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* Merge remote-tracking branch 'msm8998/lineage-20' into lineage-20Raghuram Subramani2024-10-17
| | | | Change-Id: I126075a330f305c85f8fe1b8c9d408f368be95d1
* FROMLIST: bpf: cgroup skb progs cannot access ld_abs/indDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit fb9a307d11d6 ("bpf: Allow CGROUP_SKB eBPF program to access sk_buff") enabled programs of BPF_PROG_TYPE_CGROUP_SKB type to use ld_abs/ind instructions. However, at this point, we cannot use them, since offsets relative to SKF_LL_OFF will end up pointing skb_mac_header(skb) out of bounds since in the egress path it is not yet set at that point in time, but only after __dev_queue_xmit() did a general reset on the mac header. bpf_internal_load_pointer_neg_helper() will then end up reading data from a wrong offset. BPF_PROG_TYPE_CGROUP_SKB programs can use bpf_skb_load_bytes() already to access packet data, which is also more flexible than the insns carried over from cBPF. Fixes: fb9a307d11d6 ("bpf: Allow CGROUP_SKB eBPF program to access sk_buff") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Cc: Chenbo Feng <fengc@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> (url: http://patchwork.ozlabs.org/patch/771946/) Signed-off-by: Chenbo Feng <fengc@google.com> Bug: 30950746 Change-Id: Ia32ac79d8c0d18f811ec101897284a8b60cb042a
* FROMLIST: [net-next,v2,1/2] bpf: Allow CGROUP_SKB eBPF program to access sk_buffChenbo Feng2022-04-19
| | | | | | | | | | | | | | | This allows cgroup eBPF program to classify packet based on their protocol or other detail information. Currently program need CAP_NET_ADMIN privilege to attach a cgroup eBPF program, and A process with CAP_NET_ADMIN can already see all packets on the system, for example, by creating an iptables rules that causes the packet to be passed to userspace via NFLOG. (url: http://patchwork.ozlabs.org/patch/769459/) Signed-off-by: Chenbo Feng <fengc@google.com> Bug: 30950746 Change-Id: I11bef84ce26cf8b8f1b89483c32a7fcdd61ae926
* bpf: Fix buggy rsh min/max bounds trackingDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | [ no upstream commit ] Fix incorrect bounds tracking for RSH opcode. Commit f23cc643f9ba ("bpf: fix range arithmetic for bpf map access") had a wrong assumption about min/max bounds. The new dst_reg->min_value needs to be derived by right shifting the max_val bounds, not min_val, and likewise new dst_reg->max_value needs to be derived by right shifting the min_val bounds, not max_val. Later stable kernels than 4.9 are not affected since bounds tracking was overall reworked and they already track this similarly as in the fix. Fixes: f23cc643f9ba ("bpf: fix range arithmetic for bpf map access") Reported-by: Ryota Shiga (Flatt Security) Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: John Fastabend <john.fastabend@gmail.com> Cc: Josef Bacik <jbacik@fb.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: check pending signals while verifying programsAlexei Starovoitov2022-04-19
| | | | | | | | | | | | | | | | | | [ Upstream commit c3494801cd1785e2c25f1a5735fa19ddcf9665da ] Malicious user space may try to force the verifier to use as much cpu time and memory as possible. Hence check for pending signals while verifying the program. Note that suspend of sys_bpf(PROG_LOAD) syscall will lead to EAGAIN, since the kernel has to release the resources used for program verification. Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Edward Cree <ecree@solarflare.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: Prevent memory disambiguation attackAlexei Starovoitov2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit af86ca4e3088fe5eacf2f7e58c01fa68ca067672 upstream. Detect code patterns where malicious 'speculative store bypass' can be used and sanitize such patterns. 39: (bf) r3 = r10 40: (07) r3 += -216 41: (79) r8 = *(u64 *)(r7 +0) // slow read 42: (7a) *(u64 *)(r10 -72) = 0 // verifier inserts this instruction 43: (7b) *(u64 *)(r8 +0) = r3 // this store becomes slow due to r8 44: (79) r1 = *(u64 *)(r6 +0) // cpu speculatively executes this load 45: (71) r2 = *(u8 *)(r1 +0) // speculatively arbitrary 'load byte' // is now sanitized Above code after x86 JIT becomes: e5: mov %rbp,%rdx e8: add $0xffffffffffffff28,%rdx ef: mov 0x0(%r13),%r14 f3: movq $0x0,-0x48(%rbp) fb: mov %rdx,0x0(%r14) ff: mov 0x0(%rbx),%rdi 103: movzbq 0x0(%rdi),%rsi Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bwh: Backported to 4.9: - Add bpf_verifier_env parameter to check_stack_write() - Look up stack slot_types with state->stack_slot_type[] rather than state->stack[].slot_type[] - Drop bpf_verifier_env argument to verbose() - Adjust context] Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf/verifier: Pass instruction index to check_mem_access() and check_xadd()Ben Hutchings2022-04-19
| | | | | | | | | | | Extracted from commit 31fd85816dbe "bpf: permits narrower load from bpf program context fields". Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf/verifier: Add spi variable to check_stack_write()Ben Hutchings2022-04-19
| | | | | | | | | | | Extracted from commit dc503a8ad984 "bpf/verifier: track liveness for pruning". Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: fix references to free_bpf_prog_info() in commentsJakub Kicinski2022-04-19
| | | | | | | | | | | | | | | [ Upstream commit ab7f5bf0928be2f148d000a6eaa6c0a36e74750e ] Comments in the verifier refer to free_bpf_prog_info() which seems to have never existed in tree. Replace it with free_used_maps(). Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: reject stores into ctx via st and xaddDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | [ upstream commit f37a8cb84cce18762e8f86a70bd6a49a66ab964c ] Alexei found that verifier does not reject stores into context via BPF_ST instead of BPF_STX. And while looking at it, we also should not allow XADD variant of BPF_STX. The context rewriter is only assuming either BPF_LDX_MEM- or BPF_STX_MEM-type operations, thus reject anything other than that so that assumptions in the rewriter properly hold. Add test cases as well for BPF selftests. Fixes: d691f9e8d440 ("bpf: allow programs to write to certain skb fields") Reported-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: fix 32-bit divide by zeroAlexei Starovoitov2022-04-19
| | | | | | | | | | | | | | | | [ upstream commit 68fda450a7df51cff9e5a4d4a4d9d0d5f2589153 ] due to some JITs doing if (src_reg == 0) check in 64-bit mode for div/mod operations mask upper 32-bits of src register before doing the check Fixes: 622582786c9e ("net: filter: x86: internal BPF JIT") Fixes: 7a12b5031c6b ("sparc64: Add eBPF JIT.") Reported-by: syzbot+48340bb518e88849e2e3@syzkaller.appspotmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: arsh is not supported in 32 bit alu thus reject itDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | [ upstream commit 7891a87efc7116590eaba57acc3c422487802c6f ] The following snippet was throwing an 'unknown opcode cc' warning in BPF interpreter: 0: (18) r0 = 0x0 2: (7b) *(u64 *)(r10 -16) = r0 3: (cc) (u32) r0 s>>= (u32) r0 4: (95) exit Although a number of JITs do support BPF_ALU | BPF_ARSH | BPF_{K,X} generation, not all of them do and interpreter does neither. We can leave existing ones and implement it later in bpf-next for the remaining ones, but reject this properly in verifier for the time being. Fixes: 17a5267067f3 ("bpf: verifier (add verifier core)") Reported-by: syzbot+93c4904c5c70348a6890@syzkaller.appspotmail.com Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: prevent out-of-bounds speculationAlexei Starovoitov2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit b2157399cc9898260d6031c5bfe45fe137c1fbe7 upstream. Under speculation, CPUs may mis-predict branches in bounds checks. Thus, memory accesses under a bounds check may be speculated even if the bounds check fails, providing a primitive for building a side channel. To avoid leaking kernel data round up array-based maps and mask the index after bounds check, so speculated load with out of bounds index will load either valid value from the array or zero from the padded area. Unconditionally mask index for all array types even when max_entries are not rounded to power of 2 for root user. When map is created by unpriv user generate a sequence of bpf insns that includes AND operation to make sure that JITed code includes the same 'index & index_mask' operation. If prog_array map is created by unpriv user replace bpf_tail_call(ctx, map, index); with if (index >= max_entries) { index &= map->index_mask; bpf_tail_call(ctx, map, index); } (along with roundup to power 2) to prevent out-of-bounds speculation. There is secondary redundant 'if (index >= max_entries)' in the interpreter and in all JITs, but they can be optimized later if necessary. Other array-like maps (cpumap, devmap, sockmap, perf_event_array, cgroup_array) cannot be used by unpriv, so no changes there. That fixes bpf side of "Variant 1: bounds check bypass (CVE-2017-5753)" on all architectures with and without JIT. v2->v3: Daniel noticed that attack potentially can be crafted via syscall commands without loading the program, so add masking to those paths as well. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Jiri Slaby <jslaby@suse.cz> [ Backported to 4.9 - gregkh ] Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: refactor fixup_bpf_calls()Alexei Starovoitov2022-04-19
| | | | | | | | | | | | | | | commit 79741b3bdec01a8628368fbcfccc7d189ed606cb upstream. reduce indent and make it iterate over instructions similar to convert_ctx_accesses(). Also convert hard BUG_ON into soft verifier error. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Cc: Jiri Slaby <jslaby@suse.cz> [Backported to 4.9.y - gregkh] Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: move fixup_bpf_calls() functionAlexei Starovoitov2022-04-19
| | | | | | | | | | | | | | | | commit e245c5c6a5656e4d61aa7bb08e9694fd6e5b2b9d upstream. no functional change. move fixup_bpf_calls() to verifier.c it's being refactored in the next patch Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Cc: Jiri Slaby <jslaby@suse.cz> [backported to 4.9 - gregkh] Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf/verifier: Fix states_equal() comparison of pointer and UNKNOWNBen Hutchings2022-04-19
| | | | | | | | | | | | | | | | | | | An UNKNOWN_VALUE is not supposed to be derived from a pointer, unless pointer leaks are allowed. Therefore, states_equal() must not treat a state with a pointer in a register as "equal" to a state with an UNKNOWN_VALUE in that register. This was fixed differently upstream, but the code around here was largely rewritten in 4.14 by commit f1174f77b50c "bpf/verifier: rework value tracking". The bug can be detected by the bpf/verifier sub-test "pointer/scalar confusion in state equality check (way 1)". Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Cc: Edward Cree <ecree@solarflare.com> Cc: Jann Horn <jannh@google.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: fix incorrect sign extension in check_alu_op()Jann Horn2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 95a762e2c8c942780948091f8f2a4f32fce1ac6f ] Distinguish between BPF_ALU64|BPF_MOV|BPF_K (load 32-bit immediate, sign-extended to 64-bit) and BPF_ALU|BPF_MOV|BPF_K (load 32-bit immediate, zero-padded to 64-bit); only perform sign extension in the first case. Starting with v4.14, this is exploitable by unprivileged users as long as the unprivileged_bpf_disabled sysctl isn't set. Debian assigned CVE-2017-16995 for this issue. v3: - add CVE number (Ben Hutchings) Fixes: 484611357c19 ("bpf: allow access into map value arrays") Signed-off-by: Jann Horn <jannh@google.com> Acked-by: Edward Cree <ecree@solarflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: reject out-of-bounds stack pointer calculationJann Horn2022-04-19
| | | | | | | | | | | | | | | | Reject programs that compute wildly out-of-bounds stack pointers. Otherwise, pointers can be computed with an offset that doesn't fit into an `int`, causing security issues in the stack memory access check (as well as signed integer overflow during offset addition). This is a fix specifically for the v4.9 stable tree because the mainline code looks very different at this point. Fixes: 7bca0a9702edf ("bpf: enhance verifier to understand stack pointer arithmetic") Signed-off-by: Jann Horn <jannh@google.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: fix branch pruning logicAlexei Starovoitov2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit c131187db2d3fa2f8bf32fdf4e9a4ef805168467 ] when the verifier detects that register contains a runtime constant and it's compared with another constant it will prune exploration of the branch that is guaranteed not to be taken at runtime. This is all correct, but malicious program may be constructed in such a way that it always has a constant comparison and the other branch is never taken under any conditions. In this case such path through the program will not be explored by the verifier. It won't be taken at run-time either, but since all instructions are JITed the malicious program may cause JITs to complain about using reserved fields, etc. To fix the issue we have to track the instructions explored by the verifier and sanitize instructions that are dead at run time with NOPs. We cannot reject such dead code, since llvm generates it for valid C code, since it doesn't do as much data flow analysis as the verifier does. Fixes: 17a5267067f3 ("bpf: verifier (add verifier core)") Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: adjust insn_aux_data when patching insnsAlexei Starovoitov2022-04-19
| | | | | | | | | | | | | | | [ Upstream commit 8041902dae5299c1f194ba42d14383f734631009 ] convert_ctx_accesses() replaces single bpf instruction with a set of instructions. Adjust corresponding insn_aux_data while patching. It's needed to make sure subsequent 'for(all insn)' loops have matching insn and insn_aux_data. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf/verifier: reject BPF_ALU64|BPF_ENDEdward Cree2022-04-19
| | | | | | | | | | | | | | | [ Upstream commit e67b8a685c7c984e834e3181ef4619cd7025a136 ] Neither ___bpf_prog_run nor the JITs accept it. Also adds a new test case. Fixes: 17a5267067f3 ("bpf: verifier (add verifier core)") Signed-off-by: Edward Cree <ecree@solarflare.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf/verifier: fix min/max handling in BPF_SUBEdward Cree2022-04-19
| | | | | | | | | | | | | | [ Upstream commit 9305706c2e808ae59f1eb201867f82f1ddf6d7a6 ] We have to subtract the src max from the dst min, and vice-versa, since (e.g.) the smallest result comes from the largest subtrahend. Fixes: 484611357c19 ("bpf: allow access into map value arrays") Signed-off-by: Edward Cree <ecree@solarflare.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: fix mixed signed/unsigned derived min/max value boundsDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 4cabc5b186b5427b9ee5a7495172542af105f02b ] Edward reported that there's an issue in min/max value bounds tracking when signed and unsigned compares both provide hints on limits when having unknown variables. E.g. a program such as the following should have been rejected: 0: (7a) *(u64 *)(r10 -8) = 0 1: (bf) r2 = r10 2: (07) r2 += -8 3: (18) r1 = 0xffff8a94cda93400 5: (85) call bpf_map_lookup_elem#1 6: (15) if r0 == 0x0 goto pc+7 R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R10=fp 7: (7a) *(u64 *)(r10 -16) = -8 8: (79) r1 = *(u64 *)(r10 -16) 9: (b7) r2 = -1 10: (2d) if r1 > r2 goto pc+3 R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R1=inv,min_value=0 R2=imm-1,max_value=18446744073709551615,min_align=1 R10=fp 11: (65) if r1 s> 0x1 goto pc+2 R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R1=inv,min_value=0,max_value=1 R2=imm-1,max_value=18446744073709551615,min_align=1 R10=fp 12: (0f) r0 += r1 13: (72) *(u8 *)(r0 +0) = 0 R0=map_value_adj(ks=8,vs=8,id=0),min_value=0,max_value=1 R1=inv,min_value=0,max_value=1 R2=imm-1,max_value=18446744073709551615,min_align=1 R10=fp 14: (b7) r0 = 0 15: (95) exit What happens is that in the first part ... 8: (79) r1 = *(u64 *)(r10 -16) 9: (b7) r2 = -1 10: (2d) if r1 > r2 goto pc+3 ... r1 carries an unsigned value, and is compared as unsigned against a register carrying an immediate. Verifier deduces in reg_set_min_max() that since the compare is unsigned and operation is greater than (>), that in the fall-through/false case, r1's minimum bound must be 0 and maximum bound must be r2. Latter is larger than the bound and thus max value is reset back to being 'invalid' aka BPF_REGISTER_MAX_RANGE. Thus, r1 state is now 'R1=inv,min_value=0'. The subsequent test ... 11: (65) if r1 s> 0x1 goto pc+2 ... is a signed compare of r1 with immediate value 1. Here, verifier deduces in reg_set_min_max() that since the compare is signed this time and operation is greater than (>), that in the fall-through/false case, we can deduce that r1's maximum bound must be 1, meaning with prior test, we result in r1 having the following state: R1=inv,min_value=0,max_value=1. Given that the actual value this holds is -8, the bounds are wrongly deduced. When this is being added to r0 which holds the map_value(_adj) type, then subsequent store access in above case will go through check_mem_access() which invokes check_map_access_adj(), that will then probe whether the map memory is in bounds based on the min_value and max_value as well as access size since the actual unknown value is min_value <= x <= max_value; commit fce366a9dd0d ("bpf, verifier: fix alu ops against map_value{, _adj} register types") provides some more explanation on the semantics. It's worth to note in this context that in the current code, min_value and max_value tracking are used for two things, i) dynamic map value access via check_map_access_adj() and since commit 06c1c049721a ("bpf: allow helpers access to variable memory") ii) also enforced at check_helper_mem_access() when passing a memory address (pointer to packet, map value, stack) and length pair to a helper and the length in this case is an unknown value defining an access range through min_value/max_value in that case. The min_value/max_value tracking is /not/ used in the direct packet access case to track ranges. However, the issue also affects case ii), for example, the following crafted program based on the same principle must be rejected as well: 0: (b7) r2 = 0 1: (bf) r3 = r10 2: (07) r3 += -512 3: (7a) *(u64 *)(r10 -16) = -8 4: (79) r4 = *(u64 *)(r10 -16) 5: (b7) r6 = -1 6: (2d) if r4 > r6 goto pc+5 R1=ctx R2=imm0,min_value=0,max_value=0,min_align=2147483648 R3=fp-512 R4=inv,min_value=0 R6=imm-1,max_value=18446744073709551615,min_align=1 R10=fp 7: (65) if r4 s> 0x1 goto pc+4 R1=ctx R2=imm0,min_value=0,max_value=0,min_align=2147483648 R3=fp-512 R4=inv,min_value=0,max_value=1 R6=imm-1,max_value=18446744073709551615,min_align=1 R10=fp 8: (07) r4 += 1 9: (b7) r5 = 0 10: (6a) *(u16 *)(r10 -512) = 0 11: (85) call bpf_skb_load_bytes#26 12: (b7) r0 = 0 13: (95) exit Meaning, while we initialize the max_value stack slot that the verifier thinks we access in the [1,2] range, in reality we pass -7 as length which is interpreted as u32 in the helper. Thus, this issue is relevant also for the case of helper ranges. Resetting both bounds in check_reg_overflow() in case only one of them exceeds limits is also not enough as similar test can be created that uses values which are within range, thus also here learned min value in r1 is incorrect when mixed with later signed test to create a range: 0: (7a) *(u64 *)(r10 -8) = 0 1: (bf) r2 = r10 2: (07) r2 += -8 3: (18) r1 = 0xffff880ad081fa00 5: (85) call bpf_map_lookup_elem#1 6: (15) if r0 == 0x0 goto pc+7 R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R10=fp 7: (7a) *(u64 *)(r10 -16) = -8 8: (79) r1 = *(u64 *)(r10 -16) 9: (b7) r2 = 2 10: (3d) if r2 >= r1 goto pc+3 R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R1=inv,min_value=3 R2=imm2,min_value=2,max_value=2,min_align=2 R10=fp 11: (65) if r1 s> 0x4 goto pc+2 R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R1=inv,min_value=3,max_value=4 R2=imm2,min_value=2,max_value=2,min_align=2 R10=fp 12: (0f) r0 += r1 13: (72) *(u8 *)(r0 +0) = 0 R0=map_value_adj(ks=8,vs=8,id=0),min_value=3,max_value=4 R1=inv,min_value=3,max_value=4 R2=imm2,min_value=2,max_value=2,min_align=2 R10=fp 14: (b7) r0 = 0 15: (95) exit This leaves us with two options for fixing this: i) to invalidate all prior learned information once we switch signed context, ii) to track min/max signed and unsigned boundaries separately as done in [0]. (Given latter introduces major changes throughout the whole verifier, it's rather net-next material, thus this patch follows option i), meaning we can derive bounds either from only signed tests or only unsigned tests.) There is still the case of adjust_reg_min_max_vals(), where we adjust bounds on ALU operations, meaning programs like the following where boundaries on the reg get mixed in context later on when bounds are merged on the dst reg must get rejected, too: 0: (7a) *(u64 *)(r10 -8) = 0 1: (bf) r2 = r10 2: (07) r2 += -8 3: (18) r1 = 0xffff89b2bf87ce00 5: (85) call bpf_map_lookup_elem#1 6: (15) if r0 == 0x0 goto pc+6 R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R10=fp 7: (7a) *(u64 *)(r10 -16) = -8 8: (79) r1 = *(u64 *)(r10 -16) 9: (b7) r2 = 2 10: (3d) if r2 >= r1 goto pc+2 R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R1=inv,min_value=3 R2=imm2,min_value=2,max_value=2,min_align=2 R10=fp 11: (b7) r7 = 1 12: (65) if r7 s> 0x0 goto pc+2 R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R1=inv,min_value=3 R2=imm2,min_value=2,max_value=2,min_align=2 R7=imm1,max_value=0 R10=fp 13: (b7) r0 = 0 14: (95) exit from 12 to 15: R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R1=inv,min_value=3 R2=imm2,min_value=2,max_value=2,min_align=2 R7=imm1,min_value=1 R10=fp 15: (0f) r7 += r1 16: (65) if r7 s> 0x4 goto pc+2 R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R1=inv,min_value=3 R2=imm2,min_value=2,max_value=2,min_align=2 R7=inv,min_value=4,max_value=4 R10=fp 17: (0f) r0 += r7 18: (72) *(u8 *)(r0 +0) = 0 R0=map_value_adj(ks=8,vs=8,id=0),min_value=4,max_value=4 R1=inv,min_value=3 R2=imm2,min_value=2,max_value=2,min_align=2 R7=inv,min_value=4,max_value=4 R10=fp 19: (b7) r0 = 0 20: (95) exit Meaning, in adjust_reg_min_max_vals() we must also reset range values on the dst when src/dst registers have mixed signed/ unsigned derived min/max value bounds with one unbounded value as otherwise they can be added together deducing false boundaries. Once both boundaries are established from either ALU ops or compare operations w/o mixing signed/unsigned insns, then they can safely be added to other regs also having both boundaries established. Adding regs with one unbounded side to a map value where the bounded side has been learned w/o mixing ops is possible, but the resulting map value won't recover from that, meaning such op is considered invalid on the time of actual access. Invalid bounds are set on the dst reg in case i) src reg, or ii) in case dst reg already had them. The only way to recover would be to perform i) ALU ops but only 'add' is allowed on map value types or ii) comparisons, but these are disallowed on pointers in case they span a range. This is fine as only BPF_JEQ and BPF_JNE may be performed on PTR_TO_MAP_VALUE_OR_NULL registers which potentially turn them into PTR_TO_MAP_VALUE type depending on the branch, so only here min/max value cannot be invalidated for them. In terms of state pruning, value_from_signed is considered as well in states_equal() when dealing with adjusted map values. With regards to breaking existing programs, there is a small risk, but use-cases are rather quite narrow where this could occur and mixing compares probably unlikely. Joint work with Josef and Edward. [0] https://lists.iovisor.org/pipermail/iovisor-dev/2017-June/000822.html Fixes: 484611357c19 ("bpf: allow access into map value arrays") Reported-by: Edward Cree <ecree@solarflare.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Edward Cree <ecree@solarflare.com> Signed-off-by: Josef Bacik <jbacik@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf, verifier: fix alu ops against map_value{, _adj} register typesDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit fce366a9dd0ddc47e7ce05611c266e8574a45116 ] While looking into map_value_adj, I noticed that alu operations directly on the map_value() resp. map_value_adj() register (any alu operation on a map_value() register will turn it into a map_value_adj() typed register) are not sufficiently protected against some of the operations. Two non-exhaustive examples are provided that the verifier needs to reject: i) BPF_AND on r0 (map_value_adj): 0: (bf) r2 = r10 1: (07) r2 += -8 2: (7a) *(u64 *)(r2 +0) = 0 3: (18) r1 = 0xbf842a00 5: (85) call bpf_map_lookup_elem#1 6: (15) if r0 == 0x0 goto pc+2 R0=map_value(ks=8,vs=48,id=0),min_value=0,max_value=0 R10=fp 7: (57) r0 &= 8 8: (7a) *(u64 *)(r0 +0) = 22 R0=map_value_adj(ks=8,vs=48,id=0),min_value=0,max_value=8 R10=fp 9: (95) exit from 6 to 9: R0=inv,min_value=0,max_value=0 R10=fp 9: (95) exit processed 10 insns ii) BPF_ADD in 32 bit mode on r0 (map_value_adj): 0: (bf) r2 = r10 1: (07) r2 += -8 2: (7a) *(u64 *)(r2 +0) = 0 3: (18) r1 = 0xc24eee00 5: (85) call bpf_map_lookup_elem#1 6: (15) if r0 == 0x0 goto pc+2 R0=map_value(ks=8,vs=48,id=0),min_value=0,max_value=0 R10=fp 7: (04) (u32) r0 += (u32) 0 8: (7a) *(u64 *)(r0 +0) = 22 R0=map_value_adj(ks=8,vs=48,id=0),min_value=0,max_value=0 R10=fp 9: (95) exit from 6 to 9: R0=inv,min_value=0,max_value=0 R10=fp 9: (95) exit processed 10 insns Issue is, while min_value / max_value boundaries for the access are adjusted appropriately, we change the pointer value in a way that cannot be sufficiently tracked anymore from its origin. Operations like BPF_{AND,OR,DIV,MUL,etc} on a destination register that is PTR_TO_MAP_VALUE{,_ADJ} was probably unintended, in fact, all the test cases coming with 484611357c19 ("bpf: allow access into map value arrays") perform BPF_ADD only on the destination register that is PTR_TO_MAP_VALUE_ADJ. Only for UNKNOWN_VALUE register types such operations make sense, f.e. with unknown memory content fetched initially from a constant offset from the map value memory into a register. That register is then later tested against lower / upper bounds, so that the verifier can then do the tracking of min_value / max_value, and properly check once that UNKNOWN_VALUE register is added to the destination register with type PTR_TO_MAP_VALUE{,_ADJ}. This is also what the original use-case is solving. Note, tracking on what is being added is done through adjust_reg_min_max_vals() and later access to the map value enforced with these boundaries and the given offset from the insn through check_map_access_adj(). Tests will fail for non-root environment due to prohibited pointer arithmetic, in particular in check_alu_op(), we bail out on the is_pointer_value() check on the dst_reg (which is false in root case as we allow for pointer arithmetic via env->allow_ptr_leaks). Similarly to PTR_TO_PACKET, one way to fix it is to restrict the allowed operations on PTR_TO_MAP_VALUE{,_ADJ} registers to 64 bit mode BPF_ADD. The test_verifier suite runs fine after the patch and it also rejects mentioned test cases. Fixes: 484611357c19 ("bpf: allow access into map value arrays") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Josef Bacik <jbacik@fb.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: adjust verifier heuristicsDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 3c2ce60bdd3d57051bf85615deec04a694473840 ] Current limits with regards to processing program paths do not really reflect today's needs anymore due to programs becoming more complex and verifier smarter, keeping track of more data such as const ALU operations, alignment tracking, spilling of PTR_TO_MAP_VALUE_ADJ registers, and other features allowing for smarter matching of what LLVM generates. This also comes with the side-effect that we result in fewer opportunities to prune search states and thus often need to do more work to prove safety than in the past due to different register states and stack layout where we mismatch. Generally, it's quite hard to determine what caused a sudden increase in complexity, it could be caused by something as trivial as a single branch somewhere at the beginning of the program where LLVM assigned a stack slot that is marked differently throughout other branches and thus causing a mismatch, where verifier then needs to prove safety for the whole rest of the program. Subsequently, programs with even less than half the insn size limit can get rejected. We noticed that while some programs load fine under pre 4.11, they get rejected due to hitting limits on more recent kernels. We saw that in the vast majority of cases (90+%) pruning failed due to register mismatches. In case of stack mismatches, majority of cases failed due to different stack slot types (invalid, spill, misc) rather than differences in spilled registers. This patch makes pruning more aggressive by also adding markers that sit at conditional jumps as well. Currently, we only mark jump targets for pruning. For example in direct packet access, these are usually error paths where we bail out. We found that adding these markers, it can reduce number of processed insns by up to 30%. Another option is to ignore reg->id in probing PTR_TO_MAP_VALUE_OR_NULL registers, which can help pruning slightly as well by up to 7% observed complexity reduction as stand-alone. Meaning, if a previous path with register type PTR_TO_MAP_VALUE_OR_NULL for map X was found to be safe, then in the current state a PTR_TO_MAP_VALUE_OR_NULL register for the same map X must be safe as well. Last but not least the patch also adds a scheduling point and bumps the current limit for instructions to be processed to a more adequate value. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf, verifier: add additional patterns to evaluate_reg_imm_aluJohn Fastabend2022-04-19
| | | | | | | | | | | | | | | | [ Upstream commit 43188702b3d98d2792969a3377a30957f05695e6 ] Currently the verifier does not track imm across alu operations when the source register is of unknown type. This adds additional pattern matching to catch this and track imm. We've seen LLVM generating this pattern while working on cilium. Signed-off-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: prevent leaking pointer via xadd on unpriviledgedDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 6bdf6abc56b53103324dfd270a86580306e1a232 upstream. Leaking kernel addresses on unpriviledged is generally disallowed, for example, verifier rejects the following: 0: (b7) r0 = 0 1: (18) r2 = 0xffff897e82304400 3: (7b) *(u64 *)(r1 +48) = r2 R2 leaks addr into ctx Doing pointer arithmetic on them is also forbidden, so that they don't turn into unknown value and then get leaked out. However, there's xadd as a special case, where we don't check the src reg for being a pointer register, e.g. the following will pass: 0: (b7) r0 = 0 1: (7b) *(u64 *)(r1 +48) = r0 2: (18) r2 = 0xffff897e82304400 ; map 4: (db) lock *(u64 *)(r1 +48) += r2 5: (95) exit We could store the pointer into skb->cb, loose the type context, and then read it out from there again to leak it eventually out of a map value. Or more easily in a different variant, too: 0: (bf) r6 = r1 1: (7a) *(u64 *)(r10 -8) = 0 2: (bf) r2 = r10 3: (07) r2 += -8 4: (18) r1 = 0x0 6: (85) call bpf_map_lookup_elem#1 7: (15) if r0 == 0x0 goto pc+3 R0=map_value(ks=8,vs=8,id=0),min_value=0,max_value=0 R6=ctx R10=fp 8: (b7) r3 = 0 9: (7b) *(u64 *)(r0 +0) = r3 10: (db) lock *(u64 *)(r0 +0) += r6 11: (b7) r0 = 0 12: (95) exit from 7 to 11: R0=inv,min_value=0,max_value=0 R6=ctx R10=fp 11: (b7) r0 = 0 12: (95) exit Prevent this by checking xadd src reg for pointer types. Also add a couple of test cases related to this. Fixes: 1be7f75d1668 ("bpf: enable non-root eBPF programs") Fixes: 17a5267067f3 ("bpf: verifier (add verifier core)") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Edward Cree <ecree@solarflare.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* FROMLIST: bpf: cgroup skb progs cannot access ld_abs/indDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit fb9a307d11d6 ("bpf: Allow CGROUP_SKB eBPF program to access sk_buff") enabled programs of BPF_PROG_TYPE_CGROUP_SKB type to use ld_abs/ind instructions. However, at this point, we cannot use them, since offsets relative to SKF_LL_OFF will end up pointing skb_mac_header(skb) out of bounds since in the egress path it is not yet set at that point in time, but only after __dev_queue_xmit() did a general reset on the mac header. bpf_internal_load_pointer_neg_helper() will then end up reading data from a wrong offset. BPF_PROG_TYPE_CGROUP_SKB programs can use bpf_skb_load_bytes() already to access packet data, which is also more flexible than the insns carried over from cBPF. Fixes: fb9a307d11d6 ("bpf: Allow CGROUP_SKB eBPF program to access sk_buff") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Cc: Chenbo Feng <fengc@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> (url: http://patchwork.ozlabs.org/patch/771946/) Signed-off-by: Chenbo Feng <fengc@google.com> Bug: 30950746 Change-Id: Ia32ac79d8c0d18f811ec101897284a8b60cb042a Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* FROMLIST: [net-next,v2,1/2] bpf: Allow CGROUP_SKB eBPF program to access sk_buffChenbo Feng2022-04-19
| | | | | | | | | | | | | | | | This allows cgroup eBPF program to classify packet based on their protocol or other detail information. Currently program need CAP_NET_ADMIN privilege to attach a cgroup eBPF program, and A process with CAP_NET_ADMIN can already see all packets on the system, for example, by creating an iptables rules that causes the packet to be passed to userspace via NFLOG. (url: http://patchwork.ozlabs.org/patch/769459/) Signed-off-by: Chenbo Feng <fengc@google.com> Bug: 30950746 Change-Id: I11bef84ce26cf8b8f1b89483c32a7fcdd61ae926 Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: don't let ldimm64 leak map addresses on unprivilegedDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 0d0e57697f162da4aa218b5feafe614fb666db07 ] The patch fixes two things at once: 1) It checks the env->allow_ptr_leaks and only prints the map address to the log if we have the privileges to do so, otherwise it just dumps 0 as we would when kptr_restrict is enabled on %pK. Given the latter is off by default and not every distro sets it, I don't want to rely on this, hence the 0 by default for unprivileged. 2) Printing of ldimm64 in the verifier log is currently broken in that we don't print the full immediate, but only the 32 bit part of the first insn part for ldimm64. Thus, fix this up as well; it's okay to access, since we verified all ldimm64 earlier already (including just constants) through replace_map_fd_with_map_ptr(). Fixes: 1be7f75d1668 ("bpf: enable non-root eBPF programs") Fixes: cbd357008604 ("bpf: verifier (add ability to receive verification log)") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: enhance verifier to understand stack pointer arithmeticYonghong Song2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 332270fdc8b6fba07d059a9ad44df9e1a2ad4529 ] llvm 4.0 and above generates the code like below: .... 440: (b7) r1 = 15 441: (05) goto pc+73 515: (79) r6 = *(u64 *)(r10 -152) 516: (bf) r7 = r10 517: (07) r7 += -112 518: (bf) r2 = r7 519: (0f) r2 += r1 520: (71) r1 = *(u8 *)(r8 +0) 521: (73) *(u8 *)(r2 +45) = r1 .... and the verifier complains "R2 invalid mem access 'inv'" for insn #521. This is because verifier marks register r2 as unknown value after #519 where r2 is a stack pointer and r1 holds a constant value. Teach verifier to recognize "stack_ptr + imm" and "stack_ptr + reg with const val" as valid stack_ptr with new offset. Signed-off-by: Yonghong Song <yhs@fb.com> Acked-by: Martin KaFai Lau <kafai@fb.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: improve verifier packet range checksAlexei Starovoitov2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit b1977682a3858b5584ffea7cfb7bd863f68db18d ] llvm can optimize the 'if (ptr > data_end)' checks to be in the order slightly different than the original C code which will confuse verifier. Like: if (ptr + 16 > data_end) return TC_ACT_SHOT; // may be followed by if (ptr + 14 > data_end) return TC_ACT_SHOT; while llvm can see that 'ptr' is valid for all 16 bytes, the verifier could not. Fix verifier logic to account for such case and add a test. Reported-by: Huapeng Zhou <hzhou@fb.com> Fixes: 969bf05eb3ce ("bpf: direct packet access") Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: fix mark_reg_unknown_value for spilled regs on map value markingDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 6760bf2ddde8ad64f8205a651223a93de3a35494 ] Martin reported a verifier issue that hit the BUG_ON() for his test case in the mark_reg_unknown_value() function: [ 202.861380] kernel BUG at kernel/bpf/verifier.c:467! [...] [ 203.291109] Call Trace: [ 203.296501] [<ffffffff811364d5>] mark_map_reg+0x45/0x50 [ 203.308225] [<ffffffff81136558>] mark_map_regs+0x78/0x90 [ 203.320140] [<ffffffff8113938d>] do_check+0x226d/0x2c90 [ 203.331865] [<ffffffff8113a6ab>] bpf_check+0x48b/0x780 [ 203.343403] [<ffffffff81134c8e>] bpf_prog_load+0x27e/0x440 [ 203.355705] [<ffffffff8118a38f>] ? handle_mm_fault+0x11af/0x1230 [ 203.369158] [<ffffffff812d8188>] ? security_capable+0x48/0x60 [ 203.382035] [<ffffffff811351a4>] SyS_bpf+0x124/0x960 [ 203.393185] [<ffffffff810515f6>] ? __do_page_fault+0x276/0x490 [ 203.406258] [<ffffffff816db320>] entry_SYSCALL_64_fastpath+0x13/0x94 This issue got uncovered after the fix in a08dd0da5307 ("bpf: fix regression on verifier pruning wrt map lookups"). The reason why it wasn't noticed before was, because as mentioned in a08dd0da5307, mark_map_regs() was doing the id matching incorrectly based on the uncached regs[regno].id. So, in the first loop, we walked all regs and as soon as we found regno == i, then this reg's id was cleared when calling mark_reg_unknown_value() thus that every subsequent register was probed against id of 0 (which, in combination with the PTR_TO_MAP_VALUE_OR_NULL type is an invalid condition that no other register state can hold), and therefore wasn't type transitioned such as in the spilled register case for the second loop. Now since that got fixed, it turned out that 57a09bf0a416 ("bpf: Detect identical PTR_TO_MAP_VALUE_OR_NULL registers") used mark_reg_unknown_value() incorrectly for the spilled regs, and thus hitting the BUG_ON() in some cases due to regno >= MAX_BPF_REG. Although spilled regs have the same type as the non-spilled regs for the verifier state, that is, struct bpf_reg_state, they are semantically different from the non-spilled regs. In other words, there can be up to 64 (MAX_BPF_STACK / BPF_REG_SIZE) spilled regs in the stack, for example, register R<x> could have been spilled by the program to stack location X, Y, Z, and in mark_map_regs() we need to scan these stack slots of type STACK_SPILL for potential registers that we have to transition from PTR_TO_MAP_VALUE_OR_NULL. Therefore, depending on the location, the spilled_regs regno can be a lot higher than just MAX_BPF_REG's value since we operate on stack instead. The reset in mark_reg_unknown_value() itself is just fine, only that the BUG_ON() was inappropriate for this. Fix it by making a __mark_reg_unknown_value() version that can be called from mark_map_reg() generically; we know for the non-spilled case that the regno is always < MAX_BPF_REG anyway. Fixes: 57a09bf0a416 ("bpf: Detect identical PTR_TO_MAP_VALUE_OR_NULL registers") Reported-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: fix regression on verifier pruning wrt map lookupsDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit a08dd0da5307ba01295c8383923e51e7997c3576 ] Commit 57a09bf0a416 ("bpf: Detect identical PTR_TO_MAP_VALUE_OR_NULL registers") introduced a regression where existing programs stopped loading due to reaching the verifier's maximum complexity limit, whereas prior to this commit they were loading just fine; the affected program has roughly 2k instructions. What was found is that state pruning couldn't be performed effectively anymore due to mismatches of the verifier's register state, in particular in the id tracking. It doesn't mean that 57a09bf0a416 is incorrect per se, but rather that verifier needs to perform a lot more work for the same program with regards to involved map lookups. Since commit 57a09bf0a416 is only about tracking registers with type PTR_TO_MAP_VALUE_OR_NULL, the id is only needed to follow registers until they are promoted through pattern matching with a NULL check to either PTR_TO_MAP_VALUE or UNKNOWN_VALUE type. After that point, the id becomes irrelevant for the transitioned types. For UNKNOWN_VALUE, id is already reset to 0 via mark_reg_unknown_value(), but not so for PTR_TO_MAP_VALUE where id is becoming stale. It's even transferred further into other types that don't make use of it. Among others, one example is where UNKNOWN_VALUE is set on function call return with RET_INTEGER return type. states_equal() will then fall through the memcmp() on register state; note that the second memcmp() uses offsetofend(), so the id is part of that since d2a4dd37f6b4 ("bpf: fix state equivalence"). But the bisect pointed already to 57a09bf0a416, where we really reach beyond complexity limit. What I found was that states_equal() often failed in this case due to id mismatches in spilled regs with registers in type PTR_TO_MAP_VALUE. Unlike non-spilled regs, spilled regs just perform a memcmp() on their reg state and don't have any other optimizations in place, therefore also id was relevant in this case for making a pruning decision. We can safely reset id to 0 as well when converting to PTR_TO_MAP_VALUE. For the affected program, it resulted in a ~17 fold reduction of complexity and let the program load fine again. Selftest suite also runs fine. The only other place where env->id_gen is used currently is through direct packet access, but for these cases id is long living, thus a different scenario. Also, the current logic in mark_map_regs() is not fully correct when marking NULL branch with UNKNOWN_VALUE. We need to cache the destination reg's id in any case. Otherwise, once we marked that reg as UNKNOWN_VALUE, it's id is reset and any subsequent registers that hold the original id and are of type PTR_TO_MAP_VALUE_OR_NULL won't be marked UNKNOWN_VALUE anymore, since mark_map_reg() reuses the uncached regs[regno].id that was just overridden. Note, we don't need to cache it outside of mark_map_regs(), since it's called once on this_branch and the other time on other_branch, which are both two independent verifier states. A test case for this is added here, too. Fixes: 57a09bf0a416 ("bpf: Detect identical PTR_TO_MAP_VALUE_OR_NULL registers") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Thomas Graf <tgraf@suug.ch> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: fix state equivalenceAlexei Starovoitov2022-04-19
| | | | | | | | | | | | | | | | | | [ Upstream commit d2a4dd37f6b41fbcad76efbf63124eb3126c66fe ] Commmits 57a09bf0a416 ("bpf: Detect identical PTR_TO_MAP_VALUE_OR_NULL registers") and 484611357c19 ("bpf: allow access into map value arrays") by themselves are correct, but in combination they make state equivalence ignore 'id' field of the register state which can lead to accepting invalid program. Fixes: 57a09bf0a416 ("bpf: Detect identical PTR_TO_MAP_VALUE_OR_NULL registers") Fixes: 484611357c19 ("bpf: allow access into map value arrays") Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: Detect identical PTR_TO_MAP_VALUE_OR_NULL registersThomas Graf2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 57a09bf0a416700676e77102c28f9cfcb48267e0 ] A BPF program is required to check the return register of a map_elem_lookup() call before accessing memory. The verifier keeps track of this by converting the type of the result register from PTR_TO_MAP_VALUE_OR_NULL to PTR_TO_MAP_VALUE after a conditional jump ensures safety. This check is currently exclusively performed for the result register 0. In the event the compiler reorders instructions, BPF_MOV64_REG instructions may be moved before the conditional jump which causes them to keep their type PTR_TO_MAP_VALUE_OR_NULL to which the verifier objects when the register is accessed: 0: (b7) r1 = 10 1: (7b) *(u64 *)(r10 -8) = r1 2: (bf) r2 = r10 3: (07) r2 += -8 4: (18) r1 = 0x59c00000 6: (85) call 1 7: (bf) r4 = r0 8: (15) if r0 == 0x0 goto pc+1 R0=map_value(ks=8,vs=8) R4=map_value_or_null(ks=8,vs=8) R10=fp 9: (7a) *(u64 *)(r4 +0) = 0 R4 invalid mem access 'map_value_or_null' This commit extends the verifier to keep track of all identical PTR_TO_MAP_VALUE_OR_NULL registers after a map_elem_lookup() by assigning them an ID and then marking them all when the conditional jump is observed. Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Josef Bacik <jbacik@fb.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: fix states equal logic for varlen accessJosef Bacik2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | If we have a branch that looks something like this int foo = map->value; if (condition) { foo += blah; } else { foo = bar; } map->array[foo] = baz; We will incorrectly assume that the !condition branch is equal to the condition branch as the register for foo will be UNKNOWN_VALUE in both cases. We need to adjust this logic to only do this if we didn't do a varlen access after we processed the !condition branch, otherwise we have different ranges and need to check the other branch as well. Fixes: 484611357c19 ("bpf: allow access into map value arrays") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Josef Bacik <jbacik@fb.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: fix range arithmetic for bpf map accessJosef Bacik2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | I made some invalid assumptions with BPF_AND and BPF_MOD that could result in invalid accesses to bpf map entries. Fix this up by doing a few things 1) Kill BPF_MOD support. This doesn't actually get used by the compiler in real life and just adds extra complexity. 2) Fix the logic for BPF_AND, don't allow AND of negative numbers and set the minimum value to 0 for positive AND's. 3) Don't do operations on the ranges if they are set to the limits, as they are by definition undefined, and allowing arithmetic operations on those values could make them appear valid when they really aren't. This fixes the testcase provided by Jann as well as a few other theoretical problems. Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Josef Bacik <jbacik@fb.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: allow access into map value arraysJosef Bacik2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Suppose you have a map array value that is something like this struct foo { unsigned iter; int array[SOME_CONSTANT]; }; You can easily insert this into an array, but you cannot modify the contents of foo->array[] after the fact. This is because we have no way to verify we won't go off the end of the array at verification time. This patch provides a start for this work. We accomplish this by keeping track of a minimum and maximum value a register could be while we're checking the code. Then at the time we try to do an access into a MAP_VALUE we verify that the maximum offset into that region is a valid access into that memory region. So in practice, code such as this unsigned index = 0; if (foo->iter >= SOME_CONSTANT) foo->iter = index; else index = foo->iter++; foo->array[index] = bar; would be allowed, as we can verify that index will always be between 0 and SOME_CONSTANT-1. If you wish to use signed values you'll have to have an extra check to make sure the index isn't less than 0, or do something like index %= SOME_CONSTANT. Signed-off-by: Josef Bacik <jbacik@fb.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: Set register type according to is_valid_access()Mickaël Salaün2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | This prevent future potential pointer leaks when an unprivileged eBPF program will read a pointer value from its context. Even if is_valid_access() returns a pointer type, the eBPF verifier replace it with UNKNOWN_VALUE. The register value that contains a kernel address is then allowed to leak. Moreover, this fix allows unprivileged eBPF programs to use functions with (legitimate) pointer arguments. Not an issue currently since reg_type is only set for PTR_TO_PACKET or PTR_TO_PACKET_END in XDP and TC programs that can only be loaded as privileged. For now, the only unprivileged eBPF program allowed is for socket filtering and all the types from its context are UNKNOWN_VALUE. However, this fix is important for future unprivileged eBPF programs which could use pointers in their context. Signed-off-by: Mickaël Salaün <mic@digikod.net> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: recognize 64bit immediate loads as constsJakub Kicinski2022-04-19
| | | | | | | | | | | | | | When running as parser interpret BPF_LD | BPF_IMM | BPF_DW instructions as loading CONST_IMM with the value stored in imm. The verifier will continue not recognizing those due to concerns about search space/program complexity increase. Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: enable non-core use of the verfierJakub Kicinski2022-04-19
| | | | | | | | | | | | | | | | | | Advanced JIT compilers and translators may want to use eBPF verifier as a base for parsers or to perform custom checks and validations. Add ability for external users to invoke the verifier and provide callbacks to be invoked for every intruction checked. For now only add most basic callback for per-instruction pre-interpretation checks is added. More advanced users may also like to have per-instruction post callback and state comparison callback. Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: expose internal verfier structuresJakub Kicinski2022-04-19
| | | | | | | | | | | | | Move verifier's internal structures to a header file and prefix their names with bpf_ to avoid potential namespace conflicts. Those structures will soon be used by external analyzers. Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: don't (ab)use instructions to store stateJakub Kicinski2022-04-19
| | | | | | | | | | | | | | | | | Storing state in reserved fields of instructions makes it impossible to run verifier on programs already marked as read-only. Allocate and use an array of per-instruction state instead. While touching the error path rename and move existing jump target. Suggested-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: direct packet write and access for helpers for clsact progsDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This work implements direct packet access for helpers and direct packet write in a similar fashion as already available for XDP types via commits 4acf6c0b84c9 ("bpf: enable direct packet data write for xdp progs") and 6841de8b0d03 ("bpf: allow helpers access the packet directly"), and as a complementary feature to the already available direct packet read for tc (cls/act) programs. For enabling this, we need to introduce two helpers, bpf_skb_pull_data() and bpf_csum_update(). The first is generally needed for both, read and write, because they would otherwise only be limited to the current linear skb head. Usually, when the data_end test fails, programs just bail out, or, in the direct read case, use bpf_skb_load_bytes() as an alternative to overcome this limitation. If such data sits in non-linear parts, we can just pull them in once with the new helper, retest and eventually access them. At the same time, this also makes sure the skb is uncloned, which is, of course, a necessary condition for direct write. As this needs to be an invariant for the write part only, the verifier detects writes and adds a prologue that is calling bpf_skb_pull_data() to effectively unclone the skb from the very beginning in case it is indeed cloned. The heuristic makes use of a similar trick that was done in 233577a22089 ("net: filter: constify detection of pkt_type_offset"). This comes at zero cost for other programs that do not use the direct write feature. Should a program use this feature only sparsely and has read access for the most parts with, for example, drop return codes, then such write action can be delegated to a tail called program for mitigating this cost of potential uncloning to a late point in time where it would have been paid similarly with the bpf_skb_store_bytes() as well. Advantage of direct write is that the writes are inlined whereas the helper cannot make any length assumptions and thus needs to generate a call to memcpy() also for small sizes, as well as cost of helper call itself with sanity checks are avoided. Plus, when direct read is already used, we don't need to cache or perform rechecks on the data boundaries (due to verifier invalidating previous checks for helpers that change skb->data), so more complex programs using rewrites can benefit from switching to direct read plus write. For direct packet access to helpers, we save the otherwise needed copy into a temp struct sitting on stack memory when use-case allows. Both facilities are enabled via may_access_direct_pkt_data() in verifier. For now, we limit this to map helpers and csum_diff, and can successively enable other helpers where we find it makes sense. Helpers that definitely cannot be allowed for this are those part of bpf_helper_changes_skb_data() since they can change underlying data, and those that write into memory as this could happen for packet typed args when still cloned. bpf_csum_update() helper accommodates for the fact that we need to fixup checksum_complete when using direct write instead of bpf_skb_store_bytes(), meaning the programs can use available helpers like bpf_csum_diff(), and implement csum_add(), csum_sub(), csum_block_add(), csum_block_sub() equivalents in eBPF together with the new helper. A usage example will be provided for iproute2's examples/bpf/ directory. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf, verifier: enforce larger zero range for pkt on overloading stack buffsDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Current contract for the following two helper argument types is: * ARG_CONST_STACK_SIZE: passed argument pair must be (ptr, >0). * ARG_CONST_STACK_SIZE_OR_ZERO: passed argument pair can be either (NULL, 0) or (ptr, >0). With 6841de8b0d03 ("bpf: allow helpers access the packet directly"), we can pass also raw packet data to helpers, so depending on the argument type being PTR_TO_PACKET, we now either assert memory via check_packet_access() or check_stack_boundary(). As a result, the tests in check_packet_access() currently allow more than intended with regards to reg->imm. Back in 969bf05eb3ce ("bpf: direct packet access"), check_packet_access() was fine to ignore size argument since in check_mem_access() size was bpf_size_to_bytes() derived and prior to the call to check_packet_access() guaranteed to be larger than zero. However, for the above two argument types, it currently means, we can have a <= 0 size and thus breaking current guarantees for helpers. Enforce a check for size <= 0 and bail out if so. check_stack_boundary() doesn't have such an issue since it already tests for access_size <= 0 and bails out, resp. access_size == 0 in case of NULL pointer passed when allowed. Fixes: 6841de8b0d03 ("bpf: allow helpers access the packet directly") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: fix range propagation on direct packet accessDaniel Borkmann2022-04-19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | LLVM can generate code that tests for direct packet access via skb->data/data_end in a way that currently gets rejected by the verifier, example: [...] 7: (61) r3 = *(u32 *)(r6 +80) 8: (61) r9 = *(u32 *)(r6 +76) 9: (bf) r2 = r9 10: (07) r2 += 54 11: (3d) if r3 >= r2 goto pc+12 R1=inv R2=pkt(id=0,off=54,r=0) R3=pkt_end R4=inv R6=ctx R9=pkt(id=0,off=0,r=0) R10=fp 12: (18) r4 = 0xffffff7a 14: (05) goto pc+430 [...] from 11 to 24: R1=inv R2=pkt(id=0,off=54,r=0) R3=pkt_end R4=inv R6=ctx R9=pkt(id=0,off=0,r=0) R10=fp 24: (7b) *(u64 *)(r10 -40) = r1 25: (b7) r1 = 0 26: (63) *(u32 *)(r6 +56) = r1 27: (b7) r2 = 40 28: (71) r8 = *(u8 *)(r9 +20) invalid access to packet, off=20 size=1, R9(id=0,off=0,r=0) The reason why this gets rejected despite a proper test is that we currently call find_good_pkt_pointers() only in case where we detect tests like rX > pkt_end, where rX is of type pkt(id=Y,off=Z,r=0) and derived, for example, from a register of type pkt(id=Y,off=0,r=0) pointing to skb->data. find_good_pkt_pointers() then fills the range in the current branch to pkt(id=Y,off=0,r=Z) on success. For above case, we need to extend that to recognize pkt_end >= rX pattern and mark the other branch that is taken on success with the appropriate pkt(id=Y,off=0,r=Z) type via find_good_pkt_pointers(). Since eBPF operates on BPF_JGT (>) and BPF_JGE (>=), these are the only two practical options to test for from what LLVM could have generated, since there's no such thing as BPF_JLT (<) or BPF_JLE (<=) that we would need to take into account as well. After the fix: [...] 7: (61) r3 = *(u32 *)(r6 +80) 8: (61) r9 = *(u32 *)(r6 +76) 9: (bf) r2 = r9 10: (07) r2 += 54 11: (3d) if r3 >= r2 goto pc+12 R1=inv R2=pkt(id=0,off=54,r=0) R3=pkt_end R4=inv R6=ctx R9=pkt(id=0,off=0,r=0) R10=fp 12: (18) r4 = 0xffffff7a 14: (05) goto pc+430 [...] from 11 to 24: R1=inv R2=pkt(id=0,off=54,r=54) R3=pkt_end R4=inv R6=ctx R9=pkt(id=0,off=0,r=54) R10=fp 24: (7b) *(u64 *)(r10 -40) = r1 25: (b7) r1 = 0 26: (63) *(u32 *)(r6 +56) = r1 27: (b7) r2 = 40 28: (71) r8 = *(u8 *)(r9 +20) 29: (bf) r1 = r8 30: (25) if r8 > 0x3c goto pc+47 R1=inv56 R2=imm40 R3=pkt_end R4=inv R6=ctx R8=inv56 R9=pkt(id=0,off=0,r=54) R10=fp 31: (b7) r1 = 1 [...] Verifier test cases are also added in this work, one that demonstrates the mentioned example here and one that tries a bad packet access for the current/fall-through branch (the one with types pkt(id=X,off=Y,r=0), pkt(id=X,off=0,r=0)), then a case with good and bad accesses, and two with both test variants (>, >=). Fixes: 969bf05eb3ce ("bpf: direct packet access") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: perf_event progs should only use preallocated mapsAlexei Starovoitov2022-04-19
| | | | | | | | | | | Make sure that BPF_PROG_TYPE_PERF_EVENT programs only use preallocated hash maps, since doing memory allocation in overflow_handler can crash depending on where nmi got triggered. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: support 8-byte metafield accessAlexei Starovoitov2022-04-19
| | | | | | | | | | | | | | The verifier supported only 4-byte metafields in struct __sk_buff and struct xdp_md. The metafields in upcoming struct bpf_perf_event are 8-byte to match register width in struct pt_regs. Teach verifier to recognize 8-byte metafield access. The patch doesn't affect safety of sockets and xdp programs. They check for 4-byte only ctx access before these conditions are hit. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
* bpf: allow helpers access the packet directlyAlexei Starovoitov2022-04-19
| | | | | | | | | | | | | | | | | | | | The helper functions like bpf_map_lookup_elem(map, key) were only allowing 'key' to point to the initialized stack area. That is causing performance degradation when programs need to process millions of packets per second and need to copy contents of the packet into the stack just to pass the stack pointer into the lookup() function. Allow such helpers read from the packet directly. All helpers that expect ARG_PTR_TO_MAP_KEY, ARG_PTR_TO_MAP_VALUE, ARG_PTR_TO_STACK assume byte aligned pointer, so no alignment concerns, only need to check that helper will not be accessing beyond the packet range verified by the prior 'if (ptr < data_end)' condition. For now allow this feature for XDP programs only. Later it can be relaxed for the clsact programs as well. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chatur27 <jasonbright2709@gmail.com>
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