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* bpf: Allow bpf_map_lookup_elem for SOCKMAP and SOCKHASHJakub Sitnicki2020-04-291-10/+35
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | White-list map lookup for SOCKMAP/SOCKHASH from BPF. Lookup returns a pointer to a full socket and acquires a reference if necessary. To support it we need to extend the verifier to know that: (1) register storing the lookup result holds a pointer to socket, if lookup was done on SOCKMAP/SOCKHASH, and that (2) map lookup on SOCKMAP/SOCKHASH is a reference acquiring operation, which needs a corresponding reference release with bpf_sk_release. On sock_map side, lookup handlers exposed via bpf_map_ops now bump sk_refcnt if socket is reference counted. In turn, bpf_sk_select_reuseport, the only in-kernel user of SOCKMAP/SOCKHASH ops->map_lookup_elem, was updated to release the reference. Sockets fetched from a map can be used in the same way as ones returned by BPF socket lookup helpers, such as bpf_sk_lookup_tcp. In particular, they can be used with bpf_sk_assign to direct packets toward a socket on TC ingress path. Suggested-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20200429181154.479310-2-jakub@cloudflare.com
* bpf: Add support for BPF_OBJ_GET_INFO_BY_FD for bpf_linkAndrii Nakryiko2020-04-294-21/+181
| | | | | | | | | | | | | Add ability to fetch bpf_link details through BPF_OBJ_GET_INFO_BY_FD command. Also enhance show_fdinfo to potentially include bpf_link type-specific information (similarly to obj_info). Also introduce enum bpf_link_type stored in bpf_link itself and expose it in UAPI. bpf_link_tracing also now will store and return bpf_attach_type. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200429001614.1544-5-andriin@fb.com
* bpf: Support GET_FD_BY_ID and GET_NEXT_ID for bpf_linkAndrii Nakryiko2020-04-291-0/+49
| | | | | | | | | | | | | | Add support to look up bpf_link by ID and iterate over all existing bpf_links in the system. GET_FD_BY_ID code handles not-yet-ready bpf_link by checking that its ID hasn't been set to non-zero value yet. Setting bpf_link's ID is done as the very last step in finalizing bpf_link, together with installing FD. This approach allows users of bpf_link in kernel code to not worry about races between user-space and kernel code that hasn't finished attaching and initializing bpf_link. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200429001614.1544-4-andriin@fb.com
* bpf: Allocate ID for bpf_linkAndrii Nakryiko2020-04-292-53/+104
| | | | | | | | | | | | | | | Generate ID for each bpf_link using IDR, similarly to bpf_map and bpf_prog. bpf_link creation, initialization, attachment, and exposing to user-space through FD and ID is a complicated multi-step process, abstract it away through bpf_link_primer and bpf_link_prime(), bpf_link_settle(), and bpf_link_cleanup() internal API. They guarantee that until bpf_link is properly attached, user-space won't be able to access partially-initialized bpf_link either from FD or ID. All this allows to simplify bpf_link attachment and error handling code. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200429001614.1544-3-andriin@fb.com
* bpf: Refactor bpf_link update handlingAndrii Nakryiko2020-04-292-9/+32
| | | | | | | | | | | | | Make bpf_link update support more generic by making it into another bpf_link_ops methods. This allows generic syscall handling code to be agnostic to various conditionally compiled features (e.g., the case of CONFIG_CGROUP_BPF). This also allows to keep link type-specific code to remain static within respective code base. Refactor existing bpf_cgroup_link code and take advantage of this. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200429001614.1544-2-andriin@fb.com
* Merge branch 'work.sysctl' of ↵Daniel Borkmann2020-04-281-23/+12
|\ | | | | | | | | | | | | | | | | | | | | | | ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull in Christoph Hellwig's series that changes the sysctl's ->proc_handler methods to take kernel pointers instead. It gets rid of the set_fs address space overrides used by BPF. As per discussion, pull in the feature branch into bpf-next as it relates to BPF sysctl progs. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200427071508.GV23230@ZenIV.linux.org.uk/T/
| * sysctl: pass kernel pointers to ->proc_handlerChristoph Hellwig2020-04-271-23/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Instead of having all the sysctl handlers deal with user pointers, which is rather hairy in terms of the BPF interaction, copy the input to and from userspace in common code. This also means that the strings are always NUL-terminated by the common code, making the API a little bit safer. As most handler just pass through the data to one of the common handlers a lot of the changes are mechnical. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* | bpf, cgroup: Remove unused exportsChristoph Hellwig2020-04-271-4/+0
| | | | | | | | | | | | | | | | | | | | | | Except for a few of the networking hooks called from modular ipv4 or ipv6 code, all of hooks are just called from guaranteed to be built-in code. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrey Ignatov <rdna@fb.com> Link: https://lore.kernel.org/bpf/20200424064338.538313-2-hch@lst.de
* | bpf: Make verifier log more relevant by defaultAndrii Nakryiko2020-04-261-4/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To make BPF verifier verbose log more releavant and easier to use to debug verification failures, "pop" parts of log that were successfully verified. This has effect of leaving only verifier logs that correspond to code branches that lead to verification failure, which in practice should result in much shorter and more relevant verifier log dumps. This behavior is made the default behavior and can be overriden to do exhaustive logging by specifying BPF_LOG_LEVEL2 log level. Using BPF_LOG_LEVEL2 to disable this behavior is not ideal, because in some cases it's good to have BPF_LOG_LEVEL2 per-instruction register dump verbosity, but still have only relevant verifier branches logged. But for this patch, I didn't want to add any new flags. It might be worth-while to just rethink how BPF verifier logging is performed and requested and streamline it a bit. But this trimming of successfully verified branches seems to be useful and a good default behavior. To test this, I modified runqslower slightly to introduce read of uninitialized stack variable. Log (**truncated in the middle** to save many lines out of this commit message) BEFORE this change: ; int handle__sched_switch(u64 *ctx) 0: (bf) r6 = r1 ; struct task_struct *prev = (struct task_struct *)ctx[1]; 1: (79) r1 = *(u64 *)(r6 +8) func 'sched_switch' arg1 has btf_id 151 type STRUCT 'task_struct' 2: (b7) r2 = 0 ; struct event event = {}; 3: (7b) *(u64 *)(r10 -24) = r2 last_idx 3 first_idx 0 regs=4 stack=0 before 2: (b7) r2 = 0 4: (7b) *(u64 *)(r10 -32) = r2 5: (7b) *(u64 *)(r10 -40) = r2 6: (7b) *(u64 *)(r10 -48) = r2 ; if (prev->state == TASK_RUNNING) [ ... instruction dump from insn #7 through #50 are cut out ... ] 51: (b7) r2 = 16 52: (85) call bpf_get_current_comm#16 last_idx 52 first_idx 42 regs=4 stack=0 before 51: (b7) r2 = 16 ; bpf_perf_event_output(ctx, &events, BPF_F_CURRENT_CPU, 53: (bf) r1 = r6 54: (18) r2 = 0xffff8881f3868800 56: (18) r3 = 0xffffffff 58: (bf) r4 = r7 59: (b7) r5 = 32 60: (85) call bpf_perf_event_output#25 last_idx 60 first_idx 53 regs=20 stack=0 before 59: (b7) r5 = 32 61: (bf) r2 = r10 ; event.pid = pid; 62: (07) r2 += -16 ; bpf_map_delete_elem(&start, &pid); 63: (18) r1 = 0xffff8881f3868000 65: (85) call bpf_map_delete_elem#3 ; } 66: (b7) r0 = 0 67: (95) exit from 44 to 66: safe from 34 to 66: safe from 11 to 28: R1_w=inv0 R2_w=inv0 R6_w=ctx(id=0,off=0,imm=0) R10=fp0 fp-8=mmmm???? fp-24_w=00000000 fp-32_w=00000000 fp-40_w=00000000 fp-48_w=00000000 ; bpf_map_update_elem(&start, &pid, &ts, 0); 28: (bf) r2 = r10 ; 29: (07) r2 += -16 ; tsp = bpf_map_lookup_elem(&start, &pid); 30: (18) r1 = 0xffff8881f3868000 32: (85) call bpf_map_lookup_elem#1 invalid indirect read from stack off -16+0 size 4 processed 65 insns (limit 1000000) max_states_per_insn 1 total_states 5 peak_states 5 mark_read 4 Notice how there is a successful code path from instruction 0 through 67, few successfully verified jumps (44->66, 34->66), and only after that 11->28 jump plus error on instruction #32. AFTER this change (full verifier log, **no truncation**): ; int handle__sched_switch(u64 *ctx) 0: (bf) r6 = r1 ; struct task_struct *prev = (struct task_struct *)ctx[1]; 1: (79) r1 = *(u64 *)(r6 +8) func 'sched_switch' arg1 has btf_id 151 type STRUCT 'task_struct' 2: (b7) r2 = 0 ; struct event event = {}; 3: (7b) *(u64 *)(r10 -24) = r2 last_idx 3 first_idx 0 regs=4 stack=0 before 2: (b7) r2 = 0 4: (7b) *(u64 *)(r10 -32) = r2 5: (7b) *(u64 *)(r10 -40) = r2 6: (7b) *(u64 *)(r10 -48) = r2 ; if (prev->state == TASK_RUNNING) 7: (79) r2 = *(u64 *)(r1 +16) ; if (prev->state == TASK_RUNNING) 8: (55) if r2 != 0x0 goto pc+19 R1_w=ptr_task_struct(id=0,off=0,imm=0) R2_w=inv0 R6_w=ctx(id=0,off=0,imm=0) R10=fp0 fp-24_w=00000000 fp-32_w=00000000 fp-40_w=00000000 fp-48_w=00000000 ; trace_enqueue(prev->tgid, prev->pid); 9: (61) r1 = *(u32 *)(r1 +1184) 10: (63) *(u32 *)(r10 -4) = r1 ; if (!pid || (targ_pid && targ_pid != pid)) 11: (15) if r1 == 0x0 goto pc+16 from 11 to 28: R1_w=inv0 R2_w=inv0 R6_w=ctx(id=0,off=0,imm=0) R10=fp0 fp-8=mmmm???? fp-24_w=00000000 fp-32_w=00000000 fp-40_w=00000000 fp-48_w=00000000 ; bpf_map_update_elem(&start, &pid, &ts, 0); 28: (bf) r2 = r10 ; 29: (07) r2 += -16 ; tsp = bpf_map_lookup_elem(&start, &pid); 30: (18) r1 = 0xffff8881db3ce800 32: (85) call bpf_map_lookup_elem#1 invalid indirect read from stack off -16+0 size 4 processed 65 insns (limit 1000000) max_states_per_insn 1 total_states 5 peak_states 5 mark_read 4 Notice how in this case, there are 0-11 instructions + jump from 11 to 28 is recorded + 28-32 instructions with error on insn #32. test_verifier test runner was updated to specify BPF_LOG_LEVEL2 for VERBOSE_ACCEPT expected result due to potentially "incomplete" success verbose log at BPF_LOG_LEVEL1. On success, verbose log will only have a summary of number of processed instructions, etc, but no branch tracing log. Having just a last succesful branch tracing seemed weird and confusing. Having small and clean summary log in success case seems quite logical and nice, though. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200423195850.1259827-1-andriin@fb.com
* | bpf: add bpf_ktime_get_boot_ns()Maciej Żenczykowski2020-04-262-0/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | On a device like a cellphone which is constantly suspending and resuming CLOCK_MONOTONIC is not particularly useful for keeping track of or reacting to external network events. Instead you want to use CLOCK_BOOTTIME. Hence add bpf_ktime_get_boot_ns() as a mirror of bpf_ktime_get_ns() based around CLOCK_BOOTTIME instead of CLOCK_MONOTONIC. Signed-off-by: Maciej Żenczykowski <maze@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
* | net: bpf: Make bpf_ktime_get_ns() available to non GPL programsMaciej Żenczykowski2020-04-261-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The entire implementation is in kernel/bpf/helpers.c: BPF_CALL_0(bpf_ktime_get_ns) { /* NMI safe access to clock monotonic */ return ktime_get_mono_fast_ns(); } const struct bpf_func_proto bpf_ktime_get_ns_proto = { .func = bpf_ktime_get_ns, .gpl_only = false, .ret_type = RET_INTEGER, }; and this was presumably marked GPL due to kernel/time/timekeeping.c: EXPORT_SYMBOL_GPL(ktime_get_mono_fast_ns); and while that may make sense for kernel modules (although even that is doubtful), there is currently AFAICT no other source of time available to ebpf. Furthermore this is really just equivalent to clock_gettime(CLOCK_MONOTONIC) which is exposed to userspace (via vdso even to make it performant)... As such, I see no reason to keep the GPL restriction. (In the future I'd like to have access to time from Apache licensed ebpf code) Signed-off-by: Maciej Żenczykowski <maze@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
* | bpf: Fix missing bpf_base_func_proto in cgroup_base_func_proto for CGROUP_NET=nStanislav Fomichev2020-04-262-0/+78
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | linux-next build bot reported compile issue [1] with one of its configs. It looks like when we have CONFIG_NET=n and CONFIG_BPF{,_SYSCALL}=y, we are missing the bpf_base_func_proto definition (from net/core/filter.c) in cgroup_base_func_proto. I'm reshuffling the code a bit to make it work. The common helpers are moved into kernel/bpf/helpers.c and the bpf_base_func_proto is exported from there. Also, bpf_get_raw_cpu_id goes into kernel/bpf/core.c akin to existing bpf_user_rnd_u32. [1] https://lore.kernel.org/linux-next/CAKH8qBsBvKHswiX1nx40LgO+BGeTmb1NX8tiTttt_0uu6T3dCA@mail.gmail.com/T/#mff8b0c083314c68c2e2ef0211cb11bc20dc13c72 Fixes: 0456ea170cd6 ("bpf: Enable more helpers for BPF_PROG_TYPE_CGROUP_{DEVICE,SYSCTL,SOCKOPT}") Signed-off-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200424235941.58382-1-sdf@google.com
* | bpf: Enable more helpers for BPF_PROG_TYPE_CGROUP_{DEVICE,SYSCTL,SOCKOPT}Stanislav Fomichev2020-04-261-17/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently the following prog types don't fall back to bpf_base_func_proto() (instead they have cgroup_base_func_proto which has a limited set of helpers from bpf_base_func_proto): * BPF_PROG_TYPE_CGROUP_DEVICE * BPF_PROG_TYPE_CGROUP_SYSCTL * BPF_PROG_TYPE_CGROUP_SOCKOPT I don't see any specific reason why we shouldn't use bpf_base_func_proto(), every other type of program (except bpf-lirc and, understandably, tracing) use it, so let's fall back to bpf_base_func_proto for those prog types as well. This basically boils down to adding access to the following helpers: * BPF_FUNC_get_prandom_u32 * BPF_FUNC_get_smp_processor_id * BPF_FUNC_get_numa_node_id * BPF_FUNC_tail_call * BPF_FUNC_ktime_get_ns * BPF_FUNC_spin_lock (CAP_SYS_ADMIN) * BPF_FUNC_spin_unlock (CAP_SYS_ADMIN) * BPF_FUNC_jiffies64 (CAP_SYS_ADMIN) I've also added bpf_perf_event_output() because it's really handy for logging and debugging. Signed-off-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200420174610.77494-1-sdf@google.com
* | bpf: Remove set but not used variable 'dst_known'Mao Wenan2020-04-261-3/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Fixes gcc '-Wunused-but-set-variable' warning: kernel/bpf/verifier.c:5603:18: warning: variable ‘dst_known’ set but not used [-Wunused-but-set-variable], delete this variable. Signed-off-by: Mao Wenan <maowenan@huawei.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20200418013735.67882-1-maowenan@huawei.com
* | Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/netDavid S. Miller2020-04-263-14/+39
|\ \ | | | | | | | | | | | | | | | Simple overlapping changes to linux/vermagic.h Signed-off-by: David S. Miller <davem@davemloft.net>
| * | bpf: Make bpf_link_fops staticZou Wei2020-04-251-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix the following sparse warning: kernel/bpf/syscall.c:2289:30: warning: symbol 'bpf_link_fops' was not declared. Should it be static? Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Zou Wei <zou_wei@huawei.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/1587609160-117806-1-git-send-email-zou_wei@huawei.com
| * | bpf: Propagate expected_attach_type when verifying freplace programsToke Høiland-Jørgensen2020-04-251-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For some program types, the verifier relies on the expected_attach_type of the program being verified in the verification process. However, for freplace programs, the attach type was not propagated along with the verifier ops, so the expected_attach_type would always be zero for freplace programs. This in turn caused the verifier to sometimes make the wrong call for freplace programs. For all existing uses of expected_attach_type for this purpose, the result of this was only false negatives (i.e., freplace functions would be rejected by the verifier even though they were valid programs for the target they were replacing). However, should a false positive be introduced, this can lead to out-of-bounds accesses and/or crashes. The fix introduced in this patch is to propagate the expected_attach_type to the freplace program during verification, and reset it after that is done. Fixes: be8704ff07d2 ("bpf: Introduce dynamic program extensions") Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/158773526726.293902.13257293296560360508.stgit@toke.dk
| * | bpf: Fix leak in LINK_UPDATE and enforce empty old_prog_fdAndrii Nakryiko2020-04-251-2/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | Fix bug of not putting bpf_link in LINK_UPDATE command. Also enforce zeroed old_prog_fd if no BPF_F_REPLACE flag is specified. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200424052045.4002963-1-andriin@fb.com
| * | bpf: Fix handling of XADD on BTF memoryJann Horn2020-04-211-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | check_xadd() can cause check_ptr_to_btf_access() to be executed with atype==BPF_READ and value_regno==-1 (meaning "just check whether the access is okay, don't tell me what type it will result in"). Handle that case properly and skip writing type information, instead of indexing into the registers at index -1 and writing into out-of-bounds memory. Note that at least at the moment, you can't actually write through a BTF pointer, so check_xadd() will reject the program after calling check_ptr_to_btf_access with atype==BPF_WRITE; but that's after the verifier has already corrupted memory. This patch assumes that BTF pointers are not available in unprivileged programs. Fixes: 9e15db66136a ("bpf: Implement accurate raw_tp context access via BTF") Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200417000007.10734-2-jannh@google.com
| * | bpf: Forbid XADD on spilled pointers for unprivileged usersJann Horn2020-04-211-9/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When check_xadd() verifies an XADD operation on a pointer to a stack slot containing a spilled pointer, check_stack_read() verifies that the read, which is part of XADD, is valid. However, since the placeholder value -1 is passed as `value_regno`, check_stack_read() can only return a binary decision and can't return the type of the value that was read. The intent here is to verify whether the value read from the stack slot may be used as a SCALAR_VALUE; but since check_stack_read() doesn't check the type, and the type information is lost when check_stack_read() returns, this is not enforced, and a malicious user can abuse XADD to leak spilled kernel pointers. Fix it by letting check_stack_read() verify that the value is usable as a SCALAR_VALUE if no type information is passed to the caller. To be able to use __is_pointer_value() in check_stack_read(), move it up. Fix up the expected unprivileged error message for a BPF selftest that, until now, assumed that unprivileged users can use XADD on stack-spilled pointers. This also gives us a test for the behavior introduced in this patch for free. In theory, this could also be fixed by forbidding XADD on stack spills entirely, since XADD is a locked operation (for operations on memory with concurrency) and there can't be any concurrency on the BPF stack; but Alexei has said that he wants to keep XADD on stack slots working to avoid changes to the test suite [1]. The following BPF program demonstrates how to leak a BPF map pointer as an unprivileged user using this bug: // r7 = map_pointer BPF_LD_MAP_FD(BPF_REG_7, small_map), // r8 = launder(map_pointer) BPF_STX_MEM(BPF_DW, BPF_REG_FP, BPF_REG_7, -8), BPF_MOV64_IMM(BPF_REG_1, 0), ((struct bpf_insn) { .code = BPF_STX | BPF_DW | BPF_XADD, .dst_reg = BPF_REG_FP, .src_reg = BPF_REG_1, .off = -8 }), BPF_LDX_MEM(BPF_DW, BPF_REG_8, BPF_REG_FP, -8), // store r8 into map BPF_MOV64_REG(BPF_REG_ARG1, BPF_REG_7), BPF_MOV64_REG(BPF_REG_ARG2, BPF_REG_FP), BPF_ALU64_IMM(BPF_ADD, BPF_REG_ARG2, -4), BPF_ST_MEM(BPF_W, BPF_REG_ARG2, 0, 0), BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem), BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1), BPF_EXIT_INSN(), BPF_STX_MEM(BPF_DW, BPF_REG_0, BPF_REG_8, 0), BPF_MOV64_IMM(BPF_REG_0, 0), BPF_EXIT_INSN() [1] https://lore.kernel.org/bpf/20200416211116.qxqcza5vo2ddnkdq@ast-mbp.dhcp.thefacebook.com/ Fixes: 17a5267067f3 ("bpf: verifier (add verifier core)") Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200417000007.10734-1-jannh@google.com
| * | cpumap: Avoid warning when CONFIG_DEBUG_PER_CPU_MAPS is enabledToke Høiland-Jørgensen2020-04-211-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When the kernel is built with CONFIG_DEBUG_PER_CPU_MAPS, the cpumap code can trigger a spurious warning if CONFIG_CPUMASK_OFFSTACK is also set. This happens because in this configuration, NR_CPUS can be larger than nr_cpumask_bits, so the initial check in cpu_map_alloc() is not sufficient to guard against hitting the warning in cpumask_check(). Fix this by explicitly checking the supplied key against the nr_cpumask_bits variable before calling cpu_possible(). Fixes: 6710e1126934 ("bpf: introduce new bpf cpu map type BPF_MAP_TYPE_CPUMAP") Reported-by: Xiumei Mu <xmu@redhat.com> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Tested-by: Xiumei Mu <xmu@redhat.com> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20200416083120.453718-1-toke@redhat.com
* | | xdp: export the DEV_MAP_BULK_SIZE macroIoana Ciornei2020-04-231-1/+0
|/ / | | | | | | | | | | | | | | | | | | Export the DEV_MAP_BULK_SIZE macro to the header file so that drivers can directly use it as the maximum number of xdp_frames received in the .ndo_xdp_xmit() callback. Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | bpf: remove unneeded conversion to bool in __mark_reg_unknownZou Wei2020-04-141-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | This issue was detected by using the Coccinelle software: kernel/bpf/verifier.c:1259:16-21: WARNING: conversion to bool not needed here The conversion to bool is unneeded, remove it. Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Zou Wei <zou_wei@huawei.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/1586779076-101346-1-git-send-email-zou_wei@huawei.com
* | bpf: Prevent re-mmap()'ing BPF map as writable for initially r/o mappingAndrii Nakryiko2020-04-141-9/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | VM_MAYWRITE flag during initial memory mapping determines if already mmap()'ed pages can be later remapped as writable ones through mprotect() call. To prevent user application to rewrite contents of memory-mapped as read-only and subsequently frozen BPF map, remove VM_MAYWRITE flag completely on initially read-only mapping. Alternatively, we could treat any memory-mapping on unfrozen map as writable and bump writecnt instead. But there is little legitimate reason to map BPF map as read-only and then re-mmap() it as writable through mprotect(), instead of just mmap()'ing it as read/write from the very beginning. Also, at the suggestion of Jann Horn, drop unnecessary refcounting in mmap operations. We can just rely on VMA holding reference to BPF map's file properly. Fixes: fc9702273e2e ("bpf: Add mmap() support for BPF_MAP_TYPE_ARRAY") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Jann Horn <jannh@google.com> Link: https://lore.kernel.org/bpf/20200410202613.3679837-1-andriin@fb.com
* | bpf: Fix a typo "inacitve" -> "inactive"Qiujun Huang2020-04-061-1/+1
|/ | | | | | | | | There is a typo in struct bpf_lru_list's next_inactive_rotation description, thus fix s/inacitve/inactive/. Signed-off-by: Qiujun Huang <hqjagain@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/1585901254-30377-1-git-send-email-hqjagain@gmail.com
* Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-nextDavid S. Miller2020-03-3111-737/+1830
|\ | | | | | | Signed-off-by: David S. Miller <davem@davemloft.net>
| * bpf: Implement bpf_prog replacement for an active bpf_cgroup_linkAndrii Nakryiko2020-03-312-0/+135
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add new operation (LINK_UPDATE), which allows to replace active bpf_prog from under given bpf_link. Currently this is only supported for bpf_cgroup_link, but will be extended to other kinds of bpf_links in follow-up patches. For bpf_cgroup_link, implemented functionality matches existing semantics for direct bpf_prog attachment (including BPF_F_REPLACE flag). User can either unconditionally set new bpf_prog regardless of which bpf_prog is currently active under given bpf_link, or, optionally, can specify expected active bpf_prog. If active bpf_prog doesn't match expected one, no changes are performed, old bpf_link stays intact and attached, operation returns a failure. cgroup_bpf_replace() operation is resolving race between auto-detachment and bpf_prog update in the same fashion as it's done for bpf_link detachment, except in this case update has no way of succeeding because of target cgroup marked as dying. So in this case error is returned. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200330030001.2312810-3-andriin@fb.com
| * bpf: Implement bpf_link-based cgroup BPF program attachmentAndrii Nakryiko2020-03-312-85/+294
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Implement new sub-command to attach cgroup BPF programs and return FD-based bpf_link back on success. bpf_link, once attached to cgroup, cannot be replaced, except by owner having its FD. Cgroup bpf_link supports only BPF_F_ALLOW_MULTI semantics. Both link-based and prog-based BPF_F_ALLOW_MULTI attachments can be freely intermixed. To prevent bpf_cgroup_link from keeping cgroup alive past the point when no BPF program can be executed, implement auto-detachment of link. When cgroup_bpf_release() is called, all attached bpf_links are forced to release cgroup refcounts, but they leave bpf_link otherwise active and allocated, as well as still owning underlying bpf_prog. This is because user-space might still have FDs open and active, so bpf_link as a user-referenced object can't be freed yet. Once last active FD is closed, bpf_link will be freed and underlying bpf_prog refcount will be dropped. But cgroup refcount won't be touched, because cgroup is released already. The inherent race between bpf_cgroup_link release (from closing last FD) and cgroup_bpf_release() is resolved by both operations taking cgroup_mutex. So the only additional check required is when bpf_cgroup_link attempts to detach itself from cgroup. At that time we need to check whether there is still cgroup associated with that link. And if not, exit with success, because bpf_cgroup_link was already successfully detached. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Roman Gushchin <guro@fb.com> Link: https://lore.kernel.org/bpf/20200330030001.2312810-2-andriin@fb.com
| * bpf: Verifier, refine 32bit bound in do_refine_retval_rangeJohn Fastabend2020-03-311-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Further refine return values range in do_refine_retval_range by noting these are int return types (We will assume here that int is a 32-bit type). Two reasons to pull this out of original patch. First it makes the original fix impossible to backport. And second I've not seen this as being problematic in practice unlike the other case. Fixes: 849fa50662fbc ("bpf/verifier: refine retval R0 state for bpf_get_stack helper") Signed-off-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/158560421952.10843.12496354931526965046.stgit@john-Precision-5820-Tower
| * bpf: Verifier, do explicit ALU32 bounds trackingJohn Fastabend2020-03-302-281/+852
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It is not possible for the current verifier to track ALU32 and JMP ops correctly. This can result in the verifier aborting with errors even though the program should be verifiable. BPF codes that hit this can work around it by changin int variables to 64-bit types, marking variables volatile, etc. But this is all very ugly so it would be better to avoid these tricks. But, the main reason to address this now is do_refine_retval_range() was assuming return values could not be negative. Once we fixed this code that was previously working will no longer work. See do_refine_retval_range() patch for details. And we don't want to suddenly cause programs that used to work to fail. The simplest example code snippet that illustrates the problem is likely this, 53: w8 = w0 // r8 <- [0, S32_MAX], // w8 <- [-S32_MIN, X] 54: w8 <s 0 // r8 <- [0, U32_MAX] // w8 <- [0, X] The expected 64-bit and 32-bit bounds after each line are shown on the right. The current issue is without the w* bounds we are forced to use the worst case bound of [0, U32_MAX]. To resolve this type of case, jmp32 creating divergent 32-bit bounds from 64-bit bounds, we add explicit 32-bit register bounds s32_{min|max}_value and u32_{min|max}_value. Then from branch_taken logic creating new bounds we can track 32-bit bounds explicitly. The next case we observed is ALU ops after the jmp32, 53: w8 = w0 // r8 <- [0, S32_MAX], // w8 <- [-S32_MIN, X] 54: w8 <s 0 // r8 <- [0, U32_MAX] // w8 <- [0, X] 55: w8 += 1 // r8 <- [0, U32_MAX+1] // w8 <- [0, X+1] In order to keep the bounds accurate at this point we also need to track ALU32 ops. To do this we add explicit ALU32 logic for each of the ALU ops, mov, add, sub, etc. Finally there is a question of how and when to merge bounds. The cases enumerate here, 1. MOV ALU32 - zext 32-bit -> 64-bit 2. MOV ALU64 - copy 64-bit -> 32-bit 3. op ALU32 - zext 32-bit -> 64-bit 4. op ALU64 - n/a 5. jmp ALU32 - 64-bit: var32_off | upper_32_bits(var64_off) 6. jmp ALU64 - 32-bit: (>> (<< var64_off)) Details for each case, For "MOV ALU32" BPF arch zero extends so we simply copy the bounds from 32-bit into 64-bit ensuring we truncate var_off and 64-bit bounds correctly. See zext_32_to_64. For "MOV ALU64" copy all bounds including 32-bit into new register. If the src register had 32-bit bounds the dst register will as well. For "op ALU32" zero extend 32-bit into 64-bit the same as move, see zext_32_to_64. For "op ALU64" calculate both 32-bit and 64-bit bounds no merging is done here. Except we have a special case. When RSH or ARSH is done we can't simply ignore shifting bits from 64-bit reg into the 32-bit subreg. So currently just push bounds from 64-bit into 32-bit. This will be correct in the sense that they will represent a valid state of the register. However we could lose some accuracy if an ARSH is following a jmp32 operation. We can handle this special case in a follow up series. For "jmp ALU32" mark 64-bit reg unknown and recalculate 64-bit bounds from tnum by setting var_off to ((<<(>>var_off)) | var32_off). We special case if 64-bit bounds has zero'd upper 32bits at which point we can simply copy 32-bit bounds into 64-bit register. This catches a common compiler trick where upper 32-bits are zeroed and then 32-bit ops are used followed by a 64-bit compare or 64-bit op on a pointer. See __reg_combine_64_into_32(). For "jmp ALU64" cast the bounds of the 64bit to their 32-bit counterpart. For example s32_min_value = (s32)reg->smin_value. For tnum use only the lower 32bits via, (>>(<<var_off)). See __reg_combine_64_into_32(). Signed-off-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/158560419880.10843.11448220440809118343.stgit@john-Precision-5820-Tower
| * bpf: Verifier, do_refine_retval_range may clamp umin to 0 incorrectlyJohn Fastabend2020-03-301-8/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | do_refine_retval_range() is called to refine return values from specified helpers, probe_read_str and get_stack at the moment, the reasoning is because both have a max value as part of their input arguments and because the helper ensure the return value will not be larger than this we can set smax values of the return register, r0. However, the return value is a signed integer so setting umax is incorrect It leads to further confusion when the do_refine_retval_range() then calls, __reg_deduce_bounds() which will see a umax value as meaning the value is unsigned and then assuming it is unsigned set the smin = umin which in this case results in 'smin = 0' and an 'smax = X' where X is the input argument from the helper call. Here are the comments from _reg_deduce_bounds() on why this would be safe to do. /* Learn sign from unsigned bounds. Signed bounds cross the sign * boundary, so we must be careful. */ if ((s64)reg->umax_value >= 0) { /* Positive. We can't learn anything from the smin, but smax * is positive, hence safe. */ reg->smin_value = reg->umin_value; reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value, reg->umax_value); But now we incorrectly have a return value with type int with the signed bounds (0,X). Suppose the return value is negative, which is possible the we have the verifier and reality out of sync. Among other things this may result in any error handling code being falsely detected as dead-code and removed. For instance the example below shows using bpf_probe_read_str() causes the error path to be identified as dead code and removed. >From the 'llvm-object -S' dump, r2 = 100 call 45 if r0 s< 0 goto +4 r4 = *(u32 *)(r7 + 0) But from dump xlate (b7) r2 = 100 (85) call bpf_probe_read_compat_str#-96768 (61) r4 = *(u32 *)(r7 +0) <-- dropped if goto Due to verifier state after call being R0=inv(id=0,umax_value=100,var_off=(0x0; 0x7f)) To fix omit setting the umax value because its not safe. The only actual bounds we know is the smax. This results in the correct bounds (SMIN, X) where X is the max length from the helper. After this the new verifier state looks like the following after call 45. R0=inv(id=0,smax_value=100) Then xlated version no longer removed dead code giving the expected result, (b7) r2 = 100 (85) call bpf_probe_read_compat_str#-96768 (c5) if r0 s< 0x0 goto pc+4 (61) r4 = *(u32 *)(r7 +0) Note, bpf_probe_read_* calls are root only so we wont hit this case with non-root bpf users. v3: comment had some documentation about meta set to null case which is not relevant here and confusing to include in the comment. v2 note: In original version we set msize_smax_value from check_func_arg() and propagated this into smax of retval. The logic was smax is the bound on the retval we set and because the type in the helper is ARG_CONST_SIZE we know that the reg is a positive tnum_const() so umax=smax. Alexei pointed out though this is a bit odd to read because the register in check_func_arg() has a C type of u32 and the umax bound would be the normally relavent bound here. Pulling in extra knowledge about future checks makes reading the code a bit tricky. Further having a signed meta data that can only ever be positive is also a bit odd. So dropped the msize_smax_value metadata and made it a u64 msize_max_value to indicate its unsigned. And additionally save bound from umax value in check_arg_funcs which is the same as smax due to as noted above tnumx_cont and negative check but reads better. By my analysis nothing functionally changes in v2 but it does get easier to read so that is win. Fixes: 849fa50662fbc ("bpf/verifier: refine retval R0 state for bpf_get_stack helper") Signed-off-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/158560417900.10843.14351995140624628941.stgit@john-Precision-5820-Tower
| * bpf: btf: Fix arg verification in btf_ctx_access()KP Singh2020-03-301-7/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The bounds checking for the arguments accessed in the BPF program breaks when the expected_attach_type is not BPF_TRACE_FEXIT, BPF_LSM_MAC or BPF_MODIFY_RETURN resulting in no check being done for the default case (the programs which do not receive the return value of the attached function in its arguments) when the index of the argument being accessed is equal to the number of arguments (nr_args). This was a result of a misplaced "else if" block introduced by the Commit 6ba43b761c41 ("bpf: Attachment verification for BPF_MODIFY_RETURN") Fixes: 6ba43b761c41 ("bpf: Attachment verification for BPF_MODIFY_RETURN") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200330144246.338-1-kpsingh@chromium.org
| * bpf: Simplify reg_set_min_max_inv handlingJann Horn2020-03-301-86/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | reg_set_min_max_inv() contains exactly the same logic as reg_set_min_max(), just flipped around. While this makes sense in a cBPF verifier (where ALU operations are not symmetric), it does not make sense for eBPF. Replace reg_set_min_max_inv() with a helper that flips the opcode around, then lets reg_set_min_max() do the complicated work. Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200330160324.15259-4-daniel@iogearbox.net
| * bpf: Fix tnum constraints for 32-bit comparisonsJann Horn2020-03-301-36/+72
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The BPF verifier tried to track values based on 32-bit comparisons by (ab)using the tnum state via 581738a681b6 ("bpf: Provide better register bounds after jmp32 instructions"). The idea is that after a check like this: if ((u32)r0 > 3) exit We can't meaningfully constrain the arithmetic-range-based tracking, but we can update the tnum state to (value=0,mask=0xffff'ffff'0000'0003). However, the implementation from 581738a681b6 didn't compute the tnum constraint based on the fixed operand, but instead derives it from the arithmetic-range-based tracking. This means that after the following sequence of operations: if (r0 >= 0x1'0000'0001) exit if ((u32)r0 > 7) exit The verifier assumed that the lower half of r0 is in the range (0, 0) and apply the tnum constraint (value=0,mask=0xffff'ffff'0000'0000) thus causing the overall tnum to be (value=0,mask=0x1'0000'0000), which was incorrect. Provide a fixed implementation. Fixes: 581738a681b6 ("bpf: Provide better register bounds after jmp32 instructions") Signed-off-by: Jann Horn <jannh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200330160324.15259-3-daniel@iogearbox.net
| * bpf: Undo incorrect __reg_bound_offset32 handlingDaniel Borkmann2020-03-301-19/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Anatoly has been fuzzing with kBdysch harness and reported a hang in one of the outcomes: 0: (b7) r0 = 808464432 1: (7f) r0 >>= r0 2: (14) w0 -= 808464432 3: (07) r0 += 808464432 4: (b7) r1 = 808464432 5: (de) if w1 s<= w0 goto pc+0 R0_w=invP(id=0,umin_value=808464432,umax_value=5103431727,var_off=(0x30303020;0x10000001f)) R1_w=invP808464432 R10=fp0 6: (07) r0 += -2144337872 7: (14) w0 -= -1607454672 8: (25) if r0 > 0x30303030 goto pc+0 R0_w=invP(id=0,umin_value=271581184,umax_value=271581311,var_off=(0x10300000;0x7f)) R1_w=invP808464432 R10=fp0 9: (76) if w0 s>= 0x303030 goto pc+2 12: (95) exit from 8 to 9: safe from 5 to 6: R0_w=invP(id=0,umin_value=808464432,umax_value=5103431727,var_off=(0x30303020;0x10000001f)) R1_w=invP808464432 R10=fp0 6: (07) r0 += -2144337872 7: (14) w0 -= -1607454672 8: (25) if r0 > 0x30303030 goto pc+0 R0_w=invP(id=0,umin_value=271581184,umax_value=271581311,var_off=(0x10300000;0x7f)) R1_w=invP808464432 R10=fp0 9: safe from 8 to 9: safe verification time 589 usec stack depth 0 processed 17 insns (limit 1000000) [...] The underlying program was xlated as follows: # bpftool p d x i 9 0: (b7) r0 = 808464432 1: (7f) r0 >>= r0 2: (14) w0 -= 808464432 3: (07) r0 += 808464432 4: (b7) r1 = 808464432 5: (de) if w1 s<= w0 goto pc+0 6: (07) r0 += -2144337872 7: (14) w0 -= -1607454672 8: (25) if r0 > 0x30303030 goto pc+0 9: (76) if w0 s>= 0x303030 goto pc+2 10: (05) goto pc-1 11: (05) goto pc-1 12: (95) exit The verifier rewrote original instructions it recognized as dead code with 'goto pc-1', but reality differs from verifier simulation in that we're actually able to trigger a hang due to hitting the 'goto pc-1' instructions. Taking different examples to make the issue more obvious: in this example we're probing bounds on a completely unknown scalar variable in r1: [...] 5: R0_w=inv1 R1_w=inv(id=0) R10=fp0 5: (18) r2 = 0x4000000000 7: R0_w=inv1 R1_w=inv(id=0) R2_w=inv274877906944 R10=fp0 7: (18) r3 = 0x2000000000 9: R0_w=inv1 R1_w=inv(id=0) R2_w=inv274877906944 R3_w=inv137438953472 R10=fp0 9: (18) r4 = 0x400 11: R0_w=inv1 R1_w=inv(id=0) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R10=fp0 11: (18) r5 = 0x200 13: R0_w=inv1 R1_w=inv(id=0) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R5_w=inv512 R10=fp0 13: (2d) if r1 > r2 goto pc+4 R0_w=inv1 R1_w=inv(id=0,umax_value=274877906944,var_off=(0x0; 0x7fffffffff)) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R5_w=inv512 R10=fp0 14: R0_w=inv1 R1_w=inv(id=0,umax_value=274877906944,var_off=(0x0; 0x7fffffffff)) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R5_w=inv512 R10=fp0 14: (ad) if r1 < r3 goto pc+3 R0_w=inv1 R1_w=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7fffffffff)) R2_w=inv274877906944 R3_w=inv137438953472 R4_w=inv1024 R5_w=inv512 R10=fp0 15: R0=inv1 R1=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7fffffffff)) R2=inv274877906944 R3=inv137438953472 R4=inv1024 R5=inv512 R10=fp0 15: (2e) if w1 > w4 goto pc+2 R0=inv1 R1=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7f00000000)) R2=inv274877906944 R3=inv137438953472 R4=inv1024 R5=inv512 R10=fp0 16: R0=inv1 R1=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7f00000000)) R2=inv274877906944 R3=inv137438953472 R4=inv1024 R5=inv512 R10=fp0 16: (ae) if w1 < w5 goto pc+1 R0=inv1 R1=inv(id=0,umin_value=137438953472,umax_value=274877906944,var_off=(0x0; 0x7f00000000)) R2=inv274877906944 R3=inv137438953472 R4=inv1024 R5=inv512 R10=fp0 [...] We're first probing lower/upper bounds via jmp64, later we do a similar check via jmp32 and examine the resulting var_off there. After fall-through in insn 14, we get the following bounded r1 with 0x7fffffffff unknown marked bits in the variable section. Thus, after knowing r1 <= 0x4000000000 and r1 >= 0x2000000000: max: 0b100000000000000000000000000000000000000 / 0x4000000000 var: 0b111111111111111111111111111111111111111 / 0x7fffffffff min: 0b010000000000000000000000000000000000000 / 0x2000000000 Now, in insn 15 and 16, we perform a similar probe with lower/upper bounds in jmp32. Thus, after knowing r1 <= 0x4000000000 and r1 >= 0x2000000000 and w1 <= 0x400 and w1 >= 0x200: max: 0b100000000000000000000000000000000000000 / 0x4000000000 var: 0b111111100000000000000000000000000000000 / 0x7f00000000 min: 0b010000000000000000000000000000000000000 / 0x2000000000 The lower/upper bounds haven't changed since they have high bits set in u64 space and the jmp32 tests can only refine bounds in the low bits. However, for the var part the expectation would have been 0x7f000007ff or something less precise up to 0x7fffffffff. A outcome of 0x7f00000000 is not correct since it would contradict the earlier probed bounds where we know that the result should have been in [0x200,0x400] in u32 space. Therefore, tests with such info will lead to wrong verifier assumptions later on like falsely predicting conditional jumps to be always taken, etc. The issue here is that __reg_bound_offset32()'s implementation from commit 581738a681b6 ("bpf: Provide better register bounds after jmp32 instructions") makes an incorrect range assumption: static void __reg_bound_offset32(struct bpf_reg_state *reg) { u64 mask = 0xffffFFFF; struct tnum range = tnum_range(reg->umin_value & mask, reg->umax_value & mask); struct tnum lo32 = tnum_cast(reg->var_off, 4); struct tnum hi32 = tnum_lshift(tnum_rshift(reg->var_off, 32), 32); reg->var_off = tnum_or(hi32, tnum_intersect(lo32, range)); } In the above walk-through example, __reg_bound_offset32() as-is chose a range after masking with 0xffffffff of [0x0,0x0] since umin:0x2000000000 and umax:0x4000000000 and therefore the lo32 part was clamped to 0x0 as well. However, in the umin:0x2000000000 and umax:0x4000000000 range above we'd end up with an actual possible interval of [0x0,0xffffffff] for u32 space instead. In case of the original reproducer, the situation looked as follows at insn 5 for r0: [...] 5: R0_w=invP(id=0,umin_value=808464432,umax_value=5103431727,var_off=(0x0; 0x1ffffffff)) R1_w=invP808464432 R10=fp0 0x30303030 0x13030302f 5: (de) if w1 s<= w0 goto pc+0 R0_w=invP(id=0,umin_value=808464432,umax_value=5103431727,var_off=(0x30303020; 0x10000001f)) R1_w=invP808464432 R10=fp0 0x30303030 0x13030302f [...] After the fall-through, we similarly forced the var_off result into the wrong range [0x30303030,0x3030302f] suggesting later on that fixed bits must only be of 0x30303020 with 0x10000001f unknowns whereas such assumption can only be made when both bounds in hi32 range match. Originally, I was thinking to fix this by moving reg into a temp reg and use proper coerce_reg_to_size() helper on the temp reg where we can then based on that define the range tnum for later intersection: static void __reg_bound_offset32(struct bpf_reg_state *reg) { struct bpf_reg_state tmp = *reg; struct tnum lo32, hi32, range; coerce_reg_to_size(&tmp, 4); range = tnum_range(tmp.umin_value, tmp.umax_value); lo32 = tnum_cast(reg->var_off, 4); hi32 = tnum_lshift(tnum_rshift(reg->var_off, 32), 32); reg->var_off = tnum_or(hi32, tnum_intersect(lo32, range)); } In the case of the concrete example, this gives us a more conservative unknown section. Thus, after knowing r1 <= 0x4000000000 and r1 >= 0x2000000000 and w1 <= 0x400 and w1 >= 0x200: max: 0b100000000000000000000000000000000000000 / 0x4000000000 var: 0b111111111111111111111111111111111111111 / 0x7fffffffff min: 0b010000000000000000000000000000000000000 / 0x2000000000 However, above new __reg_bound_offset32() has no effect on refining the knowledge of the register contents. Meaning, if the bounds in hi32 range mismatch we'll get the identity function given the range reg spans [0x0,0xffffffff] and we cast var_off into lo32 only to later on binary or it again with the hi32. Likewise, if the bounds in hi32 range match, then we mask both bounds with 0xffffffff, use the resulting umin/umax for the range to later intersect the lo32 with it. However, _prior_ called __reg_bound_offset() did already such intersection on the full reg and we therefore would only repeat the same operation on the lo32 part twice. Given this has no effect and the original commit had false assumptions, this patch reverts the code entirely which is also more straight forward for stable trees: apparently 581738a681b6 got auto-selected by Sasha's ML system and misclassified as a fix, so it got sucked into v5.4 where it should never have landed. A revert is low-risk also from a user PoV since it requires a recent kernel and llc to opt-into -mcpu=v3 BPF CPU to generate jmp32 instructions. A proper bounds refinement would need a significantly more complex approach which is currently being worked, but no stable material [0]. Hence revert is best option for stable. After the revert, the original reported program gets rejected as follows: 1: (7f) r0 >>= r0 2: (14) w0 -= 808464432 3: (07) r0 += 808464432 4: (b7) r1 = 808464432 5: (de) if w1 s<= w0 goto pc+0 R0_w=invP(id=0,umin_value=808464432,umax_value=5103431727,var_off=(0x0; 0x1ffffffff)) R1_w=invP808464432 R10=fp0 6: (07) r0 += -2144337872 7: (14) w0 -= -1607454672 8: (25) if r0 > 0x30303030 goto pc+0 R0_w=invP(id=0,umax_value=808464432,var_off=(0x0; 0x3fffffff)) R1_w=invP808464432 R10=fp0 9: (76) if w0 s>= 0x303030 goto pc+2 R0=invP(id=0,umax_value=3158063,var_off=(0x0; 0x3fffff)) R1=invP808464432 R10=fp0 10: (30) r0 = *(u8 *)skb[808464432] BPF_LD_[ABS|IND] uses reserved fields processed 11 insns (limit 1000000) [...] [0] https://lore.kernel.org/bpf/158507130343.15666.8018068546764556975.stgit@john-Precision-5820-Tower/T/ Fixes: 581738a681b6 ("bpf: Provide better register bounds after jmp32 instructions") Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200330160324.15259-2-daniel@iogearbox.net
| * bpf: lsm: Implement attach, detach and executionKP Singh2020-03-305-27/+105
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | JITed BPF programs are dynamically attached to the LSM hooks using BPF trampolines. The trampoline prologue generates code to handle conversion of the signature of the hook to the appropriate BPF context. The allocated trampoline programs are attached to the nop functions initialized as LSM hooks. BPF_PROG_TYPE_LSM programs must have a GPL compatible license and and need CAP_SYS_ADMIN (required for loading eBPF programs). Upon attachment: * A BPF fexit trampoline is used for LSM hooks with a void return type. * A BPF fmod_ret trampoline is used for LSM hooks which return an int. The attached programs can override the return value of the bpf LSM hook to indicate a MAC Policy decision. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Brendan Jackman <jackmanb@google.com> Reviewed-by: Florent Revest <revest@google.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: James Morris <jamorris@linux.microsoft.com> Link: https://lore.kernel.org/bpf/20200329004356.27286-5-kpsingh@chromium.org
| * bpf: lsm: Provide attachment points for BPF LSM programsKP Singh2020-03-301-0/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When CONFIG_BPF_LSM is enabled, nop functions, bpf_lsm_<hook_name>, are generated for each LSM hook. These functions are initialized as LSM hooks in a subsequent patch. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Brendan Jackman <jackmanb@google.com> Reviewed-by: Florent Revest <revest@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Yonghong Song <yhs@fb.com> Acked-by: James Morris <jamorris@linux.microsoft.com> Link: https://lore.kernel.org/bpf/20200329004356.27286-4-kpsingh@chromium.org
| * bpf: Introduce BPF_PROG_TYPE_LSMKP Singh2020-03-302-0/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Introduce types and configs for bpf programs that can be attached to LSM hooks. The programs can be enabled by the config option CONFIG_BPF_LSM. Signed-off-by: KP Singh <kpsingh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Brendan Jackman <jackmanb@google.com> Reviewed-by: Florent Revest <revest@google.com> Reviewed-by: Thomas Garnier <thgarnie@google.com> Acked-by: Yonghong Song <yhs@fb.com> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: James Morris <jamorris@linux.microsoft.com> Link: https://lore.kernel.org/bpf/20200329004356.27286-2-kpsingh@chromium.org
| * bpf: Enable bpf cgroup hooks to retrieve cgroup v2 and ancestor idDaniel Borkmann2020-03-282-0/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Enable the bpf_get_current_cgroup_id() helper for connect(), sendmsg(), recvmsg() and bind-related hooks in order to retrieve the cgroup v2 context which can then be used as part of the key for BPF map lookups, for example. Given these hooks operate in process context 'current' is always valid and pointing to the app that is performing mentioned syscalls if it's subject to a v2 cgroup. Also with same motivation of commit 7723628101aa ("bpf: Introduce bpf_skb_ancestor_cgroup_id helper") enable retrieval of ancestor from current so the cgroup id can be used for policy lookups which can then forbid connect() / bind(), for example. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/d2a7ef42530ad299e3cbb245e6c12374b72145ef.1585323121.git.daniel@iogearbox.net
| * bpf: Add netns cookie and enable it for bpf cgroup hooksDaniel Borkmann2020-03-281-6/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In Cilium we're mainly using BPF cgroup hooks today in order to implement kube-proxy free Kubernetes service translation for ClusterIP, NodePort (*), ExternalIP, and LoadBalancer as well as HostPort mapping [0] for all traffic between Cilium managed nodes. While this works in its current shape and avoids packet-level NAT for inter Cilium managed node traffic, there is one major limitation we're facing today, that is, lack of netns awareness. In Kubernetes, the concept of Pods (which hold one or multiple containers) has been built around network namespaces, so while we can use the global scope of attaching to root BPF cgroup hooks also to our advantage (e.g. for exposing NodePort ports on loopback addresses), we also have the need to differentiate between initial network namespaces and non-initial one. For example, ExternalIP services mandate that non-local service IPs are not to be translated from the host (initial) network namespace as one example. Right now, we have an ugly work-around in place where non-local service IPs for ExternalIP services are not xlated from connect() and friends BPF hooks but instead via less efficient packet-level NAT on the veth tc ingress hook for Pod traffic. On top of determining whether we're in initial or non-initial network namespace we also have a need for a socket-cookie like mechanism for network namespaces scope. Socket cookies have the nice property that they can be combined as part of the key structure e.g. for BPF LRU maps without having to worry that the cookie could be recycled. We are planning to use this for our sessionAffinity implementation for services. Therefore, add a new bpf_get_netns_cookie() helper which would resolve both use cases at once: bpf_get_netns_cookie(NULL) would provide the cookie for the initial network namespace while passing the context instead of NULL would provide the cookie from the application's network namespace. We're using a hole, so no size increase; the assignment happens only once. Therefore this allows for a comparison on initial namespace as well as regular cookie usage as we have today with socket cookies. We could later on enable this helper for other program types as well as we would see need. (*) Both externalTrafficPolicy={Local|Cluster} types [0] https://github.com/cilium/cilium/blob/master/bpf/bpf_sock.c Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/c47d2346982693a9cf9da0e12690453aded4c788.1585323121.git.daniel@iogearbox.net
| * bpf: Remove unused vairable 'bpf_xdp_link_lops'YueHaibing2020-03-271-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | kernel/bpf/syscall.c:2263:34: warning: 'bpf_xdp_link_lops' defined but not used [-Wunused-const-variable=] static const struct bpf_link_ops bpf_xdp_link_lops; ^~~~~~~~~~~~~~~~~ commit 70ed506c3bbc ("bpf: Introduce pinnable bpf_link abstraction") involded this unused variable, remove it. Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: YueHaibing <yuehaibing@huawei.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200326031613.19372-1-yuehaibing@huawei.com
| * bpf: Factor out attach_type to prog_type mapping for attach/detachAndrii Nakryiko2020-03-271-87/+66
| | | | | | | | | | | | | | | | | | | | | | Factor out logic mapping expected program attach type to program type and subsequent handling of program attach/detach. Also list out all supported cgroup BPF program types explicitly to prevent accidental bugs once more program types are added to a mapping. Do the same for prog_query API. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200325065746.640559-3-andriin@fb.com
| * bpf: Factor out cgroup storages operationsAndrii Nakryiko2020-03-271-46/+72
| | | | | | | | | | | | | | | | | | | | Refactor cgroup attach/detach code to abstract away common operations performed on all types of cgroup storages. This makes high-level logic more apparent, plus allows to reuse more code across multiple functions. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200325065746.640559-2-andriin@fb.com
| * bpf: Verifer, adjust_scalar_min_max_vals to always call update_reg_bounds()John Fastabend2020-03-261-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, for all op verification we call __red_deduce_bounds() and __red_bound_offset() but we only call __update_reg_bounds() in bitwise ops. However, we could benefit from calling __update_reg_bounds() in BPF_ADD, BPF_SUB, and BPF_MUL cases as well. For example, a register with state 'R1_w=invP0' when we subtract from it, w1 -= 2 Before coerce we will now have an smin_value=S64_MIN, smax_value=U64_MAX and unsigned bounds umin_value=0, umax_value=U64_MAX. These will then be clamped to S32_MIN, U32_MAX values by coerce in the case of alu32 op as done in above example. However tnum will be a constant because the ALU op is done on a constant. Without update_reg_bounds() we have a scenario where tnum is a const but our unsigned bounds do not reflect this. By calling update_reg_bounds after coerce to 32bit we further refine the umin_value to U64_MAX in the alu64 case or U32_MAX in the alu32 case above. Signed-off-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/158507151689.15666.566796274289413203.stgit@john-Precision-5820-Tower
| * bpf: Verifer, refactor adjust_scalar_min_max_valsJohn Fastabend2020-03-261-164/+239
| | | | | | | | | | | | | | | | | | | | Pull per op ALU logic into individual functions. We are about to add u32 versions of each of these by pull them out the code gets a bit more readable here and nicer in the next patch. Signed-off-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/158507149518.15666.15672349629329072411.stgit@john-Precision-5820-Tower
| * bpf: Support llvm-objcopy for vmlinux BTFFangrui Song2020-03-192-11/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Simplify gen_btf logic to make it work with llvm-objcopy. The existing 'file format' and 'architecture' parsing logic is brittle and does not work with llvm-objcopy/llvm-objdump. 'file format' output of llvm-objdump>=11 will match GNU objdump, but 'architecture' (bfdarch) may not. .BTF in .tmp_vmlinux.btf is non-SHF_ALLOC. Add the SHF_ALLOC flag because it is part of vmlinux image used for introspection. C code can reference the section via linker script defined __start_BTF and __stop_BTF. This fixes a small problem that previous .BTF had the SHF_WRITE flag (objcopy -I binary -O elf* synthesized .data). Additionally, `objcopy -I binary` synthesized symbols _binary__btf_vmlinux_bin_start and _binary__btf_vmlinux_bin_stop (not used elsewhere) are replaced with more commonplace __start_BTF and __stop_BTF. Add 2>/dev/null because GNU objcopy (but not llvm-objcopy) warns "empty loadable segment detected at vaddr=0xffffffff81000000, is this intentional?" We use a dd command to change the e_type field in the ELF header from ET_EXEC to ET_REL so that lld will accept .btf.vmlinux.bin.o. Accepting ET_EXEC as an input file is an extremely rare GNU ld feature that lld does not intend to support, because this is error-prone. The output section description .BTF in include/asm-generic/vmlinux.lds.h avoids potential subtle orphan section placement issues and suppresses --orphan-handling=warn warnings. Fixes: df786c9b9476 ("bpf: Force .BTF section start to zero when dumping from vmlinux") Fixes: cb0cc635c7a9 ("powerpc: Include .BTF section") Reported-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Fangrui Song <maskray@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Tested-by: Stanislav Fomichev <sdf@google.com> Tested-by: Andrii Nakryiko <andriin@fb.com> Reviewed-by: Stanislav Fomichev <sdf@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Link: https://github.com/ClangBuiltLinux/linux/issues/871 Link: https://lore.kernel.org/bpf/20200318222746.173648-1-maskray@google.com
* | Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller2020-03-302-15/+22
|\ \ | | | | | | | | | | | | | | | Minor comment conflict in mac80211. Signed-off-by: David S. Miller <davem@davemloft.net>
| * | bpf: Explicitly memset some bpf info structures declared on the stackGreg Kroah-Hartman2020-03-202-3/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Trying to initialize a structure with "= {};" will not always clean out all padding locations in a structure. So be explicit and call memset to initialize everything for a number of bpf information structures that are then copied from userspace, sometimes from smaller memory locations than the size of the structure. Reported-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20200320162258.GA794295@kroah.com
| * | bpf: Explicitly memset the bpf_attr structureGreg Kroah-Hartman2020-03-201-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For the bpf syscall, we are relying on the compiler to properly zero out the bpf_attr union that we copy userspace data into. Unfortunately that doesn't always work properly, padding and other oddities might not be correctly zeroed, and in some tests odd things have been found when the stack is pre-initialized to other values. Fix this by explicitly memsetting the structure to 0 before using it. Reported-by: Maciej Żenczykowski <maze@google.com> Reported-by: John Stultz <john.stultz@linaro.org> Reported-by: Alexander Potapenko <glider@google.com> Reported-by: Alistair Delva <adelva@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://android-review.googlesource.com/c/kernel/common/+/1235490 Link: https://lore.kernel.org/bpf/20200320094813.GA421650@kroah.com
| * | bpf: Sanitize the bpf_struct_ops tcp-cc nameMartin KaFai Lau2020-03-171-11/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The bpf_struct_ops tcp-cc name should be sanitized in order to avoid problematic chars (e.g. whitespaces). This patch reuses the bpf_obj_name_cpy() for accepting the same set of characters in order to keep a consistent bpf programming experience. A "size" param is added. Also, the strlen is returned on success so that the caller (like the bpf_tcp_ca here) can error out on empty name. The existing callers of the bpf_obj_name_cpy() only need to change the testing statement to "if (err < 0)". For all these existing callers, the err will be overwritten later, so no extra change is needed for the new strlen return value. v3: - reverse xmas tree style v2: - Save the orig_src to avoid "end - size" (Andrii) Fixes: 0baf26b0fcd7 ("bpf: tcp: Support tcp_congestion_ops in bpf") Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200314010209.1131542-1-kafai@fb.com