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: Andrew G. Morgan <morgan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@akpm@linux-foundation.org>
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@ -59,6 +59,12 @@ int cap_netlink_recv(struct sk_buff *skb, int cap)
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EXPORT_SYMBOL(cap_netlink_recv);
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/*
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* NOTE WELL: cap_capable() cannot be used like the kernel's capable()
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* function. That is, it has the reverse semantics: cap_capable()
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* returns 0 when a task has a capability, but the kernel's capable()
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* returns 1 for this case.
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*/
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int cap_capable (struct task_struct *tsk, int cap)
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{
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/* Derived from include/linux/sched.h:capable. */
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@ -107,10 +113,11 @@ static inline int cap_block_setpcap(struct task_struct *target)
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static inline int cap_inh_is_capped(void)
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{
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/*
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* return 1 if changes to the inheritable set are limited
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* to the old permitted set.
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* Return 1 if changes to the inheritable set are limited
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* to the old permitted set. That is, if the current task
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* does *not* possess the CAP_SETPCAP capability.
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*/
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return !cap_capable(current, CAP_SETPCAP);
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return (cap_capable(current, CAP_SETPCAP) != 0);
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}
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#else /* ie., ndef CONFIG_SECURITY_FILE_CAPABILITIES */
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