On Mon, 16 Jul 2007, Linus Torvalds wrote: > > > On Tue, 17 Jul 2007, Satyam Sharma wrote: > > > > [PATCH] utime(s): Honour CAP_FOWNER when times==NULL > > > > do_utimes() does not honour CAP_FOWNER when times==NULL. > > Trivial and obvious one-line fix. > > Ahh, ok. Is this old, or was it introduced recently (I'm looking at my > recent change to that area, it doesn't seem to introduce this)?
Old, I'd think. Note that this issue was hidden behind the fact that we would call vfs_permission()->generic_permission() anyway even if that check failed. Now generic_permission() returns 0 (success) if capable(CAP_DAC_OVERRIDE) and -EACCES otherwise (that's for MAY_WRITE tests, which is what this one is). Now I suspect most (all?) common userspace programs out there just don't ever have a capable(CAP_DAC_OVERRIDE) && !capable(CAP_FOWNER) kind of capability mix, so we never saw this before. [ That does not mean this is not an issue, of course, though. ] > IOW, how did you even notice this? Just code inspection. In fact I got interested in following this codepath precisely after the recent discussion on this list ... > Also, while your one-liner looks correct, it does make me wonder: the > whole > > if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER)) > > test is a rather common test, and in fact, arguably, every time you see > one part of it, you should probably see the other. Would it make sense to > make a helper inline function to do this, and replace all users? Doing a > > git grep 'fsuid.*\<i_uid\>' > > seems to show quite a few cases of this pattern.. Yes, I thought of writing a helper function for this myself. The semantics of CAP_FOWNER sort of justify that, but probably better to get Al's views on this first. Satyam - 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/
