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Commit a6dbb1ef authored by Andrew G. Morgan's avatar Andrew G. Morgan Committed by Linus Torvalds
Browse files

Fix filesystem capability support 



In linux-2.6.24-rc1, security/commoncap.c:cap_inh_is_capped() was
introduced. It has the exact reverse of its intended behavior. This
led to an unintended privilege esculation involving a process'
inheritable capability set.

To be exposed to this bug, you need to have Filesystem Capabilities
enabled and in use. That is:

- CONFIG_SECURITY_FILE_CAPABILITIES must be defined for the buggy code
  to be compiled in.

- You also need to have files on your system marked with fI bits raised.

Signed-off-by: default avatarAndrew G. Morgan <morgan@kernel.org>

Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@akpm@linux-foundation.org>
parent a1033604

security/commoncap.c

+10 −3
Original line number Diff line number Diff line
@@ -59,6 +59,12 @@ int cap_netlink_recv(struct sk_buff *skb, int cap) 


EXPORT_SYMBOL(cap_netlink_recv);



/*

 * NOTE WELL: cap_capable() cannot be used like the kernel's capable()

 * function.  That is, it has the reverse semantics: cap_capable()

 * returns 0 when a task has a capability, but the kernel's capable()

 * returns 1 for this case.

 */

int cap_capable (struct task_struct *tsk, int cap)

{

	/* Derived from include/linux/sched.h:capable. */
@@ -107,10 +113,11 @@ static inline int cap_block_setpcap(struct task_struct *target) 
static inline int cap_inh_is_capped(void)

{

	/*

	 * return 1 if changes to the inheritable set are limited

	 * to the old permitted set.

	 * Return 1 if changes to the inheritable set are limited

	 * to the old permitted set. That is, if the current task

	 * does *not* possess the CAP_SETPCAP capability.

	 */

	return !cap_capable(current, CAP_SETPCAP);

	return (cap_capable(current, CAP_SETPCAP) != 0);

}



#else /* ie., ndef CONFIG_SECURITY_FILE_CAPABILITIES */