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bpf: check that BPF programs run with preemption disabled
Introduce cant_sleep() macro for annotation of functions that cannot sleep. Use it in BPF_PROG_RUN to catch execution of BPF programs in preemptable context. Suggested-by: Jann Horn <jannh@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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3 changed files with 41 additions and 3 deletions
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@ -533,7 +533,7 @@ struct sk_filter {
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struct bpf_prog *prog;
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struct bpf_prog *prog;
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};
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};
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#define BPF_PROG_RUN(filter, ctx) (*(filter)->bpf_func)(ctx, (filter)->insnsi)
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#define BPF_PROG_RUN(filter, ctx) ({ cant_sleep(); (*(filter)->bpf_func)(ctx, (filter)->insnsi); })
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#define BPF_SKB_CB_LEN QDISC_CB_PRIV_LEN
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#define BPF_SKB_CB_LEN QDISC_CB_PRIV_LEN
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@ -245,8 +245,10 @@ extern int _cond_resched(void);
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#endif
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#endif
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#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
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#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
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void ___might_sleep(const char *file, int line, int preempt_offset);
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extern void ___might_sleep(const char *file, int line, int preempt_offset);
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void __might_sleep(const char *file, int line, int preempt_offset);
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extern void __might_sleep(const char *file, int line, int preempt_offset);
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extern void __cant_sleep(const char *file, int line, int preempt_offset);
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/**
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/**
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* might_sleep - annotation for functions that can sleep
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* might_sleep - annotation for functions that can sleep
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*
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*
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@ -259,6 +261,13 @@ extern int _cond_resched(void);
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*/
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*/
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# define might_sleep() \
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# define might_sleep() \
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do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
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do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
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/**
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* cant_sleep - annotation for functions that cannot sleep
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*
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* this macro will print a stack trace if it is executed with preemption enabled
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*/
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# define cant_sleep() \
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do { __cant_sleep(__FILE__, __LINE__, 0); } while (0)
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# define sched_annotate_sleep() (current->task_state_change = 0)
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# define sched_annotate_sleep() (current->task_state_change = 0)
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#else
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#else
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static inline void ___might_sleep(const char *file, int line,
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static inline void ___might_sleep(const char *file, int line,
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@ -266,6 +275,7 @@ extern int _cond_resched(void);
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static inline void __might_sleep(const char *file, int line,
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static inline void __might_sleep(const char *file, int line,
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int preempt_offset) { }
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int preempt_offset) { }
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# define might_sleep() do { might_resched(); } while (0)
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# define might_sleep() do { might_resched(); } while (0)
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# define cant_sleep() do { } while (0)
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# define sched_annotate_sleep() do { } while (0)
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# define sched_annotate_sleep() do { } while (0)
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#endif
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#endif
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@ -6162,6 +6162,34 @@ void ___might_sleep(const char *file, int line, int preempt_offset)
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add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
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add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
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}
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}
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EXPORT_SYMBOL(___might_sleep);
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EXPORT_SYMBOL(___might_sleep);
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void __cant_sleep(const char *file, int line, int preempt_offset)
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{
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static unsigned long prev_jiffy;
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if (irqs_disabled())
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return;
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if (!IS_ENABLED(CONFIG_PREEMPT_COUNT))
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return;
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if (preempt_count() > preempt_offset)
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return;
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if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
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return;
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prev_jiffy = jiffies;
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printk(KERN_ERR "BUG: assuming atomic context at %s:%d\n", file, line);
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printk(KERN_ERR "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
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in_atomic(), irqs_disabled(),
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current->pid, current->comm);
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debug_show_held_locks(current);
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dump_stack();
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add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
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}
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EXPORT_SYMBOL_GPL(__cant_sleep);
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#endif
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#endif
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#ifdef CONFIG_MAGIC_SYSRQ
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#ifdef CONFIG_MAGIC_SYSRQ
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