- 29 Jan, 2018 21 commits
-
-
Michael S. Tsirkin authored
This is to make ptr_ring test build again. Signed-off-by:
Michael S. Tsirkin <mst@redhat.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
-
Michael S. Tsirkin authored
Signed-off-by:
-
Michael S. Tsirkin authored
We don't rely on lockless guarantees, but it seems cleaner than inverting __ptr_ring_peek. Signed-off-by:
-
Michael S. Tsirkin authored
In theory compiler could tear queue loads or stores in two. It does not seem to be happening in practice but it seems easier to convert the cases where this would be a problem to READ/WRITE_ONCE than worry about it. Signed-off-by:
-
Michael S. Tsirkin authored
__skb_array_empty should use __ptr_ring_empty since that's the only legal lockless function. Signed-off-by:
-
Michael S. Tsirkin authored
This reverts commit bcecb4bb. If we try to allocate an extra entry as the above commit did, and when the requested size is UINT_MAX, addition overflows causing zero size to be passed to kmalloc(). kmalloc then returns ZERO_SIZE_PTR with a subsequent crash. Reported-by: syzbot+87678bcf753b44c39b67@syzkaller.appspotmail.com Cc: John Fastabend <john.fastabend@gmail.com> Signed-off-by:
John Fastabend <john.fastabend@gmail.com> Signed-off-by:
-
Michael S. Tsirkin authored
Similar to bcecb4bb ("net: ptr_ring: otherwise safe empty checks can overrun array bounds") a lockless use of __ptr_ring_full might cause an out of bounds access. We can fix this, but it's easier to just disallow lockless __ptr_ring_full for now. Signed-off-by:
-
Michael S. Tsirkin authored
Lockless access to __ptr_ring_full is only legal if ring is never resized, otherwise it might cause use-after free errors. Simply drop the lockless test, we'll drop the packet a bit later when produce fails. Fixes: 362899b8 ("macvtap: switch to use skb array") Signed-off-by:
-
Michael S. Tsirkin authored
Lockless __ptr_ring_empty requires that consumer head is read and written at once, atomically. Annotate accordingly to make sure compiler does it correctly. Switch locked callers to __ptr_ring_peek which does not support the lockless operation. Signed-off-by:
-
Michael S. Tsirkin authored
The only function safe to call without locks is __ptr_ring_empty. Move documentation about lockless use there to make sure people do not try to use __ptr_ring_peek outside locks. Signed-off-by:
-
Michael S. Tsirkin authored
The comment near __ptr_ring_peek says: * If ring is never resized, and if the pointer is merely * tested, there's no need to take the lock - see e.g. __ptr_ring_empty. but this was in fact never possible since consumer_head would sometimes point outside the ring. Refactor the code so that it's always pointing within a ring. Fixes: c5ad119f ("net: sched: pfifo_fast use skb_array") Signed-off-by:
-
Martin KaFai Lau authored
If a sk_v6_rcv_saddr is !IPV6_ADDR_ANY and !IPV6_ADDR_MAPPED, it implicitly implies it is an ipv6only socket. However, in inet6_bind(), this addr_type checking and setting sk->sk_ipv6only to 1 are only done after sk->sk_prot->get_port(sk, snum) has been completed successfully. This inconsistency between sk_v6_rcv_saddr and sk_ipv6only confuses the 'get_port()'. In particular, when binding SO_REUSEPORT UDP sockets, udp_reuseport_add_sock(sk,...) is called. udp_reuseport_add_sock() checks "ipv6_only_sock(sk2) == ipv6_only_sock(sk)" before adding sk to sk2->sk_reuseport_cb. In this case, ipv6_only_sock(sk2) could be 1 while ipv6_only_sock(sk) is still 0 here. The end result is, reuseport_alloc(sk) is called instead of adding sk to the existing sk2->sk_reuseport_cb. It can be reproduced by binding two SO_REUSEPORT UDP sockets on an IPv6 address (!ANY and !MAPPED). Only one of the socket will receive packet. The fix is to set the implicit sk_ipv6only before calling get_port(). The original sk_ipv6only has to be saved such that it can be restored in case get_port() failed. The situation is similar to the inet_reset_saddr(sk) after get_port() has failed. Thanks to Calvin Owens <calvinowens@fb.com> who created an easy reproduction which leads to a fix. Fixes: e32ea7e7 ("soreuseport: fast reuseport UDP socket selection") Signed-off-by:
Martin KaFai Lau <kafai@fb.com> Signed-off-by:
-
David S. Miller authored
Christian Brauner says: ==================== rtnetlink: enable IFLA_IF_NETNSID for RTM_{DEL,SET}LINK Based on the previous discussion this enables passing a IFLA_IF_NETNSID property along with RTM_SETLINK and RTM_DELLINK requests. The patch for RTM_NEWLINK will be sent out in a separate patch since there are more corner-cases to think about. Changelog 2018-01-24: * Preserve old behavior and report -ENODEV when either ifindex or ifname is provided and IFLA_GROUP is set. Spotted by Wolfgang Bumiller. ==================== Signed-off-by: -
Christian Brauner authored
- Backwards Compatibility: If userspace wants to determine whether RTM_DELLINK supports the IFLA_IF_NETNSID property they should first send an RTM_GETLINK request with IFLA_IF_NETNSID on lo. If either EACCESS is returned or the reply does not include IFLA_IF_NETNSID userspace should assume that IFLA_IF_NETNSID is not supported on this kernel. If the reply does contain an IFLA_IF_NETNSID property userspace can send an RTM_DELLINK with a IFLA_IF_NETNSID property. If they receive EOPNOTSUPP then the kernel does not support the IFLA_IF_NETNSID property with RTM_DELLINK. Userpace should then fallback to other means. - Security: Callers must have CAP_NET_ADMIN in the owning user namespace of the target network namespace. Signed-off-by:
Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by:
-
Christian Brauner authored
- Backwards Compatibility: If userspace wants to determine whether RTM_SETLINK supports the IFLA_IF_NETNSID property they should first send an RTM_GETLINK request with IFLA_IF_NETNSID on lo. If either EACCESS is returned or the reply does not include IFLA_IF_NETNSID userspace should assume that IFLA_IF_NETNSID is not supported on this kernel. If the reply does contain an IFLA_IF_NETNSID property userspace can send an RTM_SETLINK with a IFLA_IF_NETNSID property. If they receive EOPNOTSUPP then the kernel does not support the IFLA_IF_NETNSID property with RTM_SETLINK. Userpace should then fallback to other means. To retain backwards compatibility the kernel will first check whether a IFLA_NET_NS_PID or IFLA_NET_NS_FD property has been passed. If either one is found it will be used to identify the target network namespace. This implies that users who do not care whether their running kernel supports IFLA_IF_NETNSID with RTM_SETLINK can pass both IFLA_NET_NS_{FD,PID} and IFLA_IF_NETNSID referring to the same network namespace. - Security: Callers must have CAP_NET_ADMIN in the owning user namespace of the target network namespace. Signed-off-by: -
Christian Brauner authored
RTM_{NEW,SET}LINK already allow operations on other network namespaces by identifying the target network namespace through IFLA_NET_NS_{FD,PID} properties. This is done by looking for the corresponding properties in do_setlink(). Extend do_setlink() to also look for the IFLA_IF_NETNSID property. This introduces no functional changes since all callers of do_setlink() currently block IFLA_IF_NETNSID by reporting an error before they reach do_setlink(). This introduces the helpers: static struct net *rtnl_link_get_net_by_nlattr(struct net *src_net, struct nlattr *tb[]) static struct net *rtnl_link_get_net_capable(const struct sk_buff *skb, struct net *src_net, struct nlattr *tb[], int cap) to simplify permission checks and target network namespace retrieval for RTM_* requests that already support IFLA_NET_NS_{FD,PID} but get extended to IFLA_IF_NETNSID. To perserve backwards compatibility the helpers look for IFLA_NET_NS_{FD,PID} properties first before checking for IFLA_IF_NETNSID. Signed-off-by: -
git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller authored
Signed-off-by: -
David S. Miller authored
Merge tag 'wireless-drivers-next-for-davem-2018-01-26' of git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/wireless-drivers-next Kalle Valo says: ==================== wireless-drivers-next patches for 4.16 Major changes: wil6210 * add PCI device id for Talyn * support flashless device ath9k * improve RSSI/signal accuracy on AR9003 series mt76 * validate CCMP PN from received frames to avoid replay attacks qtnfmac * support 64-bit network stats * report more hardware information to kernel log and some via ethtool ==================== Signed-off-by:
-
kbuild test robot authored
efx_default_channel_want_txqs() is only used in efx.c, while efx_ptp_want_txqs() and efx_ptp_channel_type (a struct) are only used in ptp.c. In all cases these symbols should be static. Fixes: 2935e3c3 ("sfc: on 8000 series use TX queues for TX timestamps") Signed-off-by:
Fengguang Wu <fengguang.wu@intel.com> [ecree@solarflare.com: rewrote commit message] Signed-off-by:
Edward Cree <ecree@solarflare.com> Signed-off-by:
-
git://git.kernel.org/pub/scm/linux/kernel/git/jkirsher/next-queueDavid S. Miller authored
Jeff Kirsher says: ==================== 40GbE Intel Wired LAN Driver Updates 2018-01-26 This series contains updates to i40e and i40evf. Michal updates the driver to pass critical errors from the firmware to the caller. Patryk fixes an issue of creating multiple identical filters with the same location, by simply moving the functions so that we remove the existing filter and then add the new filter. Paweł adds back in the ability to turn off offloads when VLAN is set for the VF driver. Fixed an issue where the number of TC queue pairs was exceeding MSI-X vectors count, causing messages about invalid TC mapping and wrong selected Tx queue. Alex cleans up the i40e/i40evf_set_itr_per_queue() by dropping all the unneeded pointer chases. Puts to use the reg_idx value, which was going unused, so that we can avoid having to compute the vector every time throughout the driver. Upasana enable the driver to display LLDP information on the vSphere Web Client by exposing DCB parameters. Alice converts our flags from 32 to 64 bit size, since we have added more flags. Dave implements a private ethtool flag to disable the processing of LLDP packets by the firmware, so that the firmware will not consume LLDPDU and cause them to be sent up the stack. Alan adds a mechanism for detecting/storing the flag for processing of LLDP packets by the firmware, so that its current state is persistent across reboots/reloads of the driver. Avinash fixes kdump with i40e due to resource constraints. We were enabling VMDq and iWARP when we just have a single CPU, which was starving kdump for the lack of IRQs. Jake adds support to program the fragmented IPv4 input set PCTYPE. Fixed the reported masks to properly report that the entire field is masked, since we had accidentally swapped the mask values for the IPv4 addresses with the L4 port numbers. ==================== Signed-off-by: -
git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-nextDavid S. Miller authored
Alexei Starovoitov says: ==================== pull-request: bpf-next 2018-01-26 The following pull-request contains BPF updates for your *net-next* tree. The main changes are: 1) A number of extensions to tcp-bpf, from Lawrence. - direct R or R/W access to many tcp_sock fields via bpf_sock_ops - passing up to 3 arguments to bpf_sock_ops functions - tcp_sock field bpf_sock_ops_cb_flags for controlling callbacks - optionally calling bpf_sock_ops program when RTO fires - optionally calling bpf_sock_ops program when packet is retransmitted - optionally calling bpf_sock_ops program when TCP state changes - access to tclass and sk_txhash - new selftest 2) div/mod exception handling, from Daniel. One of the ugly leftovers from the early eBPF days is that div/mod operations based on registers have a hard-coded src_reg == 0 test in the interpreter as well as in JIT code generators that would return from the BPF program with exit code 0. This was basically adopted from cBPF interpreter for historical reasons. There are multiple reasons why this is very suboptimal and prone to bugs. To name one: the return code mapping for such abnormal program exit of 0 does not always match with a suitable program type's exit code mapping. For example, '0' in tc means action 'ok' where the packet gets passed further up the stack, which is just undesirable for such cases (e.g. when implementing policy) and also does not match with other program types. After considering _four_ different ways to address the problem, we adapt the same behavior as on some major archs like ARMv8: X div 0 results in 0, and X mod 0 results in X. aarch64 and aarch32 ISA do not generate any traps or otherwise aborts of program execution for unsigned divides. Given the options, it seems the most suitable from all of them, also since major archs have similar schemes in place. Given this is all in the realm of undefined behavior, we still have the option to adapt if deemed necessary. 3) sockmap sample refactoring, from John. 4) lpm map get_next_key fixes, from Yonghong. 5) test cleanups, from Alexei and Prashant. ==================== Signed-off-by:
-
- 28 Jan, 2018 2 commits
-
-
git://git.kernel.org/pub/scm/linux/kernel/git/jkirsher/next-queueDavid S. Miller authored
Jeff Kirsher says: ==================== 10GbE Intel Wired LAN Driver Updates 2018-01-26 This series contains updates to ixgbe and ixgbevf. Emil updates ixgbevf to match ixgbe functionality, starting with the consolidating of functions that represent logical steps in the receive process so we can later update them more easily. Updated ixgbevf to only synchronize the length of the frame, which will typically be the MTU or smaller. Updated the VF driver to use the length of the packet instead of the DD status bit to determine if a new descriptor is ready to be processed, which saves on reads and we can save time on initialization. Added support for DMA_ATTR_SKIP_CPU_SYNC/WEAK_ORDERING to help improve performance on some platforms. Updated the VF driver to do bulk updates of the page reference count instead of just incrementing it by one reference at a time. Updated the VF driver to only go through the region of the receive ring that was designated to be cleaned up, rather than process the entire ring. Colin Ian King adds the use of ARRAY_SIZE() on various arrays. Miroslav Lichvar fixes an issue where ethtool was reporting timestamping filters unsupported for X550, which is incorrect. Paul adds support for reporting 5G link speed for some devices. Dan Carpenter fixes a typo where && was used when it should have been ||. ==================== Signed-off-by: -
Leon Romanovsky authored
The "return 0" instruction follows other return instruction and it makes it impossible to execute, hence remove it. Fixes: 00fc0c51 ("rocker: Change world_ops API and implementation to be switchdev independant") Signed-off-by:
Leon Romanovsky <leonro@mellanox.com> Signed-off-by:
-
- 27 Jan, 2018 17 commits
-
-
Alexei Starovoitov authored
Yonghong Song says: ==================== A kernel page fault which happens in lpm map trie_get_next_key is reported by syzbot and Eric. The issue was introduced by commit b471f2f1 ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE map"). Patch #1 fixed the issue in the kernel and patch #2 adds a multithreaded test case in tools/testing/selftests/bpf/test_lpm_map. ==================== Signed-off-by:
Alexei Starovoitov <ast@kernel.org>
-
Yonghong Song authored
The new test will spawn four threads, doing map update, delete, lookup and get_next_key in parallel. It is able to reproduce the issue in the previous commit found by syzbot and Eric Dumazet. Signed-off-by:
Yonghong Song <yhs@fb.com> Signed-off-by:
-
Yonghong Song authored
Commit b471f2f1 ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE map") introduces a bug likes below: if (!rcu_dereference(trie->root)) return -ENOENT; if (!key || key->prefixlen > trie->max_prefixlen) { root = &trie->root; goto find_leftmost; } ...... find_leftmost: for (node = rcu_dereference(*root); node;) { In the code after label find_leftmost, it is assumed that *root should not be NULL, but it is not true as it is possbile trie->root is changed to NULL by an asynchronous delete operation. The issue is reported by syzbot and Eric Dumazet with the below error log: ...... kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 1 PID: 8033 Comm: syz-executor3 Not tainted 4.15.0-rc8+ #4 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:trie_get_next_key+0x3c2/0xf10 kernel/bpf/lpm_trie.c:682 ...... This patch fixed the issue by use local rcu_dereferenced pointer instead of *(&trie->root) later on. Fixes: b471f2f1 ("bpf: implement MAP_GET_NEXT_KEY command or LPM_TRIE map") Reported-by:
syzbot <syzkaller@googlegroups.com> Reported-by:
Eric Dumazet <edumazet@google.com> Signed-off-by:
-
Alexei Starovoitov authored
Daniel Borkmann says: ==================== This set contains a small cleanup in cBPF prologue generation and otherwise fixes an outstanding issue related to BPF to BPF calls and exception handling. For details please see related patches. Last but not least, BPF selftests is extended with several new test cases. Thanks! ==================== Signed-off-by: -
Daniel Borkmann authored
Update selftests to relfect recent changes and add various new test cases. Signed-off-by:
Daniel Borkmann <daniel@iogearbox.net> Acked-by:
-
Daniel Borkmann authored
Since we've changed div/mod exception handling for src_reg in eBPF verifier itself, remove the leftovers from arm32 JIT. Signed-off-by:
-
Daniel Borkmann authored
The verifier in both cBPF and eBPF reject div/mod by 0 imm, so this can never load. Remove emitting such test and reject it from being JITed instead (the latter is actually also not needed, but given practice in sparc64, ppc64 today, so doesn't hurt to add it here either). Signed-off-by:
David Daney <david.daney@cavium.com> Signed-off-by:
-
Daniel Borkmann authored
Since we've changed div/mod exception handling for src_reg in eBPF verifier itself, remove the leftovers from mips64 JIT. Signed-off-by:
-
Daniel Borkmann authored
Since we've changed div/mod exception handling for src_reg in eBPF verifier itself, remove the leftovers from sparc64 JIT. Signed-off-by:
-
Daniel Borkmann authored
Since we've changed div/mod exception handling for src_reg in eBPF verifier itself, remove the leftovers from ppc64 JIT. Signed-off-by:
-
Daniel Borkmann authored
Since we've changed div/mod exception handling for src_reg in eBPF verifier itself, remove the leftovers from s390x JIT. Signed-off-by:
-
Daniel Borkmann authored
Since we've changed div/mod exception handling for src_reg in eBPF verifier itself, remove the leftovers from arm64 JIT. Signed-off-by:
-
Daniel Borkmann authored
Since we've changed div/mod exception handling for src_reg in eBPF verifier itself, remove the leftovers from x86_64 JIT. Signed-off-by:
-
Daniel Borkmann authored
One of the ugly leftovers from the early eBPF days is that div/mod operations based on registers have a hard-coded src_reg == 0 test in the interpreter as well as in JIT code generators that would return from the BPF program with exit code 0. This was basically adopted from cBPF interpreter for historical reasons. There are multiple reasons why this is very suboptimal and prone to bugs. To name one: the return code mapping for such abnormal program exit of 0 does not always match with a suitable program type's exit code mapping. For example, '0' in tc means action 'ok' where the packet gets passed further up the stack, which is just undesirable for such cases (e.g. when implementing policy) and also does not match with other program types. While trying to work out an exception handling scheme, I also noticed that programs crafted like the following will currently pass the verifier: 0: (bf) r6 = r1 1: (85) call pc+8 caller: R6=ctx(id=0,off=0,imm=0) R10=fp0,call_-1 callee: frame1: R1=ctx(id=0,off=0,imm=0) R10=fp0,call_1 10: (b4) (u32) r2 = (u32) 0 11: (b4) (u32) r3 = (u32) 1 12: (3c) (u32) r3 /= (u32) r2 13: (61) r0 = *(u32 *)(r1 +76) 14: (95) exit returning from callee: frame1: R0_w=pkt(id=0,off=0,r=0,imm=0) R1=ctx(id=0,off=0,imm=0) R2_w=inv0 R3_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R10=fp0,call_1 to caller at 2: R0_w=pkt(id=0,off=0,r=0,imm=0) R6=ctx(id=0,off=0,imm=0) R10=fp0,call_-1 from 14 to 2: R0=pkt(id=0,off=0,r=0,imm=0) R6=ctx(id=0,off=0,imm=0) R10=fp0,call_-1 2: (bf) r1 = r6 3: (61) r1 = *(u32 *)(r1 +80) 4: (bf) r2 = r0 5: (07) r2 += 8 6: (2d) if r2 > r1 goto pc+1 R0=pkt(id=0,off=0,r=8,imm=0) R1=pkt_end(id=0,off=0,imm=0) R2=pkt(id=0,off=8,r=8,imm=0) R6=ctx(id=0,off=0,imm=0) R10=fp0,call_-1 7: (71) r0 = *(u8 *)(r0 +0) 8: (b7) r0 = 1 9: (95) exit from 6 to 8: safe processed 16 insns (limit 131072), stack depth 0+0 Basically what happens is that in the subprog we make use of a div/mod by 0 exception and in the 'normal' subprog's exit path we just return skb->data back to the main prog. This has the implication that the verifier thinks we always get a pkt pointer in R0 while we still have the implicit 'return 0' from the div as an alternative unconditional return path earlier. Thus, R0 then contains 0, meaning back in the parent prog we get the address range of [0x0, skb->data_end] as read and writeable. Similar can be crafted with other pointer register types. Since i) BPF_ABS/IND is not allowed in programs that contain BPF to BPF calls (and generally it's also disadvised to use in native eBPF context), ii) unknown opcodes don't return zero anymore, iii) we don't return an exception code in dead branches, the only last missing case affected and to fix is the div/mod handling. What we would really need is some infrastructure to propagate exceptions all the way to the original prog unwinding the current stack and returning that code to the caller of the BPF program. In user space such exception handling for similar runtimes is typically implemented with setjmp(3) and longjmp(3) as one possibility which is not available in the kernel, though (kgdb used to implement it in kernel long time ago). I implemented a PoC exception handling mechanism into the BPF interpreter with porting setjmp()/longjmp() into x86_64 and adding a new internal BPF_ABRT opcode that can use a program specific exception code for all exception cases we have (e.g. div/mod by 0, unknown opcodes, etc). While this seems to work in the constrained BPF environment (meaning, here, we don't need to deal with state e.g. from memory allocations that we would need to undo before going into exception state), it still has various drawbacks: i) we would need to implement the setjmp()/longjmp() for every arch supported in the kernel and for x86_64, arm64, sparc64 JITs currently supporting calls, ii) it has unconditional additional cost on main program entry to store CPU register state in initial setjmp() call, and we would need some way to pass the jmp_buf down into ___bpf_prog_run() for main prog and all subprogs, but also storing on stack is not really nice (other option would be per-cpu storage for this, but it also has the drawback that we need to disable preemption for every BPF program types). All in all this approach would add a lot of complexity. Another poor-man's solution would be to have some sort of additional shared register or scratch buffer to hold state for exceptions, and test that after every call return to chain returns and pass R0 all the way down to BPF prog caller. This is also problematic in various ways: i) an additional register doesn't map well into JITs, and some other scratch space could only be on per-cpu storage, which, again has the side-effect that this only works when we disable preemption, or somewhere in the input context which is not available everywhere either, and ii) this adds significant runtime overhead by putting conditionals after each and every call, as well as implementation complexity. Yet another option is to teach verifier that div/mod can return an integer, which however is also complex to implement as verifier would need to walk such fake 'mov r0,<code>; exit;' sequeuence and there would still be no guarantee for having propagation of this further down to the BPF caller as proper exception code. For parent prog, it is also is not distinguishable from a normal return of a constant scalar value. The approach taken here is a completely different one with little complexity and no additional overhead involved in that we make use of the fact that a div/mod by 0 is undefined behavior. Instead of bailing out, we adapt the same behavior as on some major archs like ARMv8 [0] into eBPF as well: X div 0 results in 0, and X mod 0 results in X. aarch64 and aarch32 ISA do not generate any traps or otherwise aborts of program execution for unsigned divides. I verified this also with a test program compiled by gcc and clang, and the behavior matches with the spec. Going forward we adapt the eBPF verifier to emit such rewrites once div/mod by register was seen. cBPF is not touched and will keep existing 'return 0' semantics. Given the options, it seems the most suitable from all of them, also since major archs have similar schemes in place. Given this is all in the realm of undefined behavior, we still have the option to adapt if deemed necessary and this way we would also have the option of more flexibility from LLVM code generation side (which is then fully visible to verifier). Thus, this patch i) fixes the panic seen in above program and ii) doesn't bypass the verifier observations. [0] ARM Architecture Reference Manual, ARMv8 [ARM DDI 0487B.b] http://infocenter.arm.com/help/topic/com.arm.doc.ddi0487b.b/DDI0487B_b_armv8_arm.pdf 1) aarch64 instruction set: section C3.4.7 and C6.2.279 (UDIV) "A division by zero results in a zero being written to the destination register, without any indication that the division by zero occurred." 2) aarch32 instruction set: section F1.4.8 and F5.1.263 (UDIV) "For the SDIV and UDIV instructions, division by zero always returns a zero result." Fixes: f4d7e40a ("bpf: introduce function calls (verification)") Signed-off-by: -
Daniel Borkmann authored
Recent findings by syzcaller fixed in 7891a87e ("bpf: arsh is not supported in 32 bit alu thus reject it") triggered a warning in the interpreter due to unknown opcode not being rejected by the verifier. The 'return 0' for an unknown opcode is really not optimal, since with BPF to BPF calls, this would go untracked by the verifier. Do two things here to improve the situation: i) perform basic insn sanity check early on in the verification phase and reject every non-uapi insn right there. The bpf_opcode_in_insntable() table reuses the same mapping as the jumptable in ___bpf_prog_run() sans the non-public mappings. And ii) in ___bpf_prog_run() we do need to BUG in the case where the verifier would ever create an unknown opcode due to some rewrites. Note that JITs do not have such issues since they would punt to interpreter in these situations. Moreover, the BPF_JIT_ALWAYS_ON would also help to avoid such unknown opcodes in the first place. Signed-off-by:
-
Daniel Borkmann authored
Given we recently had c131187d ("bpf: fix branch pruning logic") and 95a762e2 ("bpf: fix incorrect sign extension in check_alu_op()") in particular where before verifier skipped verification of the wrongly assumed dead branch, we should not just replace the dead code parts with nops (mov r0,r0). If there is a bug such as fixed in 95a762e2 in future again, where runtime could execute those insns, then one of the potential issues with the current setting would be that given the nops would be at the end of the program, we could execute out of bounds at some point. The best in such case would be to just exit the BPF program altogether and return an exception code. However, given this would require two instructions, and such a dead code gap could just be a single insn long, we would need to place 'r0 = X; ret' snippet at the very end after the user program or at the start before the program (where we'd skip that region on prog entry), and then place unconditional ja's into the dead code gap. While more complex but possible, there's still another block in the road that currently prevents from this, namely BPF to BPF calls. The issue here is that such exception could be returned from a callee, but the caller would not know that it's an exception that needs to be propagated further down. Alternative that has little complexity is to just use a ja-1 code for now which will trap the execution here instead of silently doing bad things if we ever get there due to bugs. Signed-off-by:
-
Daniel Borkmann authored
Very minor optimization; saves 1 byte per program in x86_64 JIT in cBPF prologue. Signed-off-by:
-
