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bpf: offload: free program id when device disappears

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Bound programs are quite useless after their device disappears.
They are simply waiting for reference count to go to zero,
don't list them in BPF_PROG_GET_NEXT_ID by freeing their ID
early.

Note that orphaned offload programs will return -ENODEV on
BPF_OBJ_GET_INFO_BY_FD so user will never see ID 0.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Jakub Kicinski 2017-12-27 18:39:07 -08:00 committed by Daniel Borkmann
parent ce3b9db4db
commit ad8ad79f4f
3 changed files with 12 additions and 2 deletions
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2
include/linux/bpf.h
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@ -357,6 +357,8 @@ void bpf_prog_put(struct bpf_prog *prog);
int __bpf_prog_charge(struct user_struct *user, u32 pages);
void __bpf_prog_uncharge(struct user_struct *user, u32 pages);
void bpf_prog_free_id(struct bpf_prog *prog, bool do_idr_lock);
struct bpf_map *bpf_map_get_with_uref(u32 ufd);
struct bpf_map *__bpf_map_get(struct fd f);
struct bpf_map * __must_check bpf_map_inc(struct bpf_map *map, bool uref);

3
kernel/bpf/offload.c
View File

@ -130,6 +130,9 @@ static void __bpf_prog_offload_destroy(struct bpf_prog *prog)
if (offload->dev_state)
WARN_ON(__bpf_offload_ndo(prog, BPF_OFFLOAD_DESTROY, &data));
/* Make sure BPF_PROG_GET_NEXT_ID can't find this dead program */
bpf_prog_free_id(prog, true);
list_del_init(&offload->offloads);
kfree(offload);
prog->aux->offload = NULL;

9
kernel/bpf/syscall.c
View File

@ -905,9 +905,13 @@ static int bpf_prog_alloc_id(struct bpf_prog *prog)
return id > 0 ? 0 : id;
}
static void bpf_prog_free_id(struct bpf_prog *prog, bool do_idr_lock)
void bpf_prog_free_id(struct bpf_prog *prog, bool do_idr_lock)
{
/* cBPF to eBPF migrations are currently not in the idr store. */
/* cBPF to eBPF migrations are currently not in the idr store.
* Offloaded programs are removed from the store when their device
* disappears - even if someone grabs an fd to them they are unusable,
* simply waiting for refcnt to drop to be freed.
*/
if (!prog->aux->id)
return;
@ -917,6 +921,7 @@ static void bpf_prog_free_id(struct bpf_prog *prog, bool do_idr_lock)
__acquire(&prog_idr_lock);
idr_remove(&prog_idr, prog->aux->id);
prog->aux->id = 0;
if (do_idr_lock)
spin_unlock_bh(&prog_idr_lock);