linux/kernel/bpf
Daniel Borkmann ef0915cacd bpf: fix loading of BPF_MAXINSNS sized programs
General assumption is that single program can hold up to BPF_MAXINSNS,
that is, 4096 number of instructions. It is the case with cBPF and
that limit was carried over to eBPF. When recently testing digest, I
noticed that it's actually not possible to feed 4096 instructions
via bpf(2).

The check for > BPF_MAXINSNS was added back then to bpf_check() in
cbd3570086 ("bpf: verifier (add ability to receive verification log)").
However, 09756af468 ("bpf: expand BPF syscall with program load/unload")
added yet another check that comes before that into bpf_prog_load(),
but this time bails out already in case of >= BPF_MAXINSNS.

Fix it up and perform the check early in bpf_prog_load(), so we can drop
the second one in bpf_check(). It makes sense, because also a 0 insn
program is useless and we don't want to waste any resources doing work
up to bpf_check() point. The existing bpf(2) man page documents E2BIG
as the official error for such cases, so just stick with it as well.

Fixes: 09756af468 ("bpf: expand BPF syscall with program load/unload")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-12-07 13:16:04 -05:00
..
arraymap.c bpf: Add bpf_current_task_under_cgroup helper 2016-08-12 21:49:41 -07:00
bpf_lru_list.c bpf: Fix compilation warning in __bpf_lru_list_rotate_inactive 2016-11-16 11:30:56 -05:00
bpf_lru_list.h bpf: Add percpu LRU list 2016-11-15 11:50:20 -05:00
cgroup.c bpf: Add new cgroup attach type to enable sock modifications 2016-12-02 13:46:08 -05:00
core.c bpf: add prog_digest and expose it via fdinfo/netlink 2016-12-05 15:33:11 -05:00
hashtab.c bpf: Add BPF_MAP_TYPE_LRU_PERCPU_HASH 2016-11-15 11:50:20 -05:00
helpers.c bpf: add helper for retrieving current numa node id 2016-10-22 17:05:52 -04:00
inode.c bpf: allow for mount options to specify permissions 2016-11-27 20:38:47 -05:00
Makefile cgroup: add support for eBPF programs 2016-11-25 16:25:52 -05:00
percpu_freelist.c bpf: introduce percpu_freelist 2016-03-08 15:28:31 -05:00
percpu_freelist.h bpf: introduce percpu_freelist 2016-03-08 15:28:31 -05:00
stackmap.c bpf: add BPF_CALL_x macros for declaring helpers 2016-09-09 19:36:04 -07:00
syscall.c bpf: fix loading of BPF_MAXINSNS sized programs 2016-12-07 13:16:04 -05:00
verifier.c bpf: fix loading of BPF_MAXINSNS sized programs 2016-12-07 13:16:04 -05:00