[Bug Report] eBPF Module Fails To Build Against CachyOS's 6.19 Kernel

[Joomzie]

Describe the bug:

This may only affect CachyOS, as Arch's owm linux package hasn't been updated to 6.19 yet, but the eBPF module fails to build when using the opensnitch-ebpf-module-git AUR package. I reported this problem there as well just in case this isn't an upstream issue.

• OpenSnitch version: 1.8.0.r125.8bc2698d-1
• OS: CachyOS
• OS version: Rolling
• Window Manager: COSMIC
• Kernel version: 6.19.0-2-cachyos

To Reproduce:

Attempt to build the eBPF module using the PKGBUILD from the AUR.

Post error logs:

clang -I. -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/ -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated/ -I/usr/lib/modules/6.19.0-2-cachyos/build/include -include /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/kconfig.h -I/usr/lib/modules/6.19.0-2-cachyos/build/include -I/usr/lib/modules/6.19.0-2-cachyos/build/include/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/include/generated/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/tools/testing/selftests/bpf/ -D__KERNEL__ -D__BPF_TRACING__ -Wno-unused-value -Wno-pointer-sign -D__TARGET_ARCH_x86 -Wno-compare-distinct-pointer-types  -Wunused -Wno-unused-value -Wno-gnu-variable-sized-type-not-at-end -Wno-address-of-packed-member -Wno-tautological-compare -Wno-unknown-warning-option -fcf-protection -fno-stack-protector -g -O2 -emit-llvm -c opensnitch.c
clang -I. -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/ -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated/ -I/usr/lib/modules/6.19.0-2-cachyos/build/include -include /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/kconfig.h -I/usr/lib/modules/6.19.0-2-cachyos/build/include -I/usr/lib/modules/6.19.0-2-cachyos/build/include/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/include/generated/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/tools/testing/selftests/bpf/ -D__KERNEL__ -D__BPF_TRACING__ -Wno-unused-value -Wno-pointer-sign -D__TARGET_ARCH_x86 -Wno-compare-distinct-pointer-types  -Wunused -Wno-unused-value -Wno-gnu-variable-sized-type-not-at-end -Wno-address-of-packed-member -Wno-tautological-compare -Wno-unknown-warning-option -fcf-protection -fno-stack-protector -g -O2 -emit-llvm -c opensnitch-dns.c
clang -I. -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/ -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated/ -I/usr/lib/modules/6.19.0-2-cachyos/build/include -include /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/kconfig.h -I/usr/lib/modules/6.19.0-2-cachyos/build/include -I/usr/lib/modules/6.19.0-2-cachyos/build/include/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/include/generated/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/tools/testing/selftests/bpf/ -D__KERNEL__ -D__BPF_TRACING__ -Wno-unused-value -Wno-pointer-sign -D__TARGET_ARCH_x86 -Wno-compare-distinct-pointer-types  -Wunused -Wno-unused-value -Wno-gnu-variable-sized-type-not-at-end -Wno-address-of-packed-member -Wno-tautological-compare -Wno-unknown-warning-option -fcf-protection -fno-stack-protector -g -O2 -emit-llvm -c opensnitch-procs.c
In file included from In file included from opensnitch.copensnitch-dns.c::325:
:
In file included from In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ptrace.h./common_defs.h::105:
:
In file included from In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/pid_namespace.h/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ptrace.h::1110:
:
In file included from In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/pid_namespace.h::511:
:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:5:
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns/ns_common_types.h:/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns/ns_common_types.h117::1173::3 : warning: warning: declaration doesdeclaration  notdoes  declarenot  anythingdeclare
 anything
            [-Wmissing-declarations][-Wmissing-declarations]

    117117 |  |                                 ssttrruucctt  nnss__ttrreeee;;

            | |                 ^~~~~~~~~~~~~~                ^~~~~~~~~~~~~~

In file included from In file included from opensnitch.copensnitch-dns.c::325:
:
In file included from In file included from ./common_defs.h/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ptrace.h::510:
:
In file included from In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ptrace.h/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/pid_namespace.h::1011:
:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/pid_namespace.h/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h::1125:
:23/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:: 25:23error: : no error: member namedno  'ns_id'member  innamed  'struct ns_common''ns_id'
in 'struct ns_common'
   25 |            V25F | S        _VWFASR_NW_AORNN__OONNC_EO(NnCsE-(>nnss-_>inds _=i=d  =0= );0
)      ;|
                         ~~  ^
|                          ~~  ^
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:26:13: /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:26error: :13:no  member error: named 'ns_id'no  inmember  'struct ns_common'named
'ns_id' in 'struct ns_common'
   26 |         r   e26t | u        rnre tnusr-n>n sn_si-d> n<s=_ iNdS _<L=A SNTS__ILNAISTT__IIDN;IT
_      I| D;               ~~  ^

      |                ~~  ^
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:60:26: error: no member named '__ns_ref_active' in/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h :'struct ns_common'60:
26: error: no member named '__ns_ref_active' in    60'struct ns_common' |
return atomi   c60_ | r        earde(t&unrsn-> _a_tnosm_irce_fr_eaacdt(i&vnes)-;>_
_      n| s_                            ~~  ^r
ef_active);
      |                             ~~  ^
In file included from opensnitch-procs.c:3:
In file included from ./common.h:4:
In file included from ./common_defs.h:5:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ptrace.h:10:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/pid_namespace.h:11:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:5:
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns/ns_common_types.h:117:3: warning: declaration does not declare anything
      [-Wmissing-declarations]
  117 |                 struct ns_tree;
      |                 ^~~~~~~~~~~~~~
In file included from opensnitch-procs.c:3:
In file included from ./common.h:4:
In file included from ./common_defs.h:5:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ptrace.h:10:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/pid_namespace.h:11:
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:25:23: error: no member named 'ns_id' in 'struct ns_common'
   25 |         VFS_WARN_ON_ONCE(ns->ns_id == 0);
      |                          ~~  ^
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:26:13: error: no member named 'ns_id' in 'struct ns_common'
   26 |         return ns->ns_id <= NS_LAST_INIT_ID;
      |                ~~  ^
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:60:26: error: no member named '__ns_ref_active' in 'struct ns_common'
   60 |         return atomic_read(&ns->__ns_ref_active);
      |                             ~~  ^
1 warning and 3 errors generated.
1 warning and 3 errors generated.
make: *** [Makefile:69: opensnitch-procs.bc] Error 1
make: *** Waiting for unfinished jobs....
make: *** [Makefile:69: opensnitch-dns.bc] Error 1
In file included from opensnitch.c:6:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/net/udp_tunnel.h:5:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/net/ip_tunnels.h:21:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/net/dst_cache.h:8:
/usr/lib/modules/6.19.0-2-cachyos/build/include/net/ip6_fib.h:272:10: warning: default initialization of an object of type 'typeof (f6i->expires)'
      (aka 'const unsigned long') leaves the object uninitialized [-Wdefault-const-init-var-unsafe]
  272 |                 return time_after(jiffies, f6i->expires);
      |                        ^
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/jiffies.h:129:3: note: expanded from macro 'time_after'
  129 |          typecheck(unsigned long, b) && \
      |          ^
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/typecheck.h:11:12: note: expanded from macro 'typecheck'
   11 |         typeof(x) __dummy2; \
      |                   ^
2 warnings and 3 errors generated.
make: *** [Makefile:69: opensnitch.bc] Error 1
==> ERROR: A failure occurred in build().
    Aborting...

[eclairevoyant]

Same goes for the mainline 6.19 kernel:

• Build failure: linuxPackages_latest.opensnitch-ebpf NixOS/nixpkgs#490127

[Joomzie]

Same goes for the mainline 6.19 kernel:

Ah, thanks for the confirmation. At least this isn't isolated to one distribution.

[munix9]

Would this patch help?

--- a/ebpf_prog/Makefile
+++ b/ebpf_prog/Makefile
@@ -6,6 +6,10 @@
 KERNEL_VER ?= $(shell ls -d /lib/modules/*/source | sort | tail -1 | cut -d/ -f4)
 KERNEL_DIR ?= /lib/modules/$(KERNEL_VER)/source
 KERNEL_HEADERS ?= /usr/src/linux-headers-$(KERNEL_VER)/
+KERNEL_6_19_CHECK = $(shell expr "$(KERNEL_VER)" \>= "6.19")
+ifeq ($(KERNEL_6_19_CHECK),1)
+       KERNEL_6_19_FLAGS = -Wno-microsoft-anon-tag -fms-extensions
+endif
 CC = clang
 LLC ?= llc
 ARCH ?= $(shell uname -m)
@@ -59,6 +63,7 @@
        -Wno-tautological-compare \
        -Wno-unknown-warning-option  \
        -fno-stack-protector \
+       $(KERNEL_6_19_FLAGS) \
        -g -O2 -emit-llvm
 
 all: $(BIN)

Should work (tested on openSUSE Tumbleweed with kernel 6.19.0).

Edit: An extended version so as not to affect kernels < 6.19.0

[gustavo-iniguez-goya]

@munix9 your patch works for me. I've tested it with kernel 6.19 (without .0), so maybe \>= "6.19" needs to be updated.

@eclairevoyant @Joomzie could you test it?

[munix9]

@gustavo-iniguez-goya Yep, 6.19 should be sufficient:

$ expr "6.19" \>= "6.19"
1
$ expr "6.19.0" \>= "6.19"
1
$ expr "6.19.1" \>= "6.19"
1
$ expr "6.18.999" \>= "6.19"
0
$ expr "6.18.0" \>= "6.19"
0
$ expr "6.18.9-1-default" \>= "6.19"
0

[munix9]

@gustavo-iniguez-goya reusing EXTRA_FLAGS is probably better ...

--- a/ebpf_prog/Makefile        
+++ b/ebpf_prog/Makefile        
@@ -6,6 +6,7 @@
 KERNEL_VER ?= $(shell ls -d /lib/modules/*/source | sort | tail -1 | cut -d/ -f4)
 KERNEL_DIR ?= /lib/modules/$(KERNEL_VER)/source
 KERNEL_HEADERS ?= /usr/src/linux-headers-$(KERNEL_VER)/
+KERNEL_6_19_CHECK = $(shell expr "$(KERNEL_VER)" \>= "6.19")
 CC = clang
 LLC ?= llc
 ARCH ?= $(shell uname -m)
@@ -32,7 +33,10 @@

 ifeq ($(ARCH),arm)
        # on previous archs, it fails with "SMP not supported on pre-ARMv6"
-       EXTRA_FLAGS = "-D__LINUX_ARM_ARCH__=7"
+       EXTRA_FLAGS = -D__LINUX_ARM_ARCH__=7  
+endif
+ifeq ($(KERNEL_6_19_CHECK),1)
+       EXTRA_FLAGS += -Wno-microsoft-anon-tag -fms-extensions
 endif
 
 SRC := $(wildcard *.c)

[Joomzie]

@munix9 @gustavo-iniguez-goya I'm still getting a failure. I've tried with both patches, though I am getting a slightly different error output when using the first patch.

clang -I. -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/ -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated/ -I/usr/lib/modules/6.19.0-2-cachyos/build/include -include /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/kconfig.h -I/usr/lib/modules/6.19.0-2-cachyos/build/include -I/usr/lib/modules/6.19.0-2-cachyos/build/include/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/include/generated/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/tools/testing/selftests/bpf/ -D__KERNEL__ -D__BPF_TRACING__ -Wno-unused-value -Wno-pointer-sign -D__TARGET_ARCH_x86 -Wno-compare-distinct-pointer-types  -Wunused -Wno-unused-value -Wno-gnu-variable-sized-type-not-at-end -Wno-address-of-packed-member -Wno-tautological-compare -Wno-unknown-warning-option -fcf-protection -fno-stack-protector  -g -O2 -emit-llvm -c opensnitch.c
clang -I. -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/ -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated/ -I/usr/lib/modules/6.19.0-2-cachyos/build/include -include /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/kconfig.h -I/usr/lib/modules/6.19.0-2-cachyos/build/include -I/usr/lib/modules/6.19.0-2-cachyos/build/include/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/include/generated/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/tools/testing/selftests/bpf/ -D__KERNEL__ -D__BPF_TRACING__ -Wno-unused-value -Wno-pointer-sign -D__TARGET_ARCH_x86 -Wno-compare-distinct-pointer-types  -Wunused -Wno-unused-value -Wno-gnu-variable-sized-type-not-at-end -Wno-address-of-packed-member -Wno-tautological-compare -Wno-unknown-warning-option -fcf-protection -fno-stack-protector  -g -O2 -emit-llvm -c opensnitch-dns.c
clang -I. -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/ -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated/ -I/usr/lib/modules/6.19.0-2-cachyos/build/include -include /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/kconfig.h -I/usr/lib/modules/6.19.0-2-cachyos/build/include -I/usr/lib/modules/6.19.0-2-cachyos/build/include/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/include/generated/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/arch/x86/include/generated/uapi -I/usr/lib/modules/6.19.0-2-cachyos/build/tools/testing/selftests/bpf/ -D__KERNEL__ -D__BPF_TRACING__ -Wno-unused-value -Wno-pointer-sign -D__TARGET_ARCH_x86 -Wno-compare-distinct-pointer-types  -Wunused -Wno-unused-value -Wno-gnu-variable-sized-type-not-at-end -Wno-address-of-packed-member -Wno-tautological-compare -Wno-unknown-warning-option -fcf-protection -fno-stack-protector  -g -O2 -emit-llvm -c opensnitch-procs.c
In file included from opensnitch.c:3:
In file included from ./common_defs.h:5:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ptrace.h:10:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/pid_namespace.h:11:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:5:
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns/ns_common_types.h:117:3: warning: declaration does not declare anything
      [-Wmissing-declarations]
  117 |                 struct ns_tree;
      |                 ^~~~~~~~~~~~~~
In file included from opensnitch.c:3:
In file included from ./common_defs.h:5:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ptrace.h:10:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/pid_namespace.h:11:
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:25:23: error: no member named 'ns_id' in 'struct ns_common'
   25 |         VFS_WARN_ON_ONCE(ns->ns_id == 0);
      |                          ~~  ^
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:26:13: error: no member named 'ns_id' in 'struct ns_common'
   26 |         return ns->ns_id <= NS_LAST_INIT_ID;
      |                ~~  ^
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:60:26: error: no member named '__ns_ref_active' in 'struct ns_common'
   60 |         return atomic_read(&ns->__ns_ref_active);
      |                             ~~  ^
In file included from opensnitch-dns.c:25:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ptrace.h:10:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/pid_namespace.h:11:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:5:
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns/ns_common_types.h:117:3: warning: declaration does not declare anything
      [-Wmissing-declarations]
  117 |                 struct ns_tree;
      |                 ^~~~~~~~~~~~~~
In file included from opensnitch-dns.c:25:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ptrace.h:10:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/pid_namespace.h:11:
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:25:23: error: no member named 'ns_id' in 'struct ns_common'
   25 |         VFS_WARN_ON_ONCE(ns->ns_id == 0);
      |                          ~~  ^
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:26:13: error: no member named 'ns_id' in 'struct ns_common'
   26 |         return ns->ns_id <= NS_LAST_INIT_ID;
      |                ~~  ^
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:60:26: error: no member named '__ns_ref_active' in 'struct ns_common'
   60 |         return atomic_read(&ns->__ns_ref_active);
      |                             ~~  ^
In file included from opensnitch-procs.c:3:
In file included from ./common.h:4:
In file included from ./common_defs.h:5:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ptrace.h:10:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/pid_namespace.h:11:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:5:
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns/ns_common_types.h:117:3: warning: declaration does not declare anything
      [-Wmissing-declarations]
  117 |                 struct ns_tree;
      |                 ^~~~~~~~~~~~~~
In file included from opensnitch-procs.c:3:
In file included from ./common.h:4:
In file included from ./common_defs.h:5:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ptrace.h:10:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/linux/pid_namespace.h:11:
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:25:23: error: no member named 'ns_id' in 'struct ns_common'
   25 |         VFS_WARN_ON_ONCE(ns->ns_id == 0);
      |                          ~~  ^
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:26:13: error: no member named 'ns_id' in 'struct ns_common'
   26 |         return ns->ns_id <= NS_LAST_INIT_ID;
      |                ~~  ^
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/ns_common.h:60:26: error: no member named '__ns_ref_active' in 'struct ns_common'
   60 |         return atomic_read(&ns->__ns_ref_active);
      |                             ~~  ^
1 warning and 3 errors generated.
make: *** [Makefile:73: opensnitch-dns.bc] Error 1
make: *** Waiting for unfinished jobs....
1 warning and 3 errors generated.
make: *** [Makefile:73: opensnitch-procs.bc] Error 1
In file included from opensnitch.c:6:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/net/udp_tunnel.h:5:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/net/ip_tunnels.h:21:
In file included from /usr/lib/modules/6.19.0-2-cachyos/build/include/net/dst_cache.h:8:
/usr/lib/modules/6.19.0-2-cachyos/build/include/net/ip6_fib.h:272:10: warning: default initialization of an object of type 'typeof (f6i->expires)'
      (aka 'const unsigned long') leaves the object uninitialized [-Wdefault-const-init-var-unsafe]
  272 |                 return time_after(jiffies, f6i->expires);
      |                        ^
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/jiffies.h:129:3: note: expanded from macro 'time_after'
  129 |          typecheck(unsigned long, b) && \
      |          ^
/usr/lib/modules/6.19.0-2-cachyos/build/include/linux/typecheck.h:11:12: note: expanded from macro 'typecheck'
   11 |         typeof(x) __dummy2; \
      |                   ^
2 warnings and 3 errors generated.
make: *** [Makefile:73: opensnitch.bc] Error 1

Also, I'm not sure if this is relevant, but for added context, the AUR package includes its own Makefile patch that throws in some extra CFLAGS for building on Arch. I used it and the first patch to create my own (the second patch from @munix9 actually throws out an error about /lib/modules/*/source not being found, so I figure it's not reliable in my environment), and I'm not sure if this is causing problems, or not.

--- a/ebpf_prog/Makefile
+++ b/ebpf_prog/Makefile
@@ -6,6 +6,9 @@
 KERNEL_VER ?= $(shell ls -d /lib/modules/*/source | sort | tail -1 | cut -d/ -f4)
 KERNEL_DIR ?= /lib/modules/$(KERNEL_VER)/source
 KERNEL_HEADERS ?= /usr/src/linux-headers-$(KERNEL_VER)/
+ifeq ($(KERNEL_6_19_CHECK),1)
+       KERNEL_6_19_FLAGS = -Wno-microsoft-anon-tag -fms-extensions
+endif
 CC = clang
 LLC ?= llc
 ARCH ?= $(shell uname -m)
@@ -38,6 +41,7 @@
 SRC := $(wildcard *.c)
 BIN := $(SRC:.c=.o)
 CFLAGS = -I. \
+	-I$(KERNEL_HEADERS)/arch/$(ARCH)/include/ \
 	-I$(KERNEL_HEADERS)/arch/$(ARCH)/include/generated/ \
 	-I$(KERNEL_HEADERS)/include \
 	-include $(KERNEL_DIR)/include/linux/kconfig.h \
@@ -57,8 +61,10 @@
 	-Wno-gnu-variable-sized-type-not-at-end \
 	-Wno-address-of-packed-member \
 	-Wno-tautological-compare \
-	-Wno-unknown-warning-option  \
+	-Wno-unknown-warning-option \
+	-fcf-protection \
 	-fno-stack-protector \
+	$(KERNEL_6_19_FLAGS) \
 	-g -O2 -emit-llvm
 
 all: $(BIN)

[munix9]

The variable KERNEL_VER is important; if an error occurs during assignment (for whatever reason), it will not work.

Please try passing KERNEL_VER to make, e.g., make KERNEL_VER=6.19.0

The question is also why KERNEL_VER ?= $(shell ls -d /lib/modules/*/source | sort | tail -1 | cut -d/ -f4) does not work - this should cause make to abort with an error.

@Joomzie does cat /usr/src/linux-obj/*/*/include/config/kernel.release provide anything useful on your system?

@gustavo-iniguez-goya what about KERNEL_VER ?= $(shell uname -r) ?

btw: -fcf-protection (for x86_64) would also be useful, see e.g. https://best.openssf.org/Compiler-Hardening-Guides/Compiler-Options-Hardening-Guide-for-C-and-C++ - but that's another issue (pr may come later).

[gustavo-iniguez-goya]

KERNEL_VER is the way it is because in containers, chroots or similar environments, it may not pick the correct headers.
In either case we'll have a problem, so for now I'd not change it.

@Joomzie see if setting KERNEL_VER works.

Also, you can test the PR #1422, it should compile fine.

[Joomzie]

@Joomzie does cat /usr/src/linux-obj/*/*/include/config/kernel.release provide anything useful on your system?

So, it looks like CachyOS is slightly different. The path is /lib/modules/*/build/include/config/kernel.release. Not sure if that's a recent change (or if Arch itself will also be following this scheme), but I'm assuming it is since I never had issues building against its kernel until now.

If I change that ls to ls -d /lib/modules/*/build | sort | tail -1 | cut -d/ -f4, I get an output.

❯ ls -d /lib/modules/*/build | sort | tail -1 | cut -d/ -f4
6.19.2-2-cachyos

That being said, I was able to cobble together a working patch now that I know the path is different. I based it on yours, and the one from the AUR that I mentioned earlier.

cachyos-619.patch:

--- a/ebpf_prog/Makefile
+++ b/ebpf_prog/Makefile
@@ -3,9 +3,10 @@
 # On Debian based distros we need the following 2 directories.
 # Otherwise, just use the kernel headers from the kernel sources.
 #
-KERNEL_VER ?= $(shell ls -d /lib/modules/*/source | sort | tail -1 | cut -d/ -f4)
-KERNEL_DIR ?= /lib/modules/$(KERNEL_VER)/source
+KERNEL_VER ?= $(shell ls -d /lib/modules/*/build | sort | tail -1 | cut -d/ -f4)
+KERNEL_DIR ?= /lib/modules/$(KERNEL_VER)/build
 KERNEL_HEADERS ?= /usr/src/linux-headers-$(KERNEL_VER)/
+KERNEL_6_19_CHECK = $(shell expr "$(KERNEL_VER)" \>= "6.19")
 CC = clang
 LLC ?= llc
 ARCH ?= $(shell uname -m)
@@ -32,12 +33,16 @@
 
 ifeq ($(ARCH),arm)
 	# on previous archs, it fails with "SMP not supported on pre-ARMv6"
-	EXTRA_FLAGS = "-D__LINUX_ARM_ARCH__=7"
+   EXTRA_FLAGS = -D__LINUX_ARM_ARCH__=7
+endif
+ifeq ($(KERNEL_6_19_CHECK),1)
+       EXTRA_FLAGS += -Wno-microsoft-anon-tag -fms-extensions
 endif
 
 SRC := $(wildcard *.c)
 BIN := $(SRC:.c=.o)
 CFLAGS = -I. \
+	-I$(KERNEL_HEADERS)/arch/$(ARCH)/include/ \
 	-I$(KERNEL_HEADERS)/arch/$(ARCH)/include/generated/ \
 	-I$(KERNEL_HEADERS)/include \
 	-include $(KERNEL_DIR)/include/linux/kconfig.h \
@@ -57,7 +62,8 @@
 	-Wno-gnu-variable-sized-type-not-at-end \
 	-Wno-address-of-packed-member \
 	-Wno-tautological-compare \
-	-Wno-unknown-warning-option  \
+	-Wno-unknown-warning-option \
+	-fcf-protection \
 	-fno-stack-protector \
 	-g -O2 -emit-llvm
 

It's looking like we could just use ls -d /lib/modules/*/* | sort | tail -1 | cut -d/ -f4, instead of explicitly defining source or build, but I'll leave that up to your discretion since you're more knowledgeable on this.