ich777/linux_media
1
0
Fork 0
mirror of https://github.com/tbsdtv/linux_media.git synced 2025-07-23 04:33:26 +02:00
Code Issues Packages Projects Releases Wiki Activity

bpf: Add per-program recursion prevention mechanism

Browse Source 
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
Download Patch File Download Diff File Expand all files Collapse all files

8
kernel/bpf/core.c
View File

@@ -91,6 +91,12 @@ struct bpf_prog *bpf_prog_alloc_no_stats(unsigned int size, gfp_t gfp_extra_flag
vfree(fp);
return NULL;
}
fp->active = alloc_percpu_gfp(int, GFP_KERNEL_ACCOUNT | gfp_extra_flags);
if (!fp->active) {
vfree(fp);
kfree(aux);
return NULL;
}
fp->pages = size / PAGE_SIZE;
fp->aux = aux;
@@ -116,6 +122,7 @@ struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags)
prog->stats = alloc_percpu_gfp(struct bpf_prog_stats, gfp_flags);
if (!prog->stats) {
free_percpu(prog->active);
kfree(prog->aux);
vfree(prog);
return NULL;
@@ -253,6 +260,7 @@ void __bpf_prog_free(struct bpf_prog *fp)
kfree(fp->aux);
}
free_percpu(fp->stats);
free_percpu(fp->active);
vfree(fp);
}

23
kernel/bpf/trampoline.c
View File

@@ -381,13 +381,16 @@ out:
mutex_unlock(&trampoline_mutex);
}
#define NO_START_TIME 0
#define NO_START_TIME 1
static u64 notrace bpf_prog_start_time(void)
{
u64 start = NO_START_TIME;
if (static_branch_unlikely(&bpf_stats_enabled_key))
if (static_branch_unlikely(&bpf_stats_enabled_key)) {
start = sched_clock();
if (unlikely(!start))
start = NO_START_TIME;
}
return start;
}
@@ -397,12 +400,20 @@ static u64 notrace bpf_prog_start_time(void)
* call __bpf_prog_enter
* call prog->bpf_func
* call __bpf_prog_exit
*
* __bpf_prog_enter returns:
* 0 - skip execution of the bpf prog
* 1 - execute bpf prog
* [2..MAX_U64] - excute bpf prog and record execution time.
* This is start time.
*/
u64 notrace __bpf_prog_enter(void)
u64 notrace __bpf_prog_enter(struct bpf_prog *prog)
__acquires(RCU)
{
rcu_read_lock();
migrate_disable();
if (unlikely(__this_cpu_inc_return(*(prog->active)) != 1))
return 0;
return bpf_prog_start_time();
}
@@ -430,21 +441,25 @@ void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start)
__releases(RCU)
{
update_prog_stats(prog, start);
__this_cpu_dec(*(prog->active));
migrate_enable();
rcu_read_unlock();
}
u64 notrace __bpf_prog_enter_sleepable(void)
u64 notrace __bpf_prog_enter_sleepable(struct bpf_prog *prog)
{
rcu_read_lock_trace();
migrate_disable();
might_fault();
if (unlikely(__this_cpu_inc_return(*(prog->active)) != 1))
return 0;
return bpf_prog_start_time();
}
void notrace __bpf_prog_exit_sleepable(struct bpf_prog *prog, u64 start)
{
update_prog_stats(prog, start);
__this_cpu_dec(*(prog->active));
migrate_enable();
rcu_read_unlock_trace();
}