user/sven/linux.git/include/uapi/linux/bpf.h, branch v4.19.20

bpf: Introduce bpf_skb_ancestor_cgroup_id helper

2018-08-12T23:02:39Z

== Problem description == It's useful to be able to identify cgroup associated with skb in TC so that a policy can be applied to this skb, and existing bpf_skb_cgroup_id helper can help with this. Though in real life cgroup hierarchy and hierarchy to apply a policy to don't map 1:1. It's often the case that there is a container and corresponding cgroup, but there are many more sub-cgroups inside container, e.g. because it's delegated to containerized application to control resources for its subsystems, or to separate application inside container from infra that belongs to containerization system (e.g. sshd). At the same time it may be useful to apply a policy to container as a whole. If multiple containers like this are run on a host (what is often the case) and many of them have sub-cgroups, it may not be possible to apply per-container policy in TC with existing helpers such as bpf_skb_under_cgroup or bpf_skb_cgroup_id: * bpf_skb_cgroup_id will return id of immediate cgroup associated with skb, i.e. if it's a sub-cgroup inside container, it can't be used to identify container's cgroup; * bpf_skb_under_cgroup can work only with one cgroup and doesn't scale, i.e. if there are N containers on a host and a policy has to be applied to M of them (0 <= M <= N), it'd require M calls to bpf_skb_under_cgroup, and, if M changes, it'd require to rebuild & load new BPF program. == Solution == The patch introduces new helper bpf_skb_ancestor_cgroup_id that can be used to get id of cgroup v2 that is an ancestor of cgroup associated with skb at specified level of cgroup hierarchy. That way admin can place all containers on one level of cgroup hierarchy (what is a good practice in general and already used in many configurations) and identify specific cgroup on this level no matter what sub-cgroup skb is associated with. E.g. if there is a cgroup hierarchy: root/ root/container1/ root/container1/app11/ root/container1/app11/sub-app-a/ root/container1/app12/ root/container2/ root/container2/app21/ root/container2/app22/ root/container2/app22/sub-app-b/ , then having skb associated with root/container1/app11/sub-app-a/ it's possible to get ancestor at level 1, what is container1 and apply policy for this container, or apply another policy if it's container2. Policies can be kept e.g. in a hash map where key is a container cgroup id and value is an action. Levels where container cgroups are created are usually known in advance whether cgroup hierarchy inside container may be hard to predict especially in case when its creation is delegated to containerized application. == Implementation details == The helper gets ancestor by walking parents up to specified level. Another option would be to get different kind of "id" from cgroup->ancestor_ids[level] and use it with idr_find() to get struct cgroup for ancestor. But that would require radix lookup what doesn't seem to be better (at least it's not obviously better). Format of return value of the new helper is same as that of bpf_skb_cgroup_id. Signed-off-by: Andrey Ignatov Signed-off-by: Daniel Borkmann

bpf: Introduce BPF_PROG_TYPE_SK_REUSEPORT

2018-08-10T23:58:46Z

This patch adds a BPF_PROG_TYPE_SK_REUSEPORT which can select a SO_REUSEPORT sk from a BPF_MAP_TYPE_REUSEPORT_ARRAY. Like other non SK_FILTER/CGROUP_SKB program, it requires CAP_SYS_ADMIN. BPF_PROG_TYPE_SK_REUSEPORT introduces "struct sk_reuseport_kern" to store the bpf context instead of using the skb->cb[48]. At the SO_REUSEPORT sk lookup time, it is in the middle of transiting from a lower layer (ipv4/ipv6) to a upper layer (udp/tcp). At this point, it is not always clear where the bpf context can be appended in the skb->cb[48] to avoid saving-and-restoring cb[]. Even putting aside the difference between ipv4-vs-ipv6 and udp-vs-tcp. It is not clear if the lower layer is only ipv4 and ipv6 in the future and will it not touch the cb[] again before transiting to the upper layer. For example, in udp_gro_receive(), it uses the 48 byte NAPI_GRO_CB instead of IP[6]CB and it may still modify the cb[] after calling the udp[46]_lib_lookup_skb(). Because of the above reason, if sk->cb is used for the bpf ctx, saving-and-restoring is needed and likely the whole 48 bytes cb[] has to be saved and restored. Instead of saving, setting and restoring the cb[], this patch opts to create a new "struct sk_reuseport_kern" and setting the needed values in there. The new BPF_PROG_TYPE_SK_REUSEPORT and "struct sk_reuseport_(kern|md)" will serve all ipv4/ipv6 + udp/tcp combinations. There is no protocol specific usage at this point and it is also inline with the current sock_reuseport.c implementation (i.e. no protocol specific requirement). In "struct sk_reuseport_md", this patch exposes data/data_end/len with semantic similar to other existing usages. Together with "bpf_skb_load_bytes()" and "bpf_skb_load_bytes_relative()", the bpf prog can peek anywhere in the skb. The "bind_inany" tells the bpf prog that the reuseport group is bind-ed to a local INANY address which cannot be learned from skb. The new "bind_inany" is added to "struct sock_reuseport" which will be used when running the new "BPF_PROG_TYPE_SK_REUSEPORT" bpf prog in order to avoid repeating the "bind INANY" test on "sk_v6_rcv_saddr/sk->sk_rcv_saddr" every time a bpf prog is run. It can only be properly initialized when a "sk->sk_reuseport" enabled sk is adding to a hashtable (i.e. during "reuseport_alloc()" and "reuseport_add_sock()"). The new "sk_select_reuseport()" is the main helper that the bpf prog will use to select a SO_REUSEPORT sk. It is the only function that can use the new BPF_MAP_TYPE_REUSEPORT_ARRAY. As mentioned in the earlier patch, the validity of a selected sk is checked in run time in "sk_select_reuseport()". Doing the check in verification time is difficult and inflexible (consider the map-in-map use case). The runtime check is to compare the selected sk's reuseport_id with the reuseport_id that we want. This helper will return -EXXX if the selected sk cannot serve the incoming request (e.g. reuseport_id not match). The bpf prog can decide if it wants to do SK_DROP as its discretion. When the bpf prog returns SK_PASS, the kernel will check if a valid sk has been selected (i.e. "reuse_kern->selected_sk != NULL"). If it does , it will use the selected sk. If not, the kernel will select one from "reuse->socks[]" (as before this patch). The SK_DROP and SK_PASS handling logic will be in the next patch. Signed-off-by: Martin KaFai Lau Acked-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann

bpf: Introduce BPF_MAP_TYPE_REUSEPORT_SOCKARRAY

2018-08-10T23:58:46Z

This patch introduces a new map type BPF_MAP_TYPE_REUSEPORT_SOCKARRAY. To unleash the full potential of a bpf prog, it is essential for the userspace to be capable of directly setting up a bpf map which can then be consumed by the bpf prog to make decision. In this case, decide which SO_REUSEPORT sk to serve the incoming request. By adding BPF_MAP_TYPE_REUSEPORT_SOCKARRAY, the userspace has total control and visibility on where a SO_REUSEPORT sk should be located in a bpf map. The later patch will introduce BPF_PROG_TYPE_SK_REUSEPORT such that the bpf prog can directly select a sk from the bpf map. That will raise the programmability of the bpf prog attached to a reuseport group (a group of sk serving the same IP:PORT). For example, in UDP, the bpf prog can peek into the payload (e.g. through the "data" pointer introduced in the later patch) to learn the application level's connection information and then decide which sk to pick from a bpf map. The userspace can tightly couple the sk's location in a bpf map with the application logic in generating the UDP payload's connection information. This connection info contact/API stays within the userspace. Also, when used with map-in-map, the userspace can switch the old-server-process's inner map to a new-server-process's inner map in one call "bpf_map_update_elem(outer_map, &index, &new_reuseport_array)". The bpf prog will then direct incoming requests to the new process instead of the old process. The old process can finish draining the pending requests (e.g. by "accept()") before closing the old-fds. [Note that deleting a fd from a bpf map does not necessary mean the fd is closed] During map_update_elem(), Only SO_REUSEPORT sk (i.e. which has already been added to a reuse->socks[]) can be used. That means a SO_REUSEPORT sk that is "bind()" for UDP or "bind()+listen()" for TCP. These conditions are ensured in "reuseport_array_update_check()". A SO_REUSEPORT sk can only be added once to a map (i.e. the same sk cannot be added twice even to the same map). SO_REUSEPORT already allows another sk to be created for the same IP:PORT. There is no need to re-create a similar usage in the BPF side. When a SO_REUSEPORT is deleted from the "reuse->socks[]" (e.g. "close()"), it will notify the bpf map to remove it from the map also. It is done through "bpf_sk_reuseport_detach()" and it will only be called if >=1 of the "reuse->sock[]" has ever been added to a bpf map. The map_update()/map_delete() has to be in-sync with the "reuse->socks[]". Hence, the same "reuseport_lock" used by "reuse->socks[]" has to be used here also. Care has been taken to ensure the lock is only acquired when the adding sk passes some strict tests. and freeing the map does not require the reuseport_lock. The reuseport_array will also support lookup from the syscall side. It will return a sock_gen_cookie(). The sock_gen_cookie() is on-demand (i.e. a sk's cookie is not generated until the very first map_lookup_elem()). The lookup cookie is 64bits but it goes against the logical userspace expectation on 32bits sizeof(fd) (and as other fd based bpf maps do also). It may catch user in surprise if we enforce value_size=8 while userspace still pass a 32bits fd during update. Supporting different value_size between lookup and update seems unintuitive also. We also need to consider what if other existing fd based maps want to return 64bits value from syscall's lookup in the future. Hence, reuseport_array supports both value_size 4 and 8, and assuming user will usually use value_size=4. The syscall's lookup will return ENOSPC on value_size=4. It will will only return 64bits value from sock_gen_cookie() when user consciously choose value_size=8 (as a signal that lookup is desired) which then requires a 64bits value in both lookup and update. Signed-off-by: Martin KaFai Lau Acked-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann

bpf: introduce the bpf_get_local_storage() helper function

2018-08-02T22:47:32Z

The bpf_get_local_storage() helper function is used to get a pointer to the bpf local storage from a bpf program. It takes a pointer to a storage map and flags as arguments. Right now it accepts only cgroup storage maps, and flags argument has to be 0. Further it can be extended to support other types of local storage: e.g. thread local storage etc. Signed-off-by: Roman Gushchin Cc: Alexei Starovoitov Cc: Daniel Borkmann Acked-by: Martin KaFai Lau Signed-off-by: Daniel Borkmann

bpf: introduce cgroup storage maps

2018-08-02T22:47:32Z

This commit introduces BPF_MAP_TYPE_CGROUP_STORAGE maps: a special type of maps which are implementing the cgroup storage. >From the userspace point of view it's almost a generic hash map with the (cgroup inode id, attachment type) pair used as a key. The only difference is that some operations are restricted: 1) a user can't create new entries, 2) a user can't remove existing entries. The lookup from userspace is o(log(n)). Signed-off-by: Roman Gushchin Cc: Alexei Starovoitov Cc: Daniel Borkmann Acked-by: Martin KaFai Lau Signed-off-by: Daniel Borkmann

bpf: Support bpf_get_socket_cookie in more prog types

2018-07-31T07:33:48Z

bpf_get_socket_cookie() helper can be used to identify skb that correspond to the same socket. Though socket cookie can be useful in many other use-cases where socket is available in program context. Specifically BPF_PROG_TYPE_CGROUP_SOCK_ADDR and BPF_PROG_TYPE_SOCK_OPS programs can benefit from it so that one of them can augment a value in a map prepared earlier by other program for the same socket. The patch adds support to call bpf_get_socket_cookie() from BPF_PROG_TYPE_CGROUP_SOCK_ADDR and BPF_PROG_TYPE_SOCK_OPS. It doesn't introduce new helpers. Instead it reuses same helper name bpf_get_socket_cookie() but adds support to this helper to accept `struct bpf_sock_addr` and `struct bpf_sock_ops`. Documentation in bpf.h is changed in a way that should not break automatic generation of markdown. Signed-off-by: Andrey Ignatov Acked-by: Yonghong Song Signed-off-by: Daniel Borkmann

bpf: Add BPF_SOCK_OPS_TCP_LISTEN_CB

2018-07-14T22:08:41Z

Add new TCP-BPF callback that is called on listen(2) right after socket transition to TCP_LISTEN state. It fills the gap for listening sockets in TCP-BPF. For example BPF program can set BPF_SOCK_OPS_STATE_CB_FLAG when socket becomes listening and track later transition from TCP_LISTEN to TCP_CLOSE with BPF_SOCK_OPS_STATE_CB callback. Before there was no way to do it with TCP-BPF and other options were much harder to work with. E.g. socket state tracking can be done with tracepoints (either raw or regular) but they can't be attached to cgroup and their lifetime has to be managed separately. Signed-off-by: Andrey Ignatov Acked-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann

bpf: fix documentation for eBPF helpers

2018-07-12T16:55:53Z

Minor formatting edits for eBPF helpers documentation, including blank lines removal, fix of item list for return values in bpf_fib_lookup(), and missing prefix on bpf_skb_load_bytes_relative(). Signed-off-by: Quentin Monnet Reviewed-by: Jakub Kicinski Signed-off-by: Daniel Borkmann

bpf: Change bpf_fib_lookup to return lookup status

2018-06-28T22:02:02Z

For ACLs implemented using either FIB rules or FIB entries, the BPF program needs the FIB lookup status to be able to drop the packet. Since the bpf_fib_lookup API has not reached a released kernel yet, change the return code to contain an encoding of the FIB lookup result and return the nexthop device index in the params struct. In addition, inform the BPF program of any post FIB lookup reason as to why the packet needs to go up the stack. The fib result for unicast routes must have an egress device, so remove the check that it is non-NULL. Signed-off-by: David Ahern Signed-off-by: Daniel Borkmann

Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

2018-06-05T16:42:19Z

Daniel Borkmann says: ==================== pull-request: bpf-next 2018-06-05 The following pull-request contains BPF updates for your *net-next* tree. The main changes are: 1) Add a new BPF hook for sendmsg similar to existing hooks for bind and connect: "This allows to override source IP (including the case when it's set via cmsg(3)) and destination IP:port for unconnected UDP (slow path). TCP and connected UDP (fast path) are not affected. This makes UDP support complete, that is, connected UDP is handled by connect hooks, unconnected by sendmsg ones.", from Andrey. 2) Rework of the AF_XDP API to allow extending it in future for type writer model if necessary. In this mode a memory window is passed to hardware and multiple frames might be filled into that window instead of just one that is the case in the current fixed frame-size model. With the new changes made this can be supported without having to add a new descriptor format. Also, core bits for the zero-copy support for AF_XDP have been merged as agreed upon, where i40e bits will be routed via Jeff later on. Various improvements to documentation and sample programs included as well, all from Björn and Magnus. 3) Given BPF's flexibility, a new program type has been added to implement infrared decoders. Quote: "The kernel IR decoders support the most widely used IR protocols, but there are many protocols which are not supported. [...] There is a 'long tail' of unsupported IR protocols, for which lircd is need to decode the IR. IR encoding is done in such a way that some simple circuit can decode it; therefore, BPF is ideal. [...] user-space can define a decoder in BPF, attach it to the rc device through the lirc chardev.", from Sean. 4) Several improvements and fixes to BPF core, among others, dumping map and prog IDs into fdinfo which is a straight forward way to correlate BPF objects used by applications, removing an indirect call and therefore retpoline in all map lookup/update/delete calls by invoking the callback directly for 64 bit archs, adding a new bpf_skb_cgroup_id() BPF helper for tc BPF programs to have an efficient way of looking up cgroup v2 id for policy or other use cases. Fixes to make sure we zero tunnel/xfrm state that hasn't been filled, to allow context access wrt pt_regs in 32 bit archs for tracing, and last but not least various test cases for fixes that landed in bpf earlier, from Daniel. 5) Get rid of the ndo_xdp_flush API and extend the ndo_xdp_xmit with a XDP_XMIT_FLUSH flag instead which allows to avoid one indirect call as flushing is now merged directly into ndo_xdp_xmit(), from Jesper. 6) Add a new bpf_get_current_cgroup_id() helper that can be used in tracing to retrieve the cgroup id from the current process in order to allow for e.g. aggregation of container-level events, from Yonghong. 7) Two follow-up fixes for BTF to reject invalid input values and related to that also two test cases for BPF kselftests, from Martin. 8) Various API improvements to the bpf_fib_lookup() helper, that is, dropping MPLS bits which are not fully hashed out yet, rejecting invalid helper flags, returning error for unsupported address families as well as renaming flowlabel to flowinfo, from David. 9) Various fixes and improvements to sockmap BPF kselftests in particular in proper error detection and data verification, from Prashant. 10) Two arm32 BPF JIT improvements. One is to fix imm range check with regards to whether immediate fits into 24 bits, and a naming cleanup to get functions related to rsh handling consistent to those handling lsh, from Wang. 11) Two compile warning fixes in BPF, one for BTF and a false positive to silent gcc in stack_map_get_build_id_offset(), from Arnd. 12) Add missing seg6.h header into tools include infrastructure in order to fix compilation of BPF kselftests, from Mathieu. 13) Several formatting cleanups in the BPF UAPI helper description that also fix an error during rst2man compilation, from Quentin. 14) Hide an unused variable in sk_msg_convert_ctx_access() when IPv6 is not built into the kernel, from Yue. 15) Remove a useless double assignment in dev_map_enqueue(), from Colin. ==================== Signed-off-by: David S. Miller