Messages in this thread | | | Date | Sun, 3 Jun 2001 22:38:29 +0200 (MET DST) | From | Andries.Brouwer@cwi ... | Subject | mount --bind accounting |
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Something entirely different.
Last year I added the comment /* No capabilities? What if users do thousands of these? */ in super.c for "mount --bind". Now that I do some polishing there I noticed the comment again.
Each bind does an alloc_vfsmnt() and hence takes some kernel memory. Any user can therefore take all kernel memory, until kmalloc(sizeof(struct vfsmount), GFP_KERNEL) fails. Bad security. I suppose something needs to be done about that.
Invent an arbitrary limit #define MAX_NUMBER_OF_USER_BINDS 666 and refuse the "mount --bind" when inspection of the mnt_owner fields of the entries in the vfsmntlist shows that this user already has too many mounts?
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