modify or delete it.

$ chmod -t /path/to/file