bpf: New approach for BPF MTU handling #270
Closed
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Multiple BPF-helpers that can manipulate/increase the size of the SKB uses __bpf_skb_max_len() as the max-length. This function limit size against the current net_device MTU (skb->dev->mtu). When a BPF-prog grow the packet size, then it should not be limited to the MTU. The MTU is a transmit limitation, and software receiving this packet should be allowed to increase the size. Further more, current MTU check in __bpf_skb_max_len uses the MTU from ingress/current net_device, which in case of redirects uses the wrong net_device. Patch V4 keeps a sanity max limit of SKB_MAX_ALLOC (16KiB). The real limit is elsewhere in the system. Jesper's testing[1] showed it was not possible to exceed 8KiB when expanding the SKB size via BPF-helper. The limiting factor is the define KMALLOC_MAX_CACHE_SIZE which is 8192 for SLUB-allocator (CONFIG_SLUB) in-case PAGE_SIZE is 4096. This define is in-effect due to this being called from softirq context see code __gfp_pfmemalloc_flags() and __do_kmalloc_node(). Jakub's testing showed that frames above 16KiB can cause NICs to reset (but not crash). Keep this sanity limit at this level as memory layer can differ based on kernel config. [1] https://github.com/xdp-project/bpf-examples/tree/master/MTU-tests V3: replace __bpf_skb_max_len() with define and use IPv6 max MTU size. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
The BPF-helpers for FIB lookup (bpf_xdp_fib_lookup and bpf_skb_fib_lookup) can perform MTU check and return BPF_FIB_LKUP_RET_FRAG_NEEDED. The BPF-prog don't know the MTU value that caused this rejection. If the BPF-prog wants to implement PMTU (Path MTU Discovery) (rfc1191) it need to know this MTU value for the ICMP packet. Patch change lookup and result struct bpf_fib_lookup, to contain this MTU value as output via a union with 'tot_len' as this is the value used for the MTU lookup. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
This BPF-helper bpf_check_mtu() works for both XDP and TC-BPF programs. The API is designed to help the BPF-programmer, that want to do packet context size changes, which involves other helpers. These other helpers usually does a delta size adjustment. This helper also support a delta size (len_diff), which allow BPF-programmer to reuse arguments needed by these other helpers, and perform the MTU check prior to doing any actual size adjustment of the packet context. It is on purpose, that we allow the len adjustment to become a negative result, that will pass the MTU check. This might seem weird, but it's not this helpers responsibility to "catch" wrong len_diff adjustments. Other helpers will take care of these checks, if BPF-programmer chooses to do actual size adjustment. V4: Lot of changes - ifindex 0 now use current netdev for MTU lookup - rename helper from bpf_mtu_check to bpf_check_mtu - fix bug for GSO pkt length (as skb->len is total len) - remove __bpf_len_adj_positive, simply allow negative len adj V3: Take L2/ETH_HLEN header size into account and document it. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
The use-case for dropping the MTU check when TC-BPF does redirect to ingress, is described by Eyal Birger in email[0]. The summary is the ability to increase packet size (e.g. with IPv6 headers for NAT64) and ingress redirect packet and let normal netstack fragment packet as needed. [0] https://lore.kernel.org/netdev/CAHsH6Gug-hsLGHQ6N0wtixdOa85LDZ3HNRHVd0opR=19Qo4W4Q@mail.gmail.com/ V4: - Keep net_device "up" (IFF_UP) check. - Adjustment to handle bpf_redirect_peer() helper Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
This change makes it possible to identify SKBs that have been redirected by TC-BPF (cls_act). This is needed for a number of cases. (1) For collaborating with driver ifb net_devices. (2) For avoiding starting generic-XDP prog on TC ingress redirect. It is most important to fix XDP case(2), because this can break userspace when a driver gets support for native-XDP. Imagine userspace loads XDP prog on eth0, which fallback to generic-XDP, and it process TC-redirected packets. When kernel is updated with native-XDP support for eth0, then the program no-longer see the TC-redirected packets. Therefore it is important to keep the order intact; that XDP runs before TC-BPF. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
|
Master branch: 3cb12d2 |
|
At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=371551 expired. Closing PR. |
kernel-patches-bot
pushed a commit
that referenced
this pull request
Aug 11, 2021
…CKOPT Add verifier ctx test to call bpf_get_netns_cookie from cgroup/setsockopt. #269/p pass ctx or null check, 1: ctx Did not run the program (not supported) OK #270/p pass ctx or null check, 2: null Did not run the program (not supported) OK #271/p pass ctx or null check, 3: 1 OK #272/p pass ctx or null check, 4: ctx - const OK #273/p pass ctx or null check, 5: null (connect) Did not run the program (not supported) OK #274/p pass ctx or null check, 6: null (bind) Did not run the program (not supported) OK #275/p pass ctx or null check, 7: ctx (bind) Did not run the program (not supported) OK #276/p pass ctx or null check, 8: null (bind) OK #277/p pass ctx or null check, 9: ctx (cgroup/setsockopt) Did not run the program (not supported) OK #278/p pass ctx or null check, 10: null (cgroup/setsockopt) Did not run the program (not supported) OK Signed-off-by: Stanislav Fomichev <sdf@google.com>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Aug 12, 2021
…CKOPT Add verifier ctx test to call bpf_get_netns_cookie from cgroup/setsockopt. #269/p pass ctx or null check, 1: ctx Did not run the program (not supported) OK #270/p pass ctx or null check, 2: null Did not run the program (not supported) OK #271/p pass ctx or null check, 3: 1 OK #272/p pass ctx or null check, 4: ctx - const OK #273/p pass ctx or null check, 5: null (connect) Did not run the program (not supported) OK #274/p pass ctx or null check, 6: null (bind) Did not run the program (not supported) OK #275/p pass ctx or null check, 7: ctx (bind) Did not run the program (not supported) OK #276/p pass ctx or null check, 8: null (bind) OK #277/p pass ctx or null check, 9: ctx (cgroup/setsockopt) Did not run the program (not supported) OK #278/p pass ctx or null check, 10: null (cgroup/setsockopt) Did not run the program (not supported) OK Signed-off-by: Stanislav Fomichev <sdf@google.com>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Aug 12, 2021
…CKOPT Add verifier ctx test to call bpf_get_netns_cookie from cgroup/setsockopt. #269/p pass ctx or null check, 1: ctx Did not run the program (not supported) OK #270/p pass ctx or null check, 2: null Did not run the program (not supported) OK #271/p pass ctx or null check, 3: 1 OK #272/p pass ctx or null check, 4: ctx - const OK #273/p pass ctx or null check, 5: null (connect) Did not run the program (not supported) OK #274/p pass ctx or null check, 6: null (bind) Did not run the program (not supported) OK #275/p pass ctx or null check, 7: ctx (bind) Did not run the program (not supported) OK #276/p pass ctx or null check, 8: null (bind) OK #277/p pass ctx or null check, 9: ctx (cgroup/setsockopt) Did not run the program (not supported) OK #278/p pass ctx or null check, 10: null (cgroup/setsockopt) Did not run the program (not supported) OK Signed-off-by: Stanislav Fomichev <sdf@google.com>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Aug 13, 2021
…CKOPT Add verifier ctx test to call bpf_get_netns_cookie from cgroup/setsockopt. #269/p pass ctx or null check, 1: ctx Did not run the program (not supported) OK #270/p pass ctx or null check, 2: null Did not run the program (not supported) OK #271/p pass ctx or null check, 3: 1 OK #272/p pass ctx or null check, 4: ctx - const OK #273/p pass ctx or null check, 5: null (connect) Did not run the program (not supported) OK #274/p pass ctx or null check, 6: null (bind) Did not run the program (not supported) OK #275/p pass ctx or null check, 7: ctx (bind) Did not run the program (not supported) OK #276/p pass ctx or null check, 8: null (bind) OK #277/p pass ctx or null check, 9: ctx (cgroup/setsockopt) Did not run the program (not supported) OK #278/p pass ctx or null check, 10: null (cgroup/setsockopt) Did not run the program (not supported) OK Signed-off-by: Stanislav Fomichev <sdf@google.com>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Aug 13, 2021
…CKOPT Add verifier ctx test to call bpf_get_netns_cookie from cgroup/setsockopt. #269/p pass ctx or null check, 1: ctx Did not run the program (not supported) OK #270/p pass ctx or null check, 2: null Did not run the program (not supported) OK #271/p pass ctx or null check, 3: 1 OK #272/p pass ctx or null check, 4: ctx - const OK #273/p pass ctx or null check, 5: null (connect) Did not run the program (not supported) OK #274/p pass ctx or null check, 6: null (bind) Did not run the program (not supported) OK #275/p pass ctx or null check, 7: ctx (bind) Did not run the program (not supported) OK #276/p pass ctx or null check, 8: null (bind) OK #277/p pass ctx or null check, 9: ctx (cgroup/setsockopt) Did not run the program (not supported) OK #278/p pass ctx or null check, 10: null (cgroup/setsockopt) Did not run the program (not supported) OK Signed-off-by: Stanislav Fomichev <sdf@google.com>
kernel-patches-daemon-bpf bot
pushed a commit
that referenced
this pull request
Oct 6, 2023
Add a new test case which performs double query of the bpf_mprog through libbpf API, but also via raw bpf(2) syscall. This is testing to gather first the count and then in a subsequent probe the full information with the program array without clearing passed structs in between. # ./vmtest.sh -- ./test_progs -t tc_opts [...] ./test_progs -t tc_opts [ 1.398818] tsc: Refined TSC clocksource calibration: 3407.999 MHz [ 1.400263] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x311fd336761, max_idle_ns: 440795243819 ns [ 1.402734] clocksource: Switched to clocksource tsc [ 1.426639] bpf_testmod: loading out-of-tree module taints kernel. [ 1.428112] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel #252 tc_opts_after:OK #253 tc_opts_append:OK #254 tc_opts_basic:OK #255 tc_opts_before:OK #256 tc_opts_chain_classic:OK #257 tc_opts_chain_mixed:OK #258 tc_opts_delete_empty:OK #259 tc_opts_demixed:OK #260 tc_opts_detach:OK #261 tc_opts_detach_after:OK #262 tc_opts_detach_before:OK #263 tc_opts_dev_cleanup:OK #264 tc_opts_invalid:OK #265 tc_opts_max:OK #266 tc_opts_mixed:OK #267 tc_opts_prepend:OK #268 tc_opts_query:OK <--- (new test) #269 tc_opts_replace:OK #270 tc_opts_revision:OK Summary: 19/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
kernel-patches-daemon-bpf bot
pushed a commit
that referenced
this pull request
Oct 6, 2023
Add a new test case to query on an empty bpf_mprog and pass the revision directly into expected_revision for attachment to assert that this does succeed. ./test_progs -t tc_opts [ 1.406778] tsc: Refined TSC clocksource calibration: 3407.990 MHz [ 1.408863] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x311fcaf6eb0, max_idle_ns: 440795321766 ns [ 1.412419] clocksource: Switched to clocksource tsc [ 1.428671] bpf_testmod: loading out-of-tree module taints kernel. [ 1.430260] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel #252 tc_opts_after:OK #253 tc_opts_append:OK #254 tc_opts_basic:OK #255 tc_opts_before:OK #256 tc_opts_chain_classic:OK #257 tc_opts_chain_mixed:OK #258 tc_opts_delete_empty:OK #259 tc_opts_demixed:OK #260 tc_opts_detach:OK #261 tc_opts_detach_after:OK #262 tc_opts_detach_before:OK #263 tc_opts_dev_cleanup:OK #264 tc_opts_invalid:OK #265 tc_opts_max:OK #266 tc_opts_mixed:OK #267 tc_opts_prepend:OK #268 tc_opts_query:OK #269 tc_opts_query_attach:OK <--- (new test) #270 tc_opts_replace:OK #271 tc_opts_revision:OK Summary: 20/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
kernel-patches-daemon-bpf bot
pushed a commit
that referenced
this pull request
Oct 7, 2023
Add a new test case which performs double query of the bpf_mprog through libbpf API, but also via raw bpf(2) syscall. This is testing to gather first the count and then in a subsequent probe the full information with the program array without clearing passed structs in between. # ./vmtest.sh -- ./test_progs -t tc_opts [...] ./test_progs -t tc_opts [ 1.398818] tsc: Refined TSC clocksource calibration: 3407.999 MHz [ 1.400263] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x311fd336761, max_idle_ns: 440795243819 ns [ 1.402734] clocksource: Switched to clocksource tsc [ 1.426639] bpf_testmod: loading out-of-tree module taints kernel. [ 1.428112] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel #252 tc_opts_after:OK #253 tc_opts_append:OK #254 tc_opts_basic:OK #255 tc_opts_before:OK #256 tc_opts_chain_classic:OK #257 tc_opts_chain_mixed:OK #258 tc_opts_delete_empty:OK #259 tc_opts_demixed:OK #260 tc_opts_detach:OK #261 tc_opts_detach_after:OK #262 tc_opts_detach_before:OK #263 tc_opts_dev_cleanup:OK #264 tc_opts_invalid:OK #265 tc_opts_max:OK #266 tc_opts_mixed:OK #267 tc_opts_prepend:OK #268 tc_opts_query:OK <--- (new test) #269 tc_opts_replace:OK #270 tc_opts_revision:OK Summary: 19/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20231006220655.1653-4-daniel@iogearbox.net Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
kernel-patches-daemon-bpf bot
pushed a commit
that referenced
this pull request
Oct 7, 2023
Add a new test case to query on an empty bpf_mprog and pass the revision directly into expected_revision for attachment to assert that this does succeed. ./test_progs -t tc_opts [ 1.406778] tsc: Refined TSC clocksource calibration: 3407.990 MHz [ 1.408863] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x311fcaf6eb0, max_idle_ns: 440795321766 ns [ 1.412419] clocksource: Switched to clocksource tsc [ 1.428671] bpf_testmod: loading out-of-tree module taints kernel. [ 1.430260] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel #252 tc_opts_after:OK #253 tc_opts_append:OK #254 tc_opts_basic:OK #255 tc_opts_before:OK #256 tc_opts_chain_classic:OK #257 tc_opts_chain_mixed:OK #258 tc_opts_delete_empty:OK #259 tc_opts_demixed:OK #260 tc_opts_detach:OK #261 tc_opts_detach_after:OK #262 tc_opts_detach_before:OK #263 tc_opts_dev_cleanup:OK #264 tc_opts_invalid:OK #265 tc_opts_max:OK #266 tc_opts_mixed:OK #267 tc_opts_prepend:OK #268 tc_opts_query:OK #269 tc_opts_query_attach:OK <--- (new test) #270 tc_opts_replace:OK #271 tc_opts_revision:OK Summary: 20/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20231006220655.1653-6-daniel@iogearbox.net Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
kernel-patches-daemon-bpf bot
pushed a commit
that referenced
this pull request
Oct 17, 2023
Add several new test cases which assert corner cases on the mprog query mechanism, for example, around passing in a too small or a larger array than the current count. ./test_progs -t tc_opts #252 tc_opts_after:OK #253 tc_opts_append:OK #254 tc_opts_basic:OK #255 tc_opts_before:OK #256 tc_opts_chain_classic:OK #257 tc_opts_chain_mixed:OK #258 tc_opts_delete_empty:OK #259 tc_opts_demixed:OK #260 tc_opts_detach:OK #261 tc_opts_detach_after:OK #262 tc_opts_detach_before:OK #263 tc_opts_dev_cleanup:OK #264 tc_opts_invalid:OK #265 tc_opts_max:OK #266 tc_opts_mixed:OK #267 tc_opts_prepend:OK #268 tc_opts_query:OK #269 tc_opts_query_attach:OK #270 tc_opts_replace:OK #271 tc_opts_revision:OK Summary: 20/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
kernel-patches-daemon-bpf bot
pushed a commit
that referenced
this pull request
Oct 17, 2023
Add several new test cases which assert corner cases on the mprog query mechanism, for example, around passing in a too small or a larger array than the current count. ./test_progs -t tc_opts #252 tc_opts_after:OK #253 tc_opts_append:OK #254 tc_opts_basic:OK #255 tc_opts_before:OK #256 tc_opts_chain_classic:OK #257 tc_opts_chain_mixed:OK #258 tc_opts_delete_empty:OK #259 tc_opts_demixed:OK #260 tc_opts_detach:OK #261 tc_opts_detach_after:OK #262 tc_opts_detach_before:OK #263 tc_opts_dev_cleanup:OK #264 tc_opts_invalid:OK #265 tc_opts_max:OK #266 tc_opts_mixed:OK #267 tc_opts_prepend:OK #268 tc_opts_query:OK #269 tc_opts_query_attach:OK #270 tc_opts_replace:OK #271 tc_opts_revision:OK Summary: 20/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
kernel-patches-daemon-bpf bot
pushed a commit
that referenced
this pull request
Oct 17, 2023
Add several new test cases which assert corner cases on the mprog query mechanism, for example, around passing in a too small or a larger array than the current count. ./test_progs -t tc_opts #252 tc_opts_after:OK #253 tc_opts_append:OK #254 tc_opts_basic:OK #255 tc_opts_before:OK #256 tc_opts_chain_classic:OK #257 tc_opts_chain_mixed:OK #258 tc_opts_delete_empty:OK #259 tc_opts_demixed:OK #260 tc_opts_detach:OK #261 tc_opts_detach_after:OK #262 tc_opts_detach_before:OK #263 tc_opts_dev_cleanup:OK #264 tc_opts_invalid:OK #265 tc_opts_max:OK #266 tc_opts_mixed:OK #267 tc_opts_prepend:OK #268 tc_opts_query:OK #269 tc_opts_query_attach:OK #270 tc_opts_replace:OK #271 tc_opts_revision:OK Summary: 20/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
kernel-patches-daemon-bpf bot
pushed a commit
that referenced
this pull request
Oct 17, 2023
Add several new test cases which assert corner cases on the mprog query mechanism, for example, around passing in a too small or a larger array than the current count. ./test_progs -t tc_opts #252 tc_opts_after:OK #253 tc_opts_append:OK #254 tc_opts_basic:OK #255 tc_opts_before:OK #256 tc_opts_chain_classic:OK #257 tc_opts_chain_mixed:OK #258 tc_opts_delete_empty:OK #259 tc_opts_demixed:OK #260 tc_opts_detach:OK #261 tc_opts_detach_after:OK #262 tc_opts_detach_before:OK #263 tc_opts_dev_cleanup:OK #264 tc_opts_invalid:OK #265 tc_opts_max:OK #266 tc_opts_mixed:OK #267 tc_opts_prepend:OK #268 tc_opts_query:OK #269 tc_opts_query_attach:OK #270 tc_opts_replace:OK #271 tc_opts_revision:OK Summary: 20/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
kernel-patches-daemon-bpf bot
pushed a commit
that referenced
this pull request
Oct 17, 2023
Add several new test cases which assert corner cases on the mprog query mechanism, for example, around passing in a too small or a larger array than the current count. ./test_progs -t tc_opts #252 tc_opts_after:OK #253 tc_opts_append:OK #254 tc_opts_basic:OK #255 tc_opts_before:OK #256 tc_opts_chain_classic:OK #257 tc_opts_chain_mixed:OK #258 tc_opts_delete_empty:OK #259 tc_opts_demixed:OK #260 tc_opts_detach:OK #261 tc_opts_detach_after:OK #262 tc_opts_detach_before:OK #263 tc_opts_dev_cleanup:OK #264 tc_opts_invalid:OK #265 tc_opts_max:OK #266 tc_opts_mixed:OK #267 tc_opts_prepend:OK #268 tc_opts_query:OK #269 tc_opts_query_attach:OK #270 tc_opts_replace:OK #271 tc_opts_revision:OK Summary: 20/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Alan Maguire <alan.maguire@oracle.com> Link: https://lore.kernel.org/bpf/20231017081728.24769-1-daniel@iogearbox.net
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Pull request for series with
subject: bpf: New approach for BPF MTU handling
version: 4
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=371551