kernel/linux.git/lib/test_bpf.c, branch v4.14.181

test_bpf: Fix testing with CONFIG_BPF_JIT_ALWAYS_ON=y on other arches

2018-11-04T13:52:43+00:00

[ Upstream commit 52fda36d63bfc8c8e8ae5eda8eb5ac6f52cd67ed ] Function bpf_fill_maxinsns11 is designed to not be able to be JITed on x86_64. So, it fails when CONFIG_BPF_JIT_ALWAYS_ON=y, and commit 09584b406742 ("bpf: fix selftests/bpf test_kmod.sh failure when CONFIG_BPF_JIT_ALWAYS_ON=y") makes sure that failure is detected on that case. However, it does not fail on other architectures, which have a different JIT compiler design. So, test_bpf has started to fail to load on those. After this fix, test_bpf loads fine on both x86_64 and ppc64el. Fixes: 09584b406742 ("bpf: fix selftests/bpf test_kmod.sh failure when CONFIG_BPF_JIT_ALWAYS_ON=y") Signed-off-by: Thadeu Lima de Souza Cascardo Reviewed-by: Yonghong Song Signed-off-by: Daniel Borkmann Signed-off-by: Sasha Levin

bpf: fix selftests/bpf test_kmod.sh failure when CONFIG_BPF_JIT_ALWAYS_ON=y

2018-04-26T09:02:16+00:00

[ Upstream commit 09584b406742413ac4c8d7e030374d4daa045b69 ] With CONFIG_BPF_JIT_ALWAYS_ON is defined in the config file, tools/testing/selftests/bpf/test_kmod.sh failed like below: [root@localhost bpf]# ./test_kmod.sh sysctl: setting key "net.core.bpf_jit_enable": Invalid argument [ JIT enabled:0 hardened:0 ] [ 132.175681] test_bpf: #297 BPF_MAXINSNS: Jump, gap, jump, ... FAIL to prog_create err=-524 len=4096 [ 132.458834] test_bpf: Summary: 348 PASSED, 1 FAILED, [340/340 JIT'ed] [ JIT enabled:1 hardened:0 ] [ 133.456025] test_bpf: #297 BPF_MAXINSNS: Jump, gap, jump, ... FAIL to prog_create err=-524 len=4096 [ 133.730935] test_bpf: Summary: 348 PASSED, 1 FAILED, [340/340 JIT'ed] [ JIT enabled:1 hardened:1 ] [ 134.769730] test_bpf: #297 BPF_MAXINSNS: Jump, gap, jump, ... FAIL to prog_create err=-524 len=4096 [ 135.050864] test_bpf: Summary: 348 PASSED, 1 FAILED, [340/340 JIT'ed] [ JIT enabled:1 hardened:2 ] [ 136.442882] test_bpf: #297 BPF_MAXINSNS: Jump, gap, jump, ... FAIL to prog_create err=-524 len=4096 [ 136.821810] test_bpf: Summary: 348 PASSED, 1 FAILED, [340/340 JIT'ed] [root@localhost bpf]# The test_kmod.sh load/remove test_bpf.ko multiple times with different settings for sysctl net.core.bpf_jit_{enable,harden}. The failed test #297 of test_bpf.ko is designed such that JIT always fails. Commit 290af86629b2 (bpf: introduce BPF_JIT_ALWAYS_ON config) introduced the following tightening logic: ... if (!bpf_prog_is_dev_bound(fp->aux)) { fp = bpf_int_jit_compile(fp); #ifdef CONFIG_BPF_JIT_ALWAYS_ON if (!fp->jited) { *err = -ENOTSUPP; return fp; } #endif ... With this logic, Test #297 always gets return value -ENOTSUPP when CONFIG_BPF_JIT_ALWAYS_ON is defined, causing the test failure. This patch fixed the failure by marking Test #297 as expected failure when CONFIG_BPF_JIT_ALWAYS_ON is defined. Fixes: 290af86629b2 (bpf: introduce BPF_JIT_ALWAYS_ON config) Signed-off-by: Yonghong Song Signed-off-by: Daniel Borkmann Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

bpf: introduce BPF_JIT_ALWAYS_ON config

2018-01-31T13:03:49+00:00

[ upstream commit 290af86629b25ffd1ed6232c4e9107da031705cb ] The BPF interpreter has been used as part of the spectre 2 attack CVE-2017-5715. A quote from goolge project zero blog: "At this point, it would normally be necessary to locate gadgets in the host kernel code that can be used to actually leak data by reading from an attacker-controlled location, shifting and masking the result appropriately and then using the result of that as offset to an attacker-controlled address for a load. But piecing gadgets together and figuring out which ones work in a speculation context seems annoying. So instead, we decided to use the eBPF interpreter, which is built into the host kernel - while there is no legitimate way to invoke it from inside a VM, the presence of the code in the host kernel's text section is sufficient to make it usable for the attack, just like with ordinary ROP gadgets." To make attacker job harder introduce BPF_JIT_ALWAYS_ON config option that removes interpreter from the kernel in favor of JIT-only mode. So far eBPF JIT is supported by: x64, arm64, arm32, sparc64, s390, powerpc64, mips64 The start of JITed program is randomized and code page is marked as read-only. In addition "constant blinding" can be turned on with net.core.bpf_jit_harden v2->v3: - move __bpf_prog_ret0 under ifdef (Daniel) v1->v2: - fix init order, test_bpf and cBPF (Daniel's feedback) - fix offloaded bpf (Jakub's feedback) - add 'return 0' dummy in case something can invoke prog->bpf_func - retarget bpf tree. For bpf-next the patch would need one extra hunk. It will be sent when the trees are merged back to net-next Considered doing: int bpf_jit_enable __read_mostly = BPF_EBPF_JIT_DEFAULT; but it seems better to land the patch as-is and in bpf-next remove bpf_jit_enable global variable from all JITs, consolidate in one place and remove this jit_init() function. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Signed-off-by: Greg Kroah-Hartman

bpf: add BPF_J{LT,LE,SLT,SLE} instructions

2017-08-09T23:53:56+00:00

Currently, eBPF only understands BPF_JGT (>), BPF_JGE (>=), BPF_JSGT (s>), BPF_JSGE (s>=) instructions, this means that particularly *JLT/*JLE counterparts involving immediates need to be rewritten from e.g. X < [IMM] by swapping arguments into [IMM] > X, meaning the immediate first is required to be loaded into a register Y := [IMM], such that then we can compare with Y > X. Note that the destination operand is always required to be a register. This has the downside of having unnecessarily increased register pressure, meaning complex program would need to spill other registers temporarily to stack in order to obtain an unused register for the [IMM]. Loading to registers will thus also affect state pruning since we need to account for that register use and potentially those registers that had to be spilled/filled again. As a consequence slightly more stack space might have been used due to spilling, and BPF programs are a bit longer due to extra code involving the register load and potentially required spill/fills. Thus, add BPF_JLT (<), BPF_JLE (<=), BPF_JSLT (s<), BPF_JSLE (s<=) counterparts to the eBPF instruction set. Modifying LLVM to remove the NegateCC() workaround in a PoC patch at [1] and allowing it to also emit the new instructions resulted in cilium's BPF programs that are injected into the fast-path to have a reduced program length in the range of 2-3% (e.g. accumulated main and tail call sections from one of the object file reduced from 4864 to 4729 insns), reduced complexity in the range of 10-30% (e.g. accumulated sections reduced in one of the cases from 116432 to 88428 insns), and reduced stack usage in the range of 1-5% (e.g. accumulated sections from one of the object files reduced from 824 to 784b). The modification for LLVM will be incorporated in a backwards compatible way. Plan is for LLVM to have i) a target specific option to offer a possibility to explicitly enable the extension by the user (as we have with -m target specific extensions today for various CPU insns), and ii) have the kernel checked for presence of the extensions and enable them transparently when the user is selecting more aggressive options such as -march=native in a bpf target context. (Other frontends generating BPF byte code, e.g. ply can probe the kernel directly for its code generation.) [1] https://github.com/borkmann/llvm/tree/bpf-insns Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller

net: introduce __skb_put_[zero, data, u8]

2017-06-20T17:30:14+00:00

follow Johannes Berg, semantic patch file as below, @@ identifier p, p2; expression len; expression skb; type t, t2; @@ ( -p = __skb_put(skb, len); +p = __skb_put_zero(skb, len); | -p = (t)__skb_put(skb, len); +p = __skb_put_zero(skb, len); ) ... when != p ( p2 = (t2)p; -memset(p2, 0, len); | -memset(p, 0, len); ) @@ identifier p; expression len; expression skb; type t; @@ ( -t p = __skb_put(skb, len); +t p = __skb_put_zero(skb, len); ) ... when != p ( -memset(p, 0, len); ) @@ type t, t2; identifier p, p2; expression skb; @@ t *p; ... ( -p = __skb_put(skb, sizeof(t)); +p = __skb_put_zero(skb, sizeof(t)); | -p = (t *)__skb_put(skb, sizeof(t)); +p = __skb_put_zero(skb, sizeof(t)); ) ... when != p ( p2 = (t2)p; -memset(p2, 0, sizeof(*p)); | -memset(p, 0, sizeof(*p)); ) @@ expression skb, len; @@ -memset(__skb_put(skb, len), 0, len); +__skb_put_zero(skb, len); @@ expression skb, len, data; @@ -memcpy(__skb_put(skb, len), data, len); +__skb_put_data(skb, data, len); @@ expression SKB, C, S; typedef u8; identifier fn = {__skb_put}; fresh identifier fn2 = fn ## "_u8"; @@ - *(u8 *)fn(SKB, S) = C; + fn2(SKB, C); Signed-off-by: yuan linyu Signed-off-by: David S. Miller

test_bpf: Add test to make conditional jump cross a large number of insns.

2017-06-14T19:03:22+00:00

On MIPS, conditional branches can only span 32k instructions. To exceed this limit in the JIT with the BPF maximum of 4k insns, we need to choose eBPF insns that expand to more than 8 machine instructions. Use BPF_LD_ABS as it is quite complex. This forces the JIT to invert the sense of the branch to branch around a long jump to the end. This (somewhat) verifies that the branch inversion logic and target address calculation of the long jumps are done correctly. Signed-off-by: David Daney Acked-by: Daniel Borkmann Signed-off-by: David S. Miller

bpf: fix stack_depth usage by test_bpf.ko

2017-05-31T23:29:48+00:00

test_bpf.ko doesn't call verifier before selecting interpreter or JITing, hence the tests need to manually specify the amount of stack they consume. Signed-off-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller

test_bpf: Add a couple of tests for BPF_JSGE.

2017-05-25T18:37:56+00:00

Some JITs can optimize comparisons with zero. Add a couple of BPF_JSGE tests against immediate zero. Signed-off-by: David Daney Acked-by: Daniel Borkmann Signed-off-by: David S. Miller

test_bpf: Use ULL suffix for 64-bit constants

2017-05-03T13:51:26+00:00

On 32-bit: lib/test_bpf.c:4772: warning: integer constant is too large for ‘unsigned long’ type lib/test_bpf.c:4772: warning: integer constant is too large for ‘unsigned long’ type lib/test_bpf.c:4773: warning: integer constant is too large for ‘unsigned long’ type lib/test_bpf.c:4773: warning: integer constant is too large for ‘unsigned long’ type lib/test_bpf.c:4787: warning: integer constant is too large for ‘unsigned long’ type lib/test_bpf.c:4787: warning: integer constant is too large for ‘unsigned long’ type lib/test_bpf.c:4801: warning: integer constant is too large for ‘unsigned long’ type lib/test_bpf.c:4801: warning: integer constant is too large for ‘unsigned long’ type lib/test_bpf.c:4802: warning: integer constant is too large for ‘unsigned long’ type lib/test_bpf.c:4802: warning: integer constant is too large for ‘unsigned long’ type On 32-bit systems, "long" is only 32-bit. Replace the "UL" suffix by "ULL" to fix this. Fixes: 85f68fe898320575 ("bpf, arm64: implement jiting of BPF_XADD") Signed-off-by: Geert Uytterhoeven Acked-by: Daniel Borkmann Signed-off-by: David S. Miller

bpf, arm64: fix jit branch offset related to ldimm64

2017-05-02T19:04:50+00:00

When the instruction right before the branch destination is a 64 bit load immediate, we currently calculate the wrong jump offset in the ctx->offset[] array as we only account one instruction slot for the 64 bit load immediate although it uses two BPF instructions. Fix it up by setting the offset into the right slot after we incremented the index. Before (ldimm64 test 1): [...] 00000020: 52800007 mov w7, #0x0 // #0 00000024: d2800060 mov x0, #0x3 // #3 00000028: d2800041 mov x1, #0x2 // #2 0000002c: eb01001f cmp x0, x1 00000030: 54ffff82 b.cs 0x00000020 00000034: d29fffe7 mov x7, #0xffff // #65535 00000038: f2bfffe7 movk x7, #0xffff, lsl #16 0000003c: f2dfffe7 movk x7, #0xffff, lsl #32 00000040: f2ffffe7 movk x7, #0xffff, lsl #48 00000044: d29dddc7 mov x7, #0xeeee // #61166 00000048: f2bdddc7 movk x7, #0xeeee, lsl #16 0000004c: f2ddddc7 movk x7, #0xeeee, lsl #32 00000050: f2fdddc7 movk x7, #0xeeee, lsl #48 [...] After (ldimm64 test 1): [...] 00000020: 52800007 mov w7, #0x0 // #0 00000024: d2800060 mov x0, #0x3 // #3 00000028: d2800041 mov x1, #0x2 // #2 0000002c: eb01001f cmp x0, x1 00000030: 540000a2 b.cs 0x00000044 00000034: d29fffe7 mov x7, #0xffff // #65535 00000038: f2bfffe7 movk x7, #0xffff, lsl #16 0000003c: f2dfffe7 movk x7, #0xffff, lsl #32 00000040: f2ffffe7 movk x7, #0xffff, lsl #48 00000044: d29dddc7 mov x7, #0xeeee // #61166 00000048: f2bdddc7 movk x7, #0xeeee, lsl #16 0000004c: f2ddddc7 movk x7, #0xeeee, lsl #32 00000050: f2fdddc7 movk x7, #0xeeee, lsl #48 [...] Also, add a couple of test cases to make sure JITs pass this test. Tested on Cavium ThunderX ARMv8. The added test cases all pass after the fix. Fixes: 8eee539ddea0 ("arm64: bpf: fix out-of-bounds read in bpf2a64_offset()") Reported-by: David S. Miller Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov Cc: Xi Wang Signed-off-by: David S. Miller