Add file_ns_capable() helper function for open-time capability checking

Nothing is using it yet, but this will allow us to delay the open-time
checks to use time, without breaking the normal UNIX permission
semantics where permissions are determined by the opener (and the file
descriptor can then be passed to a different process, or the process can
drop capabilities).

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2013-04-14 10:06:31 -07:00
parent 5b55d70833
commit 935d8aabd4
2 changed files with 26 additions and 0 deletions

View file

@ -392,6 +392,30 @@ bool ns_capable(struct user_namespace *ns, int cap)
}
EXPORT_SYMBOL(ns_capable);
/**
* file_ns_capable - Determine if the file's opener had a capability in effect
* @file: The file we want to check
* @ns: The usernamespace we want the capability in
* @cap: The capability to be tested for
*
* Return true if task that opened the file had a capability in effect
* when the file was opened.
*
* This does not set PF_SUPERPRIV because the caller may not
* actually be privileged.
*/
bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap)
{
if (WARN_ON_ONCE(!cap_valid(cap)))
return false;
if (security_capable(file->f_cred, ns, cap) == 0)
return true;
return false;
}
EXPORT_SYMBOL(file_ns_capable);
/**
* capable - Determine if the current task has a superior capability in effect
* @cap: The capability to be tested for