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bpf: Add per-program recursion prevention mechanism

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Since both sleepable and non-sleepable programs execute under migrate_disable
add recursion prevention mechanism to both types of programs when they're
executed via bpf trampoline.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210210033634.62081-5-alexei.starovoitov@gmail.com
This commit is contained in:
Alexei Starovoitov 2021-02-09 19:36:29 -08:00 • committed by Daniel Borkmann
parent f2dd3b3946
commit ca06f55b90
7 changed files with 50 additions and 11 deletions
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6
include/linux/bpf.h
View file

@ -529,7 +529,7 @@ struct btf_func_model {
/* Each call __bpf_prog_enter + call bpf_func + call __bpf_prog_exit is ~50
* bytes on x86. Pick a number to fit into BPF_IMAGE_SIZE / 2
*/
#define BPF_MAX_TRAMP_PROGS 40
#define BPF_MAX_TRAMP_PROGS 38
struct bpf_tramp_progs {
struct bpf_prog *progs[BPF_MAX_TRAMP_PROGS];
@ -561,9 +561,9 @@ int arch_prepare_bpf_trampoline(void *image, void *image_end,
struct bpf_tramp_progs *tprogs,
void *orig_call);
/* these two functions are called from generated trampoline */
u64 notrace __bpf_prog_enter(void);
u64 notrace __bpf_prog_enter(struct bpf_prog *prog);
void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start);
u64 notrace __bpf_prog_enter_sleepable(void);
u64 notrace __bpf_prog_enter_sleepable(struct bpf_prog *prog);
void notrace __bpf_prog_exit_sleepable(struct bpf_prog *prog, u64 start);
struct bpf_ksym {

1
include/linux/filter.h
View file

@ -565,6 +565,7 @@ struct bpf_prog {
u32 jited_len; /* Size of jited insns in bytes */
u8 tag[BPF_TAG_SIZE];
struct bpf_prog_stats __percpu *stats;
int __percpu *active;
unsigned int (*bpf_func)(const void *ctx,
const struct bpf_insn *insn);
struct bpf_prog_aux *aux; /* Auxiliary fields */