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Casey Schaufler authored
Linux file locking does not follow the same rules as other mechanisms. Even though it is a write operation a process can set a read lock on files which it has open only for read access. Two programs with read access to a file can use read locks to communicate. This is not acceptable in a Mandatory Access Control environment. Smack treats setting a read lock as the write operation that it is. Unfortunately, many programs assume that setting a read lock is a read operation. These programs are unhappy in the Smack environment. This patch introduces a new access mode (lock) to address this problem. A process with lock access to a file can set a read lock. A process with write access to a file can set a read lock or a write lock. This prevents a situation where processes are granted write access just so they can set read locks. Targeted for git://git.gitorious.org/smack-next/kernel.gitSigned-off-by: Casey Schaufler <casey@schaufler-ca.com>
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