On Thursday 28 June 2007 18:12, James Morris wrote: > Are you trying to cater for the case where you're holding an open fd for a > file which has been deleted, and thus has no pathname?
Yes, see the AA_CHECK_FD flag in security/apparmor/main.c:aa_perm_dentry(). We want to distinguish between the following two cases: - process performs an operation on an open file descriptor, - process performs an operation on a pathname, and between the dentry lookup and the LSM permission check, the file gets deleted. In the former case, we obviously want to continue giving the process access to his fd (the classical pattern: open temporary file; delete it so that it will self-recycle, continue using the open file descriptor). In the latter case, The file still existed at the time of the lookup but not anymore at the time of the permission check. The file obviously doesn't have a filename anymore, so we cannot check permissions. If we granted access in that case, processes could bypass their profile permissions in that race window. We close the race by returning -ENOENT in that case, the same result as if the file had already been deleted before the lookup. Andreas - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
