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* BACKPORT: UPSTREAM: Add a eBPF helper function to retrieve socket uidChenbo Feng2022-04-19
| | | | | | | | | | | | | | | Cherry-pick from commit 6acc5c2910689fc6ee181bf63085c5efff6a42bd Returns the owner uid of the socket inside a sk_buff. This is useful to perform per-UID accounting of network traffic or per-UID packet filtering. The socket need to be a fullsock otherwise overflowuid is returned. Signed-off-by: Chenbo Feng <fengc@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Bug: 30950746 Change-Id: Idc00947ccfdd4e9f2214ffc4178d701cd9ead0ac Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* BACKPORT: UPSTREAM: Add a helper function to get socket cookie in eBPFChenbo Feng2022-04-19
| | | | | | | | | | | | | | | | | | | Cherrypick from commit: 91b8270f2a4d1d9b268de90451cdca63a70052d6 Retrieve the socket cookie generated by sock_gen_cookie() from a sk_buff with a known socket. Generates a new cookie if one was not yet set.If the socket pointer inside sk_buff is NULL, 0 is returned. The helper function coud be useful in monitoring per socket networking traffic statistics and provide a unique socket identifier per namespace. Acked-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Chenbo Feng <fengc@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Bug: 30950746 Change-Id: I95918dcc3ceffb3061495a859d28aee88e3cde3c Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: add helper to invalidate hashDaniel Borkmann2022-04-19
| | | | | | | | | | | Add a small helper that complements 36bbef52c7eb ("bpf: direct packet write and access for helpers for clsact progs") for invalidating the current skb->hash after mangling on headers via direct packet write. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* net: take compile fix from 4.9Anay Wadhera2022-04-19
| | | | Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* ip_tunnel: add support for setting flow label via collect metadataDaniel Borkmann2022-04-19
| | | | | | | | | | | | This patch extends udp_tunnel6_xmit_skb() to pass in the IPv6 flow label from call sites. Currently, there's no such option and it's always set to zero when writing ip6_flow_hdr(). Add a label member to ip_tunnel_key, so that flow-based tunnels via collect metadata frontends can make use of it. vxlan and geneve will be converted to add flow label support separately. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* vfs: Pass data, ns, and ns->userns to mount_nsEric W. Biederman2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Today what is normally called data (the mount options) is not passed to fill_super through mount_ns. Pass the mount options and the namespace separately to mount_ns so that filesystems such as proc that have mount options, can use mount_ns. Pass the user namespace to mount_ns so that the standard permission check that verifies the mounter has permissions over the namespace can be performed in mount_ns instead of in each filesystems .mount method. Thus removing the duplication between mqueuefs and proc in terms of permission checks. The extra permission check does not currently affect the rpc_pipefs filesystem and the nfsd filesystem as those filesystems do not currently allow unprivileged mounts. Without unpvileged mounts it is guaranteed that the caller has already passed capable(CAP_SYS_ADMIN) which guarantees extra permission check will pass. Update rpc_pipefs and the nfsd filesystem to ensure that the network namespace reference is always taken in fill_super and always put in kill_sb so that the logic is simpler and so that errors originating inside of fill_super do not cause a network namespace leak. Acked-by: Seth Forshee <seth.forshee@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* UPSTREAM: cgroup: move CONFIG_SOCK_CGROUP_DATA to init/KconfigArnd Bergmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | We now 'select SOCK_CGROUP_DATA' but Kconfig complains that this is not right when CONFIG_NET is disabled and there is no socket interface: warning: (CGROUP_BPF) selects SOCK_CGROUP_DATA which has unmet direct dependencies (NET) I don't know what the correct solution for this is, but simply removing the dependency on NET from SOCK_CGROUP_DATA by moving it out of the 'if NET' section avoids the warning and does not produce other build errors. Fixes: 483c4933ea09 ("cgroup: Fix CGROUP_BPF config") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: David S. Miller <davem@davemloft.net> Fixes: Change-Id: Ib41ef78fba02eb9e592558ddbf06f9ec0aa337b6 ("UPSTREAM: cgroup: Fix CGROUP_BPF config") (cherry picked from commit 73b351473547e543e9c8166dd67fd99c64c15b0b) Signed-off-by: Amit Pundir <amit.pundir@linaro.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: add bpf_jit_limit knob to restrict unpriv allocationsDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit ede95a63b5e84ddeea6b0c473b36ab8bfd8c6ce3 upstream. Rick reported that the BPF JIT could potentially fill the entire module space with BPF programs from unprivileged users which would prevent later attempts to load normal kernel modules or privileged BPF programs, for example. If JIT was enabled but unsuccessful to generate the image, then before commit 290af86629b2 ("bpf: introduce BPF_JIT_ALWAYS_ON config") we would always fall back to the BPF interpreter. Nowadays in the case where the CONFIG_BPF_JIT_ALWAYS_ON could be set, then the load will abort with a failure since the BPF interpreter was compiled out. Add a global limit and enforce it for unprivileged users such that in case of BPF interpreter compiled out we fail once the limit has been reached or we fall back to BPF interpreter earlier w/o using module mem if latter was compiled in. In a next step, fair share among unprivileged users can be resolved in particular for the case where we would fail hard once limit is reached. Fixes: 290af86629b2 ("bpf: introduce BPF_JIT_ALWAYS_ON config") Fixes: 0a14842f5a3c ("net: filter: Just In Time compiler for x86-64") Co-Developed-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Jann Horn <jannh@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: LKML <linux-kernel@vger.kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> [bwh: Backported to 4.9: adjust context] Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: restrict access to core bpf sysctlsDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | commit 2e4a30983b0f9b19b59e38bbf7427d7fdd480d98 upstream. Given BPF reaches far beyond just networking these days, it was never intended to allow setting and in some cases reading those knobs out of a user namespace root running without CAP_SYS_ADMIN, thus tighten such access. Also the bpf_jit_enable = 2 debugging mode should only be allowed if kptr_restrict is not set since it otherwise can leak addresses to the kernel log. Dump a note to the kernel log that this is for debugging JITs only when enabled. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> [bwh: Backported to 4.9: - We don't have bpf_dump_raw_ok(), so drop the condition based on it. This condition only made it a bit harder for a privileged user to do something silly. - Drop change to bpf_jit_kallsyms] Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: get rid of pure_initcall dependency to enable jitsDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | commit fa9dd599b4dae841924b022768354cfde9affecb upstream. Having a pure_initcall() callback just to permanently enable BPF JITs under CONFIG_BPF_JIT_ALWAYS_ON is unnecessary and could leave a small race window in future where JIT is still disabled on boot. Since we know about the setting at compilation time anyway, just initialize it properly there. Also consolidate all the individual bpf_jit_enable variables into a single one and move them under one location. Moreover, don't allow for setting unspecified garbage values on them. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> [bwh: Backported to 4.9 as dependency of commit 2e4a30983b0f "bpf: restrict access to core bpf sysctls": - Drop change in arch/mips/net/ebpf_jit.c - Drop change to bpf_jit_kallsyms - Adjust filenames, context] Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* BACKPORT: fix "netfilter: xt_bpf: Fix XT_BPF_MODE_FD_PINNED mode of ↵Al Viro2022-04-19
| | | | | | | | | | | | | | | | | | | | 'xt_bpf_info_v1'" Descriptor table is a shared object; it's not a place where you can stick temporary references to files, especially when we don't need an opened file at all. Cc: stable@vger.kernel.org # v4.14 Fixes: 98589a0998b8 ("netfilter: xt_bpf: Fix XT_BPF_MODE_FD_PINNED mode of 'xt_bpf_info_v1'") Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Chenbo Feng <fengc@google.com> Removed the code related to function bpf_prog_get_ok() since it is not exsit in current android tree. (cherry picked from commit 040ee69226f8a96b7943645d68f41d5d44b5ff7d) Change-Id: If7a602128cdea4b4b50c8effb215c9bca7449515 Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* UPSTREAM: netfilter: xt_bpf: add overflow checksJann Horn2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Check whether inputs from userspace are too long (explicit length field too big or string not null-terminated) to avoid out-of-bounds reads. As far as I can tell, this can at worst lead to very limited kernel heap memory disclosure or oopses. This bug can be triggered by an unprivileged user even if the xt_bpf module is not loaded: iptables is available in network namespaces, and the xt_bpf module can be autoloaded. Triggering the bug with a classic BPF filter with fake length 0x1000 causes the following KASAN report: ================================================================== BUG: KASAN: slab-out-of-bounds in bpf_prog_create+0x84/0xf0 Read of size 32768 at addr ffff8801eff2c494 by task test/4627 CPU: 0 PID: 4627 Comm: test Not tainted 4.15.0-rc1+ #1 [...] Call Trace: dump_stack+0x5c/0x85 print_address_description+0x6a/0x260 kasan_report+0x254/0x370 ? bpf_prog_create+0x84/0xf0 memcpy+0x1f/0x50 bpf_prog_create+0x84/0xf0 bpf_mt_check+0x90/0xd6 [xt_bpf] [...] Allocated by task 4627: kasan_kmalloc+0xa0/0xd0 __kmalloc_node+0x47/0x60 xt_alloc_table_info+0x41/0x70 [x_tables] [...] The buggy address belongs to the object at ffff8801eff2c3c0 which belongs to the cache kmalloc-2048 of size 2048 The buggy address is located 212 bytes inside of 2048-byte region [ffff8801eff2c3c0, ffff8801eff2cbc0) [...] ================================================================== Fixes: e6f30c731718 ("netfilter: x_tables: add xt_bpf match") Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Chenbo Feng <fengc@google.com> (cherry picked from commit 6ab405114b0b229151ef06f4e31c7834dd09d0c0) Change-Id: Ie066a9df84812853a9c9d2e51aa53646f4001542 Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* UPSTREAM: netfilter: xt_bpf: Fix XT_BPF_MODE_FD_PINNED mode of 'xt_bpf_info_v1'Shmulik Ladkani2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 2c16d6033264 ("netfilter: xt_bpf: support ebpf") introduced support for attaching an eBPF object by an fd, with the 'bpf_mt_check_v1' ABI expecting the '.fd' to be specified upon each IPT_SO_SET_REPLACE call. However this breaks subsequent iptables calls: # iptables -A INPUT -m bpf --object-pinned /sys/fs/bpf/xxx -j ACCEPT # iptables -A INPUT -s 5.6.7.8 -j ACCEPT iptables: Invalid argument. Run `dmesg' for more information. That's because iptables works by loading existing rules using IPT_SO_GET_ENTRIES to userspace, then issuing IPT_SO_SET_REPLACE with the replacement set. However, the loaded 'xt_bpf_info_v1' has an arbitrary '.fd' number (from the initial "iptables -m bpf" invocation) - so when 2nd invocation occurs, userspace passes a bogus fd number, which leads to 'bpf_mt_check_v1' to fail. One suggested solution [1] was to hack iptables userspace, to perform a "entries fixup" immediatley after IPT_SO_GET_ENTRIES, by opening a new, process-local fd per every 'xt_bpf_info_v1' entry seen. However, in [2] both Pablo Neira Ayuso and Willem de Bruijn suggested to depricate the xt_bpf_info_v1 ABI dealing with pinned ebpf objects. This fix changes the XT_BPF_MODE_FD_PINNED behavior to ignore the given '.fd' and instead perform an in-kernel lookup for the bpf object given the provided '.path'. It also defines an alias for the XT_BPF_MODE_FD_PINNED mode, named XT_BPF_MODE_PATH_PINNED, to better reflect the fact that the user is expected to provide the path of the pinned object. Existing XT_BPF_MODE_FD_ELF behavior (non-pinned fd mode) is preserved. References: [1] https://marc.info/?l=netfilter-devel&m=150564724607440&w=2 [2] https://marc.info/?l=netfilter-devel&m=150575727129880&w=2 Reported-by: Rafael Buchbinder <rafi@rbk.ms> Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com> Acked-by: Willem de Bruijn <willemb@google.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Chenbo Feng <fengc@google.com> (cherry picked from commit 98589a0998b8b13c4a8fa1ccb0e62751a019faa5) Change-Id: Ia0d15a76823cca3afb38786a3d2c25c13ccf941d Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* UPSTREAM: netfilter: xt_bpf: support ebpfWillem de Bruijn2022-04-19
| | | | | | | | | | | | | | | Add support for attaching an eBPF object by file descriptor. The iptables binary can be called with a path to an elf object or a pinned bpf object. Also pass the mode and path to the kernel to be able to return it later for iptables dump and save. Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Chenbo Feng <fengc@google.com> (cherry picked from commit 2c16d60332643e90d4fa244f4a706c454b8c7569) Change-Id: I31b8831a7ffd7c44985ee906ff194c1d934dafbe
* bpf: fix 32-bit divide by zeroAlexei Starovoitov2022-04-19
| | | | | | | | | | | | | | | | [ upstream commit 68fda450a7df51cff9e5a4d4a4d9d0d5f2589153 ] due to some JITs doing if (src_reg == 0) check in 64-bit mode for div/mod operations mask upper 32-bits of src register before doing the check Fixes: 622582786c9e ("net: filter: x86: internal BPF JIT") Fixes: 7a12b5031c6b ("sparc64: Add eBPF JIT.") Reported-by: syzbot+48340bb518e88849e2e3@syzkaller.appspotmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: introduce BPF_JIT_ALWAYS_ON configAlexei Starovoitov2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ upstream commit 290af86629b25ffd1ed6232c4e9107da031705cb ] The BPF interpreter has been used as part of the spectre 2 attack CVE-2017-5715. A quote from goolge project zero blog: "At this point, it would normally be necessary to locate gadgets in the host kernel code that can be used to actually leak data by reading from an attacker-controlled location, shifting and masking the result appropriately and then using the result of that as offset to an attacker-controlled address for a load. But piecing gadgets together and figuring out which ones work in a speculation context seems annoying. So instead, we decided to use the eBPF interpreter, which is built into the host kernel - while there is no legitimate way to invoke it from inside a VM, the presence of the code in the host kernel's text section is sufficient to make it usable for the attack, just like with ordinary ROP gadgets." To make attacker job harder introduce BPF_JIT_ALWAYS_ON config option that removes interpreter from the kernel in favor of JIT-only mode. So far eBPF JIT is supported by: x64, arm64, arm32, sparc64, s390, powerpc64, mips64 The start of JITed program is randomized and code page is marked as read-only. In addition "constant blinding" can be turned on with net.core.bpf_jit_harden v2->v3: - move __bpf_prog_ret0 under ifdef (Daniel) v1->v2: - fix init order, test_bpf and cBPF (Daniel's feedback) - fix offloaded bpf (Jakub's feedback) - add 'return 0' dummy in case something can invoke prog->bpf_func - retarget bpf tree. For bpf-next the patch would need one extra hunk. It will be sent when the trees are merged back to net-next Considered doing: int bpf_jit_enable __read_mostly = BPF_EBPF_JIT_DEFAULT; but it seems better to land the patch as-is and in bpf-next remove bpf_jit_enable global variable from all JITs, consolidate in one place and remove this jit_init() function. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* UPSTREAM: bpf: add new prog type for cgroup socket filteringDaniel Mack2022-04-19
| | | | | | | | | | | | | | | | | | Cherry-pick from commit 0e33661de493db325435d565a4a722120ae4cbf3 This program type is similar to BPF_PROG_TYPE_SOCKET_FILTER, except that it does not allow BPF_LD_[ABS|IND] instructions and hooks up the bpf_skb_load_bytes() helper. Programs of this type will be attached to cgroups for network filtering and accounting. Signed-off-by: Daniel Mack <daniel@zonque.org> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Bug: 30950746 Change-Id: I7b9e063d5d7a91da80917c6d353a60b877133752 Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* BACKPORT: UPSTREAM: bpf: pass sk to helper functionsWillem de Bruijn2022-04-19
| | | | | | | | | | | | | | | | | | Cherrypick from commit 8f917bba0042f1e3b7693743fbe9782709e936e7 BPF helper functions access socket fields through skb->sk. This is not set in ingress cgroup and socket filters. The association is only made in skb_set_owner_r once the filter has accepted the packet. Sk is available as socket lookup has taken place. Temporarily set skb->sk to sk in these cases. Signed-off-by: Willem de Bruijn <willemb@google.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Bug: 30950746 Change-Id: Ifcbcbe2ab2882dc79c56f9707be1d6aef08c7fd3 Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* kernel: add a helper to get an owning user namespace for a namespaceAndrey Vagin2022-04-19
| | | | | | | | | | | | | | | | Return -EPERM if an owning user namespace is outside of a process current user namespace. v2: In a first version ns_get_owner returned ENOENT for init_user_ns. This special cases was removed from this version. There is nothing outside of init_user_ns, so we can return EPERM. v3: rename ns->get_owner() to ns->owner(). get_* usually means that it grabs a reference. Acked-by: Serge Hallyn <serge@hallyn.com> Signed-off-by: Andrei Vagin <avagin@openvz.org> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* cgroup: duplicate cgroup reference when cloning socketsJohannes Weiner2022-04-19
| | | | | | | | | | | | | | | | | When a socket is cloned, the associated sock_cgroup_data is duplicated but not its reference on the cgroup. As a result, the cgroup reference count will underflow when both sockets are destroyed later on. Fixes: bd1060a1d671 ("sock, cgroup: add sock->sk_cgroup") Link: http://lkml.kernel.org/r/20160914194846.11153-2-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Tejun Heo <tj@kernel.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: <stable@vger.kernel.org> [4.5+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* sock, cgroup: add sock->sk_cgroupTejun Heo2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In cgroup v1, dealing with cgroup membership was difficult because the number of membership associations was unbound. As a result, cgroup v1 grew several controllers whose primary purpose is either tagging membership or pull in configuration knobs from other subsystems so that cgroup membership test can be avoided. net_cls and net_prio controllers are examples of the latter. They allow configuring network-specific attributes from cgroup side so that network subsystem can avoid testing cgroup membership; unfortunately, these are not only cumbersome but also problematic. Both net_cls and net_prio aren't properly hierarchical. Both inherit configuration from the parent on creation but there's no interaction afterwards. An ancestor doesn't restrict the behavior in its subtree in anyway and configuration changes aren't propagated downwards. Especially when combined with cgroup delegation, this is problematic because delegatees can mess up whatever network configuration implemented at the system level. net_prio would allow the delegatees to set whatever priority value regardless of CAP_NET_ADMIN and net_cls the same for classid. While it is possible to solve these issues from controller side by implementing hierarchical allowable ranges in both controllers, it would involve quite a bit of complexity in the controllers and further obfuscate network configuration as it becomes even more difficult to tell what's actually being configured looking from the network side. While not much can be done for v1 at this point, as membership handling is sane on cgroup v2, it'd be better to make cgroup matching behave like other network matches and classifiers than introducing further complications. In preparation, this patch updates sock->sk_cgrp_data handling so that it points to the v2 cgroup that sock was created in until either net_prio or net_cls is used. Once either of the two is used, sock->sk_cgrp_data reverts to its previous role of carrying prioidx and classid. This is to avoid adding yet another cgroup related field to struct sock. As the mode switching can happen at most once per boot, the switching mechanism is aimed at lowering hot path overhead. It may leak a finite, likely small, number of cgroup refs and report spurious prioidx or classid on switching; however, dynamic updates of prioidx and classid have always been racy and lossy - socks between creation and fd installation are never updated, config changes don't update existing sockets at all, and prioidx may index with dead and recycled cgroup IDs. Non-critical inaccuracies from small race windows won't make any noticeable difference. This patch doesn't make use of the pointer yet. The following patch will implement netfilter match for cgroup2 membership. v2: Use sock_cgroup_data to avoid inflating struct sock w/ another cgroup specific field. v3: Add comments explaining why sock_data_prioidx() and sock_data_classid() use different fallback values. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Daniel Wagner <daniel.wagner@bmw-carit.de> CC: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* net: wrap sock->sk_cgrp_prioidx and ->sk_classid inside a structTejun Heo2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | Introduce sock->sk_cgrp_data which is a struct sock_cgroup_data. ->sk_cgroup_prioidx and ->sk_classid are moved into it. The struct and its accessors are defined in cgroup-defs.h. This is to prepare for overloading the fields with a cgroup pointer. This patch mostly performs equivalent conversions but the followings are noteworthy. * Equality test before updating classid is removed from sock_update_classid(). This shouldn't make any noticeable difference and a similar test will be implemented on the helper side later. * sock_update_netprioidx() now takes struct sock_cgroup_data and can be moved to netprio_cgroup.h without causing include dependency loop. Moved. * The dummy version of sock_update_netprioidx() converted to a static inline function while at it. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* netprio_cgroup: limit the maximum css->id to USHRT_MAXTejun Heo2022-04-19
| | | | | | | | | | | | | | | | | | | | netprio builds per-netdev contiguous priomap array which is indexed by css->id. The array is allocated using kzalloc() effectively limiting the maximum ID supported to some thousand range. This patch caps the maximum supported css->id to USHRT_MAX which should be way above what is actually useable. This allows reducing sock->sk_cgrp_prioidx to u16 from u32. The freed up part will be used to overload the cgroup related fields. sock->sk_cgrp_prioidx's position is swapped with sk_mark so that the two cgroup related fields are adjacent. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de> Cc: Daniel Borkmann <daniel@iogearbox.net> CC: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: direct packet write and access for helpers for clsact progsDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This work implements direct packet access for helpers and direct packet write in a similar fashion as already available for XDP types via commits 4acf6c0b84c9 ("bpf: enable direct packet data write for xdp progs") and 6841de8b0d03 ("bpf: allow helpers access the packet directly"), and as a complementary feature to the already available direct packet read for tc (cls/act) programs. For enabling this, we need to introduce two helpers, bpf_skb_pull_data() and bpf_csum_update(). The first is generally needed for both, read and write, because they would otherwise only be limited to the current linear skb head. Usually, when the data_end test fails, programs just bail out, or, in the direct read case, use bpf_skb_load_bytes() as an alternative to overcome this limitation. If such data sits in non-linear parts, we can just pull them in once with the new helper, retest and eventually access them. At the same time, this also makes sure the skb is uncloned, which is, of course, a necessary condition for direct write. As this needs to be an invariant for the write part only, the verifier detects writes and adds a prologue that is calling bpf_skb_pull_data() to effectively unclone the skb from the very beginning in case it is indeed cloned. The heuristic makes use of a similar trick that was done in 233577a22089 ("net: filter: constify detection of pkt_type_offset"). This comes at zero cost for other programs that do not use the direct write feature. Should a program use this feature only sparsely and has read access for the most parts with, for example, drop return codes, then such write action can be delegated to a tail called program for mitigating this cost of potential uncloning to a late point in time where it would have been paid similarly with the bpf_skb_store_bytes() as well. Advantage of direct write is that the writes are inlined whereas the helper cannot make any length assumptions and thus needs to generate a call to memcpy() also for small sizes, as well as cost of helper call itself with sanity checks are avoided. Plus, when direct read is already used, we don't need to cache or perform rechecks on the data boundaries (due to verifier invalidating previous checks for helpers that change skb->data), so more complex programs using rewrites can benefit from switching to direct read plus write. For direct packet access to helpers, we save the otherwise needed copy into a temp struct sitting on stack memory when use-case allows. Both facilities are enabled via may_access_direct_pkt_data() in verifier. For now, we limit this to map helpers and csum_diff, and can successively enable other helpers where we find it makes sense. Helpers that definitely cannot be allowed for this are those part of bpf_helper_changes_skb_data() since they can change underlying data, and those that write into memory as this could happen for packet typed args when still cloned. bpf_csum_update() helper accommodates for the fact that we need to fixup checksum_complete when using direct write instead of bpf_skb_store_bytes(), meaning the programs can use available helpers like bpf_csum_diff(), and implement csum_add(), csum_sub(), csum_block_add(), csum_block_sub() equivalents in eBPF together with the new helper. A usage example will be provided for iproute2's examples/bpf/ directory. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: add BPF_CALL_x macros for declaring helpersDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This work adds BPF_CALL_<n>() macros and converts all the eBPF helper functions to use them, in a similar fashion like we do with SYSCALL_DEFINE<n>() macros that are used today. Motivation for this is to hide all the register handling and all necessary casts from the user, so that it is done automatically in the background when adding a BPF_CALL_<n>() call. This makes current helpers easier to review, eases to write future helpers, avoids getting the casting mess wrong, and allows for extending all helpers at once (f.e. build time checks, etc). It also helps detecting more easily in code reviews that unused registers are not instrumented in the code by accident, breaking compatibility with existing programs. BPF_CALL_<n>() internals are quite similar to SYSCALL_DEFINE<n>() ones with some fundamental differences, for example, for generating the actual helper function that carries all u64 regs, we need to fill unused regs, so that we always end up with 5 u64 regs as an argument. I reviewed several 0-5 generated BPF_CALL_<n>() variants of the .i results and they look all as expected. No sparse issue spotted. We let this also sit for a few days with Fengguang's kbuild test robot, and there were no issues seen. On s390, it barked on the "uses dynamic stack allocation" notice, which is an old one from bpf_perf_event_output{,_tp}() reappearing here due to the conversion to the call wrapper, just telling that the perf raw record/frag sits on stack (gcc with s390's -mwarn-dynamicstack), but that's all. Did various runtime tests and they were fine as well. All eBPF helpers are now converted to use these macros, getting rid of a good chunk of all the raw castings. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: fix checksum for vlan push/pop helperDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When having skbs on ingress with CHECKSUM_COMPLETE, tc BPF programs don't push rcsum of mac header back in and after BPF run back pull out again as opposed to some other subsystems (ovs, for example). For cases like q-in-q, meaning when a vlan tag for offloading is already present and we're about to push another one, then skb_vlan_push() pushes the inner one into the skb, increasing mac header and skb_postpush_rcsum()'ing the 4 bytes vlan header diff. Likewise, for the reverse operation in skb_vlan_pop() for the case where vlan header needs to be pulled out of the skb, we're decreasing the mac header and skb_postpull_rcsum()'ing the 4 bytes rcsum of the vlan header that was removed. However mangling the rcsum here will lead to hw csum failure for BPF case, since we're pulling or pushing data that was not part of the current rcsum. Changing tc BPF programs in general to push/pull rcsum around BPF_PROG_RUN() is also not really an option since current behaviour is ABI by now, but apart from that would also mean to do quite a bit of useless work in the sense that usually 12 bytes need to be rcsum pushed/pulled also when we don't need to touch this vlan related corner case. One way to fix it would be to push the necessary rcsum fixup down into vlan helpers that are (mostly) slow-path anyway. Fixes: 4e10df9a60d9 ("bpf: introduce bpf_skb_vlan_push/pop() helpers") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: fix checksum fixups on bpf_skb_store_bytesDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | bpf_skb_store_bytes() invocations above L2 header need BPF_F_RECOMPUTE_CSUM flag for updates, so that CHECKSUM_COMPLETE will be fixed up along the way. Where we ran into an issue with bpf_skb_store_bytes() is when we did a single-byte update on the IPv6 hoplimit despite using BPF_F_RECOMPUTE_CSUM flag; simple ping via ICMPv6 triggered a hw csum failure as a result. The underlying issue has been tracked down to a buffer alignment issue. Meaning, that csum_partial() computations via skb_postpull_rcsum() and skb_postpush_rcsum() pair invoked had a wrong result since they operated on an odd address for the hoplimit, while other computations were done on an even address. This mix doesn't work as-is with skb_postpull_rcsum(), skb_postpush_rcsum() pair as it always expects at least half-word alignment of input buffers, which is normally the case. Thus, instead of these helpers using csum_sub() and (implicitly) csum_add(), we need to use csum_block_sub(), csum_block_add(), respectively. For unaligned offsets, they rotate the sum to align it to a half-word boundary again, otherwise they work the same as csum_sub() and csum_add(). Adding __skb_postpull_rcsum(), __skb_postpush_rcsum() variants that take the offset as an input and adapting bpf_skb_store_bytes() to them fixes the hw csum failures again. The skb_postpull_rcsum(), skb_postpush_rcsum() helpers use a 0 constant for offset so that the compiler optimizes the offset & 1 test away and generates the same code as with csum_sub()/_add(). Fixes: 608cd71a9c7c ("tc: bpf: generalize pedit action") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: also call skb_postpush_rcsum on xmit occasionsDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | Follow-up to commit f8ffad69c9f8 ("bpf: add skb_postpush_rcsum and fix dev_forward_skb occasions") to fix an issue for dev_queue_xmit() redirect locations which need CHECKSUM_COMPLETE fixups on ingress. For the same reasons as described in f8ffad69c9f8 already, we of course also need this here, since dev_queue_xmit() on a veth device will let us end up in the dev_forward_skb() helper again to cross namespaces. Latter then calls into skb_postpull_rcsum() to pull out L2 header, so that netif_rx_internal() sees CHECKSUM_COMPLETE as it is expected. That is, CHECKSUM_COMPLETE on ingress covering L2 _payload_, not L2 headers. Also here we have to address bpf_redirect() and bpf_clone_redirect(). Fixes: 3896d655f4d4 ("bpf: introduce bpf_clone_redirect() helper") Fixes: 27b29f63058d ("bpf: add bpf_redirect() helper") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: enforce recursion limit on redirectsDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | Respect the stack's xmit_recursion limit for calls into dev_queue_xmit(). Currently, they are not handeled by the limiter when attached to clsact's egress parent, for example, and a buggy program redirecting it to the same device again could run into stack overflow eventually. It would be good if we could notify an admin to give him a chance to react. We reuse xmit_recursion instead of having one private to eBPF, so that the stack's current recursion depth will be taken into account as well. Follow-up to commit 3896d655f4d4 ("bpf: introduce bpf_clone_redirect() helper") and 27b29f63058d ("bpf: add bpf_redirect() helper"). Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: add own ctx rewriter on ifindex for clsact progsDaniel Borkmann2022-04-19
| | | | | | | | | | | When fetching ifindex, we don't need to test dev for being NULL since we're always guaranteed to have a valid dev for clsact programs. Thus, avoid this test in fast path. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: add BPF_SIZEOF and BPF_FIELD_SIZEOF macrosDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | Add BPF_SIZEOF() and BPF_FIELD_SIZEOF() macros to improve the code a bit which otherwise often result in overly long bytes_to_bpf_size(sizeof()) and bytes_to_bpf_size(FIELD_SIZEOF()) lines. So place them into a macro helper instead. Moreover, we currently have a BUILD_BUG_ON(BPF_FIELD_SIZEOF()) check in convert_bpf_extensions(), but we should rather make that generic as well and add a BUILD_BUG_ON() test in all BPF_SIZEOF()/BPF_FIELD_SIZEOF() users to detect any rewriter size issues at compile time. Note, there are currently none, but we want to assert that it stays this way. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: minor cleanups in helpersDaniel Borkmann2022-04-19
| | | | | | | | | | | | Some minor misc cleanups, f.e. use sizeof(__u32) instead of hardcoding and in __bpf_skb_max_len(), I missed that we always have skb->dev valid anyway, so we can drop the unneeded test for dev; also few more other misc bits addressed here. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: get rid of cgroup helper related ifdefsDaniel Borkmann2022-04-19
| | | | | | | | | | | | As recently discussed during the task_under_cgroup_hierarchy() addition, we should get rid of the ifdefs surrounding the bpf_skb_under_cgroup() helper. If related functionality is not built-in, the helper cannot be used anyway, which is also in line with what we do for all other helpers. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: enable event output helper also for xdp typesDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | Follow-up to 555c8a8623a3 ("bpf: avoid stack copy and use skb ctx for event output") for also adding the event output helper for XDP typed programs. The event output helper has been very useful in particular for debugging or event notification purposes, since it's much faster and flexible than regular trace printk due to programmatically being able to attach meta data. Same flags structure applies as with tc BPF programs. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: add bpf_skb_change_tail helperDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | This work adds a bpf_skb_change_tail() helper for tc BPF programs. The basic idea is to expand or shrink the skb in a controlled manner. The eBPF program can then rewrite the rest via helpers like bpf_skb_store_bytes(), bpf_lX_csum_replace() and others rather than passing a raw buffer for writing here. bpf_skb_change_tail() is really a slow path helper and intended for replies with f.e. ICMP control messages. Concept is similar to other helpers like bpf_skb_change_proto() helper to keep the helper without protocol specifics and let the BPF program mangle the remaining parts. A flags field has been added and is reserved for now should we extend the helper in future. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: use skb_pkt_type_ok helper in bpf_skb_change_typeDaniel Borkmann2022-04-19
| | | | | | | | | | | | | Since we have a skb_pkt_type_ok() helper for checking the type before mangling, make use of it instead of open coding. Follow-up to commit 8b10cab64c13 ("net: simplify and make pkt_type_ok() available for other users") that came in after d2485c4242a8 ("bpf: add bpf_skb_change_type helper"). Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: fix write helpers with regards to non-linear partsDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix the bpf_try_make_writable() helper and all call sites we have in BPF, it's currently defect with regards to skbs when the write_len spans into non-linear parts, no matter if cloned or not. There are multiple issues at once. First, using skb_store_bits() is not correct since even if we have a cloned skb, page frags can still be shared. To really make them private, we need to pull them in via __pskb_pull_tail() first, which also gets us a private head via pskb_expand_head() implicitly. This is for helpers like bpf_skb_store_bytes(), bpf_l3_csum_replace(), bpf_l4_csum_replace(). Really, the only thing reasonable and working here is to call skb_ensure_writable() before any write operation. Meaning, via pskb_may_pull() it makes sure that parts we want to access are pulled in and if not does so plus unclones the skb implicitly. If our write_len still fits the headlen and we're cloned and our header of the clone is not writable, then we need to make a private copy via pskb_expand_head(). skb_store_bits() is a bit misleading and only safe to store into non-linear data in different contexts such as 357b40a18b04 ("[IPV6]: IPV6_CHECKSUM socket option can corrupt kernel memory"). For above BPF helper functions, it means after fixed bpf_try_make_writable(), we've pulled in enough, so that we operate always based on skb->data. Thus, the call to skb_header_pointer() and skb_store_bits() becomes superfluous. In bpf_skb_store_bytes(), the len check is unnecessary too since it can only pass in maximum of BPF stack size, so adding offset is guaranteed to never overflow. Also bpf_l3/4_csum_replace() helpers must test for proper offset alignment since they use __sum16 pointer for writing resulting csum. The remaining helpers that change skb data not discussed here yet are bpf_skb_vlan_push(), bpf_skb_vlan_pop() and bpf_skb_change_proto(). The vlan helpers internally call either skb_ensure_writable() (pop case) and skb_cow_head() (push case, for head expansion), respectively. Similarly, bpf_skb_proto_xlat() takes care to not mangle page frags. Fixes: 608cd71a9c7c ("tc: bpf: generalize pedit action") Fixes: 91bc4822c3d6 ("tc: bpf: add checksum helpers") Fixes: 3697649ff29e ("bpf: try harder on clones when writing into skb") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: fix bpf_skb_in_cgroup helper namingDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | While hashing out BPF's current_task_under_cgroup helper bits, it came to discussion that the skb_in_cgroup helper name was suboptimally chosen. Tejun says: So, I think in_cgroup should mean that the object is in that particular cgroup while under_cgroup in the subhierarchy of that cgroup. Let's rename the other subhierarchy test to under too. I think that'd be a lot less confusing going forward. [...] It's more intuitive and gives us the room to implement the real "in" test if ever necessary in the future. Since this touches uapi bits, we need to change this as long as v4.8 is not yet officially released. Thus, change the helper enum and rename related bits. Fixes: 4a482f34afcc ("cgroup: bpf: Add bpf_skb_in_cgroup_proto") Reference: http://patchwork.ozlabs.org/patch/658500/ Suggested-by: Sargun Dhillon <sargun@sargun.me> Suggested-by: Tejun Heo <tj@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: add bpf_get_hash_recalc helperDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | If skb_clear_hash() was invoked due to mangling of relevant headers and BPF program needs skb->hash later on, we can add a helper to trigger hash recalculation via bpf_get_hash_recalc(). The helper will return the newly retrieved hash directly, but later access can also be done via skb context again through skb->hash directly (inline) without needing to call the helper once more. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: add XDP prog type for early driver filterBrenden Blanco2022-04-19
| | | | | | | | | | | | | | | | | | Add a new bpf prog type that is intended to run in early stages of the packet rx path. Only minimal packet metadata will be available, hence a new context type, struct xdp_md, is exposed to userspace. So far only expose the packet start and end pointers, and only in read mode. An XDP program must return one of the well known enum values, all other return codes are reserved for future use. Unfortunately, this restriction is hard to enforce at verification time, so take the approach of warning at runtime when such programs are encountered. Out of bounds return codes should alias to XDP_ABORTED. Signed-off-by: Brenden Blanco <bblanco@plumgrid.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: wire in data and data_end for cls_act_bpfAlexei Starovoitov2022-04-19
| | | | | | | | | | | | | | allow cls_bpf and act_bpf programs access skb->data and skb->data_end pointers. The bpf helpers that change skb->data need to update data_end pointer as well. The verifier checks that programs always reload data, data_end pointers after calls to such bpf helpers. We cannot add 'data_end' pointer to struct qdisc_skb_cb directly, since it's embedded as-is by infiniband ipoib, so wrapper struct is needed. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: avoid stack copy and use skb ctx for event outputDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This work addresses a couple of issues bpf_skb_event_output() helper currently has: i) We need two copies instead of just a single one for the skb data when it should be part of a sample. The data can be non-linear and thus needs to be extracted via bpf_skb_load_bytes() helper first, and then copied once again into the ring buffer slot. ii) Since bpf_skb_load_bytes() currently needs to be used first, the helper needs to see a constant size on the passed stack buffer to make sure BPF verifier can do sanity checks on it during verification time. Thus, just passing skb->len (or any other non-constant value) wouldn't work, but changing bpf_skb_load_bytes() is also not the proper solution, since the two copies are generally still needed. iii) bpf_skb_load_bytes() is just for rather small buffers like headers, since they need to sit on the limited BPF stack anyway. Instead of working around in bpf_skb_load_bytes(), this work improves the bpf_skb_event_output() helper to address all 3 at once. We can make use of the passed in skb context that we have in the helper anyway, and use some of the reserved flag bits as a length argument. The helper will use the new __output_custom() facility from perf side with bpf_skb_copy() as callback helper to walk and extract the data. It will pass the data for setup to bpf_event_output(), which generates and pushes the raw record with an additional frag part. The linear data used in the first frag of the record serves as programmatically defined meta data passed along with the appended sample. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* cgroup: bpf: Add bpf_skb_in_cgroup_protoMartin KaFai Lau2022-04-19
| | | | | | | | | | | | | | | | | | | | | Adds a bpf helper, bpf_skb_in_cgroup, to decide if a skb->sk belongs to a descendant of a cgroup2. It is similar to the feature added in netfilter: commit c38c4597e4bf ("netfilter: implement xt_cgroup cgroup2 path match") The user is expected to populate a BPF_MAP_TYPE_CGROUP_ARRAY which will be used by the bpf_skb_in_cgroup. Modifications to the bpf verifier is to ensure BPF_MAP_TYPE_CGROUP_ARRAY and bpf_skb_in_cgroup() are always used together. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Cc: Alexei Starovoitov <ast@fb.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Tejun Heo <tj@kernel.org> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: add bpf_skb_change_type helperDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | This work adds a helper for changing skb->pkt_type in a controlled way. We only allow a subset of possible values and can extend that in future should other use cases come up. Doing this as a helper has the advantage that errors can be handeled gracefully and thus helper kept extensible. It's a write counterpart to pkt_type member we can already read from struct __sk_buff context. Major use case is to change incoming skbs to PACKET_HOST in a programmatic way instead of having to recirculate via redirect(..., BPF_F_INGRESS), for example. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: add bpf_skb_change_proto helperDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds a minimal helper for doing the groundwork of changing the skb->protocol in a controlled way. Currently supported is v4 to v6 and vice versa transitions, which allows f.e. for a minimal, static nat64 implementation where applications in containers that still require IPv4 can be transparently operated in an IPv6-only environment. For example, host facing veth of the container can transparently do the transitions in a programmatic way with the help of clsact qdisc and cls_bpf. Idea is to separate concerns for keeping complexity of the helper lower, which means that the programs utilize bpf_skb_change_proto(), bpf_skb_store_bytes() and bpf_lX_csum_replace() to get the job done, instead of doing everything in a single helper (and thus partially duplicating helper functionality). Also, bpf_skb_change_proto() shouldn't need to deal with raw packet data as this is done by other helpers. bpf_skb_proto_6_to_4() and bpf_skb_proto_4_to_6() unclone the skb to operate on a private one, push or pop additionally required header space and migrate the gso/gro meta data from the shared info. We do mark the gso type as dodgy so that headers are checked and segs recalculated by the gso/gro engine. The gso_size target is adapted as well. The flags argument added is currently reserved and can be used for future extensions. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: refactor bpf_prog_get and type check into helperDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | Since bpf_prog_get() and program type check is used in a couple of places, refactor this into a small helper function that we can make use of. Since the non RO prog->aux part is not used in performance critical paths and a program destruction via RCU is rather very unlikley when doing the put, we shouldn't have an issue just doing the bpf_prog_get() + prog->type != type check, but actually not taking the ref at all (due to being in fdget() / fdput() section of the bpf fd) is even cleaner and makes the diff smaller as well, so just go for that. Callsites are changed to make use of the new helper where possible. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: don't use raw processor id in generic helperDaniel Borkmann2022-04-19
| | | | | | | | | | | | | Use smp_processor_id() for the generic helper bpf_get_smp_processor_id() instead of the raw variant. This allows for preemption checks when we have DEBUG_PREEMPT, and otherwise uses the raw variant anyway. We only need to keep the raw variant for socket filters, but we can reuse the helper that is already there from cBPF side. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: fix matching of data/data_end in verifierAlexei Starovoitov2022-04-19
| | | | | | | | | | | | | | | | | The ctx structure passed into bpf programs is different depending on bpf program type. The verifier incorrectly marked ctx->data and ctx->data_end access based on ctx offset only. That caused loads in tracing programs int bpf_prog(struct pt_regs *ctx) { .. ctx->ax .. } to be incorrectly marked as PTR_TO_PACKET which later caused verifier to reject the program that was actually valid in tracing context. Fix this by doing program type specific matching of ctx offsets. Fixes: 969bf05eb3ce ("bpf: direct packet access") Reported-by: Sasha Goldshtein <goldshtn@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: add generic constant blinding for use in jitsDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This work adds a generic facility for use from eBPF JIT compilers that allows for further hardening of JIT generated images through blinding constants. In response to the original work on BPF JIT spraying published by Keegan McAllister [1], most BPF JITs were changed to make images read-only and start at a randomized offset in the page, where the rest was filled with trap instructions. We have this nowadays in x86, arm, arm64 and s390 JIT compilers. Additionally, later work also made eBPF interpreter images read only for kernels supporting DEBUG_SET_MODULE_RONX, that is, x86, arm, arm64 and s390 archs as well currently. This is done by default for mentioned JITs when JITing is enabled. Furthermore, we had a generic and configurable constant blinding facility on our todo for quite some time now to further make spraying harder, and first implementation since around netconf 2016. We found that for systems where untrusted users can load cBPF/eBPF code where JIT is enabled, start offset randomization helps a bit to make jumps into crafted payload harder, but in case where larger programs that cross page boundary are injected, we again have some part of the program opcodes at a page start offset. With improved guessing and more reliable payload injection, chances can increase to jump into such payload. Elena Reshetova recently wrote a test case for it [2, 3]. Moreover, eBPF comes with 64 bit constants, which can leave some more room for payloads. Note that for all this, additional bugs in the kernel are still required to make the jump (and of course to guess right, to not jump into a trap) and naturally the JIT must be enabled, which is disabled by default. For helping mitigation, the general idea is to provide an option bpf_jit_harden that admins can tweak along with bpf_jit_enable, so that for cases where JIT should be enabled for performance reasons, the generated image can be further hardened with blinding constants for unpriviledged users (bpf_jit_harden == 1), with trading off performance for these, but not for privileged ones. We also added the option of blinding for all users (bpf_jit_harden == 2), which is quite helpful for testing f.e. with test_bpf.ko. There are no further e.g. hardening levels of bpf_jit_harden switch intended, rationale is to have it dead simple to use as on/off. Since this functionality would need to be duplicated over and over for JIT compilers to use, which are already complex enough, we provide a generic eBPF byte-code level based blinding implementation, which is then just transparently JITed. JIT compilers need to make only a few changes to integrate this facility and can be migrated one by one. This option is for eBPF JITs and will be used in x86, arm64, s390 without too much effort, and soon ppc64 JITs, thus that native eBPF can be blinded as well as cBPF to eBPF migrations, so that both can be covered with a single implementation. The rule for JITs is that bpf_jit_blind_constants() must be called from bpf_int_jit_compile(), and in case blinding is disabled, we follow normally with JITing the passed program. In case blinding is enabled and we fail during the process of blinding itself, we must return with the interpreter. Similarly, in case the JITing process after the blinding failed, we return normally to the interpreter with the non-blinded code. Meaning, interpreter doesn't change in any way and operates on eBPF code as usual. For doing this pre-JIT blinding step, we need to make use of a helper/auxiliary register, here BPF_REG_AX. This is strictly internal to the JIT and not in any way part of the eBPF architecture. Just like in the same way as JITs internally make use of some helper registers when emitting code, only that here the helper register is one abstraction level higher in eBPF bytecode, but nevertheless in JIT phase. That helper register is needed since f.e. manually written program can issue loads to all registers of eBPF architecture. The core concept with the additional register is: blind out all 32 and 64 bit constants by converting BPF_K based instructions into a small sequence from K_VAL into ((RND ^ K_VAL) ^ RND). Therefore, this is transformed into: BPF_REG_AX := (RND ^ K_VAL), BPF_REG_AX ^= RND, and REG <OP> BPF_REG_AX, so actual operation on the target register is translated from BPF_K into BPF_X one that is operating on BPF_REG_AX's content. During rewriting phase when blinding, RND is newly generated via prandom_u32() for each processed instruction. 64 bit loads are split into two 32 bit loads to make translation and patching not too complex. Only basic thing required by JITs is to call the helper bpf_jit_blind_constants()/bpf_jit_prog_release_other() pair, and to map BPF_REG_AX into an unused register. Small bpf_jit_disasm extract from [2] when applied to x86 JIT: echo 0 > /proc/sys/net/core/bpf_jit_harden ffffffffa034f5e9 + <x>: [...] 39: mov $0xa8909090,%eax 3e: mov $0xa8909090,%eax 43: mov $0xa8ff3148,%eax 48: mov $0xa89081b4,%eax 4d: mov $0xa8900bb0,%eax 52: mov $0xa810e0c1,%eax 57: mov $0xa8908eb4,%eax 5c: mov $0xa89020b0,%eax [...] echo 1 > /proc/sys/net/core/bpf_jit_harden ffffffffa034f1e5 + <x>: [...] 39: mov $0xe1192563,%r10d 3f: xor $0x4989b5f3,%r10d 46: mov %r10d,%eax 49: mov $0xb8296d93,%r10d 4f: xor $0x10b9fd03,%r10d 56: mov %r10d,%eax 59: mov $0x8c381146,%r10d 5f: xor $0x24c7200e,%r10d 66: mov %r10d,%eax 69: mov $0xeb2a830e,%r10d 6f: xor $0x43ba02ba,%r10d 76: mov %r10d,%eax 79: mov $0xd9730af,%r10d 7f: xor $0xa5073b1f,%r10d 86: mov %r10d,%eax 89: mov $0x9a45662b,%r10d 8f: xor $0x325586ea,%r10d 96: mov %r10d,%eax [...] As can be seen, original constants that carry payload are hidden when enabled, actual operations are transformed from constant-based to register-based ones, making jumps into constants ineffective. Above extract/example uses single BPF load instruction over and over, but of course all instructions with constants are blinded. Performance wise, JIT with blinding performs a bit slower than just JIT and faster than interpreter case. This is expected, since we still get all the performance benefits from JITing and in normal use-cases not every single instruction needs to be blinded. Summing up all 296 test cases averaged over multiple runs from test_bpf.ko suite, interpreter was 55% slower than JIT only and JIT with blinding was 8% slower than JIT only. Since there are also some extremes in the test suite, I expect for ordinary workloads that the performance for the JIT with blinding case is even closer to JIT only case, f.e. nmap test case from suite has averaged timings in ns 29 (JIT), 35 (+ blinding), and 151 (interpreter). BPF test suite, seccomp test suite, eBPF sample code and various bigger networking eBPF programs have been tested with this and were running fine. For testing purposes, I also adapted interpreter and redirected blinded eBPF image to interpreter and also here all tests pass. [1] http://mainisusuallyafunction.blogspot.com/2012/11/attacking-hardened-linux-systems-with.html [2] https://github.com/01org/jit-spray-poc-for-ksp/ [3] http://www.openwall.com/lists/kernel-hardening/2016/05/03/5 Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Elena Reshetova <elena.reshetova@intel.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: prepare bpf_int_jit_compile/bpf_prog_select_runtime apisDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | Since the blinding is strictly only called from inside eBPF JITs, we need to change signatures for bpf_int_jit_compile() and bpf_prog_select_runtime() first in order to prepare that the eBPF program we're dealing with can change underneath. Hence, for call sites, we need to return the latest prog. No functional change in this patch. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
generated by cgit v1.2.3 (git 2.25.1) at 2026-07-10 09:23:16 +0000