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2023-12-06bpf: introduce BPF token objectAndrii Nakryiko4-6/+239
Add new kind of BPF kernel object, BPF token. BPF token is meant to allow delegating privileged BPF functionality, like loading a BPF program or creating a BPF map, from privileged process to a *trusted* unprivileged process, all while having a good amount of control over which privileged operations could be performed using provided BPF token. This is achieved through mounting BPF FS instance with extra delegation mount options, which determine what operations are delegatable, and also constraining it to the owning user namespace (as mentioned in the previous patch). BPF token itself is just a derivative from BPF FS and can be created through a new bpf() syscall command, BPF_TOKEN_CREATE, which accepts BPF FS FD, which can be attained through open() API by opening BPF FS mount point. Currently, BPF token "inherits" delegated command, map types, prog type, and attach type bit sets from BPF FS as is. In the future, having an BPF token as a separate object with its own FD, we can allow to further restrict BPF token's allowable set of things either at the creation time or after the fact, allowing the process to guard itself further from unintentionally trying to load undesired kind of BPF programs. But for now we keep things simple and just copy bit sets as is. When BPF token is created from BPF FS mount, we take reference to the BPF super block's owning user namespace, and then use that namespace for checking all the {CAP_BPF, CAP_PERFMON, CAP_NET_ADMIN, CAP_SYS_ADMIN} capabilities that are normally only checked against init userns (using capable()), but now we check them using ns_capable() instead (if BPF token is provided). See bpf_token_capable() for details. Such setup means that BPF token in itself is not sufficient to grant BPF functionality. User namespaced process has to *also* have necessary combination of capabilities inside that user namespace. So while previously CAP_BPF was useless when granted within user namespace, now it gains a meaning and allows container managers and sys admins to have a flexible control over which processes can and need to use BPF functionality within the user namespace (i.e., container in practice). And BPF FS delegation mount options and derived BPF tokens serve as a per-container "flag" to grant overall ability to use bpf() (plus further restrict on which parts of bpf() syscalls are treated as namespaced). Note also, BPF_TOKEN_CREATE command itself requires ns_capable(CAP_BPF) within the BPF FS owning user namespace, rounding up the ns_capable() story of BPF token. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231130185229.2688956-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-06bpf: add BPF token delegation mount options to BPF FSAndrii Nakryiko1-10/+78
Add few new mount options to BPF FS that allow to specify that a given BPF FS instance allows creation of BPF token (added in the next patch), and what sort of operations are allowed under BPF token. As such, we get 4 new mount options, each is a bit mask - `delegate_cmds` allow to specify which bpf() syscall commands are allowed with BPF token derived from this BPF FS instance; - if BPF_MAP_CREATE command is allowed, `delegate_maps` specifies a set of allowable BPF map types that could be created with BPF token; - if BPF_PROG_LOAD command is allowed, `delegate_progs` specifies a set of allowable BPF program types that could be loaded with BPF token; - if BPF_PROG_LOAD command is allowed, `delegate_attachs` specifies a set of allowable BPF program attach types that could be loaded with BPF token; delegate_progs and delegate_attachs are meant to be used together, as full BPF program type is, in general, determined through both program type and program attach type. Currently, these mount options accept the following forms of values: - a special value "any", that enables all possible values of a given bit set; - numeric value (decimal or hexadecimal, determined by kernel automatically) that specifies a bit mask value directly; - all the values for a given mount option are combined, if specified multiple times. E.g., `mount -t bpf nodev /path/to/mount -o delegate_maps=0x1 -o delegate_maps=0x2` will result in a combined 0x3 mask. Ideally, more convenient (for humans) symbolic form derived from corresponding UAPI enums would be accepted (e.g., `-o delegate_progs=kprobe|tracepoint`) and I intend to implement this, but it requires a bunch of UAPI header churn, so I postponed it until this feature lands upstream or at least there is a definite consensus that this feature is acceptable and is going to make it, just to minimize amount of wasted effort and not increase amount of non-essential code to be reviewed. Attentive reader will notice that BPF FS is now marked as FS_USERNS_MOUNT, which theoretically makes it mountable inside non-init user namespace as long as the process has sufficient *namespaced* capabilities within that user namespace. But in reality we still restrict BPF FS to be mountable only by processes with CAP_SYS_ADMIN *in init userns* (extra check in bpf_fill_super()). FS_USERNS_MOUNT is added to allow creating BPF FS context object (i.e., fsopen("bpf")) from inside unprivileged process inside non-init userns, to capture that userns as the owning userns. It will still be required to pass this context object back to privileged process to instantiate and mount it. This manipulation is important, because capturing non-init userns as the owning userns of BPF FS instance (super block) allows to use that userns to constraint BPF token to that userns later on (see next patch). So creating BPF FS with delegation inside unprivileged userns will restrict derived BPF token objects to only "work" inside that intended userns, making it scoped to a intended "container". Also, setting these delegation options requires capable(CAP_SYS_ADMIN), so unprivileged process cannot set this up without involvement of a privileged process. There is a set of selftests at the end of the patch set that simulates this sequence of steps and validates that everything works as intended. But careful review is requested to make sure there are no missed gaps in the implementation and testing. This somewhat subtle set of aspects is the result of previous discussions ([0]) about various user namespace implications and interactions with BPF token functionality and is necessary to contain BPF token inside intended user namespace. [0] https://lore.kernel.org/bpf/20230704-hochverdient-lehne-eeb9eeef785e@brauner/ Acked-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231130185229.2688956-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-06bpf: align CAP_NET_ADMIN checks with bpf_capable() approachAndrii Nakryiko1-4/+9
Within BPF syscall handling code CAP_NET_ADMIN checks stand out a bit compared to CAP_BPF and CAP_PERFMON checks. For the latter, CAP_BPF or CAP_PERFMON are checked first, but if they are not set, CAP_SYS_ADMIN takes over and grants whatever part of BPF syscall is required. Similar kind of checks that involve CAP_NET_ADMIN are not so consistent. One out of four uses does follow CAP_BPF/CAP_PERFMON model: during BPF_PROG_LOAD, if the type of BPF program is "network-related" either CAP_NET_ADMIN or CAP_SYS_ADMIN is required to proceed. But in three other cases CAP_NET_ADMIN is required even if CAP_SYS_ADMIN is set: - when creating DEVMAP/XDKMAP/CPU_MAP maps; - when attaching CGROUP_SKB programs; - when handling BPF_PROG_QUERY command. This patch is changing the latter three cases to follow BPF_PROG_LOAD model, that is allowing to proceed under either CAP_NET_ADMIN or CAP_SYS_ADMIN. This also makes it cleaner in subsequent BPF token patches to switch wholesomely to a generic bpf_token_capable(int cap) check, that always falls back to CAP_SYS_ADMIN if requested capability is missing. Cc: Jakub Kicinski <kuba@kernel.org> Acked-by: Yafang Shao <laoar.shao@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231130185229.2688956-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-06bpf: track aligned STACK_ZERO cases as imprecise spilled registersAndrii Nakryiko1-3/+7
Now that precision backtracing is supporting register spill/fill to/from stack, there is another oportunity to be exploited here: minimizing precise STACK_ZERO cases. With a simple code change we can rely on initially imprecise register spill tracking for cases when register spilled to stack was a known zero. This is a very common case for initializing on the stack variables, including rather large structures. Often times zero has no special meaning for the subsequent BPF program logic and is often overwritten with non-zero values soon afterwards. But due to STACK_ZERO vs STACK_MISC tracking, such initial zero initialization actually causes duplication of verifier states as STACK_ZERO is clearly different than STACK_MISC or spilled SCALAR_VALUE register. The effect of this (now) trivial change is huge, as can be seen below. These are differences between BPF selftests, Cilium, and Meta-internal BPF object files relative to previous patch in this series. You can see improvements ranging from single-digit percentage improvement for instructions and states, all the way to 50-60% reduction for some of Meta-internal host agent programs, and even some Cilium programs. For Meta-internal ones I left only the differences for largest BPF object files by states/instructions, as there were too many differences in the overall output. All the differences were improvements, reducting number of states and thus instructions validated. Note, Meta-internal BPF object file names are not printed below. Many copies of balancer_ingress are actually many different configurations of Katran, so they are different BPF programs, which explains state reduction going from -16% all the way to 31%, depending on BPF program logic complexity. I also tooked a closer look at a few small-ish BPF programs to validate the behavior. Let's take bpf_iter_netrlink.bpf.o (first row below). While it's just 8 vs 5 states, verifier log is still pretty long to include it here. But the reduction in states is due to the following piece of C code: unsigned long ino; ... sk = s->sk_socket; if (!sk) { ino = 0; } else { inode = SOCK_INODE(sk); bpf_probe_read_kernel(&ino, sizeof(ino), &inode->i_ino); } BPF_SEQ_PRINTF(seq, "%-8u %-8lu\n", s->sk_drops.counter, ino); return 0; You can see that in some situations `ino` is zero-initialized, while in others it's unknown value filled out by bpf_probe_read_kernel(). Before this change code after if/else branches have to be validated twice. Once with (precise) ino == 0, due to eager STACK_ZERO logic, and then again for when ino is just STACK_MISC. But BPF_SEQ_PRINTF() doesn't care about precise value of ino, so with the change in this patch verifier is able to prune states from after one of the branches, reducing number of total states (and instructions) required for successful validation. Similar principle applies to bigger real-world applications, just at a much larger scale. SELFTESTS ========= File Program Insns (A) Insns (B) Insns (DIFF) States (A) States (B) States (DIFF) --------------------------------------- ----------------------- --------- --------- --------------- ---------- ---------- ------------- bpf_iter_netlink.bpf.linked3.o dump_netlink 148 104 -44 (-29.73%) 8 5 -3 (-37.50%) bpf_iter_unix.bpf.linked3.o dump_unix 8474 8404 -70 (-0.83%) 151 147 -4 (-2.65%) bpf_loop.bpf.linked3.o stack_check 560 324 -236 (-42.14%) 42 24 -18 (-42.86%) local_storage_bench.bpf.linked3.o get_local 120 77 -43 (-35.83%) 9 6 -3 (-33.33%) loop6.bpf.linked3.o trace_virtqueue_add_sgs 10167 9868 -299 (-2.94%) 226 206 -20 (-8.85%) pyperf600_bpf_loop.bpf.linked3.o on_event 4872 3423 -1449 (-29.74%) 322 229 -93 (-28.88%) strobemeta.bpf.linked3.o on_event 180697 176036 -4661 (-2.58%) 4780 4734 -46 (-0.96%) test_cls_redirect.bpf.linked3.o cls_redirect 65594 65401 -193 (-0.29%) 4230 4212 -18 (-0.43%) test_global_func_args.bpf.linked3.o test_cls 145 136 -9 (-6.21%) 10 9 -1 (-10.00%) test_l4lb.bpf.linked3.o balancer_ingress 4760 2612 -2148 (-45.13%) 113 102 -11 (-9.73%) test_l4lb_noinline.bpf.linked3.o balancer_ingress 4845 4877 +32 (+0.66%) 219 221 +2 (+0.91%) test_l4lb_noinline_dynptr.bpf.linked3.o balancer_ingress 2072 2087 +15 (+0.72%) 97 98 +1 (+1.03%) test_seg6_loop.bpf.linked3.o __add_egr_x 12440 9975 -2465 (-19.82%) 364 353 -11 (-3.02%) test_tcp_hdr_options.bpf.linked3.o estab 2558 2572 +14 (+0.55%) 179 180 +1 (+0.56%) test_xdp_dynptr.bpf.linked3.o _xdp_tx_iptunnel 645 596 -49 (-7.60%) 26 24 -2 (-7.69%) test_xdp_noinline.bpf.linked3.o balancer_ingress_v6 3520 3516 -4 (-0.11%) 216 216 +0 (+0.00%) xdp_synproxy_kern.bpf.linked3.o syncookie_tc 82661 81241 -1420 (-1.72%) 5073 5155 +82 (+1.62%) xdp_synproxy_kern.bpf.linked3.o syncookie_xdp 84964 82297 -2667 (-3.14%) 5130 5157 +27 (+0.53%) META-INTERNAL ============= Program Insns (A) Insns (B) Insns (DIFF) States (A) States (B) States (DIFF) -------------------------------------- --------- --------- ----------------- ---------- ---------- --------------- balancer_ingress 27925 23608 -4317 (-15.46%) 1488 1482 -6 (-0.40%) balancer_ingress 31824 27546 -4278 (-13.44%) 1658 1652 -6 (-0.36%) balancer_ingress 32213 27935 -4278 (-13.28%) 1689 1683 -6 (-0.36%) balancer_ingress 32213 27935 -4278 (-13.28%) 1689 1683 -6 (-0.36%) balancer_ingress 31824 27546 -4278 (-13.44%) 1658 1652 -6 (-0.36%) balancer_ingress 38647 29562 -9085 (-23.51%) 2069 1835 -234 (-11.31%) balancer_ingress 38647 29562 -9085 (-23.51%) 2069 1835 -234 (-11.31%) balancer_ingress 40339 30792 -9547 (-23.67%) 2193 1934 -259 (-11.81%) balancer_ingress 37321 29055 -8266 (-22.15%) 1972 1795 -177 (-8.98%) balancer_ingress 38176 29753 -8423 (-22.06%) 2008 1831 -177 (-8.81%) balancer_ingress 29193 20910 -8283 (-28.37%) 1599 1422 -177 (-11.07%) balancer_ingress 30013 21452 -8561 (-28.52%) 1645 1447 -198 (-12.04%) balancer_ingress 28691 24290 -4401 (-15.34%) 1545 1531 -14 (-0.91%) balancer_ingress 34223 28965 -5258 (-15.36%) 1984 1875 -109 (-5.49%) balancer_ingress 35481 26158 -9323 (-26.28%) 2095 1806 -289 (-13.79%) balancer_ingress 35481 26158 -9323 (-26.28%) 2095 1806 -289 (-13.79%) balancer_ingress 35868 26455 -9413 (-26.24%) 2140 1827 -313 (-14.63%) balancer_ingress 35868 26455 -9413 (-26.24%) 2140 1827 -313 (-14.63%) balancer_ingress 35481 26158 -9323 (-26.28%) 2095 1806 -289 (-13.79%) balancer_ingress 35481 26158 -9323 (-26.28%) 2095 1806 -289 (-13.79%) balancer_ingress 34844 29485 -5359 (-15.38%) 2036 1918 -118 (-5.80%) fbflow_egress 3256 2652 -604 (-18.55%) 218 192 -26 (-11.93%) fbflow_ingress 1026 944 -82 (-7.99%) 70 63 -7 (-10.00%) sslwall_tc_egress 8424 7360 -1064 (-12.63%) 498 458 -40 (-8.03%) syar_accept_protect 15040 9539 -5501 (-36.58%) 364 220 -144 (-39.56%) syar_connect_tcp_v6 15036 9535 -5501 (-36.59%) 360 216 -144 (-40.00%) syar_connect_udp_v4 15039 9538 -5501 (-36.58%) 361 217 -144 (-39.89%) syar_connect_connect4_protect4 24805 15833 -8972 (-36.17%) 756 480 -276 (-36.51%) syar_lsm_file_open 167772 151813 -15959 (-9.51%) 1836 1667 -169 (-9.20%) syar_namespace_create_new 14805 9304 -5501 (-37.16%) 353 209 -144 (-40.79%) syar_python3_detect 17531 12030 -5501 (-31.38%) 391 247 -144 (-36.83%) syar_ssh_post_fork 16412 10911 -5501 (-33.52%) 405 261 -144 (-35.56%) syar_enter_execve 14728 9227 -5501 (-37.35%) 345 201 -144 (-41.74%) syar_enter_execveat 14728 9227 -5501 (-37.35%) 345 201 -144 (-41.74%) syar_exit_execve 16622 11121 -5501 (-33.09%) 376 232 -144 (-38.30%) syar_exit_execveat 16622 11121 -5501 (-33.09%) 376 232 -144 (-38.30%) syar_syscalls_kill 15288 9787 -5501 (-35.98%) 398 254 -144 (-36.18%) syar_task_enter_pivot_root 14898 9397 -5501 (-36.92%) 357 213 -144 (-40.34%) syar_syscalls_setreuid 16678 11177 -5501 (-32.98%) 429 285 -144 (-33.57%) syar_syscalls_setuid 16678 11177 -5501 (-32.98%) 429 285 -144 (-33.57%) syar_syscalls_process_vm_readv 14959 9458 -5501 (-36.77%) 364 220 -144 (-39.56%) syar_syscalls_process_vm_writev 15757 10256 -5501 (-34.91%) 390 246 -144 (-36.92%) do_uprobe 15519 10018 -5501 (-35.45%) 373 229 -144 (-38.61%) edgewall 179715 55783 -123932 (-68.96%) 12607 3999 -8608 (-68.28%) bictcp_state 7570 4131 -3439 (-45.43%) 496 269 -227 (-45.77%) cubictcp_state 7570 4131 -3439 (-45.43%) 496 269 -227 (-45.77%) tcp_rate_skb_delivered 447 272 -175 (-39.15%) 29 18 -11 (-37.93%) kprobe__bbr_set_state 4566 2615 -1951 (-42.73%) 209 124 -85 (-40.67%) kprobe__bictcp_state 4566 2615 -1951 (-42.73%) 209 124 -85 (-40.67%) inet_sock_set_state 1501 1337 -164 (-10.93%) 93 85 -8 (-8.60%) tcp_retransmit_skb 1145 981 -164 (-14.32%) 67 59 -8 (-11.94%) tcp_retransmit_synack 1183 951 -232 (-19.61%) 67 55 -12 (-17.91%) bpf_tcptuner 1459 1187 -272 (-18.64%) 99 80 -19 (-19.19%) tw_egress 801 776 -25 (-3.12%) 69 66 -3 (-4.35%) tw_ingress 795 770 -25 (-3.14%) 69 66 -3 (-4.35%) ttls_tc_ingress 19025 19383 +358 (+1.88%) 470 465 -5 (-1.06%) ttls_nat_egress 490 299 -191 (-38.98%) 33 20 -13 (-39.39%) ttls_nat_ingress 448 285 -163 (-36.38%) 32 21 -11 (-34.38%) tw_twfw_egress 511127 212071 -299056 (-58.51%) 16733 8504 -8229 (-49.18%) tw_twfw_ingress 500095 212069 -288026 (-57.59%) 16223 8504 -7719 (-47.58%) tw_twfw_tc_eg 511113 212064 -299049 (-58.51%) 16732 8504 -8228 (-49.18%) tw_twfw_tc_in 500095 212069 -288026 (-57.59%) 16223 8504 -7719 (-47.58%) tw_twfw_egress 12632 12435 -197 (-1.56%) 276 260 -16 (-5.80%) tw_twfw_ingress 12631 12454 -177 (-1.40%) 278 261 -17 (-6.12%) tw_twfw_tc_eg 12595 12435 -160 (-1.27%) 274 259 -15 (-5.47%) tw_twfw_tc_in 12631 12454 -177 (-1.40%) 278 261 -17 (-6.12%) tw_xdp_dump 266 209 -57 (-21.43%) 9 8 -1 (-11.11%) CILIUM ========= File Program Insns (A) Insns (B) Insns (DIFF) States (A) States (B) States (DIFF) ------------- -------------------------------- --------- --------- ---------------- ---------- ---------- -------------- bpf_host.o cil_to_netdev 6047 4578 -1469 (-24.29%) 362 249 -113 (-31.22%) bpf_host.o handle_lxc_traffic 2227 1585 -642 (-28.83%) 156 103 -53 (-33.97%) bpf_host.o tail_handle_ipv4_from_netdev 2244 1458 -786 (-35.03%) 163 106 -57 (-34.97%) bpf_host.o tail_handle_nat_fwd_ipv4 21022 10479 -10543 (-50.15%) 1289 670 -619 (-48.02%) bpf_host.o tail_handle_nat_fwd_ipv6 15433 11375 -4058 (-26.29%) 905 643 -262 (-28.95%) bpf_host.o tail_ipv4_host_policy_ingress 2219 1367 -852 (-38.40%) 161 96 -65 (-40.37%) bpf_host.o tail_nodeport_nat_egress_ipv4 22460 19862 -2598 (-11.57%) 1469 1293 -176 (-11.98%) bpf_host.o tail_nodeport_nat_ingress_ipv4 5526 3534 -1992 (-36.05%) 366 243 -123 (-33.61%) bpf_host.o tail_nodeport_nat_ingress_ipv6 5132 4256 -876 (-17.07%) 241 219 -22 (-9.13%) bpf_host.o tail_nodeport_nat_ipv6_egress 3702 3542 -160 (-4.32%) 215 205 -10 (-4.65%) bpf_lxc.o tail_handle_nat_fwd_ipv4 21022 10479 -10543 (-50.15%) 1289 670 -619 (-48.02%) bpf_lxc.o tail_handle_nat_fwd_ipv6 15433 11375 -4058 (-26.29%) 905 643 -262 (-28.95%) bpf_lxc.o tail_ipv4_ct_egress 5073 3374 -1699 (-33.49%) 262 172 -90 (-34.35%) bpf_lxc.o tail_ipv4_ct_ingress 5093 3385 -1708 (-33.54%) 262 172 -90 (-34.35%) bpf_lxc.o tail_ipv4_ct_ingress_policy_only 5093 3385 -1708 (-33.54%) 262 172 -90 (-34.35%) bpf_lxc.o tail_ipv6_ct_egress 4593 3878 -715 (-15.57%) 194 151 -43 (-22.16%) bpf_lxc.o tail_ipv6_ct_ingress 4606 3891 -715 (-15.52%) 194 151 -43 (-22.16%) bpf_lxc.o tail_ipv6_ct_ingress_policy_only 4606 3891 -715 (-15.52%) 194 151 -43 (-22.16%) bpf_lxc.o tail_nodeport_nat_ingress_ipv4 5526 3534 -1992 (-36.05%) 366 243 -123 (-33.61%) bpf_lxc.o tail_nodeport_nat_ingress_ipv6 5132 4256 -876 (-17.07%) 241 219 -22 (-9.13%) bpf_overlay.o tail_handle_nat_fwd_ipv4 20524 10114 -10410 (-50.72%) 1271 638 -633 (-49.80%) bpf_overlay.o tail_nodeport_nat_egress_ipv4 22718 19490 -3228 (-14.21%) 1475 1275 -200 (-13.56%) bpf_overlay.o tail_nodeport_nat_ingress_ipv4 5526 3534 -1992 (-36.05%) 366 243 -123 (-33.61%) bpf_overlay.o tail_nodeport_nat_ingress_ipv6 5132 4256 -876 (-17.07%) 241 219 -22 (-9.13%) bpf_overlay.o tail_nodeport_nat_ipv6_egress 3638 3548 -90 (-2.47%) 209 203 -6 (-2.87%) bpf_overlay.o tail_rev_nodeport_lb4 4368 3820 -548 (-12.55%) 248 215 -33 (-13.31%) bpf_overlay.o tail_rev_nodeport_lb6 2867 2428 -439 (-15.31%) 167 140 -27 (-16.17%) bpf_sock.o cil_sock6_connect 1718 1703 -15 (-0.87%) 100 99 -1 (-1.00%) bpf_xdp.o tail_handle_nat_fwd_ipv4 12917 12443 -474 (-3.67%) 875 849 -26 (-2.97%) bpf_xdp.o tail_handle_nat_fwd_ipv6 13515 13264 -251 (-1.86%) 715 702 -13 (-1.82%) bpf_xdp.o tail_lb_ipv4 39492 36367 -3125 (-7.91%) 2430 2251 -179 (-7.37%) bpf_xdp.o tail_lb_ipv6 80441 78058 -2383 (-2.96%) 3647 3523 -124 (-3.40%) bpf_xdp.o tail_nodeport_ipv6_dsr 1038 901 -137 (-13.20%) 61 55 -6 (-9.84%) bpf_xdp.o tail_nodeport_nat_egress_ipv4 13027 12096 -931 (-7.15%) 868 809 -59 (-6.80%) bpf_xdp.o tail_nodeport_nat_ingress_ipv4 7617 5900 -1717 (-22.54%) 522 413 -109 (-20.88%) bpf_xdp.o tail_nodeport_nat_ingress_ipv6 7575 7395 -180 (-2.38%) 383 374 -9 (-2.35%) bpf_xdp.o tail_rev_nodeport_lb4 6808 6739 -69 (-1.01%) 403 396 -7 (-1.74%) bpf_xdp.o tail_rev_nodeport_lb6 16173 15847 -326 (-2.02%) 1010 990 -20 (-1.98%) Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231205184248.1502704-9-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-06bpf: preserve constant zero when doing partial register restoreAndrii Nakryiko1-4/+21
Similar to special handling of STACK_ZERO, when reading 1/2/4 bytes from stack from slot that has register spilled into it and that register has a constant value zero, preserve that zero and mark spilled register as precise for that. This makes spilled const zero register and STACK_ZERO cases equivalent in their behavior. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231205184248.1502704-7-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-06bpf: preserve STACK_ZERO slots on partial reg spillsAndrii Nakryiko1-5/+23
Instead of always forcing STACK_ZERO slots to STACK_MISC, preserve it in situations where this is possible. E.g., when spilling register as 1/2/4-byte subslots on the stack, all the remaining bytes in the stack slot do not automatically become unknown. If we knew they contained zeroes, we can preserve those STACK_ZERO markers. Add a helper mark_stack_slot_misc(), similar to scrub_spilled_slot(), but that doesn't overwrite either STACK_INVALID nor STACK_ZERO. Note that we need to take into account possibility of being in unprivileged mode, in which case STACK_INVALID is forced to STACK_MISC for correctness, as treating STACK_INVALID as equivalent STACK_MISC is only enabled in privileged mode. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231205184248.1502704-5-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-06bpf: fix check for attempt to corrupt spilled pointerAndrii Nakryiko1-1/+1
When register is spilled onto a stack as a 1/2/4-byte register, we set slot_type[BPF_REG_SIZE - 1] (plus potentially few more below it, depending on actual spill size). So to check if some stack slot has spilled register we need to consult slot_type[7], not slot_type[0]. To avoid the need to remember and double-check this in the future, just use is_spilled_reg() helper. Fixes: 27113c59b6d0 ("bpf: Check the other end of slot_type for STACK_SPILL") Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231205184248.1502704-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-06bpf: support non-r10 register spill/fill to/from stack in precision trackingAndrii Nakryiko1-73/+102
Use instruction (jump) history to record instructions that performed register spill/fill to/from stack, regardless if this was done through read-only r10 register, or any other register after copying r10 into it *and* potentially adjusting offset. To make this work reliably, we push extra per-instruction flags into instruction history, encoding stack slot index (spi) and stack frame number in extra 10 bit flags we take away from prev_idx in instruction history. We don't touch idx field for maximum performance, as it's checked most frequently during backtracking. This change removes basically the last remaining practical limitation of precision backtracking logic in BPF verifier. It fixes known deficiencies, but also opens up new opportunities to reduce number of verified states, explored in the subsequent patches. There are only three differences in selftests' BPF object files according to veristat, all in the positive direction (less states). File Program Insns (A) Insns (B) Insns (DIFF) States (A) States (B) States (DIFF) -------------------------------------- ------------- --------- --------- ------------- ---------- ---------- ------------- test_cls_redirect_dynptr.bpf.linked3.o cls_redirect 2987 2864 -123 (-4.12%) 240 231 -9 (-3.75%) xdp_synproxy_kern.bpf.linked3.o syncookie_tc 82848 82661 -187 (-0.23%) 5107 5073 -34 (-0.67%) xdp_synproxy_kern.bpf.linked3.o syncookie_xdp 85116 84964 -152 (-0.18%) 5162 5130 -32 (-0.62%) Note, I avoided renaming jmp_history to more generic insn_hist to minimize number of lines changed and potential merge conflicts between bpf and bpf-next trees. Notice also cur_hist_entry pointer reset to NULL at the beginning of instruction verification loop. This pointer avoids the problem of relying on last jump history entry's insn_idx to determine whether we already have entry for current instruction or not. It can happen that we added jump history entry because current instruction is_jmp_point(), but also we need to add instruction flags for stack access. In this case, we don't want to entries, so we need to reuse last added entry, if it is present. Relying on insn_idx comparison has the same ambiguity problem as the one that was fixed recently in [0], so we avoid that. [0] https://patchwork.kernel.org/project/netdevbpf/patch/20231110002638.4168352-3-andrii@kernel.org/ Acked-by: Eduard Zingerman <eddyz87@gmail.com> Reported-by: Tao Lyu <tao.lyu@epfl.ch> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231205184248.1502704-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-05bpf: Optimize the free of inner mapHou Tao4-6/+24
When removing the inner map from the outer map, the inner map will be freed after one RCU grace period and one RCU tasks trace grace period, so it is certain that the bpf program, which may access the inner map, has exited before the inner map is freed. However there is no need to wait for one RCU tasks trace grace period if the outer map is only accessed by non-sleepable program. So adding sleepable_refcnt in bpf_map and increasing sleepable_refcnt when adding the outer map into env->used_maps for sleepable program. Although the max number of bpf program is INT_MAX - 1, the number of bpf programs which are being loaded may be greater than INT_MAX, so using atomic64_t instead of atomic_t for sleepable_refcnt. When removing the inner map from the outer map, using sleepable_refcnt to decide whether or not a RCU tasks trace grace period is needed before freeing the inner map. Signed-off-by: Hou Tao <houtao1@huawei.com> Link: https://lore.kernel.org/r/20231204140425.1480317-6-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-05bpf: Defer the free of inner map when necessaryHou Tao2-8/+35
When updating or deleting an inner map in map array or map htab, the map may still be accessed by non-sleepable program or sleepable program. However bpf_map_fd_put_ptr() decreases the ref-counter of the inner map directly through bpf_map_put(), if the ref-counter is the last one (which is true for most cases), the inner map will be freed by ops->map_free() in a kworker. But for now, most .map_free() callbacks don't use synchronize_rcu() or its variants to wait for the elapse of a RCU grace period, so after the invocation of ops->map_free completes, the bpf program which is accessing the inner map may incur use-after-free problem. Fix the free of inner map by invoking bpf_map_free_deferred() after both one RCU grace period and one tasks trace RCU grace period if the inner map has been removed from the outer map before. The deferment is accomplished by using call_rcu() or call_rcu_tasks_trace() when releasing the last ref-counter of bpf map. The newly-added rcu_head field in bpf_map shares the same storage space with work field to reduce the size of bpf_map. Fixes: bba1dc0b55ac ("bpf: Remove redundant synchronize_rcu.") Fixes: 638e4b825d52 ("bpf: Allows per-cpu maps and map-in-map in sleepable programs") Signed-off-by: Hou Tao <houtao1@huawei.com> Link: https://lore.kernel.org/r/20231204140425.1480317-5-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-05bpf: Set need_defer as false when clearing fd array during map freeHou Tao1-9/+14
Both map deletion operation, map release and map free operation use fd_array_map_delete_elem() to remove the element from fd array and need_defer is always true in fd_array_map_delete_elem(). For the map deletion operation and map release operation, need_defer=true is necessary, because the bpf program, which accesses the element in fd array, may still alive. However for map free operation, it is certain that the bpf program which owns the fd array has already been exited, so setting need_defer as false is appropriate for map free operation. So fix it by adding need_defer parameter to bpf_fd_array_map_clear() and adding a new helper __fd_array_map_delete_elem() to handle the map deletion, map release and map free operations correspondingly. Signed-off-by: Hou Tao <houtao1@huawei.com> Link: https://lore.kernel.org/r/20231204140425.1480317-4-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-05bpf: Add map and need_defer parameters to .map_fd_put_ptr()Hou Tao4-10/+12
map is the pointer of outer map, and need_defer needs some explanation. need_defer tells the implementation to defer the reference release of the passed element and ensure that the element is still alive before the bpf program, which may manipulate it, exits. The following three cases will invoke map_fd_put_ptr() and different need_defer values will be passed to these callers: 1) release the reference of the old element in the map during map update or map deletion. The release must be deferred, otherwise the bpf program may incur use-after-free problem, so need_defer needs to be true. 2) release the reference of the to-be-added element in the error path of map update. The to-be-added element is not visible to any bpf program, so it is OK to pass false for need_defer parameter. 3) release the references of all elements in the map during map release. Any bpf program which has access to the map must have been exited and released, so need_defer=false will be OK. These two parameters will be used by the following patches to fix the potential use-after-free problem for map-in-map. Signed-off-by: Hou Tao <houtao1@huawei.com> Link: https://lore.kernel.org/r/20231204140425.1480317-3-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-05bpf: Check rcu_read_lock_trace_held() before calling bpf map helpersHou Tao1-5/+8
These three bpf_map_{lookup,update,delete}_elem() helpers are also available for sleepable bpf program, so add the corresponding lock assertion for sleepable bpf program, otherwise the following warning will be reported when a sleepable bpf program manipulates bpf map under interpreter mode (aka bpf_jit_enable=0): WARNING: CPU: 3 PID: 4985 at kernel/bpf/helpers.c:40 ...... CPU: 3 PID: 4985 Comm: test_progs Not tainted 6.6.0+ #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) ...... RIP: 0010:bpf_map_lookup_elem+0x54/0x60 ...... Call Trace: <TASK> ? __warn+0xa5/0x240 ? bpf_map_lookup_elem+0x54/0x60 ? report_bug+0x1ba/0x1f0 ? handle_bug+0x40/0x80 ? exc_invalid_op+0x18/0x50 ? asm_exc_invalid_op+0x1b/0x20 ? __pfx_bpf_map_lookup_elem+0x10/0x10 ? rcu_lockdep_current_cpu_online+0x65/0xb0 ? rcu_is_watching+0x23/0x50 ? bpf_map_lookup_elem+0x54/0x60 ? __pfx_bpf_map_lookup_elem+0x10/0x10 ___bpf_prog_run+0x513/0x3b70 __bpf_prog_run32+0x9d/0xd0 ? __bpf_prog_enter_sleepable_recur+0xad/0x120 ? __bpf_prog_enter_sleepable_recur+0x3e/0x120 bpf_trampoline_6442580665+0x4d/0x1000 __x64_sys_getpgid+0x5/0x30 ? do_syscall_64+0x36/0xb0 entry_SYSCALL_64_after_hwframe+0x6e/0x76 </TASK> Signed-off-by: Hou Tao <houtao1@huawei.com> Link: https://lore.kernel.org/r/20231204140425.1480317-2-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-04bpf: Minor logging improvementAndrei Matei1-2/+2
One place where we were logging a register was only logging the variable part, not also the fixed part. Signed-off-by: Andrei Matei <andreimatei1@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20231204011248.2040084-1-andreimatei1@gmail.com
2023-12-02bpf: simplify tnum output if a fully known constantAndrii Nakryiko2-6/+13
Emit tnum representation as just a constant if all bits are known. Use decimal-vs-hex logic to determine exact format of emitted constant value, just like it's done for register range values. For that move tnum_strn() to kernel/bpf/log.c to reuse decimal-vs-hex determination logic and constants. Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231202175705.885270-12-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-02bpf: enforce precision of R0 on program/async callback returnAndrii Nakryiko1-0/+4
Given we enforce a valid range for program and async callback return value, we must mark R0 as precise to avoid incorrect state pruning. Fixes: b5dc0163d8fd ("bpf: precise scalar_value tracking") Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231202175705.885270-9-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-02bpf: unify async callback and program retval checksAndrii Nakryiko1-18/+12
Use common logic to verify program return values and async callback return values. This allows to avoid duplication of any extra steps necessary, like precision marking, which will be added in the next patch. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231202175705.885270-8-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-02bpf: enforce precise retval range on program exitAndrii Nakryiko1-27/+29
Similarly to subprog/callback logic, enforce return value of BPF program using more precise smin/smax range. We need to adjust a bunch of tests due to a changed format of an error message. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231202175705.885270-7-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-02bpf: enforce exact retval range on subprog/callback exitAndrii Nakryiko1-11/+22
Instead of relying on potentially imprecise tnum representation of expected return value range for callbacks and subprogs, validate that smin/smax range satisfy exact expected range of return values. E.g., if callback would need to return [0, 2] range, tnum can't represent this precisely and instead will allow [0, 3] range. By checking smin/smax range, we can make sure that subprog/callback indeed returns only valid [0, 2] range. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231202175705.885270-5-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-02bpf: enforce precision of R0 on callback returnAndrii Nakryiko1-0/+7
Given verifier checks actual value, r0 has to be precise, so we need to propagate precision properly. r0 also has to be marked as read, otherwise subsequent state comparisons will ignore such register as unimportant and precision won't really help here. Fixes: 69c087ba6225 ("bpf: Add bpf_for_each_map_elem() helper") Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231202175705.885270-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-02bpf: provide correct register name for exception callback retval checkAndrii Nakryiko1-6/+6
bpf_throw() is checking R1, so let's report R1 in the log. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231202175705.885270-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-12-02bpf: Fix a verifier bug due to incorrect branch offset comparison with cpu=v4Yonghong Song1-4/+8
Bpf cpu=v4 support is introduced in [1] and Commit 4cd58e9af8b9 ("bpf: Support new 32bit offset jmp instruction") added support for new 32bit offset jmp instruction. Unfortunately, in function bpf_adj_delta_to_off(), for new branch insn with 32bit offset, the offset (plus/minor a small delta) compares to 16-bit offset bound [S16_MIN, S16_MAX], which caused the following verification failure: $ ./test_progs-cpuv4 -t verif_scale_pyperf180 ... insn 10 cannot be patched due to 16-bit range ... libbpf: failed to load object 'pyperf180.bpf.o' scale_test:FAIL:expect_success unexpected error: -12 (errno 12) #405 verif_scale_pyperf180:FAIL Note that due to recent llvm18 development, the patch [2] (already applied in bpf-next) needs to be applied to bpf tree for testing purpose. The fix is rather simple. For 32bit offset branch insn, the adjusted offset compares to [S32_MIN, S32_MAX] and then verification succeeded. [1] https://lore.kernel.org/all/20230728011143.3710005-1-yonghong.song@linux.dev [2] https://lore.kernel.org/bpf/20231110193644.3130906-1-yonghong.song@linux.dev Fixes: 4cd58e9af8b9 ("bpf: Support new 32bit offset jmp instruction") Signed-off-by: Yonghong Song <yonghong.song@linux.dev> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20231201024640.3417057-1-yonghong.song@linux.dev
2023-12-01Merge tag 'for-netdev' of ↵Jakub Kicinski1-17/+66
https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next Daniel Borkmann says: ==================== pull-request: bpf-next 2023-11-30 We've added 30 non-merge commits during the last 7 day(s) which contain a total of 58 files changed, 1598 insertions(+), 154 deletions(-). The main changes are: 1) Add initial TX metadata implementation for AF_XDP with support in mlx5 and stmmac drivers. Two types of offloads are supported right now, that is, TX timestamp and TX checksum offload, from Stanislav Fomichev with stmmac implementation from Song Yoong Siang. 2) Change BPF verifier logic to validate global subprograms lazily instead of unconditionally before the main program, so they can be guarded using BPF CO-RE techniques, from Andrii Nakryiko. 3) Add BPF link_info support for uprobe multi link along with bpftool integration for the latter, from Jiri Olsa. 4) Use pkg-config in BPF selftests to determine ld flags which is in particular needed for linking statically, from Akihiko Odaki. 5) Fix a few BPF selftest failures to adapt to the upcoming LLVM18, from Yonghong Song. * tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (30 commits) bpf/tests: Remove duplicate JSGT tests selftests/bpf: Add TX side to xdp_hw_metadata selftests/bpf: Convert xdp_hw_metadata to XDP_USE_NEED_WAKEUP selftests/bpf: Add TX side to xdp_metadata selftests/bpf: Add csum helpers selftests/xsk: Support tx_metadata_len xsk: Add option to calculate TX checksum in SW xsk: Validate xsk_tx_metadata flags xsk: Document tx_metadata_len layout net: stmmac: Add Tx HWTS support to XDP ZC net/mlx5e: Implement AF_XDP TX timestamp and checksum offload tools: ynl: Print xsk-features from the sample xsk: Add TX timestamp and TX checksum offload support xsk: Support tx_metadata_len selftests/bpf: Use pkg-config for libelf selftests/bpf: Override PKG_CONFIG for static builds selftests/bpf: Choose pkg-config for the target bpftool: Add support to display uprobe_multi links selftests/bpf: Add link_info test for uprobe_multi link selftests/bpf: Use bpf_link__destroy in fill_link_info tests ... ==================== Conflicts: Documentation/netlink/specs/netdev.yaml: 839ff60df3ab ("net: page_pool: add nlspec for basic access to page pools") 48eb03dd2630 ("xsk: Add TX timestamp and TX checksum offload support") https://lore.kernel.org/all/20231201094705.1ee3cab8@canb.auug.org.au/ While at it also regen, tree is dirty after: 48eb03dd2630 ("xsk: Add TX timestamp and TX checksum offload support") looks like code wasn't re-rendered after "render-max" was removed. Link: https://lore.kernel.org/r/20231130145708.32573-1-daniel@iogearbox.net Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-12-01Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski1-0/+2
Cross-merge networking fixes after downstream PR. No conflicts. Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-11-27bpf: Add missed allocation hint for bpf_mem_cache_alloc_flags()Hou Tao1-0/+2
bpf_mem_cache_alloc_flags() may call __alloc() directly when there is no free object in free list, but it doesn't initialize the allocation hint for the returned pointer. It may lead to bad memory dereference when freeing the pointer, so fix it by initializing the allocation hint. Fixes: 822fb26bdb55 ("bpf: Add a hint to allocated objects.") Signed-off-by: Hou Tao <houtao1@huawei.com> Acked-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20231111043821.2258513-1-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-24bpf: Validate global subprogs lazilyAndrii Nakryiko1-6/+42
Slightly change BPF verifier logic around eagerness and order of global subprog validation. Instead of going over every global subprog eagerly and validating it before main (entry) BPF program is verified, turn it around. Validate main program first, mark subprogs that were called from main program for later verification, but otherwise assume it is valid. Afterwards, go over marked global subprogs and validate those, potentially marking some more global functions as being called. Continue this process until all (transitively) callable global subprogs are validated. It's a BFS traversal at its heart and will always converge. This is an important change because it allows to feature-gate some subprograms that might not be verifiable on some older kernel, depending on supported set of features. E.g., at some point, global functions were allowed to accept a pointer to memory, which size is identified by user-provided type. Unfortunately, older kernels don't support this feature. With BPF CO-RE approach, the natural way would be to still compile BPF object file once and guard calls to this global subprog with some CO-RE check or using .rodata variables. That's what people do to guard usage of new helpers or kfuncs, and any other new BPF-side feature that might be missing on old kernels. That's currently impossible to do with global subprogs, unfortunately, because they are eagerly and unconditionally validated. This patch set aims to change this, so that in the future when global funcs gain new features, those can be guarded using BPF CO-RE techniques in the same fashion as any other new kernel feature. Two selftests had to be adjusted in sync with these changes. test_global_func12 relied on eager global subprog validation failing before main program failure is detected (unknown return value). Fix by making sure that main program is always valid. verifier_subprog_precision's parent_stack_slot_precise subtest relied on verifier checkpointing heuristic to do a checkpoint at instruction #5, but that's no longer true because we don't have enough jumps validated before reaching insn #5 due to global subprogs being validated later. Other than that, no changes, as one would expect. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20231124035937.403208-3-andrii@kernel.org
2023-11-24bpf: Emit global subprog name in verifier logsAndrii Nakryiko1-11/+24
We have the name, instead of emitting just func#N to identify global subprog, augment verifier log messages with actual function name to make it more user-friendly. Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20231124035937.403208-2-andrii@kernel.org
2023-11-23Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netJakub Kicinski1-136/+266
Cross-merge networking fixes after downstream PR. Conflicts: drivers/net/ethernet/intel/ice/ice_main.c c9663f79cd82 ("ice: adjust switchdev rebuild path") 7758017911a4 ("ice: restore timestamp configuration after device reset") https://lore.kernel.org/all/20231121211259.3348630-1-anthony.l.nguyen@intel.com/ Adjacent changes: kernel/bpf/verifier.c bb124da69c47 ("bpf: keep track of max number of bpf_loop callback iterations") 5f99f312bd3b ("bpf: add register bounds sanity checks and sanitization") Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-11-22Merge tag 'for-netdev' of ↵Jakub Kicinski9-1036/+1230
https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next Daniel Borkmann says: ==================== pull-request: bpf-next 2023-11-21 We've added 85 non-merge commits during the last 12 day(s) which contain a total of 63 files changed, 4464 insertions(+), 1484 deletions(-). The main changes are: 1) Huge batch of verifier changes to improve BPF register bounds logic and range support along with a large test suite, and verifier log improvements, all from Andrii Nakryiko. 2) Add a new kfunc which acquires the associated cgroup of a task within a specific cgroup v1 hierarchy where the latter is identified by its id, from Yafang Shao. 3) Extend verifier to allow bpf_refcount_acquire() of a map value field obtained via direct load which is a use-case needed in sched_ext, from Dave Marchevsky. 4) Fix bpf_get_task_stack() helper to add the correct crosstask check for the get_perf_callchain(), from Jordan Rome. 5) Fix BPF task_iter internals where lockless usage of next_thread() was wrong. The rework also simplifies the code, from Oleg Nesterov. 6) Fix uninitialized tail padding via LIBBPF_OPTS_RESET, and another fix for certain BPF UAPI structs to fix verifier failures seen in bpf_dynptr usage, from Yonghong Song. 7) Add BPF selftest fixes for map_percpu_stats flakes due to per-CPU BPF memory allocator not being able to allocate per-CPU pointer successfully, from Hou Tao. 8) Add prep work around dynptr and string handling for kfuncs which is later going to be used by file verification via BPF LSM and fsverity, from Song Liu. 9) Improve BPF selftests to update multiple prog_tests to use ASSERT_* macros, from Yuran Pereira. 10) Optimize LPM trie lookup to check prefixlen before walking the trie, from Florian Lehner. 11) Consolidate virtio/9p configs from BPF selftests in config.vm file given they are needed consistently across archs, from Manu Bretelle. 12) Small BPF verifier refactor to remove register_is_const(), from Shung-Hsi Yu. * tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (85 commits) selftests/bpf: Replaces the usage of CHECK calls for ASSERTs in vmlinux selftests/bpf: Replaces the usage of CHECK calls for ASSERTs in bpf_obj_id selftests/bpf: Replaces the usage of CHECK calls for ASSERTs in bind_perm selftests/bpf: Replaces the usage of CHECK calls for ASSERTs in bpf_tcp_ca selftests/bpf: reduce verboseness of reg_bounds selftest logs bpf: bpf_iter_task_next: use next_task(kit->task) rather than next_task(kit->pos) bpf: bpf_iter_task_next: use __next_thread() rather than next_thread() bpf: task_group_seq_get_next: use __next_thread() rather than next_thread() bpf: emit frameno for PTR_TO_STACK regs if it differs from current one bpf: smarter verifier log number printing logic bpf: omit default off=0 and imm=0 in register state log bpf: emit map name in register state if applicable and available bpf: print spilled register state in stack slot bpf: extract register state printing bpf: move verifier state printing code to kernel/bpf/log.c bpf: move verbose_linfo() into kernel/bpf/log.c bpf: rename BPF_F_TEST_SANITY_STRICT to BPF_F_TEST_REG_INVARIANTS bpf: Remove test for MOVSX32 with offset=32 selftests/bpf: add iter test requiring range x range logic veristat: add ability to set BPF_F_TEST_SANITY_STRICT flag with -r flag ... ==================== Link: https://lore.kernel.org/r/20231122000500.28126-1-daniel@iogearbox.net Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-11-21bpf: keep track of max number of bpf_loop callback iterationsEduard Zingerman1-2/+17
In some cases verifier can't infer convergence of the bpf_loop() iteration. E.g. for the following program: static int cb(__u32 idx, struct num_context* ctx) { ctx->i++; return 0; } SEC("?raw_tp") int prog(void *_) { struct num_context ctx = { .i = 0 }; __u8 choice_arr[2] = { 0, 1 }; bpf_loop(2, cb, &ctx, 0); return choice_arr[ctx.i]; } Each 'cb' simulation would eventually return to 'prog' and reach 'return choice_arr[ctx.i]' statement. At which point ctx.i would be marked precise, thus forcing verifier to track multitude of separate states with {.i=0}, {.i=1}, ... at bpf_loop() callback entry. This commit allows "brute force" handling for such cases by limiting number of callback body simulations using 'umax' value of the first bpf_loop() parameter. For this, extend bpf_func_state with 'callback_depth' field. Increment this field when callback visiting state is pushed to states traversal stack. For frame #N it's 'callback_depth' field counts how many times callback with frame depth N+1 had been executed. Use bpf_func_state specifically to allow independent tracking of callback depths when multiple nested bpf_loop() calls are present. Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20231121020701.26440-11-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-21bpf: widening for callback iteratorsEduard Zingerman1-2/+22
Callbacks are similar to open coded iterators, so add imprecise widening logic for callback body processing. This makes callback based loops behave identically to open coded iterators, e.g. allowing to verify programs like below: struct ctx { u32 i; }; int cb(u32 idx, struct ctx* ctx) { ++ctx->i; return 0; } ... struct ctx ctx = { .i = 0 }; bpf_loop(100, cb, &ctx, 0); ... Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20231121020701.26440-9-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-21bpf: verify callbacks as if they are called unknown number of timesEduard Zingerman1-99/+175
Prior to this patch callbacks were handled as regular function calls, execution of callback body was modeled exactly once. This patch updates callbacks handling logic as follows: - introduces a function push_callback_call() that schedules callback body verification in env->head stack; - updates prepare_func_exit() to reschedule callback body verification upon BPF_EXIT; - as calls to bpf_*_iter_next(), calls to callback invoking functions are marked as checkpoints; - is_state_visited() is updated to stop callback based iteration when some identical parent state is found. Paths with callback function invoked zero times are now verified first, which leads to necessity to modify some selftests: - the following negative tests required adding release/unlock/drop calls to avoid previously masked unrelated error reports: - cb_refs.c:underflow_prog - exceptions_fail.c:reject_rbtree_add_throw - exceptions_fail.c:reject_with_cp_reference - the following precision tracking selftests needed change in expected log trace: - verifier_subprog_precision.c:callback_result_precise (note: r0 precision is no longer propagated inside callback and I think this is a correct behavior) - verifier_subprog_precision.c:parent_callee_saved_reg_precise_with_callback - verifier_subprog_precision.c:parent_stack_slot_precise_with_callback Reported-by: Andrew Werner <awerner32@gmail.com> Closes: https://lore.kernel.org/bpf/CA+vRuzPChFNXmouzGG+wsy=6eMcfr1mFG0F3g7rbg-sedGKW3w@mail.gmail.com/ Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20231121020701.26440-7-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-21bpf: extract setup_func_entry() utility functionEduard Zingerman1-36/+48
Move code for simulated stack frame creation to a separate utility function. This function would be used in the follow-up change for callbacks handling. Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20231121020701.26440-6-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-21bpf: extract __check_reg_arg() utility functionEduard Zingerman1-6/+13
Split check_reg_arg() into two utility functions: - check_reg_arg() operating on registers from current verifier state; - __check_reg_arg() operating on a specific set of registers passed as a parameter; The __check_reg_arg() function would be used by a follow-up change for callbacks handling. Acked-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20231121020701.26440-5-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-19bpf: bpf_iter_task_next: use next_task(kit->task) rather than ↵Oleg Nesterov1-9/+5
next_task(kit->pos) This looks more clear and simplifies the code. While at it, remove the unnecessary initialization of pos/task at the start of bpf_iter_task_new(). Note that we can even kill kit->task, we can just use pos->group_leader, but I don't understand the BUILD_BUG_ON() checks in bpf_iter_task_new(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20231114163239.GA903@redhat.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-19bpf: bpf_iter_task_next: use __next_thread() rather than next_thread()Oleg Nesterov1-5/+4
Lockless use of next_thread() should be avoided, kernel/bpf/task_iter.c is the last user and the usage is wrong. bpf_iter_task_next() can loop forever, "kit->pos == kit->task" can never happen if kit->pos execs. Change this code to use __next_thread(). With or without this change the usage of kit->pos/task and next_task() doesn't look nice, see the next patch. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20231114163237.GA897@redhat.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-19bpf: task_group_seq_get_next: use __next_thread() rather than next_thread()Oleg Nesterov1-7/+5
Lockless use of next_thread() should be avoided, kernel/bpf/task_iter.c is the last user and the usage is wrong. task_group_seq_get_next() can return the group leader twice if it races with mt-thread exec which changes the group->leader's pid. Change the main loop to use __next_thread(), kill "next_tid == common->pid" check. __next_thread() can't loop forever, we can also change this code to retry if next_tid == 0. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20231114163234.GA890@redhat.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-18bpf: emit frameno for PTR_TO_STACK regs if it differs from current oneAndrii Nakryiko1-6/+14
It's possible to pass a pointer to parent's stack to child subprogs. In such case verifier state output is ambiguous not showing whether register container a pointer to "current" stack, belonging to current subprog (frame), or it's actually a pointer to one of parent frames. So emit this information if frame number differs between the state which register is part of. E.g., if current state is in frame 2 and it has a register pointing to stack in grand parent state (frame #0), we'll see something like 'R1=fp[0]-16', while "local stack pointer" will be just 'R2=fp-16'. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231118034623.3320920-9-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-18bpf: smarter verifier log number printing logicAndrii Nakryiko1-11/+68
Instead of always printing numbers as either decimals (and in some cases, like for "imm=%llx", in hexadecimals), decide the form based on actual values. For numbers in a reasonably small range (currently, [0, U16_MAX] for unsigned values, and [S16_MIN, S16_MAX] for signed ones), emit them as decimals. In all other cases, even for signed values, emit them in hexadecimals. For large values hex form is often times way more useful: it's easier to see an exact difference between 0xffffffff80000000 and 0xffffffff7fffffff, than between 18446744071562067966 and 18446744071562067967, as one particular example. Small values representing small pointer offsets or application constants, on the other hand, are way more useful to be represented in decimal notation. Adjust reg_bounds register state parsing logic to take into account this change. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231118034623.3320920-8-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-18bpf: omit default off=0 and imm=0 in register state logAndrii Nakryiko1-6/+4
Simplify BPF verifier log further by omitting default (and frequently irrelevant) off=0 and imm=0 parts for non-SCALAR_VALUE registers. As can be seen from fixed tests, this is often a visual noise for PTR_TO_CTX register and even for PTR_TO_PACKET registers. Omitting default values follows the rest of register state logic: we omit default values to keep verifier log succinct and to highlight interesting state that deviates from default one. E.g., we do the same for var_off, when it's unknown, which gives no additional information. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231118034623.3320920-7-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-18bpf: emit map name in register state if applicable and availableAndrii Nakryiko1-6/+18
In complicated real-world applications, whenever debugging some verification error through verifier log, it often would be very useful to see map name for PTR_TO_MAP_VALUE register. Usually this needs to be inferred from key/value sizes and maybe trying to guess C code location, but it's not always clear. Given verifier has the name, and it's never too long, let's just emit it for ptr_to_map_key, ptr_to_map_value, and const_ptr_to_map registers. We reshuffle the order a bit, so that map name, key size, and value size appear before offset and immediate values, which seems like a more logical order. Current output: R1_w=map_ptr(map=array_map,ks=4,vs=8,off=0,imm=0) But we'll get rid of useless off=0 and imm=0 parts in the next patch. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231118034623.3320920-6-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-18bpf: print spilled register state in stack slotAndrii Nakryiko1-19/+17
Print the same register state representation when printing stack state, as we do for normal registers. Note that if stack slot contains subregister spill (1, 2, or 4 byte long), we'll still emit "m0?" mask for those bytes that are not part of spilled register. While means we can get something like fp-8=0000scalar() for a 4-byte spill with other 4 bytes still being STACK_ZERO. Some example before and after, taken from the log of pyperf_subprogs.bpf.o: 49: (7b) *(u64 *)(r10 -256) = r1 ; frame1: R1_w=ctx(off=0,imm=0) R10=fp0 fp-256_w=ctx 49: (7b) *(u64 *)(r10 -256) = r1 ; frame1: R1_w=ctx(off=0,imm=0) R10=fp0 fp-256_w=ctx(off=0,imm=0) 150: (7b) *(u64 *)(r10 -264) = r0 ; frame1: R0_w=map_value_or_null(id=6,off=0,ks=192,vs=4,imm=0) R10=fp0 fp-264_w=map_value_or_null 150: (7b) *(u64 *)(r10 -264) = r0 ; frame1: R0_w=map_value_or_null(id=6,off=0,ks=192,vs=4,imm=0) R10=fp0 fp-264_w=map_value_or_null(id=6,off=0,ks=192,vs=4,imm=0) 5192: (61) r1 = *(u32 *)(r10 -272) ; frame1: R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=15,var_off=(0x0; 0xf)) R10=fp0 fp-272= 5192: (61) r1 = *(u32 *)(r10 -272) ; frame1: R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=15,var_off=(0x0; 0xf)) R10=fp0 fp-272=????scalar(smin=smin32=0,smax=umax=smax32=umax32=15,var_off=(0x0; 0xf)) While at it, do a few other simple clean ups: - skip slot if it's not scratched before detecting whether it's valid; - move taking spilled_reg pointer outside of switch (only DYNPTR has to adjust that to get to the "main" slot); - don't recalculate types_buf second time for MISC/ZERO/default case. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231118034623.3320920-5-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-18bpf: extract register state printingAndrii Nakryiko1-57/+63
Extract printing register state representation logic into a separate helper, as we are going to reuse it for spilled register state printing in the next patch. This also nicely reduces code nestedness. No functional changes. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231118034623.3320920-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-18bpf: move verifier state printing code to kernel/bpf/log.cAndrii Nakryiko2-403/+342
Move a good chunk of code from verifier.c to log.c: verifier state verbose printing logic. This is an important and very much logging/debugging oriented code. It fits the overlall log.c's focus on verifier logging, and moving it allows to keep growing it without unnecessarily adding to verifier.c code that otherwise contains a core verification logic. There are not many shared dependencies between this code and the rest of verifier.c code, except a few single-line helpers for various register type checks and a bit of state "scratching" helpers. We move all such trivial helpers into include/bpf/bpf_verifier.h as static inlines. No functional changes in this patch. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231118034623.3320920-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-18bpf: move verbose_linfo() into kernel/bpf/log.cAndrii Nakryiko2-57/+59
verifier.c is huge. Let's try to move out parts that are logging-related into log.c, as we previously did with bpf_log() and other related stuff. This patch moves line info verbose output routines: it's pretty self-contained and isolated code, so there is no problem with this. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231118034623.3320920-2-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-17bpf: rename BPF_F_TEST_SANITY_STRICT to BPF_F_TEST_REG_INVARIANTSAndrii Nakryiko2-4/+4
Rename verifier internal flag BPF_F_TEST_SANITY_STRICT to more neutral BPF_F_TEST_REG_INVARIANTS. This is a follow up to [0]. A few selftests and veristat need to be adjusted in the same patch as well. [0] https://patchwork.kernel.org/project/netdevbpf/patch/20231112010609.848406-5-andrii@kernel.org/ Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231117171404.225508-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-15bpf: make __reg{32,64}_deduce_bounds logic more robustAndrii Nakryiko1-16/+8
This change doesn't seem to have any effect on selftests and production BPF object files, but we preemptively try to make it more robust. First, "learn sign from signed bounds" comment is misleading, as we are learning not just sign, but also values. Second, we simplify the check for determining whether entire range is positive or negative similarly to other checks added earlier, using appropriate u32/u64 cast and single comparisons. As explain in comments in __reg64_deduce_bounds(), the checks are equivalent. Last but not least, smin/smax and s32_min/s32_max reassignment based on min/max of both umin/umax and smin/smax (and 32-bit equivalents) is hard to explain and justify. We are updating unsigned bounds from signed bounds, why would we update signed bounds at the same time? This might be correct, but it's far from obvious why and the code or comments don't try to justify this. Given we've added a separate deduction of signed bounds from unsigned bounds earlier, this seems at least redundant, if not just wrong. In short, we remove doubtful pieces, and streamline the rest to follow the logic and approach of the rest of reg_bounds_sync() checks. Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231112010609.848406-7-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-15bpf: remove redundant s{32,64} -> u{32,64} deduction logicAndrii Nakryiko1-36/+0
Equivalent checks were recently added in more succinct and, arguably, safer form in: - f188765f23a5 ("bpf: derive smin32/smax32 from umin32/umax32 bounds"); - 2e74aef782d3 ("bpf: derive smin/smax from umin/max bounds"). The checks we are removing in this patch set do similar checks to detect if entire u32/u64 range has signed bit set or not set, but does it with two separate checks. Further, we forcefully overwrite either smin or smax (and 32-bit equvalents) without applying normal min/max intersection logic. It's not clear why that would be correct in all cases and seems to work by accident. This logic is also "gated" by previous signed -> unsigned derivation, which returns early. All this is quite confusing and seems error-prone, while we already have at least equivalent checks happening earlier. So remove this duplicate and error-prone logic to simplify things a bit. Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231112010609.848406-6-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-15bpf: add register bounds sanity checks and sanitizationAndrii Nakryiko2-26/+94
Add simple sanity checks that validate well-formed ranges (min <= max) across u64, s64, u32, and s32 ranges. Also for cases when the value is constant (either 64-bit or 32-bit), we validate that ranges and tnums are in agreement. These bounds checks are performed at the end of BPF_ALU/BPF_ALU64 operations, on conditional jumps, and for LDX instructions (where subreg zero/sign extension is probably the most important to check). This covers most of the interesting cases. Also, we validate the sanity of the return register when manually adjusting it for some special helpers. By default, sanity violation will trigger a warning in verifier log and resetting register bounds to "unbounded" ones. But to aid development and debugging, BPF_F_TEST_SANITY_STRICT flag is added, which will trigger hard failure of verification with -EFAULT on register bounds violations. This allows selftests to catch such issues. veristat will also gain a CLI option to enable this behavior. Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com> Link: https://lore.kernel.org/r/20231112010609.848406-5-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2023-11-15bpf: enhance BPF_JEQ/BPF_JNE is_branch_taken logicAndrii Nakryiko1-0/+24
Use 32-bit subranges to prune some 64-bit BPF_JEQ/BPF_JNE conditions that otherwise would be "inconclusive" (i.e., is_branch_taken() would return -1). This can happen, for example, when registers are initialized as 64-bit u64/s64, then compared for inequality as 32-bit subregisters, and then followed by 64-bit equality/inequality check. That 32-bit inequality can establish some pattern for lower 32 bits of a register (e.g., s< 0 condition determines whether the bit #31 is zero or not), while overall 64-bit value could be anything (according to a value range representation). This is not a fancy quirky special case, but actually a handling that's necessary to prevent correctness issue with BPF verifier's range tracking: set_range_min_max() assumes that register ranges are non-overlapping, and if that condition is not guaranteed by is_branch_taken() we can end up with invalid ranges, where min > max. [0] https://lore.kernel.org/bpf/CACkBjsY2q1_fUohD7hRmKGqv1MV=eP2f6XK8kjkYNw7BaiF8iQ@mail.gmail.com/ Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com> Acked-by: Eduard Zingerman <eddyz87@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20231112010609.848406-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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