diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2019-01-28 17:21:52 -0800 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2019-02-19 21:53:07 +0100 |
| commit | 568f196756ad9fe2b49c46bbf6a9de1b190438b4 (patch) | |
| tree | a8c84a1e56786296cd005d6c7ca7ad741c2367ea | |
| parent | a5d9265e017f081f0dc133c0e2f45103d027b874 (diff) | |
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>
| -rw-r--r-- | include/linux/filter.h | 2 | ||||
| -rw-r--r-- | include/linux/kernel.h | 14 | ||||
| -rw-r--r-- | kernel/sched/core.c | 28 |
3 files changed, 41 insertions, 3 deletions
diff --git a/include/linux/filter.h b/include/linux/filter.h index 95e2d7ebdf21..f32b3eca5a04 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -533,7 +533,7 @@ struct sk_filter { struct bpf_prog *prog; }; -#define BPF_PROG_RUN(filter, ctx) (*(filter)->bpf_func)(ctx, (filter)->insnsi) +#define BPF_PROG_RUN(filter, ctx) ({ cant_sleep(); (*(filter)->bpf_func)(ctx, (filter)->insnsi); }) #define BPF_SKB_CB_LEN QDISC_CB_PRIV_LEN diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 8f0e68e250a7..a8868a32098c 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -245,8 +245,10 @@ extern int _cond_resched(void); #endif #ifdef CONFIG_DEBUG_ATOMIC_SLEEP - void ___might_sleep(const char *file, int line, int preempt_offset); - void __might_sleep(const char *file, int line, int preempt_offset); +extern void ___might_sleep(const char *file, int line, int preempt_offset); +extern void __might_sleep(const char *file, int line, int preempt_offset); +extern void __cant_sleep(const char *file, int line, int preempt_offset); + /** * might_sleep - annotation for functions that can sleep * @@ -259,6 +261,13 @@ extern int _cond_resched(void); */ # define might_sleep() \ do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0) +/** + * cant_sleep - annotation for functions that cannot sleep + * + * this macro will print a stack trace if it is executed with preemption enabled + */ +# define cant_sleep() \ + do { __cant_sleep(__FILE__, __LINE__, 0); } while (0) # define sched_annotate_sleep() (current->task_state_change = 0) #else static inline void ___might_sleep(const char *file, int line, @@ -266,6 +275,7 @@ extern int _cond_resched(void); static inline void __might_sleep(const char *file, int line, int preempt_offset) { } # define might_sleep() do { might_resched(); } while (0) +# define cant_sleep() do { } while (0) # define sched_annotate_sleep() do { } while (0) #endif diff --git a/kernel/sched/core.c b/kernel/sched/core.c index d8d76a65cfdd..7cbb5658be80 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6162,6 +6162,34 @@ void ___might_sleep(const char *file, int line, int preempt_offset) add_taint(TAINT_WARN, LOCKDEP_STILL_OK); } EXPORT_SYMBOL(___might_sleep); + +void __cant_sleep(const char *file, int line, int preempt_offset) +{ + static unsigned long prev_jiffy; + + if (irqs_disabled()) + return; + + if (!IS_ENABLED(CONFIG_PREEMPT_COUNT)) + return; + + if (preempt_count() > preempt_offset) + return; + + if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy) + return; + prev_jiffy = jiffies; + + printk(KERN_ERR "BUG: assuming atomic context at %s:%d\n", file, line); + printk(KERN_ERR "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n", + in_atomic(), irqs_disabled(), + current->pid, current->comm); + + debug_show_held_locks(current); + dump_stack(); + add_taint(TAINT_WARN, LOCKDEP_STILL_OK); +} +EXPORT_SYMBOL_GPL(__cant_sleep); #endif #ifdef CONFIG_MAGIC_SYSRQ |