- 29 Jul, 2024 40 commits
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Eduard Zingerman authored
Non-functional change: use a separate data structure to represented expected messages in test_loader. This would allow to use the same functionality for expected set of disassembled instructions in the follow-up commit. Acked-by:
Andrii Nakryiko <andrii@kernel.org> Signed-off-by:
Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20240722233844.1406874-8-eddyz87@gmail.comSigned-off-by:
Alexei Starovoitov <ast@kernel.org> Signed-off-by:
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Eduard Zingerman authored
The call stack for validate_case() function looks as follows: - test_loader__run_subtests() - process_subtest() - run_subtest() - prepare_case(), which does 'tester->next_match_pos = 0'; - validate_case(), which increments tester->next_match_pos. Hence, each subtest is run with next_match_pos freshly set to zero. Meaning that there is no need to persist this variable in the struct test_loader, use local variable instead. Acked-by: -
Eduard Zingerman authored
Adjust disasm_helpers.c:disasm_insn() to account for the following part of the verifier.c:jit_subprogs: for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) { /* ... */ if (!bpf_pseudo_call(insn)) continue; insn->off = env->insn_aux_data[i].call_imm; subprog = find_subprog(env, i + insn->off + 1); insn->imm = subprog; } Where verifier moves offset of the subprogram to the insn->off field. Signed-off-by: -
Eduard Zingerman authored
struct bpf_insn *disasm_insn(struct bpf_insn *insn, char *buf, size_t buf_sz); Disassembles instruction 'insn' to a text buffer 'buf'. Removes insn->code hex prefix added by kernel disassembly routine. Returns a pointer to the next instruction (increments insn by either 1 or 2). Acked-by:
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Eduard Zingerman authored
The function bpf_get_smp_processor_id() is processed in a different way, depending on the arch: - on x86 verifier replaces call to bpf_get_smp_processor_id() with a sequence of instructions that modify only r0; - on riscv64 jit replaces call to bpf_get_smp_processor_id() with a sequence of instructions that modify only r0; - on arm64 jit replaces call to bpf_get_smp_processor_id() with a sequence of instructions that modify only r0 and tmp registers. These rewrites satisfy attribute no_caller_saved_registers contract. Allow rewrite of no_caller_saved_registers patterns for bpf_get_smp_processor_id() in order to use this function as a canary for no_caller_saved_registers tests. Signed-off-by:
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Eduard Zingerman authored
GCC and LLVM define a no_caller_saved_registers function attribute. This attribute means that function scratches only some of the caller saved registers defined by ABI. For BPF the set of such registers could be defined as follows: - R0 is scratched only if function is non-void; - R1-R5 are scratched only if corresponding parameter type is defined in the function prototype. This commit introduces flag bpf_func_prot->allow_nocsr. If this flag is set for some helper function, verifier assumes that it follows no_caller_saved_registers calling convention. The contract between kernel and clang allows to simultaneously use such functions and maintain backwards compatibility with old kernels that don't understand no_caller_saved_registers calls (nocsr for short): - clang generates a simple pattern for nocsr calls, e.g.: r1 = 1; r2 = 2; *(u64 *)(r10 - 8) = r1; *(u64 *)(r10 - 16) = r2; call %[to_be_inlined] r2 = *(u64 *)(r10 - 16); r1 = *(u64 *)(r10 - 8); r0 = r1; r0 += r2; exit; - kernel removes unnecessary spills and fills, if called function is inlined by verifier or current JIT (with assumption that patch inserted by verifier or JIT honors nocsr contract, e.g. does not scratch r3-r5 for the example above), e.g. the code above would be transformed to: r1 = 1; r2 = 2; call %[to_be_inlined] r0 = r1; r0 += r2; exit; Technically, the transformation is split into the following phases: - function mark_nocsr_patterns(), called from bpf_check() searches and marks potential patterns in instruction auxiliary data; - upon stack read or write access, function check_nocsr_stack_contract() is used to verify if stack offsets, presumably reserved for nocsr patterns, are used only from those patterns; - function remove_nocsr_spills_fills(), called from bpf_check(), applies the rewrite for valid patterns. See comment in mark_nocsr_pattern_for_call() for more details. Suggested-by:Alexei Starovoitov <alexei.starovoitov@gmail.com> Signed-off-by:
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Eduard Zingerman authored
Extract the part of check_helper_call() as a utility function allowing to query 'struct bpf_func_proto' for a specific helper function id. Acked-by:
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Yonghong Song authored
Add a few reg_bounds selftests to test 32/16/8-bit ldsx and subreg comparison. Without the previous patch, all added tests will fail. Acked-by:
Yonghong Song <yonghong.song@linux.dev> Link: https://lore.kernel.org/r/20240723162940.2732171-1-yonghong.song@linux.devSigned-off-by:
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Yonghong Song authored
With latest llvm19, the selftest iters/iter_arr_with_actual_elem_count failed with -mcpu=v4. The following are the details: 0: R1=ctx() R10=fp0 ; int iter_arr_with_actual_elem_count(const void *ctx) @ iters.c:1420 0: (b4) w7 = 0 ; R7_w=0 ; int i, n = loop_data.n, sum = 0; @ iters.c:1422 1: (18) r1 = 0xffffc90000191478 ; R1_w=map_value(map=iters.bss,ks=4,vs=1280,off=1144) 3: (61) r6 = *(u32 *)(r1 +128) ; R1_w=map_value(map=iters.bss,ks=4,vs=1280,off=1144) R6_w=scalar(smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff)) ; if (n > ARRAY_SIZE(loop_data.data)) @ iters.c:1424 4: (26) if w6 > 0x20 goto pc+27 ; R6_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=32,var_off=(0x0; 0x3f)) 5: (bf) r8 = r10 ; R8_w=fp0 R10=fp0 6: (07) r8 += -8 ; R8_w=fp-8 ; bpf_for(i, 0, n) { @ iters.c:1427 7: (bf) r1 = r8 ; R1_w=fp-8 R8_w=fp-8 8: (b4) w2 = 0 ; R2_w=0 9: (bc) w3 = w6 ; R3_w=scalar(id=1,smin=smin32=0,smax=umax=smax32=umax32=32,var_off=(0x0; 0x3f)) R6_w=scalar(id=1,smin=smin32=0,smax=umax=smax32=umax32=32,var_off=(0x0; 0x3f)) 10: (85) call bpf_iter_num_new#45179 ; R0=scalar() fp-8=iter_num(ref_id=2,state=active,depth=0) refs=2 11: (bf) r1 = r8 ; R1=fp-8 R8=fp-8 refs=2 12: (85) call bpf_iter_num_next#45181 13: R0=rdonly_mem(id=3,ref_obj_id=2,sz=4) R6=scalar(id=1,smin=smin32=0,smax=umax=smax32=umax32=32,var_off=(0x0; 0x3f)) R7=0 R8=fp-8 R10=fp0 fp-8=iter_num(ref_id=2,state=active,depth=1) refs=2 ; bpf_for(i, 0, n) { @ iters.c:1427 13: (15) if r0 == 0x0 goto pc+2 ; R0=rdonly_mem(id=3,ref_obj_id=2,sz=4) refs=2 14: (81) r1 = *(s32 *)(r0 +0) ; R0=rdonly_mem(id=3,ref_obj_id=2,sz=4) R1_w=scalar(smin=0xffffffff80000000,smax=0x7fffffff) refs=2 15: (ae) if w1 < w6 goto pc+4 20: R0=rdonly_mem(id=3,ref_obj_id=2,sz=4) R1=scalar(smin=0xffffffff80000000,smax=smax32=umax32=31,umax=0xffffffff0000001f,smin32=0,var_off=(0x0; 0xffffffff0000001f)) R6=scalar(id=1,smin=umin=smin32=umin32=1,smax=umax=smax32=umax32=32,var_off=(0x0; 0x3f)) R7=0 R8=fp-8 R10=fp0 fp-8=iter_num(ref_id=2,state=active,depth=1) refs=2 ; sum += loop_data.data[i]; @ iters.c:1429 20: (67) r1 <<= 2 ; R1_w=scalar(smax=0x7ffffffc0000007c,umax=0xfffffffc0000007c,smin32=0,smax32=umax32=124,var_off=(0x0; 0xfffffffc0000007c)) refs=2 21: (18) r2 = 0xffffc90000191478 ; R2_w=map_value(map=iters.bss,ks=4,vs=1280,off=1144) refs=2 23: (0f) r2 += r1 math between map_value pointer and register with unbounded min value is not allowed The source code: int iter_arr_with_actual_elem_count(const void *ctx) { int i, n = loop_data.n, sum = 0; if (n > ARRAY_SIZE(loop_data.data)) return 0; bpf_for(i, 0, n) { /* no rechecking of i against ARRAY_SIZE(loop_data.n) */ sum += loop_data.data[i]; } return sum; } The insn #14 is a sign-extenstion load which is related to 'int i'. The insn #15 did a subreg comparision. Note that smin=0xffffffff80000000 and this caused later insn #23 failed verification due to unbounded min value. Actually insn #15 R1 smin range can be better. Before insn #15, we have R1_w=scalar(smin=0xffffffff80000000,smax=0x7fffffff) With the above range, we know for R1, upper 32bit can only be 0xffffffff or 0. Otherwise, the value range for R1 could be beyond [smin=0xffffffff80000000,smax=0x7fffffff]. After insn #15, for the true patch, we know smin32=0 and smax32=32. With the upper 32bit 0xffffffff, then the corresponding value is [0xffffffff00000000, 0xffffffff00000020]. The range is obviously beyond the original range [smin=0xffffffff80000000,smax=0x7fffffff] and the range is not possible. So the upper 32bit must be 0, which implies smin = smin32 and smax = smax32. This patch fixed the issue by adding additional register deduction after 32-bit compare insn. If the signed 32-bit register range is non-negative then 64-bit smin is in range of [S32_MIN, S32_MAX], then the actual 64-bit smin/smax should be the same as 32-bit smin32/smax32. With this patch, iters/iter_arr_with_actual_elem_count succeeded with better register range: from 15 to 20: R0=rdonly_mem(id=7,ref_obj_id=2,sz=4) R1_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=31,var_off=(0x0; 0x1f)) R6=scalar(id=1,smin=umin=smin32=umin32=1,smax=umax=smax32=umax32=32,var_off=(0x0; 0x3f)) R7=scalar(id=9,smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff)) R8=scalar(id=9,smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff)) R10=fp0 fp-8=iter_num(ref_id=2,state=active,depth=3) refs=2 Acked-by:Shung-Hsi Yu <shung-hsi.yu@suse.com> Signed-off-by:
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Yonghong Song authored
The following tests are added to verifier_ldsx.c: - sign extension of data/data_end/data_meta for tcx programs. The actual checking is in bpf_skb_is_valid_access() which is called by sk_filter, cg_skb, lwt, tc(tcx) and sk_skb. - sign extension of data/data_end/data_meta for xdp programs. - sign extension of data/data_end for flow_dissector programs. All newly-added tests have verification failure with message "invalid bpf_context access". Without previous patch, all these tests succeeded verification. Acked-by: -
Yonghong Song authored
syzbot reported a kernel crash due to commit 1f1e864b ("bpf: Handle sign-extenstin ctx member accesses"). The reason is due to sign-extension of 32-bit load for packet data/data_end/data_meta uapi field. The original code looks like: r2 = *(s32 *)(r1 + 76) /* load __sk_buff->data */ r3 = *(u32 *)(r1 + 80) /* load __sk_buff->data_end */ r0 = r2 r0 += 8 if r3 > r0 goto +1 ... Note that __sk_buff->data load has 32-bit sign extension. After verification and convert_ctx_accesses(), the final asm code looks like: r2 = *(u64 *)(r1 +208) r2 = (s32)r2 r3 = *(u64 *)(r1 +80) r0 = r2 r0 += 8 if r3 > r0 goto pc+1 ... Note that 'r2 = (s32)r2' may make the kernel __sk_buff->data address invalid which may cause runtime failure. Currently, in C code, typically we have void *data = (void *)(long)skb->data; void *data_end = (void *)(long)skb->data_end; ... and it will generate r2 = *(u64 *)(r1 +208) r3 = *(u64 *)(r1 +80) r0 = r2 r0 += 8 if r3 > r0 goto pc+1 If we allow sign-extension, void *data = (void *)(long)(int)skb->data; void *data_end = (void *)(long)skb->data_end; ... the generated code looks like r2 = *(u64 *)(r1 +208) r2 <<= 32 r2 s>>= 32 r3 = *(u64 *)(r1 +80) r0 = r2 r0 += 8 if r3 > r0 goto pc+1 and this will cause verification failure since "r2 <<= 32" is not allowed as "r2" is a packet pointer. To fix this issue for case r2 = *(s32 *)(r1 + 76) /* load __sk_buff->data */ this patch added additional checking in is_valid_access() callback function for packet data/data_end/data_meta access. If those accesses are with sign-extenstion, the verification will fail. [1] https://lore.kernel.org/bpf/000000000000c90eee061d236d37@google.com/ Reported-by: syzbot+ad9ec60c8eaf69e6f99c@syzkaller.appspotmail.com Fixes: 1f1e864b ("bpf: Handle sign-extenstin ctx member accesses") Acked-by:
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Tony Ambardar authored
Actually use previously defined LDFLAGS during build and add support for LDLIBS to link extra standalone libraries e.g. 'argp' which is not provided by musl libc. Fixes: 585bf464 ("tools: runqslower: Add EXTRA_CFLAGS and EXTRA_LDFLAGS support") Signed-off-by:
Tony Ambardar <tony.ambardar@gmail.com> Signed-off-by:
Ilya Leoshkevich <iii@linux.ibm.com> Link: https://lore.kernel.org/bpf/20240723003045.2273499-1-tony.ambardar@gmail.com
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Tony Ambardar authored
Make log output incorrectly shows 'test_maps' as the binary name for every 'CLNG-BPF' build step, apparently picking up the last value defined for the $(TRUNNER_BINARY) variable. Update the 'CLANG_BPF_BUILD_RULE' variants to fix this confusing output. Current output: CLNG-BPF [test_maps] access_map_in_map.bpf.o GEN-SKEL [test_progs] access_map_in_map.skel.h ... CLNG-BPF [test_maps] access_map_in_map.bpf.o GEN-SKEL [test_progs-no_alu32] access_map_in_map.skel.h ... CLNG-BPF [test_maps] access_map_in_map.bpf.o GEN-SKEL [test_progs-cpuv4] access_map_in_map.skel.h After fix: CLNG-BPF [test_progs] access_map_in_map.bpf.o GEN-SKEL [test_progs] access_map_in_map.skel.h ... CLNG-BPF [test_progs-no_alu32] access_map_in_map.bpf.o GEN-SKEL [test_progs-no_alu32] access_map_in_map.skel.h ... CLNG-BPF [test_progs-cpuv4] access_map_in_map.bpf.o GEN-SKEL [test_progs-cpuv4] access_map_in_map.skel.h Fixes: a5d0c26a ("selftests/bpf: Add a cpuv4 test runner for cpu=v4 testing") Fixes: 89ad7420 ("selftests/bpf: Drop the need for LLVM's llc") Signed-off-by:
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Andrii Nakryiko authored
Jiri Olsa says: ==================== selftests/bpf: Add more uprobe multi tests hi, adding more uprobe multi tests for failed attachments inside the uprobe register code. v3 changes: - renamed several variables/functions, null check [Andrii] - fixed CI issue thanks, jirka --- ==================== Link: https://lore.kernel.org/r/20240722202758.3889061-1-jolsa@kernel.orgSigned-off-by:
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Artem Savkov authored
Without CONFIG_NET_FOU bpf selftests are unable to build because of missing definitions. Add ___local versions of struct bpf_fou_encap and enum bpf_fou_encap_type to fix the issue. Signed-off-by:
Artem Savkov <asavkov@redhat.com> Signed-off-by:
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Jiri Olsa authored
Adding test that attaches/detaches multiple consumers on single uprobe and verifies all were hit as expected. Signed-off-by:
Jiri Olsa <jolsa@kernel.org> Signed-off-by:
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Tony Ambardar authored
Linking uprobe_multi.c on mips64el fails due to relocation overflows, when the GOT entries required exceeds the default maximum. Add a specific CFLAGS (-mxgot) for uprobe_multi.c on MIPS that allows using a larger GOT and avoids errors such as: /tmp/ccBTNQzv.o: in function `bench': uprobe_multi.c:49:(.text+0x1d7720): relocation truncated to fit: R_MIPS_GOT_DISP against `uprobe_multi_func_08188' uprobe_multi.c:49:(.text+0x1d7730): relocation truncated to fit: R_MIPS_GOT_DISP against `uprobe_multi_func_08189' ... collect2: error: ld returned 1 exit status Fixes: 519dfeaf ("selftests/bpf: Add uprobe_multi test program") Signed-off-by:
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Jiri Olsa authored
Adding tests for checking on recovery after failing to attach uprobe. Signed-off-by:
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Tony Ambardar authored
Update get_sys_includes in Makefile with missing MIPS-related definitions to fix many, many compilation errors building selftests/bpf. The following added defines drive conditional logic in system headers for word-size and endianness selection: MIPSEL, MIPSEB _MIPS_SZPTR _MIPS_SZLONG _MIPS_SIM, _ABIO32, _ABIN32, _ABI64 Signed-off-by:
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Ihor Solodrai authored
Ignore generated %.test.o dependencies when make goal is clean or docs-clean. Signed-off-by:
Ihor Solodrai <ihor.solodrai@pm.me> Signed-off-by:
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Song Liu authored
Regular BPF hash map is not mmap-able from user space. However, map-in-map with outer map of type BPF_MAP_TYPE_HASH_OF_MAPS and mmap-able array as inner map can perform similar operations as a mmap-able hash map. This can be used by applications that benefit from fast accesses to some local data. Add a selftest to show this use case. Signed-off-by:
Song Liu <song@kernel.org> Link: https://lore.kernel.org/r/20240723051455.1589192-1-song@kernel.orgSigned-off-by:
Martin KaFai Lau <martin.lau@kernel.org> Signed-off-by:
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Martin KaFai Lau authored
Geliang Tang says: ==================== This set is part 10 of series "use network helpers" all BPF selftests wide. Patches 1-3 drop local functions make_client(), make_socket() and inetaddr_len() in sk_lookup.c. Patch 4 drops a useless function __start_server() in network_helpers.c. ==================== Signed-off-by:
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Geliang Tang authored
The helper start_server_addr() is a wrapper of __start_server(), the only difference between them is __start_server() accepts a sockaddr type address parameter, but start_server_addr() accepts a sockaddr_storage one. This patch drops __start_server(), and updates the callers to invoke start_server_addr() instead. Signed-off-by:
Geliang Tang <tanggeliang@kylinos.cn> Link: https://lore.kernel.org/r/31399df7cb957b7c233e79963b0aa0dc4278d273.1721475357.git.tanggeliang@kylinos.cnSigned-off-by:
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Geliang Tang authored
No need to use a dedicated helper inetaddr_len() to get the length of the IPv4 or IPv6 address, it can be got by make_sockaddr(), this patch drops it. Signed-off-by:
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Geliang Tang authored
This patch uses the public network helers client_socket() + make_sockaddr() in sk_lookup.c to create the client socket, set the timeout sockopts, and make the connecting address. The local defined function make_socket() can be dropped then. Signed-off-by:
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Geliang Tang authored
This patch uses the new helper connect_to_addr_str() in sk_lookup.c to create the client socket and connect to the server, instead of using local defined function make_client(). This local function can be dropped then. Signed-off-by:
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Alexei Starovoitov authored
test_progs-no_alu32 -t libbpf_get_fd_by_id_opts is being rejected by the verifier with the following error due to compiler optimization: 6: (67) r0 <<= 62 ; R0_w=scalar(smax=0x4000000000000000,umax=0xc000000000000000,smin32=0,smax32=umax32=0,var_off=(0x0; 0xc000000000000000)) 7: (c7) r0 s>>= 63 ; R0_w=scalar(smin=smin32=-1,smax=smax32=0) ; @ test_libbpf_get_fd_by_id_opts.c:0 8: (57) r0 &= -13 ; R0_w=scalar(smax=0x7ffffffffffffff3,umax=0xfffffffffffffff3,smax32=0x7ffffff3,umax32=0xfffffff3,var_off=(0x0; 0xfffffffffffffff3)) ; int BPF_PROG(check_access, struct bpf_map *map, fmode_t fmode) @ test_libbpf_get_fd_by_id_opts.c:27 9: (95) exit At program exit the register R0 has smax=9223372036854775795 should have been in [-4095, 0] Workaround by adding barrier(). Eventually the verifier will be able to recognize it. Fixes: 5d99e198 ("bpf, lsm: Add check for BPF LSM return value") Signed-off-by:
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Alexei Starovoitov authored
Xu Kuohai says: ==================== Add BPF LSM return value range check, BPF part From: Xu Kuohai <xukuohai@huawei.com> LSM BPF prog may make kernel panic when returning an unexpected value, such as returning positive value on hook file_alloc_security. To fix it, series [1] refactored LSM hook return values and added BPF return value check on top of that. Since the refactoring of LSM hooks and checking BPF prog return value patches is not closely related, this series separates BPF-related patches from [1]. v2: - Update Shung-Hsi's patch with [3] v1: https://lore.kernel.org/bpf/20240719081749.769748-1-xukuohai@huaweicloud.com/ Changes to [1]: 1. Extend LSM disabled list to include hooks refactored in [1] to avoid dependency on the hooks return value refactoring patches. 2. Replace the special case patch for bitwise AND on [-1, 0] with Shung-Hsi's general bitwise AND improvement patch [2]. 3. Remove unused patches. [1] https://lore.kernel.org/bpf/20240711111908.3817636-1-xukuohai@huaweicloud.com https://lore.kernel.org/bpf/20240711113828.3818398-1-xukuohai@huaweicloud.com [2] https://lore.kernel.org/bpf/ykuhustu7vt2ilwhl32kj655xfdgdlm2xkl5rff6tw2ycksovp@ss2n4gpjysnw [3] https://lore.kernel.org/bpf/20240719081702.137173-1-shung-hsi.yu@suse.com/ Shung-Hsi Yu (1): bpf, verifier: improve signed ranges inference for BPF_AND ==================== Link: https://lore.kernel.org/r/20240719110059.797546-1-xukuohai@huaweicloud.comSigned-off-by:
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Xu Kuohai authored
Add verifier tests to check bpf lsm return values and disabled hooks. Signed-off-by:
Xu Kuohai <xukuohai@huawei.com> Link: https://lore.kernel.org/r/20240719110059.797546-10-xukuohai@huaweicloud.comSigned-off-by:
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Xu Kuohai authored
Add test for lsm tail call to ensure tail call can only be used between bpf lsm progs attached to the same hook. Signed-off-by:
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Xu Kuohai authored
The return ranges of some bpf lsm test progs can not be deduced by the verifier accurately. To avoid erroneous rejections, add explicit return value checks for these progs. Signed-off-by:
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Xu Kuohai authored
The compiler optimized the two bpf progs in token_lsm.c to make return value from the bool variable in the "return -1" path, causing an unexpected rejection: 0: R1=ctx() R10=fp0 ; int BPF_PROG(bpf_token_capable, struct bpf_token *token, int cap) @ bpf_lsm.c:17 0: (b7) r6 = 0 ; R6_w=0 ; if (my_pid == 0 || my_pid != (bpf_get_current_pid_tgid() >> 32)) @ bpf_lsm.c:19 1: (18) r1 = 0xffffc9000102a000 ; R1_w=map_value(map=bpf_lsm.bss,ks=4,vs=5) 3: (61) r7 = *(u32 *)(r1 +0) ; R1_w=map_value(map=bpf_lsm.bss,ks=4,vs=5) R7_w=scalar(smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff)) 4: (15) if r7 == 0x0 goto pc+11 ; R7_w=scalar(smin=umin=umin32=1,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff)) 5: (67) r7 <<= 32 ; R7_w=scalar(smax=0x7fffffff00000000,umax=0xffffffff00000000,smin32=0,smax32=umax32=0,var_off=(0x0; 0xffffffff00000000)) 6: (c7) r7 s>>= 32 ; R7_w=scalar(smin=0xffffffff80000000,smax=0x7fffffff) 7: (85) call bpf_get_current_pid_tgid#14 ; R0=scalar() 8: (77) r0 >>= 32 ; R0_w=scalar(smin=0,smax=umax=0xffffffff,var_off=(0x0; 0xffffffff)) 9: (5d) if r0 != r7 goto pc+6 ; R0_w=scalar(smin=smin32=0,smax=umax=umax32=0x7fffffff,var_off=(0x0; 0x7fffffff)) R7=scalar(smin=smin32=0,smax=umax=umax32=0x7fffffff,var_off=(0x0; 0x7fffffff)) ; if (reject_capable) @ bpf_lsm.c:21 10: (18) r1 = 0xffffc9000102a004 ; R1_w=map_value(map=bpf_lsm.bss,ks=4,vs=5,off=4) 12: (71) r6 = *(u8 *)(r1 +0) ; R1_w=map_value(map=bpf_lsm.bss,ks=4,vs=5,off=4) R6_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff)) ; @ bpf_lsm.c:0 13: (87) r6 = -r6 ; R6_w=scalar() 14: (67) r6 <<= 56 ; R6_w=scalar(smax=0x7f00000000000000,umax=0xff00000000000000,smin32=0,smax32=umax32=0,var_off=(0x0; 0xff00000000000000)) 15: (c7) r6 s>>= 56 ; R6_w=scalar(smin=smin32=-128,smax=smax32=127) ; int BPF_PROG(bpf_token_capable, struct bpf_token *token, int cap) @ bpf_lsm.c:17 16: (bf) r0 = r6 ; R0_w=scalar(id=1,smin=smin32=-128,smax=smax32=127) R6_w=scalar(id=1,smin=smin32=-128,smax=smax32=127) 17: (95) exit At program exit the register R0 has smin=-128 smax=127 should have been in [-4095, 0] To avoid this failure, change the variable type from bool to int. Signed-off-by:
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Xu Kuohai authored
After checking lsm hook return range in verifier, the test case "test_progs -t test_lsm" failed, and the failure log says: libbpf: prog 'test_int_hook': BPF program load failed: Invalid argument libbpf: prog 'test_int_hook': -- BEGIN PROG LOAD LOG -- 0: R1=ctx() R10=fp0 ; int BPF_PROG(test_int_hook, struct vm_area_struct *vma, @ lsm.c:89 0: (79) r0 = *(u64 *)(r1 +24) ; R0_w=scalar(smin=smin32=-4095,smax=smax32=0) R1=ctx() [...] 24: (b4) w0 = -1 ; R0_w=0xffffffff ; int BPF_PROG(test_int_hook, struct vm_area_struct *vma, @ lsm.c:89 25: (95) exit At program exit the register R0 has smin=4294967295 smax=4294967295 should have been in [-4095, 0] It can be seen that instruction "w0 = -1" zero extended -1 to 64-bit register r0, setting both smin and smax values of r0 to 4294967295. This resulted in a false reject when r0 was checked with range [-4095, 0]. Given bpf lsm does not return 64-bit values, this patch fixes it by changing the compare between r0 and return range from 64-bit operation to 32-bit operation for bpf lsm. Fixes: 8fa4ecd4 ("bpf: enforce exact retval range on subprog/callback exit") Signed-off-by:
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Xu Kuohai authored
bpf progs can be attached to kernel functions, and the attached functions can take different parameters or return different return values. If prog attached to one kernel function tail calls prog attached to another kernel function, the ctx access or return value verification could be bypassed. For example, if prog1 is attached to func1 which takes only 1 parameter and prog2 is attached to func2 which takes two parameters. Since verifier assumes the bpf ctx passed to prog2 is constructed based on func2's prototype, verifier allows prog2 to access the second parameter from the bpf ctx passed to it. The problem is that verifier does not prevent prog1 from passing its bpf ctx to prog2 via tail call. In this case, the bpf ctx passed to prog2 is constructed from func1 instead of func2, that is, the assumption for ctx access verification is bypassed. Another example, if BPF LSM prog1 is attached to hook file_alloc_security, and BPF LSM prog2 is attached to hook bpf_lsm_audit_rule_known. Verifier knows the return value rules for these two hooks, e.g. it is legal for bpf_lsm_audit_rule_known to return positive number 1, and it is illegal for file_alloc_security to return positive number. So verifier allows prog2 to return positive number 1, but does not allow prog1 to return positive number. The problem is that verifier does not prevent prog1 from calling prog2 via tail call. In this case, prog2's return value 1 will be used as the return value for prog1's hook file_alloc_security. That is, the return value rule is bypassed. This patch adds restriction for tail call to prevent such bypasses. Signed-off-by:
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Xu Kuohai authored
A bpf prog returning a positive number attached to file_alloc_security hook makes kernel panic. This happens because file system can not filter out the positive number returned by the LSM prog using IS_ERR, and misinterprets this positive number as a file pointer. Given that hook file_alloc_security never returned positive number before the introduction of BPF LSM, and other BPF LSM hooks may encounter similar issues, this patch adds LSM return value check in verifier, to ensure no unexpected value is returned. Fixes: 520b7aa0 ("bpf: lsm: Initialize the BPF LSM hooks") Reported-by:
Xin Liu <liuxin350@huawei.com> Signed-off-by:
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Xu Kuohai authored
Add a disabled hooks list for BPF LSM. progs being attached to the listed hooks will be rejected by the verifier. Suggested-by:
KP Singh <kpsingh@kernel.org> Signed-off-by:
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Alexei Starovoitov authored
Martin KaFai Lau says: ==================== bpf: Retire the unsupported_ops usage in struct_ops From: Martin KaFai Lau <martin.lau@kernel.org> This series retires the unsupported_ops usage and depends on the null-ness check on the cfi_stubs instead. Please see individual patches for details. v2: - Fixed a gcc compiler warning on Patch 1. ==================== Link: https://lore.kernel.org/r/20240722183049.2254692-1-martin.lau@linux.devSigned-off-by:
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Martin KaFai Lau authored
There is an existing "bpf_tcp_ca/unsupp_cong_op" test to ensure the unsupported tcp-cc "get_info" struct_ops prog cannot be loaded. This patch adds a new test in the bpf_testmod such that the unsupported ops test does not depend on other kernel subsystem where its supporting ops may be changed in the future. Signed-off-by:
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Martin KaFai Lau authored
The tramp_1 to tramp_40 ops is not set in the cfi_stubs in the bpf_testmod_ops. It fails the struct_ops_multi_pages test after retiring the unsupported_ops in the earlier patch. This patch initializes them in a loop during the bpf_testmod_init(). Signed-off-by:
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Martin KaFai Lau authored
The bpf_tcp_ca struct_ops currently uses a "u32 unsupported_ops[]" array to track which ops is not supported. After cfi_stubs had been added, the function pointer in cfi_stubs is also NULL for the unsupported ops. Thus, the "u32 unsupported_ops[]" becomes redundant. This observation was originally brought up in the bpf/cfi discussion: https://lore.kernel.org/bpf/CAADnVQJoEkdjyCEJRPASjBw1QGsKYrF33QdMGc1RZa9b88bAEA@mail.gmail.com/ The recent bpf qdisc patch (https://lore.kernel.org/bpf/20240714175130.4051012-6-amery.hung@bytedance.com/) also needs to specify quite many unsupported ops. It is a good time to clean it up. This patch removes the need of "u32 unsupported_ops[]" and tests for null-ness in the cfi_stubs instead. Testing the cfi_stubs is done in a new function bpf_struct_ops_supported(). The verifier will call bpf_struct_ops_supported() when loading the struct_ops program. The ".check_member" is removed from the bpf_tcp_ca in this patch. ".check_member" could still be useful for other subsytems to enforce other restrictions (e.g. sched_ext checks for prog->sleepable). To keep the same error return, ENOTSUPP is used. Cc: Amery Hung <ameryhung@gmail.com> Signed-off-by:
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