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bpf: Add BPF_PROG_GET_FD_BY_ID

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Add BPF_PROG_GET_FD_BY_ID command to allow user to get a fd
from a bpf_prog's ID.

bpf_prog_inc_not_zero() is added and is called with prog_idr_lock
held.

__bpf_prog_put() is also added which has the 'bool do_idr_lock'
param to decide if the prog_idr_lock should be acquired when
freeing the prog->id.

In the error path of bpf_prog_inc_not_zero(), it may have to
call __bpf_prog_put(map, false) which does not need
to take the prog_idr_lock when freeing the prog->id.

It is currently limited to CAP_SYS_ADMIN which we can
consider to lift it in followup patches.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Alexei Starovoitov <ast@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Martin KaFai Lau
2017-06-05 12:15:49 -07:00
committed by David S. Miller
parent 34ad5580f8
commit b16d9aa4c2
2 changed files with 87 additions and 12 deletions
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8
include/uapi/linux/bpf.h
View File

@@ -84,6 +84,7 @@ enum bpf_cmd {
BPF_PROG_TEST_RUN,
BPF_PROG_GET_NEXT_ID,
BPF_MAP_GET_NEXT_ID,
BPF_PROG_GET_FD_BY_ID,
};
enum bpf_map_type {
@@ -212,8 +213,11 @@ union bpf_attr {
__u32 duration;
} test;
struct { /* anonymous struct used by BPF_*_GET_NEXT_ID */
__u32 start_id;
struct { /* anonymous struct used by BPF_*_GET_*_ID */
union {
__u32 start_id;
__u32 prog_id;
};
__u32 next_id;
};
} __attribute__((aligned(8)));