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| author | Chuyi Zhou <zhouchuyi@bytedance.com> | 2023-10-18 09:17:43 +0300 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2023-10-20 03:02:46 +0300 |
| commit | dfab99df147b0d364f0c199f832ff2aedfb2265a (patch) | |
| tree | 6bbe3fa26b07cf39eaa8a0657f03079be79c85ef /include/linux/btf.h | |
| parent | 7251d0905e7518bcb990c8e9a3615b1bb23c78f2 (diff) | |
| download | linux-dfab99df147b0d364f0c199f832ff2aedfb2265a.tar.xz | |
bpf: teach the verifier to enforce css_iter and task_iter in RCU CS
css_iter and task_iter should be used in rcu section. Specifically, in
sleepable progs explicit bpf_rcu_read_lock() is needed before use these
iters. In normal bpf progs that have implicit rcu_read_lock(), it's OK to
use them directly.
This patch adds a new a KF flag KF_RCU_PROTECTED for bpf_iter_task_new and
bpf_iter_css_new. It means the kfunc should be used in RCU CS. We check
whether we are in rcu cs before we want to invoke this kfunc. If the rcu
protection is guaranteed, we would let st->type = PTR_TO_STACK | MEM_RCU.
Once user do rcu_unlock during the iteration, state MEM_RCU of regs would
be cleared. is_iter_reg_valid_init() will reject if reg->type is UNTRUSTED.
It is worth noting that currently, bpf_rcu_read_unlock does not
clear the state of the STACK_ITER reg, since bpf_for_each_spilled_reg
only considers STACK_SPILL. This patch also let bpf_for_each_spilled_reg
search STACK_ITER.
Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231018061746.111364-6-zhouchuyi@bytedance.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'include/linux/btf.h')
| -rw-r--r-- | include/linux/btf.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/btf.h b/include/linux/btf.h index 928113a80a95..c2231c64d60b 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -74,6 +74,7 @@ #define KF_ITER_NEW (1 << 8) /* kfunc implements BPF iter constructor */ #define KF_ITER_NEXT (1 << 9) /* kfunc implements BPF iter next method */ #define KF_ITER_DESTROY (1 << 10) /* kfunc implements BPF iter destructor */ +#define KF_RCU_PROTECTED (1 << 11) /* kfunc should be protected by rcu cs when they are invoked */ /* * Tag marking a kernel function as a kfunc. This is meant to minimize the |