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Hao Sun e8d3872b61 bpf: Reject variable offset alu on PTR_TO_FLOW_KEYS 
[ Upstream commit 22c7fa171a02d310e3a3f6ed46a698ca8a0060ed ]

For PTR_TO_FLOW_KEYS, check_flow_keys_access() only uses fixed off
for validation. However, variable offset ptr alu is not prohibited
for this ptr kind. So the variable offset is not checked.

The following prog is accepted:

  func#0 @0
  0: R1=ctx() R10=fp0
  0: (bf) r6 = r1                       ; R1=ctx() R6_w=ctx()
  1: (79) r7 = *(u64 *)(r6 +144)        ; R6_w=ctx() R7_w=flow_keys()
  2: (b7) r8 = 1024                     ; R8_w=1024
  3: (37) r8 /= 1                       ; R8_w=scalar()
  4: (57) r8 &= 1024                    ; R8_w=scalar(smin=smin32=0,
  smax=umax=smax32=umax32=1024,var_off=(0x0; 0x400))
  5: (0f) r7 += r8
  mark_precise: frame0: last_idx 5 first_idx 0 subseq_idx -1
  mark_precise: frame0: regs=r8 stack= before 4: (57) r8 &= 1024
  mark_precise: frame0: regs=r8 stack= before 3: (37) r8 /= 1
  mark_precise: frame0: regs=r8 stack= before 2: (b7) r8 = 1024
  6: R7_w=flow_keys(smin=smin32=0,smax=umax=smax32=umax32=1024,var_off
  =(0x0; 0x400)) R8_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=1024,
  var_off=(0x0; 0x400))
  6: (79) r0 = *(u64 *)(r7 +0)          ; R0_w=scalar()
  7: (95) exit

This prog loads flow_keys to r7, and adds the variable offset r8
to r7, and finally causes out-of-bounds access:

  BUG: unable to handle page fault for address: ffffc90014c80038
  [...]
  Call Trace:
   <TASK>
   bpf_dispatcher_nop_func include/linux/bpf.h:1231 [inline]
   __bpf_prog_run include/linux/filter.h:651 [inline]
   bpf_prog_run include/linux/filter.h:658 [inline]
   bpf_prog_run_pin_on_cpu include/linux/filter.h:675 [inline]
   bpf_flow_dissect+0x15f/0x350 net/core/flow_dissector.c:991
   bpf_prog_test_run_flow_dissector+0x39d/0x620 net/bpf/test_run.c:1359
   bpf_prog_test_run kernel/bpf/syscall.c:4107 [inline]
   __sys_bpf+0xf8f/0x4560 kernel/bpf/syscall.c:5475
   __do_sys_bpf kernel/bpf/syscall.c:5561 [inline]
   __se_sys_bpf kernel/bpf/syscall.c:5559 [inline]
   __x64_sys_bpf+0x73/0xb0 kernel/bpf/syscall.c:5559
   do_syscall_x64 arch/x86/entry/common.c:52 [inline]
   do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:83
   entry_SYSCALL_64_after_hwframe+0x63/0x6b

Fix this by rejecting ptr alu with variable offset on flow_keys.
Applying the patch rejects the program with "R7 pointer arithmetic
on flow_keys prohibited".

Fixes: d58e468b11 ("flow_dissector: implements flow dissector BPF hook")
Signed-off-by: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/bpf/20240115082028.9992-1-sunhao.th@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
 		2024-01-25 15:35:58 -08:00
..
preload bpf: make preloaded map iterators to display map elements count 2023-07-06 12:42:25 -07:00
Kconfig bpf: Add fd-based tcx multi-prog infra with link support 2023-07-19 10:07:27 -07:00
Makefile bpf: Add fd-based tcx multi-prog infra with link support 2023-07-19 10:07:27 -07:00
arraymap.c bpf: Add map and need_defer parameters to .map_fd_put_ptr() 2024-01-25 15:35:22 -08:00
bloom_filter.c bpf: Centralize permissions checks for all BPF map types 2023-06-19 14:04:04 +02:00
bpf_cgrp_storage.c bpf: Teach verifier that certain helpers accept NULL pointer. 2023-04-04 16:57:16 -07:00
bpf_inode_storage.c Networking changes for 6.4. 2023-04-26 16:07:23 -07:00
bpf_iter.c bpf: implement numbers iterator 2023-03-08 16:19:51 -08:00
bpf_local_storage.c bpf: bpf_sk_storage: Fix the missing uncharge in sk_omem_alloc 2023-09-06 11:08:14 +02:00
bpf_lru_list.c bpf: Address KCSAN report on bpf_lru_list 2023-05-12 12:01:03 -07:00
bpf_lru_list.h bpf: lru: Remove unused declaration bpf_lru_promote() 2023-08-08 17:21:42 -07:00
bpf_lsm.c bpf: Fix the kernel crash caused by bpf_setsockopt(). 2023-01-26 23:26:40 -08:00
bpf_struct_ops.c bpf: Support default .validate() and .update() behavior for struct_ops links 2023-08-14 22:23:39 -07:00
bpf_struct_ops_types.h bpf: Add dummy BPF STRUCT_OPS for test purpose 2021-11-01 14:10:00 -07:00
bpf_task_storage.c bpf: Teach verifier that certain helpers accept NULL pointer. 2023-04-04 16:57:16 -07:00
btf.c bpf: Fix a erroneous check after snprintf() 2023-09-12 13:15:46 -07:00
cgroup.c bpf, cgroup: fix multiple kernel-doc warnings 2023-09-12 13:19:07 -07:00
cgroup_iter.c cgroup: bpf: use cgroup_lock()/cgroup_unlock() wrappers 2023-03-17 12:07:13 -10:00
core.c bpf: Fix a verifier bug due to incorrect branch offset comparison with cpu=v4 2023-12-13 18:45:04 +01:00
cpumap.c bpf, cpumask: Clean up bpf_cpu_map_entry directly in cpu_map_free 2023-08-21 15:21:16 -07:00
cpumask.c bpf: Convert bpf_cpumask to bpf_mem_cache_free_rcu. 2023-07-12 23:45:23 +02:00
devmap.c bpf, devmap: Remove unused dtab field from bpf_dtab_netdev 2023-07-31 18:26:08 -07:00
disasm.c bpf: change bpf_alu_sign_string and bpf_movsx_string to static 2023-08-04 16:15:50 -07:00
disasm.h bpf: Relicense disassembler as GPL-2.0-only OR BSD-2-Clause 2021-09-02 14:49:23 +02:00
dispatcher.c bpf: Synchronize dispatcher update with bpf_dispatcher_xdp_func 2022-12-14 12:02:14 -08:00
hashtab.c bpf: Add map and need_defer parameters to .map_fd_put_ptr() 2024-01-25 15:35:22 -08:00
helpers.c bpf: Check map->usercnt after timer->timer is assigned 2023-11-20 11:59:34 +01:00
inode.c bpf: convert to ctime accessor functions 2023-07-24 10:30:07 +02:00
link_iter.c bpf: Add bpf_link iterator 2022-05-10 11:20:45 -07:00
local_storage.c cgroup changes for v6.4-rc1 2023-04-29 10:05:22 -07:00
log.c bpf: drop unnecessary user-triggerable WARN_ONCE in verifierl log 2023-05-16 22:34:50 -07:00
lpm_trie.c bpf, lpm: Fix check prefixlen before walking trie 2024-01-25 15:35:19 -08:00
map_in_map.c bpf: Defer the free of inner map when necessary 2024-01-25 15:35:22 -08:00
map_in_map.h bpf: Add map and need_defer parameters to .map_fd_put_ptr() 2024-01-25 15:35:22 -08:00
map_iter.c bpf: allow any program to use the bpf_map_sum_elem_count kfunc 2023-07-19 09:48:53 -07:00
memalloc.c bpf: Use c->unit_size to select target cache during free 2024-01-25 15:35:28 -08:00
mmap_unlock_work.h bpf: Introduce helper bpf_find_vma 2021-11-07 11:54:51 -08:00
mprog.c bpf: Handle bpf_mprog_query with NULL entry 2023-10-06 17:11:20 -07:00
net_namespace.c net: Add includes masked by netdevice.h including uapi/bpf.h 2021-12-29 20:03:05 -08:00
offload.c bpf: Avoid dummy bpf_offload_netdev in __bpf_prog_dev_bound_init 2023-09-11 22:06:06 -07:00
percpu_freelist.c bpf: Initialize same number of free nodes for each pcpu_freelist 2022-11-11 12:05:14 -08:00
percpu_freelist.h bpf: Use raw_spin_trylock() for pcpu_freelist_push/pop in NMI 2020-10-06 00:04:11 +02:00
prog_iter.c bpf: Refactor bpf_iter_reg to have separate seq_info member 2020-07-25 20:16:32 -07:00
queue_stack_maps.c bpf: Avoid deadlock when using queue and stack maps from NMI 2023-09-11 19:04:49 -07:00
reuseport_array.c bpf: Centralize permissions checks for all BPF map types 2023-06-19 14:04:04 +02:00
ringbuf.c bpf: Remove unnecessary ring buffer size check 2023-07-05 14:09:45 +02:00
stackmap.c bpf: Add crosstask check to __bpf_get_stack 2024-01-25 15:35:19 -08:00
syscall.c bpf: Fix re-attachment branch in bpf_tracing_prog_attach 2024-01-25 15:35:46 -08:00
sysfs_btf.c bpf: Load and verify kernel module BTFs 2020-11-10 15:25:53 -08:00
task_iter.c bpf: keep a reference to the mm, in case the task is dead. 2022-12-28 14:11:48 -08:00
tcx.c bpf: Handle bpf_mprog_query with NULL entry 2023-10-06 17:11:20 -07:00
tnum.c bpf, tnums: Provably sound, faster, and more precise algorithm for tnum_mul 2021-06-01 13:34:15 +02:00
trampoline.c bpf, x64: Fix tailcall infinite loop 2023-11-20 11:58:55 +01:00
verifier.c bpf: Reject variable offset alu on PTR_TO_FLOW_KEYS 2024-01-25 15:35:58 -08:00