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2020-05-20bpf: Prevent mmap()'ing read-only maps as writableAndrii Nakryiko
As discussed in [0], it's dangerous to allow mapping BPF map, that's meant to be frozen and is read-only on BPF program side, because that allows user-space to actually store a writable view to the page even after it is frozen. This is exacerbated by BPF verifier making a strong assumption that contents of such frozen map will remain unchanged. To prevent this, disallow mapping BPF_F_RDONLY_PROG mmap()'able BPF maps as writable, ever. [0] https://lore.kernel.org/bpf/CAEf4BzYGWYhXdp6BJ7_=9OQPJxQpgug080MMjdSB72i9R+5c6g@mail.gmail.com/ Fixes: fc9702273e2e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY") Suggested-by: Jann Horn <jannh@google.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Reviewed-by: Jann Horn <jannh@google.com> Link: https://lore.kernel.org/bpf/20200519053824.1089415-1-andriin@fb.com
2020-05-19bpf: Add get{peer, sock}name attach types for sock_addrDaniel Borkmann
As stated in 983695fa6765 ("bpf: fix unconnected udp hooks"), the objective for the existing cgroup connect/sendmsg/recvmsg/bind BPF hooks is to be transparent to applications. In Cilium we make use of these hooks [0] in order to enable E-W load balancing for existing Kubernetes service types for all Cilium managed nodes in the cluster. Those backends can be local or remote. The main advantage of this approach is that it operates as close as possible to the socket, and therefore allows to avoid packet-based NAT given in connect/sendmsg/recvmsg hooks we only need to xlate sock addresses. This also allows to expose NodePort services on loopback addresses in the host namespace, for example. As another advantage, this also efficiently blocks bind requests for applications in the host namespace for exposed ports. However, one missing item is that we also need to perform reverse xlation for inet{,6}_getname() hooks such that we can return the service IP/port tuple back to the application instead of the remote peer address. The vast majority of applications does not bother about getpeername(), but in a few occasions we've seen breakage when validating the peer's address since it returns unexpectedly the backend tuple instead of the service one. Therefore, this trivial patch allows to customise and adds a getpeername() as well as getsockname() BPF cgroup hook for both IPv4 and IPv6 in order to address this situation. Simple example: # ./cilium/cilium service list ID Frontend Service Type Backend 1 1.2.3.4:80 ClusterIP 1 => 10.0.0.10:80 Before; curl's verbose output example, no getpeername() reverse xlation: # curl --verbose 1.2.3.4 * Rebuilt URL to: 1.2.3.4/ * Trying 1.2.3.4... * TCP_NODELAY set * Connected to 1.2.3.4 (10.0.0.10) port 80 (#0) > GET / HTTP/1.1 > Host: 1.2.3.4 > User-Agent: curl/7.58.0 > Accept: */* [...] After; with getpeername() reverse xlation: # curl --verbose 1.2.3.4 * Rebuilt URL to: 1.2.3.4/ * Trying 1.2.3.4... * TCP_NODELAY set * Connected to 1.2.3.4 (1.2.3.4) port 80 (#0) > GET / HTTP/1.1 > Host: 1.2.3.4 > User-Agent: curl/7.58.0 > Accept: */* [...] Originally, I had both under a BPF_CGROUP_INET{4,6}_GETNAME type and exposed peer to the context similar as in inet{,6}_getname() fashion, but API-wise this is suboptimal as it always enforces programs having to test for ctx->peer which can easily be missed, hence BPF_CGROUP_INET{4,6}_GET{PEER,SOCK}NAME split. Similarly, the checked return code is on tnum_range(1, 1), but if a use case comes up in future, it can easily be changed to return an error code instead. Helper and ctx member access is the same as with connect/sendmsg/etc hooks. [0] https://github.com/cilium/cilium/blob/master/bpf/bpf_sock.c Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Andrey Ignatov <rdna@fb.com> Link: https://lore.kernel.org/bpf/61a479d759b2482ae3efb45546490bacd796a220.1589841594.git.daniel@iogearbox.net
2020-05-15Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netDavid S. Miller
Move the bpf verifier trace check into the new switch statement in HEAD. Resolve the overlapping changes in hinic, where bug fixes overlap the addition of VF support. Signed-off-by: David S. Miller <davem@davemloft.net>
2020-05-15bpf: Implement CAP_BPFAlexei Starovoitov
Implement permissions as stated in uapi/linux/capability.h In order to do that the verifier allow_ptr_leaks flag is split into four flags and they are set as: env->allow_ptr_leaks = bpf_allow_ptr_leaks(); env->bypass_spec_v1 = bpf_bypass_spec_v1(); env->bypass_spec_v4 = bpf_bypass_spec_v4(); env->bpf_capable = bpf_capable(); The first three currently equivalent to perfmon_capable(), since leaking kernel pointers and reading kernel memory via side channel attacks is roughly equivalent to reading kernel memory with cap_perfmon. 'bpf_capable' enables bounded loops, precision tracking, bpf to bpf calls and other verifier features. 'allow_ptr_leaks' enable ptr leaks, ptr conversions, subtraction of pointers. 'bypass_spec_v1' disables speculative analysis in the verifier, run time mitigations in bpf array, and enables indirect variable access in bpf programs. 'bypass_spec_v4' disables emission of sanitation code by the verifier. That means that the networking BPF program loaded with CAP_BPF + CAP_NET_ADMIN will have speculative checks done by the verifier and other spectre mitigation applied. Such networking BPF program will not be able to leak kernel pointers and will not be able to access arbitrary kernel memory. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200513230355.7858-3-alexei.starovoitov@gmail.com
2020-05-09bpf: Add bpf_map iteratorYonghong Song
Implement seq_file operations to traverse all bpf_maps. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200509175909.2476096-1-yhs@fb.com
2020-05-09bpf: Create anonymous bpf iteratorYonghong Song
A new bpf command BPF_ITER_CREATE is added. The anonymous bpf iterator is seq_file based. The seq_file private data are referenced by targets. The bpf_iter infrastructure allocated additional space at seq_file->private before the space used by targets to store some meta data, e.g., prog: prog to run session_id: an unique id for each opened seq_file seq_num: how many times bpf programs are queried in this session done_stop: an internal state to decide whether bpf program should be called in seq_ops->stop() or not The seq_num will start from 0 for valid objects. The bpf program may see the same seq_num more than once if - seq_file buffer overflow happens and the same object is retried by bpf_seq_read(), or - the bpf program explicitly requests a retry of the same object Since module is not supported for bpf_iter, all target registeration happens at __init time, so there is no need to change bpf_iter_unreg_target() as it is used mostly in error path of the init function at which time no bpf iterators have been created yet. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200509175905.2475770-1-yhs@fb.com
2020-05-09bpf: Support bpf tracing/iter programs for BPF_LINK_CREATEYonghong Song
Given a bpf program, the step to create an anonymous bpf iterator is: - create a bpf_iter_link, which combines bpf program and the target. In the future, there could be more information recorded in the link. A link_fd will be returned to the user space. - create an anonymous bpf iterator with the given link_fd. The bpf_iter_link can be pinned to bpffs mount file system to create a file based bpf iterator as well. The benefit to use of bpf_iter_link: - using bpf link simplifies design and implementation as bpf link is used for other tracing bpf programs. - for file based bpf iterator, bpf_iter_link provides a standard way to replace underlying bpf programs. - for both anonymous and free based iterators, bpf link query capability can be leveraged. The patch added support of tracing/iter programs for BPF_LINK_CREATE. A new link type BPF_LINK_TYPE_ITER is added to facilitate link querying. Currently, only prog_id is needed, so there is no additional in-kernel show_fdinfo() and fill_link_info() hook is needed for BPF_LINK_TYPE_ITER link. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200509175901.2475084-1-yhs@fb.com
2020-05-01bpf: Fix use-after-free of bpf_link when priming half-failsAndrii Nakryiko
If bpf_link_prime() succeeds to allocate new anon file, but then fails to allocate ID for it, link priming is considered to be failed and user is supposed ot be able to directly kfree() bpf_link, because it was never exposed to user-space. But at that point file already keeps a pointer to bpf_link and will eventually call bpf_link_release(), so if bpf_link was kfree()'d by caller, that would lead to use-after-free. Fix this by first allocating ID and only then allocating file. Adding ID to link_idr is ok, because link at that point still doesn't have its ID set, so no user-space process can create a new FD for it. Fixes: a3b80e107894 ("bpf: Allocate ID for bpf_link") Reported-by: syzbot+39b64425f91b5aab714d@syzkaller.appspotmail.com Suggested-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20200501185622.3088964-1-andriin@fb.com
2020-05-01bpf: Sharing bpf runtime stats with BPF_ENABLE_STATSSong Liu
Currently, sysctl kernel.bpf_stats_enabled controls BPF runtime stats. Typical userspace tools use kernel.bpf_stats_enabled as follows: 1. Enable kernel.bpf_stats_enabled; 2. Check program run_time_ns; 3. Sleep for the monitoring period; 4. Check program run_time_ns again, calculate the difference; 5. Disable kernel.bpf_stats_enabled. The problem with this approach is that only one userspace tool can toggle this sysctl. If multiple tools toggle the sysctl at the same time, the measurement may be inaccurate. To fix this problem while keep backward compatibility, introduce a new bpf command BPF_ENABLE_STATS. On success, this command enables stats and returns a valid fd. BPF_ENABLE_STATS takes argument "type". Currently, only one type, BPF_STATS_RUN_TIME, is supported. We can extend the command to support other types of stats in the future. With BPF_ENABLE_STATS, user space tool would have the following flow: 1. Get a fd with BPF_ENABLE_STATS, and make sure it is valid; 2. Check program run_time_ns; 3. Sleep for the monitoring period; 4. Check program run_time_ns again, calculate the difference; 5. Close the fd. Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200430071506.1408910-2-songliubraving@fb.com
2020-04-30bpf: Fix error return code in map_lookup_and_delete_elem()Wei Yongjun
Fix to return negative error code -EFAULT from the copy_to_user() error handling case instead of 0, as done elsewhere in this function. Fixes: bd513cd08f10 ("bpf: add MAP_LOOKUP_AND_DELETE_ELEM syscall") Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200430081851.166996-1-weiyongjun1@huawei.com
2020-04-30bpf: Fix unused variable warningArnd Bergmann
Hiding the only using of bpf_link_type_strs[] in an #ifdef causes an unused-variable warning: kernel/bpf/syscall.c:2280:20: error: 'bpf_link_type_strs' defined but not used [-Werror=unused-variable] 2280 | static const char *bpf_link_type_strs[] = { Move the definition into the same #ifdef. Fixes: f2e10bff16a0 ("bpf: Add support for BPF_OBJ_GET_INFO_BY_FD for bpf_link") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200429132217.1294289-1-arnd@arndb.de
2020-04-28bpf: Add support for BPF_OBJ_GET_INFO_BY_FD for bpf_linkAndrii Nakryiko
Add ability to fetch bpf_link details through BPF_OBJ_GET_INFO_BY_FD command. Also enhance show_fdinfo to potentially include bpf_link type-specific information (similarly to obj_info). Also introduce enum bpf_link_type stored in bpf_link itself and expose it in UAPI. bpf_link_tracing also now will store and return bpf_attach_type. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200429001614.1544-5-andriin@fb.com
2020-04-28bpf: Support GET_FD_BY_ID and GET_NEXT_ID for bpf_linkAndrii Nakryiko
Add support to look up bpf_link by ID and iterate over all existing bpf_links in the system. GET_FD_BY_ID code handles not-yet-ready bpf_link by checking that its ID hasn't been set to non-zero value yet. Setting bpf_link's ID is done as the very last step in finalizing bpf_link, together with installing FD. This approach allows users of bpf_link in kernel code to not worry about races between user-space and kernel code that hasn't finished attaching and initializing bpf_link. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200429001614.1544-4-andriin@fb.com
2020-04-28bpf: Allocate ID for bpf_linkAndrii Nakryiko
Generate ID for each bpf_link using IDR, similarly to bpf_map and bpf_prog. bpf_link creation, initialization, attachment, and exposing to user-space through FD and ID is a complicated multi-step process, abstract it away through bpf_link_primer and bpf_link_prime(), bpf_link_settle(), and bpf_link_cleanup() internal API. They guarantee that until bpf_link is properly attached, user-space won't be able to access partially-initialized bpf_link either from FD or ID. All this allows to simplify bpf_link attachment and error handling code. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200429001614.1544-3-andriin@fb.com
2020-04-28bpf: Refactor bpf_link update handlingAndrii Nakryiko
Make bpf_link update support more generic by making it into another bpf_link_ops methods. This allows generic syscall handling code to be agnostic to various conditionally compiled features (e.g., the case of CONFIG_CGROUP_BPF). This also allows to keep link type-specific code to remain static within respective code base. Refactor existing bpf_cgroup_link code and take advantage of this. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200429001614.1544-2-andriin@fb.com
2020-04-24bpf: Make bpf_link_fops staticZou Wei
Fix the following sparse warning: kernel/bpf/syscall.c:2289:30: warning: symbol 'bpf_link_fops' was not declared. Should it be static? Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Zou Wei <zou_wei@huawei.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/1587609160-117806-1-git-send-email-zou_wei@huawei.com
2020-04-24bpf: Fix leak in LINK_UPDATE and enforce empty old_prog_fdAndrii Nakryiko
Fix bug of not putting bpf_link in LINK_UPDATE command. Also enforce zeroed old_prog_fd if no BPF_F_REPLACE flag is specified. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200424052045.4002963-1-andriin@fb.com
2020-04-14bpf: Prevent re-mmap()'ing BPF map as writable for initially r/o mappingAndrii Nakryiko
VM_MAYWRITE flag during initial memory mapping determines if already mmap()'ed pages can be later remapped as writable ones through mprotect() call. To prevent user application to rewrite contents of memory-mapped as read-only and subsequently frozen BPF map, remove VM_MAYWRITE flag completely on initially read-only mapping. Alternatively, we could treat any memory-mapping on unfrozen map as writable and bump writecnt instead. But there is little legitimate reason to map BPF map as read-only and then re-mmap() it as writable through mprotect(), instead of just mmap()'ing it as read/write from the very beginning. Also, at the suggestion of Jann Horn, drop unnecessary refcounting in mmap operations. We can just rely on VMA holding reference to BPF map's file properly. Fixes: fc9702273e2e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Jann Horn <jannh@google.com> Link: https://lore.kernel.org/bpf/20200410202613.3679837-1-andriin@fb.com
2020-03-30Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-nextDavid S. Miller
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-30bpf: Implement bpf_prog replacement for an active bpf_cgroup_linkAndrii Nakryiko
Add new operation (LINK_UPDATE), which allows to replace active bpf_prog from under given bpf_link. Currently this is only supported for bpf_cgroup_link, but will be extended to other kinds of bpf_links in follow-up patches. For bpf_cgroup_link, implemented functionality matches existing semantics for direct bpf_prog attachment (including BPF_F_REPLACE flag). User can either unconditionally set new bpf_prog regardless of which bpf_prog is currently active under given bpf_link, or, optionally, can specify expected active bpf_prog. If active bpf_prog doesn't match expected one, no changes are performed, old bpf_link stays intact and attached, operation returns a failure. cgroup_bpf_replace() operation is resolving race between auto-detachment and bpf_prog update in the same fashion as it's done for bpf_link detachment, except in this case update has no way of succeeding because of target cgroup marked as dying. So in this case error is returned. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200330030001.2312810-3-andriin@fb.com
2020-03-30bpf: Implement bpf_link-based cgroup BPF program attachmentAndrii Nakryiko
Implement new sub-command to attach cgroup BPF programs and return FD-based bpf_link back on success. bpf_link, once attached to cgroup, cannot be replaced, except by owner having its FD. Cgroup bpf_link supports only BPF_F_ALLOW_MULTI semantics. Both link-based and prog-based BPF_F_ALLOW_MULTI attachments can be freely intermixed. To prevent bpf_cgroup_link from keeping cgroup alive past the point when no BPF program can be executed, implement auto-detachment of link. When cgroup_bpf_release() is called, all attached bpf_links are forced to release cgroup refcounts, but they leave bpf_link otherwise active and allocated, as well as still owning underlying bpf_prog. This is because user-space might still have FDs open and active, so bpf_link as a user-referenced object can't be freed yet. Once last active FD is closed, bpf_link will be freed and underlying bpf_prog refcount will be dropped. But cgroup refcount won't be touched, because cgroup is released already. The inherent race between bpf_cgroup_link release (from closing last FD) and cgroup_bpf_release() is resolved by both operations taking cgroup_mutex. So the only additional check required is when bpf_cgroup_link attempts to detach itself from cgroup. At that time we need to check whether there is still cgroup associated with that link. And if not, exit with success, because bpf_cgroup_link was already successfully detached. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Roman Gushchin <guro@fb.com> Link: https://lore.kernel.org/bpf/20200330030001.2312810-2-andriin@fb.com
2020-03-29Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller
Minor comment conflict in mac80211. Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-30bpf: lsm: Implement attach, detach and executionKP Singh
JITed BPF programs are dynamically attached to the LSM hooks using BPF trampolines. The trampoline prologue generates code to handle conversion of the signature of the hook to the appropriate BPF context. The allocated trampoline programs are attached to the nop functions initialized as LSM hooks. BPF_PROG_TYPE_LSM programs must have a GPL compatible license and and need CAP_SYS_ADMIN (required for loading eBPF programs). Upon attachment: * A BPF fexit trampoline is used for LSM hooks with a void return type. * A BPF fmod_ret trampoline is used for LSM hooks which return an int. The attached programs can override the return value of the bpf LSM hook to indicate a MAC Policy decision. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Brendan Jackman <jackmanb@google.com> Reviewed-by: Florent Revest <revest@google.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: James Morris <jamorris@linux.microsoft.com> Link: https://lore.kernel.org/bpf/20200329004356.27286-5-kpsingh@chromium.org
2020-03-26bpf: Remove unused vairable 'bpf_xdp_link_lops'YueHaibing
kernel/bpf/syscall.c:2263:34: warning: 'bpf_xdp_link_lops' defined but not used [-Wunused-const-variable=] static const struct bpf_link_ops bpf_xdp_link_lops; ^~~~~~~~~~~~~~~~~ commit 70ed506c3bbc ("bpf: Introduce pinnable bpf_link abstraction") involded this unused variable, remove it. Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: YueHaibing <yuehaibing@huawei.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200326031613.19372-1-yuehaibing@huawei.com
2020-03-26bpf: Factor out attach_type to prog_type mapping for attach/detachAndrii Nakryiko
Factor out logic mapping expected program attach type to program type and subsequent handling of program attach/detach. Also list out all supported cgroup BPF program types explicitly to prevent accidental bugs once more program types are added to a mapping. Do the same for prog_query API. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200325065746.640559-3-andriin@fb.com
2020-03-25Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netDavid S. Miller
Overlapping header include additions in macsec.c A bug fix in 'net' overlapping with the removal of 'version' string in ena_netdev.c Overlapping test additions in selftests Makefile Overlapping PCI ID table adjustments in iwlwifi driver. Signed-off-by: David S. Miller <davem@davemloft.net>
2020-03-20bpf: Explicitly memset some bpf info structures declared on the stackGreg Kroah-Hartman
Trying to initialize a structure with "= {};" will not always clean out all padding locations in a structure. So be explicit and call memset to initialize everything for a number of bpf information structures that are then copied from userspace, sometimes from smaller memory locations than the size of the structure. Reported-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20200320162258.GA794295@kroah.com
2020-03-20bpf: Explicitly memset the bpf_attr structureGreg Kroah-Hartman
For the bpf syscall, we are relying on the compiler to properly zero out the bpf_attr union that we copy userspace data into. Unfortunately that doesn't always work properly, padding and other oddities might not be correctly zeroed, and in some tests odd things have been found when the stack is pre-initialized to other values. Fix this by explicitly memsetting the structure to 0 before using it. Reported-by: Maciej Żenczykowski <maze@google.com> Reported-by: John Stultz <john.stultz@linaro.org> Reported-by: Alexander Potapenko <glider@google.com> Reported-by: Alistair Delva <adelva@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://android-review.googlesource.com/c/kernel/common/+/1235490 Link: https://lore.kernel.org/bpf/20200320094813.GA421650@kroah.com
2020-03-17bpf: Sanitize the bpf_struct_ops tcp-cc nameMartin KaFai Lau
The bpf_struct_ops tcp-cc name should be sanitized in order to avoid problematic chars (e.g. whitespaces). This patch reuses the bpf_obj_name_cpy() for accepting the same set of characters in order to keep a consistent bpf programming experience. A "size" param is added. Also, the strlen is returned on success so that the caller (like the bpf_tcp_ca here) can error out on empty name. The existing callers of the bpf_obj_name_cpy() only need to change the testing statement to "if (err < 0)". For all these existing callers, the err will be overwritten later, so no extra change is needed for the new strlen return value. v3: - reverse xmas tree style v2: - Save the orig_src to avoid "end - size" (Andrii) Fixes: 0baf26b0fcd7 ("bpf: tcp: Support tcp_congestion_ops in bpf") Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200314010209.1131542-1-kafai@fb.com
2020-03-13bpf: Abstract away entire bpf_link clean up procedureAndrii Nakryiko
Instead of requiring users to do three steps for cleaning up bpf_link, its anon_inode file, and unused fd, abstract that away into bpf_link_cleanup() helper. bpf_link_defunct() is removed, as it shouldn't be needed as an individual operation anymore. v1->v2: - keep bpf_link_cleanup() static for now (Daniel). Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20200313002128.2028680-1-andriin@fb.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2020-03-11bpf: Add bpf_link_new_file that doesn't install FDAndrii Nakryiko
Add bpf_link_new_file() API for cases when we need to ensure anon_inode is successfully created before we proceed with expensive BPF program attachment procedure, which will require equally (if not more so) expensive and potentially failing compensation detachment procedure just because anon_inode creation failed. This API allows to simplify code by ensuring first that anon_inode is created and after BPF program is attached proceed with fd_install() that can't fail. After anon_inode file is created, link can't be just kfree()'d anymore, because its destruction will be performed by deferred file_operations->release call. For this, bpf_link API required specifying two separate operations: release() and dealloc(), former performing detachment only, while the latter frees memory used by bpf_link itself. dealloc() needs to be specified, because struct bpf_link is frequently embedded into link type-specific container struct (e.g., struct bpf_raw_tp_link), so bpf_link itself doesn't know how to properly free the memory. In case when anon_inode file was successfully created, but subsequent BPF attachment failed, bpf_link needs to be marked as "defunct", so that file's release() callback will perform only memory deallocation, but no detachment. Convert raw tracepoint and tracing attachment to new API and eliminate detachment from error handling path. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20200309231051.1270337-1-andriin@fb.com
2020-03-05bpf: Do not allow map_freeze in struct_ops mapMartin KaFai Lau
struct_ops map cannot support map_freeze. Otherwise, a struct_ops cannot be unregistered from the subsystem. Fixes: 85d33df357b6 ("bpf: Introduce BPF_MAP_TYPE_STRUCT_OPS") Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200305013454.535397-1-kafai@fb.com
2020-03-04bpf: Introduce BPF_MODIFY_RETURNKP Singh
When multiple programs are attached, each program receives the return value from the previous program on the stack and the last program provides the return value to the attached function. The fmod_ret bpf programs are run after the fentry programs and before the fexit programs. The original function is only called if all the fmod_ret programs return 0 to avoid any unintended side-effects. The success value, i.e. 0 is not currently configurable but can be made so where user-space can specify it at load time. For example: int func_to_be_attached(int a, int b) { <--- do_fentry do_fmod_ret: <update ret by calling fmod_ret> if (ret != 0) goto do_fexit; original_function: <side_effects_happen_here> } <--- do_fexit The fmod_ret program attached to this function can be defined as: SEC("fmod_ret/func_to_be_attached") int BPF_PROG(func_name, int a, int b, int ret) { // This will skip the original function logic. return 1; } The first fmod_ret program is passed 0 in its return argument. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200304191853.1529-4-kpsingh@chromium.org
2020-03-02bpf: Introduce pinnable bpf_link abstractionAndrii Nakryiko
Introduce bpf_link abstraction, representing an attachment of BPF program to a BPF hook point (e.g., tracepoint, perf event, etc). bpf_link encapsulates ownership of attached BPF program, reference counting of a link itself, when reference from multiple anonymous inodes, as well as ensures that release callback will be called from a process context, so that users can safely take mutex locks and sleep. Additionally, with a new abstraction it's now possible to generalize pinning of a link object in BPF FS, allowing to explicitly prevent BPF program detachment on process exit by pinning it in a BPF FS and let it open from independent other process to keep working with it. Convert two existing bpf_link-like objects (raw tracepoint and tracing BPF program attachments) into utilizing bpf_link framework, making them pinnable in BPF FS. More FD-based bpf_links will be added in follow up patches. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200303043159.323675-2-andriin@fb.com
2020-02-27bpf: INET_DIAG support in bpf_sk_storageMartin KaFai Lau
This patch adds INET_DIAG support to bpf_sk_storage. 1. Although this series adds bpf_sk_storage diag capability to inet sk, bpf_sk_storage is in general applicable to all fullsock. Hence, the bpf_sk_storage logic will operate on SK_DIAG_* nlattr. The caller will pass in its specific nesting nlattr (e.g. INET_DIAG_*) as the argument. 2. The request will be like: INET_DIAG_REQ_SK_BPF_STORAGES (nla_nest) (defined in latter patch) SK_DIAG_BPF_STORAGE_REQ_MAP_FD (nla_put_u32) SK_DIAG_BPF_STORAGE_REQ_MAP_FD (nla_put_u32) ...... Considering there could have multiple bpf_sk_storages in a sk, instead of reusing INET_DIAG_INFO ("ss -i"), the user can select some specific bpf_sk_storage to dump by specifying an array of SK_DIAG_BPF_STORAGE_REQ_MAP_FD. If no SK_DIAG_BPF_STORAGE_REQ_MAP_FD is specified (i.e. an empty INET_DIAG_REQ_SK_BPF_STORAGES), it will dump all bpf_sk_storages of a sk. 3. The reply will be like: INET_DIAG_BPF_SK_STORAGES (nla_nest) (defined in latter patch) SK_DIAG_BPF_STORAGE (nla_nest) SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32) SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit) SK_DIAG_BPF_STORAGE (nla_nest) SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32) SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit) ...... 4. Unlike other INET_DIAG info of a sk which is pretty static, the size required to dump the bpf_sk_storage(s) of a sk is dynamic as the system adding more bpf_sk_storage_map. It is hard to set a static min_dump_alloc size. Hence, this series learns it at the runtime and adjust the cb->min_dump_alloc as it iterates all sk(s) of a system. The "unsigned int *res_diag_size" in bpf_sk_storage_diag_put() is for this purpose. The next patch will update the cb->min_dump_alloc as it iterates the sk(s). Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20200225230421.1975729-1-kafai@fb.com
2020-02-24bpf: Replace open coded recursion prevention in sys_bpf()Thomas Gleixner
The required protection is that the caller cannot be migrated to a different CPU as these functions end up in places which take either a hash bucket lock or might trigger a kprobe inside the memory allocator. Both scenarios can lead to deadlocks. The deadlock prevention is per CPU by incrementing a per CPU variable which temporarily blocks the invocation of BPF programs from perf and kprobes. Replace the open coded preempt_[dis|en]able and __this_cpu_[inc|dec] pairs with the new helper functions. These functions are already prepared to make BPF work on PREEMPT_RT enabled kernels. No functional change for !RT kernels. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200224145644.317843926@linutronix.de
2020-01-22bpf: Introduce dynamic program extensionsAlexei Starovoitov
Introduce dynamic program extensions. The users can load additional BPF functions and replace global functions in previously loaded BPF programs while these programs are executing. Global functions are verified individually by the verifier based on their types only. Hence the global function in the new program which types match older function can safely replace that corresponding function. This new function/program is called 'an extension' of old program. At load time the verifier uses (attach_prog_fd, attach_btf_id) pair to identify the function to be replaced. The BPF program type is derived from the target program into extension program. Technically bpf_verifier_ops is copied from target program. The BPF_PROG_TYPE_EXT program type is a placeholder. It has empty verifier_ops. The extension program can call the same bpf helper functions as target program. Single BPF_PROG_TYPE_EXT type is used to extend XDP, SKB and all other program types. The verifier allows only one level of replacement. Meaning that the extension program cannot recursively extend an extension. That also means that the maximum stack size is increasing from 512 to 1024 bytes and maximum function nesting level from 8 to 16. The programs don't always consume that much. The stack usage is determined by the number of on-stack variables used by the program. The verifier could have enforced 512 limit for combined original plus extension program, but it makes for difficult user experience. The main use case for extensions is to provide generic mechanism to plug external programs into policy program or function call chaining. BPF trampoline is used to track both fentry/fexit and program extensions because both are using the same nop slot at the beginning of every BPF function. Attaching fentry/fexit to a function that was replaced is not allowed. The opposite is true as well. Replacing a function that currently being analyzed with fentry/fexit is not allowed. The executable page allocated by BPF trampoline is not used by program extensions. This inefficiency will be optimized in future patches. Function by function verification of global function supports scalars and pointer to context only. Hence program extensions are supported for such class of global functions only. In the future the verifier will be extended with support to pointers to structures, arrays with sizes, etc. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Toke Høiland-Jørgensen <toke@redhat.com> Link: https://lore.kernel.org/bpf/20200121005348.2769920-2-ast@kernel.org
2020-01-20bpf: Fix memory leaks in generic update/delete batch opsBrian Vazquez
Generic update/delete batch ops functions were using __bpf_copy_key without properly freeing the memory. Handle the memory allocation and copy_from_user separately. Fixes: aa2e93b8e58e ("bpf: Add generic support for update and delete batch ops") Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Brian Vazquez <brianvv@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20200119194040.128369-1-brianvv@google.com
2020-01-16bpf: Remove set but not used variable 'first_key'YueHaibing
kernel/bpf/syscall.c: In function generic_map_lookup_batch: kernel/bpf/syscall.c:1339:7: warning: variable first_key set but not used [-Wunused-but-set-variable] It is never used, so remove it. Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: YueHaibing <yuehaibing@huawei.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Brian Vazquez <brianvv@google.com> Link: https://lore.kernel.org/bpf/20200116145300.59056-1-yuehaibing@huawei.com
2020-01-15bpf: Add batch ops to all htab bpf mapYonghong Song
htab can't use generic batch support due some problematic behaviours inherent to the data structre, i.e. while iterating the bpf map a concurrent program might delete the next entry that batch was about to use, in that case there's no easy solution to retrieve the next entry, the issue has been discussed multiple times (see [1] and [2]). The only way hmap can be traversed without the problem previously exposed is by making sure that the map is traversing entire buckets. This commit implements those strict requirements for hmap, the implementation follows the same interaction that generic support with some exceptions: - If keys/values buffer are not big enough to traverse a bucket, ENOSPC will be returned. - out_batch contains the value of the next bucket in the iteration, not the next key, but this is transparent for the user since the user should never use out_batch for other than bpf batch syscalls. This commits implements BPF_MAP_LOOKUP_BATCH and adds support for new command BPF_MAP_LOOKUP_AND_DELETE_BATCH. Note that for update/delete batch ops it is possible to use the generic implementations. [1] https://lore.kernel.org/bpf/20190724165803.87470-1-brianvv@google.com/ [2] https://lore.kernel.org/bpf/20190906225434.3635421-1-yhs@fb.com/ Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Brian Vazquez <brianvv@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200115184308.162644-6-brianvv@google.com
2020-01-15bpf: Add generic support for update and delete batch opsBrian Vazquez
This commit adds generic support for update and delete batch ops that can be used for almost all the bpf maps. These commands share the same UAPI attr that lookup and lookup_and_delete batch ops use and the syscall commands are: BPF_MAP_UPDATE_BATCH BPF_MAP_DELETE_BATCH The main difference between update/delete and lookup batch ops is that for update/delete keys/values must be specified for userspace and because of that, neither in_batch nor out_batch are used. Suggested-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Brian Vazquez <brianvv@google.com> Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200115184308.162644-4-brianvv@google.com
2020-01-15bpf: Add generic support for lookup batch opBrian Vazquez
This commit introduces generic support for the bpf_map_lookup_batch. This implementation can be used by almost all the bpf maps since its core implementation is relying on the existing map_get_next_key and map_lookup_elem. The bpf syscall subcommand introduced is: BPF_MAP_LOOKUP_BATCH The UAPI attribute is: struct { /* struct used by BPF_MAP_*_BATCH commands */ __aligned_u64 in_batch; /* start batch, * NULL to start from beginning */ __aligned_u64 out_batch; /* output: next start batch */ __aligned_u64 keys; __aligned_u64 values; __u32 count; /* input/output: * input: # of key/value * elements * output: # of filled elements */ __u32 map_fd; __u64 elem_flags; __u64 flags; } batch; in_batch/out_batch are opaque values use to communicate between user/kernel space, in_batch/out_batch must be of key_size length. To start iterating from the beginning in_batch must be null, count is the # of key/value elements to retrieve. Note that the 'keys' buffer must be a buffer of key_size * count size and the 'values' buffer must be value_size * count, where value_size must be aligned to 8 bytes by userspace if it's dealing with percpu maps. 'count' will contain the number of keys/values successfully retrieved. Note that 'count' is an input/output variable and it can contain a lower value after a call. If there's no more entries to retrieve, ENOENT will be returned. If error is ENOENT, count might be > 0 in case it copied some values but there were no more entries to retrieve. Note that if the return code is an error and not -EFAULT, count indicates the number of elements successfully processed. Suggested-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Brian Vazquez <brianvv@google.com> Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200115184308.162644-3-brianvv@google.com
2020-01-15bpf: Add bpf_map_{value_size, update_value, map_copy_value} functionsBrian Vazquez
This commit moves reusable code from map_lookup_elem and map_update_elem to avoid code duplication in kernel/bpf/syscall.c. Signed-off-by: Brian Vazquez <brianvv@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20200115184308.162644-2-brianvv@google.com
2020-01-09bpf: Introduce BPF_MAP_TYPE_STRUCT_OPSMartin KaFai Lau
The patch introduces BPF_MAP_TYPE_STRUCT_OPS. The map value is a kernel struct with its func ptr implemented in bpf prog. This new map is the interface to register/unregister/introspect a bpf implemented kernel struct. The kernel struct is actually embedded inside another new struct (or called the "value" struct in the code). For example, "struct tcp_congestion_ops" is embbeded in: struct bpf_struct_ops_tcp_congestion_ops { refcount_t refcnt; enum bpf_struct_ops_state state; struct tcp_congestion_ops data; /* <-- kernel subsystem struct here */ } The map value is "struct bpf_struct_ops_tcp_congestion_ops". The "bpftool map dump" will then be able to show the state ("inuse"/"tobefree") and the number of subsystem's refcnt (e.g. number of tcp_sock in the tcp_congestion_ops case). This "value" struct is created automatically by a macro. Having a separate "value" struct will also make extending "struct bpf_struct_ops_XYZ" easier (e.g. adding "void (*init)(void)" to "struct bpf_struct_ops_XYZ" to do some initialization works before registering the struct_ops to the kernel subsystem). The libbpf will take care of finding and populating the "struct bpf_struct_ops_XYZ" from "struct XYZ". Register a struct_ops to a kernel subsystem: 1. Load all needed BPF_PROG_TYPE_STRUCT_OPS prog(s) 2. Create a BPF_MAP_TYPE_STRUCT_OPS with attr->btf_vmlinux_value_type_id set to the btf id "struct bpf_struct_ops_tcp_congestion_ops" of the running kernel. Instead of reusing the attr->btf_value_type_id, btf_vmlinux_value_type_id s added such that attr->btf_fd can still be used as the "user" btf which could store other useful sysadmin/debug info that may be introduced in the furture, e.g. creation-date/compiler-details/map-creator...etc. 3. Create a "struct bpf_struct_ops_tcp_congestion_ops" object as described in the running kernel btf. Populate the value of this object. The function ptr should be populated with the prog fds. 4. Call BPF_MAP_UPDATE with the object created in (3) as the map value. The key is always "0". During BPF_MAP_UPDATE, the code that saves the kernel-func-ptr's args as an array of u64 is generated. BPF_MAP_UPDATE also allows the specific struct_ops to do some final checks in "st_ops->init_member()" (e.g. ensure all mandatory func ptrs are implemented). If everything looks good, it will register this kernel struct to the kernel subsystem. The map will not allow further update from this point. Unregister a struct_ops from the kernel subsystem: BPF_MAP_DELETE with key "0". Introspect a struct_ops: BPF_MAP_LOOKUP_ELEM with key "0". The map value returned will have the prog _id_ populated as the func ptr. The map value state (enum bpf_struct_ops_state) will transit from: INIT (map created) => INUSE (map updated, i.e. reg) => TOBEFREE (map value deleted, i.e. unreg) The kernel subsystem needs to call bpf_struct_ops_get() and bpf_struct_ops_put() to manage the "refcnt" in the "struct bpf_struct_ops_XYZ". This patch uses a separate refcnt for the purose of tracking the subsystem usage. Another approach is to reuse the map->refcnt and then "show" (i.e. during map_lookup) the subsystem's usage by doing map->refcnt - map->usercnt to filter out the map-fd/pinned-map usage. However, that will also tie down the future semantics of map->refcnt and map->usercnt. The very first subsystem's refcnt (during reg()) holds one count to map->refcnt. When the very last subsystem's refcnt is gone, it will also release the map->refcnt. All bpf_prog will be freed when the map->refcnt reaches 0 (i.e. during map_free()). Here is how the bpftool map command will look like: [root@arch-fb-vm1 bpf]# bpftool map show 6: struct_ops name dctcp flags 0x0 key 4B value 256B max_entries 1 memlock 4096B btf_id 6 [root@arch-fb-vm1 bpf]# bpftool map dump id 6 [{ "value": { "refcnt": { "refs": { "counter": 1 } }, "state": 1, "data": { "list": { "next": 0, "prev": 0 }, "key": 0, "flags": 2, "init": 24, "release": 0, "ssthresh": 25, "cong_avoid": 30, "set_state": 27, "cwnd_event": 28, "in_ack_event": 26, "undo_cwnd": 29, "pkts_acked": 0, "min_tso_segs": 0, "sndbuf_expand": 0, "cong_control": 0, "get_info": 0, "name": [98,112,102,95,100,99,116,99,112,0,0,0,0,0,0,0 ], "owner": 0 } } } ] Misc Notes: * bpf_struct_ops_map_sys_lookup_elem() is added for syscall lookup. It does an inplace update on "*value" instead returning a pointer to syscall.c. Otherwise, it needs a separate copy of "zero" value for the BPF_STRUCT_OPS_STATE_INIT to avoid races. * The bpf_struct_ops_map_delete_elem() is also called without preempt_disable() from map_delete_elem(). It is because the "->unreg()" may requires sleepable context, e.g. the "tcp_unregister_congestion_control()". * "const" is added to some of the existing "struct btf_func_model *" function arg to avoid a compiler warning caused by this patch. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20200109003505.3855919-1-kafai@fb.com
2020-01-09bpf: Introduce BPF_PROG_TYPE_STRUCT_OPSMartin KaFai Lau
This patch allows the kernel's struct ops (i.e. func ptr) to be implemented in BPF. The first use case in this series is the "struct tcp_congestion_ops" which will be introduced in a latter patch. This patch introduces a new prog type BPF_PROG_TYPE_STRUCT_OPS. The BPF_PROG_TYPE_STRUCT_OPS prog is verified against a particular func ptr of a kernel struct. The attr->attach_btf_id is the btf id of a kernel struct. The attr->expected_attach_type is the member "index" of that kernel struct. The first member of a struct starts with member index 0. That will avoid ambiguity when a kernel struct has multiple func ptrs with the same func signature. For example, a BPF_PROG_TYPE_STRUCT_OPS prog is written to implement the "init" func ptr of the "struct tcp_congestion_ops". The attr->attach_btf_id is the btf id of the "struct tcp_congestion_ops" of the _running_ kernel. The attr->expected_attach_type is 3. The ctx of BPF_PROG_TYPE_STRUCT_OPS is an array of u64 args saved by arch_prepare_bpf_trampoline that will be done in the next patch when introducing BPF_MAP_TYPE_STRUCT_OPS. "struct bpf_struct_ops" is introduced as a common interface for the kernel struct that supports BPF_PROG_TYPE_STRUCT_OPS prog. The supporting kernel struct will need to implement an instance of the "struct bpf_struct_ops". The supporting kernel struct also needs to implement a bpf_verifier_ops. During BPF_PROG_LOAD, bpf_struct_ops_find() will find the right bpf_verifier_ops by searching the attr->attach_btf_id. A new "btf_struct_access" is also added to the bpf_verifier_ops such that the supporting kernel struct can optionally provide its own specific check on accessing the func arg (e.g. provide limited write access). After btf_vmlinux is parsed, the new bpf_struct_ops_init() is called to initialize some values (e.g. the btf id of the supporting kernel struct) and it can only be done once the btf_vmlinux is available. The R0 checks at BPF_EXIT is excluded for the BPF_PROG_TYPE_STRUCT_OPS prog if the return type of the prog->aux->attach_func_proto is "void". Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20200109003503.3855825-1-kafai@fb.com
2019-12-19bpf: Support replacing cgroup-bpf program in MULTI modeAndrey Ignatov
The common use-case in production is to have multiple cgroup-bpf programs per attach type that cover multiple use-cases. Such programs are attached with BPF_F_ALLOW_MULTI and can be maintained by different people. Order of programs usually matters, for example imagine two egress programs: the first one drops packets and the second one counts packets. If they're swapped the result of counting program will be different. It brings operational challenges with updating cgroup-bpf program(s) attached with BPF_F_ALLOW_MULTI since there is no way to replace a program: * One way to update is to detach all programs first and then attach the new version(s) again in the right order. This introduces an interruption in the work a program is doing and may not be acceptable (e.g. if it's egress firewall); * Another way is attach the new version of a program first and only then detach the old version. This introduces the time interval when two versions of same program are working, what may not be acceptable if a program is not idempotent. It also imposes additional burden on program developers to make sure that two versions of their program can co-exist. Solve the problem by introducing a "replace" mode in BPF_PROG_ATTACH command for cgroup-bpf programs being attached with BPF_F_ALLOW_MULTI flag. This mode is enabled by newly introduced BPF_F_REPLACE attach flag and bpf_attr.replace_bpf_fd attribute to pass fd of the old program to replace That way user can replace any program among those attached with BPF_F_ALLOW_MULTI flag without the problems described above. Details of the new API: * If BPF_F_REPLACE is set but replace_bpf_fd doesn't have valid descriptor of BPF program, BPF_PROG_ATTACH will return corresponding error (EINVAL or EBADF). * If replace_bpf_fd has valid descriptor of BPF program but such a program is not attached to specified cgroup, BPF_PROG_ATTACH will return ENOENT. BPF_F_REPLACE is introduced to make the user intent clear, since replace_bpf_fd alone can't be used for this (its default value, 0, is a valid fd). BPF_F_REPLACE also makes it possible to extend the API in the future (e.g. add BPF_F_BEFORE and BPF_F_AFTER if needed). Signed-off-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Andrii Narkyiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/30cd850044a0057bdfcaaf154b7d2f39850ba813.1576741281.git.rdna@fb.com
2019-12-13bpf, xdp: Start using the BPF dispatcher for XDPBjörn Töpel
This commit adds a BPF dispatcher for XDP. The dispatcher is updated from the XDP control-path, dev_xdp_install(), and used when an XDP program is run via bpf_prog_run_xdp(). Signed-off-by: Björn Töpel <bjorn.topel@intel.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20191213175112.30208-4-bjorn.topel@gmail.com
2019-12-11bpf: Emit audit messages upon successful prog load and unloadDaniel Borkmann
Allow for audit messages to be emitted upon BPF program load and unload for having a timeline of events. The load itself is in syscall context, so additional info about the process initiating the BPF prog creation can be logged and later directly correlated to the unload event. The only info really needed from BPF side is the globally unique prog ID where then audit user space tooling can query / dump all info needed about the specific BPF program right upon load event and enrich the record, thus these changes needed here can be kept small and non-intrusive to the core. Raw example output: # auditctl -D # auditctl -a always,exit -F arch=x86_64 -S bpf # ausearch --start recent -m 1334 ... ---- time->Wed Nov 27 16:04:13 2019 type=PROCTITLE msg=audit(1574867053.120:84664): proctitle="./bpf" type=SYSCALL msg=audit(1574867053.120:84664): arch=c000003e syscall=321 \ success=yes exit=3 a0=5 a1=7ffea484fbe0 a2=70 a3=0 items=0 ppid=7477 \ pid=12698 auid=1001 uid=1001 gid=1001 euid=1001 suid=1001 fsuid=1001 \ egid=1001 sgid=1001 fsgid=1001 tty=pts2 ses=4 comm="bpf" \ exe="/home/jolsa/auditd/audit-testsuite/tests/bpf/bpf" \ subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 key=(null) type=UNKNOWN[1334] msg=audit(1574867053.120:84664): prog-id=76 op=LOAD ---- time->Wed Nov 27 16:04:13 2019 type=UNKNOWN[1334] msg=audit(1574867053.120:84665): prog-id=76 op=UNLOAD ... Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Co-developed-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Acked-by: Paul Moore <paul@paul-moore.com> Link: https://lore.kernel.org/bpf/20191206214934.11319-1-jolsa@kernel.org
2019-11-24bpf: Add poke dependency tracking for prog array mapsDaniel Borkmann
This work adds program tracking to prog array maps. This is needed such that upon prog array updates/deletions we can fix up all programs which make use of this tail call map. We add ops->map_poke_{un,}track() helpers to maps to maintain the list of programs and ops->map_poke_run() for triggering the actual update. bpf_array_aux is extended to contain the list head and poke_mutex in order to serialize program patching during updates/deletions. bpf_free_used_maps() will untrack the program shortly before dropping the reference to the map. For clearing out the prog array once all urefs are dropped we need to use schedule_work() to have a sleepable context. The prog_array_map_poke_run() is triggered during updates/deletions and walks the maintained prog list. It checks in their poke_tabs whether the map and key is matching and runs the actual bpf_arch_text_poke() for patching in the nop or new jmp location. Depending on the type of update, we use one of BPF_MOD_{NOP_TO_JUMP,JUMP_TO_NOP,JUMP_TO_JUMP}. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/1fb364bb3c565b3e415d5ea348f036ff379e779d.1574452833.git.daniel@iogearbox.net
2019-11-24bpf: Move owner type, jited info into array auxiliary dataDaniel Borkmann
We're going to extend this with further information which is only relevant for prog array at this point. Given this info is not used in critical path, move it into its own structure such that the main array map structure can be kept on diet. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/b9ddccdb0f6f7026489ee955f16c96381e1e7238.1574452833.git.daniel@iogearbox.net
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