bpf: cgroup_sock lsm flavor #3227
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Master branch: 697fb80 |
I'll be adding lsm cgroup specific helpers that grab trampoline mutex. No functional changes. Reviewed-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Stanislav Fomichev <sdf@google.com>
This lets us reclaim some space to be used by new cgroup lsm slots.
Before:
struct cgroup_bpf {
struct bpf_prog_array * effective[23]; /* 0 184 */
/* --- cacheline 2 boundary (128 bytes) was 56 bytes ago --- */
struct list_head progs[23]; /* 184 368 */
/* --- cacheline 8 boundary (512 bytes) was 40 bytes ago --- */
u32 flags[23]; /* 552 92 */
/* XXX 4 bytes hole, try to pack */
/* --- cacheline 10 boundary (640 bytes) was 8 bytes ago --- */
struct list_head storages; /* 648 16 */
struct bpf_prog_array * inactive; /* 664 8 */
struct percpu_ref refcnt; /* 672 16 */
struct work_struct release_work; /* 688 32 */
/* size: 720, cachelines: 12, members: 7 */
/* sum members: 716, holes: 1, sum holes: 4 */
/* last cacheline: 16 bytes */
};
After:
struct cgroup_bpf {
struct bpf_prog_array * effective[23]; /* 0 184 */
/* --- cacheline 2 boundary (128 bytes) was 56 bytes ago --- */
struct hlist_head progs[23]; /* 184 184 */
/* --- cacheline 5 boundary (320 bytes) was 48 bytes ago --- */
u8 flags[23]; /* 368 23 */
/* XXX 1 byte hole, try to pack */
/* --- cacheline 6 boundary (384 bytes) was 8 bytes ago --- */
struct list_head storages; /* 392 16 */
struct bpf_prog_array * inactive; /* 408 8 */
struct percpu_ref refcnt; /* 416 16 */
struct work_struct release_work; /* 432 72 */
/* size: 504, cachelines: 8, members: 7 */
/* sum members: 503, holes: 1, sum holes: 1 */
/* last cacheline: 56 bytes */
};
Suggested-by: Jakub Sitnicki <jakub@cloudflare.com>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Reviewed-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Allow attaching to lsm hooks in the cgroup context. Attaching to per-cgroup LSM works exactly like attaching to other per-cgroup hooks. New BPF_LSM_CGROUP is added to trigger new mode; the actual lsm hook we attach to is signaled via existing attach_btf_id. For the hooks that have 'struct socket' or 'struct sock' as its first argument, we use the cgroup associated with that socket. For the rest, we use 'current' cgroup (this is all on default hierarchy == v2 only). Note that for some hooks that work on 'struct sock' we still take the cgroup from 'current' because some of them work on the socket that hasn't been properly initialized yet. Behind the scenes, we allocate a shim program that is attached to the trampoline and runs cgroup effective BPF programs array. This shim has some rudimentary ref counting and can be shared between several programs attaching to the same lsm hook from different cgroups. Note that this patch bloats cgroup size because we add 211 cgroup_bpf_attach_type(s) for simplicity sake. This will be addressed in the subsequent patch. Also note that we only add non-sleepable flavor for now. To enable sleepable use-cases, bpf_prog_run_array_cg has to grab trace rcu, shim programs have to be freed via trace rcu, cgroup_bpf.effective should be also trace-rcu-managed + maybe some other changes that I'm not aware of. Reviewed-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Stanislav Fomichev <sdf@google.com>
Previous patch adds 1:1 mapping between all 211 LSM hooks
and bpf_cgroup program array. Instead of reserving a slot per
possible hook, reserve 10 slots per cgroup for lsm programs.
Those slots are dynamically allocated on demand and reclaimed.
struct cgroup_bpf {
struct bpf_prog_array * effective[33]; /* 0 264 */
/* --- cacheline 4 boundary (256 bytes) was 8 bytes ago --- */
struct hlist_head progs[33]; /* 264 264 */
/* --- cacheline 8 boundary (512 bytes) was 16 bytes ago --- */
u8 flags[33]; /* 528 33 */
/* XXX 7 bytes hole, try to pack */
struct list_head storages; /* 568 16 */
/* --- cacheline 9 boundary (576 bytes) was 8 bytes ago --- */
struct bpf_prog_array * inactive; /* 584 8 */
struct percpu_ref refcnt; /* 592 16 */
struct work_struct release_work; /* 608 72 */
/* size: 680, cachelines: 11, members: 7 */
/* sum members: 673, holes: 1, sum holes: 7 */
/* last cacheline: 40 bytes */
};
Reviewed-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
We have two options: 1. Treat all BPF_LSM_CGROUP the same, regardless of attach_btf_id 2. Treat BPF_LSM_CGROUP+attach_btf_id as a separate hook point I was doing (2) in the original patch, but switching to (1) here: * bpf_prog_query returns all attached BPF_LSM_CGROUP programs regardless of attach_btf_id * attach_btf_id is exported via bpf_prog_info Reviewed-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Stanislav Fomichev <sdf@google.com>
I don't see how to make it nice without introducing btf id lists for the hooks where these helpers are allowed. Some LSM hooks work on the locked sockets, some are triggering early and don't grab any locks, so have two lists for now: 1. LSM hooks which trigger under socket lock - minority of the hooks, but ideal case for us, we can expose existing BTF-based helpers 2. LSM hooks which trigger without socket lock, but they trigger early in the socket creation path where it should be safe to do setsockopt without any locks 3. The rest are prohibited. I'm thinking that this use-case might be a good gateway to sleeping lsm cgroup hooks in the future. We can either expose lock/unlock operations (and add tracking to the verifier) or have another set of bpf_setsockopt wrapper that grab the locks and might sleep. Reviewed-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Stanislav Fomichev <sdf@google.com>
Has been slowly getting out of sync, let's update it. resolve_btfids usage has been updated to match the header changes. Also bring new parts of tools/include/uapi/linux/bpf.h. Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Stanislav Fomichev <sdf@google.com>
lsm_cgroup/ is the prefix for BPF_LSM_CGROUP. Acked-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Stanislav Fomichev <sdf@google.com>
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Master branch: c5c7358 |
Implement bpf_prog_query_opts as a more expendable version of bpf_prog_query. Expose new prog_attach_flags and attach_btf_func_id as well: * prog_attach_flags is a per-program attach_type; relevant only for lsm cgroup program which might have different attach_flags per attach_btf_id * attach_btf_func_id is a new field expose for prog_query which specifies real btf function id for lsm cgroup attachments Acked-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Stanislav Fomichev <sdf@google.com>
$ bpftool --nomount prog loadall $KDIR/tools/testing/selftests/bpf/lsm_cgroup.o /sys/fs/bpf/x $ bpftool cgroup attach /sys/fs/cgroup lsm_cgroup pinned /sys/fs/bpf/x/socket_alloc $ bpftool cgroup attach /sys/fs/cgroup lsm_cgroup pinned /sys/fs/bpf/x/socket_bind $ bpftool cgroup attach /sys/fs/cgroup lsm_cgroup pinned /sys/fs/bpf/x/socket_clone $ bpftool cgroup attach /sys/fs/cgroup lsm_cgroup pinned /sys/fs/bpf/x/socket_post_create $ bpftool cgroup tree CgroupPath ID AttachType AttachFlags Name /sys/fs/cgroup 6 lsm_cgroup socket_post_create bpf_lsm_socket_post_create 8 lsm_cgroup socket_bind bpf_lsm_socket_bind 10 lsm_cgroup socket_alloc bpf_lsm_sk_alloc_security 11 lsm_cgroup socket_clone bpf_lsm_inet_csk_clone $ bpftool cgroup detach /sys/fs/cgroup lsm_cgroup pinned /sys/fs/bpf/x/socket_post_create $ bpftool cgroup tree CgroupPath ID AttachType AttachFlags Name /sys/fs/cgroup 8 lsm_cgroup socket_bind bpf_lsm_socket_bind 10 lsm_cgroup socket_alloc bpf_lsm_sk_alloc_security 11 lsm_cgroup socket_clone bpf_lsm_inet_csk_clone Reviewed-by: Quentin Monnet <quentin@isovalent.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Stanislav Fomichev <sdf@google.com>
Functional test that exercises the following: 1. apply default sk_priority policy 2. permit TX-only AF_PACKET socket 3. cgroup attach/detach/replace 4. reusing trampoline shim Signed-off-by: Stanislav Fomichev <sdf@google.com>
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=654721 irrelevant now. Closing PR. |
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Pull request for series with
subject: bpf: cgroup_sock lsm flavor
version: 11
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=654721