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bpf: Use bpf_prog_run_pin_on_cpu() at simple call sites.

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All of these cases are strictly of the form:

	preempt_disable();
	BPF_PROG_RUN(...);
	preempt_enable();

Replace this with bpf_prog_run_pin_on_cpu() which wraps BPF_PROG_RUN()
with:

	migrate_disable();
	BPF_PROG_RUN(...);
	migrate_enable();

On non RT enabled kernels this maps to preempt_disable/enable() and on RT
enabled kernels this solely prevents migration, which is sufficient as
there is no requirement to prevent reentrancy to any BPF program from a
preempting task. The only requirement is that the program stays on the same
CPU.

Therefore, this is a trivially correct transformation.

The seccomp loop does not need protection over the loop. It only needs
protection per BPF filter program

[ tglx: Converted to bpf_prog_run_pin_on_cpu() ]

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200224145643.691493094@linutronix.de
This commit is contained in:
David Miller 2020-02-24 15:01:43 +01:00 • committed by Alexei Starovoitov
parent 37e1d92022
commit 3d9f773cf2
5 changed files with 6 additions and 18 deletions
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4
kernel/seccomp.c
View file

@ -268,16 +268,14 @@ static u32 seccomp_run_filters(const struct seccomp_data *sd,
* All filters in the list are evaluated and the lowest BPF return
* value always takes priority (ignoring the DATA).
*/
preempt_disable();
for (; f; f = f->prev) {
u32 cur_ret = BPF_PROG_RUN(f->prog, sd);
u32 cur_ret = bpf_prog_run_pin_on_cpu(f->prog, sd);
if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) {
ret = cur_ret;
*match = f;
}
}
preempt_enable();
return ret;
}
#endif /* CONFIG_SECCOMP_FILTER */