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

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
......@@ -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 */
......
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