commit 2918f066d5539d2c35d3dbc87463585a3aefbeec
author LuK1337 <priv.luk@gmail.com> Mon Nov 04 18:41:05 2024 +0100
committer LuK1337 <priv.luk@gmail.com> Mon Nov 04 18:49:24 2024 +0100
tree e99bf072204182cb58c87a16620a599ef26fd235
parent 1de84f2fd219c072ec9190a58e0b91964ca08fae

BpfHandler: Add kver checks around V BPF attach program checks

Same as the netd change prior, but this is just to make it easier for
AOSP forks to work on legacy devices not meeting V requirements.

Change-Id: I2ebb479b6c9d3d82ee300bb6bf978184bb6c802b

bpf/netd/BpfHandler.cpp

diff --git a/bpf/netd/BpfHandler.cpp b/bpf/netd/BpfHandler.cpp
index 8e4c2c6..50e0329 100644
--- a/bpf/netd/BpfHandler.cpp
+++ b/bpf/netd/BpfHandler.cpp
@@ -120,18 +120,22 @@
     }
 
     if (modules::sdklevel::IsAtLeastV()) {
-        RETURN_IF_NOT_OK(attachProgramToCgroup(CGROUP_CONNECT4_PROG_PATH,
-                                    cg_fd, BPF_CGROUP_INET4_CONNECT));
-        RETURN_IF_NOT_OK(attachProgramToCgroup(CGROUP_CONNECT6_PROG_PATH,
-                                    cg_fd, BPF_CGROUP_INET6_CONNECT));
-        RETURN_IF_NOT_OK(attachProgramToCgroup(CGROUP_UDP4_RECVMSG_PROG_PATH,
-                                    cg_fd, BPF_CGROUP_UDP4_RECVMSG));
-        RETURN_IF_NOT_OK(attachProgramToCgroup(CGROUP_UDP6_RECVMSG_PROG_PATH,
-                                    cg_fd, BPF_CGROUP_UDP6_RECVMSG));
-        RETURN_IF_NOT_OK(attachProgramToCgroup(CGROUP_UDP4_SENDMSG_PROG_PATH,
-                                    cg_fd, BPF_CGROUP_UDP4_SENDMSG));
-        RETURN_IF_NOT_OK(attachProgramToCgroup(CGROUP_UDP6_SENDMSG_PROG_PATH,
-                                    cg_fd, BPF_CGROUP_UDP6_SENDMSG));
+        // V requires 4.19+, so technically this 2nd 'if' is not required, but it
+        // doesn't hurt us to try to support AOSP forks that try to support older kernels.
+        if (bpf::isAtLeastKernelVersion(4, 19, 0)) {
+            RETURN_IF_NOT_OK(attachProgramToCgroup(CGROUP_CONNECT4_PROG_PATH,
+                                        cg_fd, BPF_CGROUP_INET4_CONNECT));
+            RETURN_IF_NOT_OK(attachProgramToCgroup(CGROUP_CONNECT6_PROG_PATH,
+                                        cg_fd, BPF_CGROUP_INET6_CONNECT));
+            RETURN_IF_NOT_OK(attachProgramToCgroup(CGROUP_UDP4_RECVMSG_PROG_PATH,
+                                        cg_fd, BPF_CGROUP_UDP4_RECVMSG));
+            RETURN_IF_NOT_OK(attachProgramToCgroup(CGROUP_UDP6_RECVMSG_PROG_PATH,
+                                        cg_fd, BPF_CGROUP_UDP6_RECVMSG));
+            RETURN_IF_NOT_OK(attachProgramToCgroup(CGROUP_UDP4_SENDMSG_PROG_PATH,
+                                        cg_fd, BPF_CGROUP_UDP4_SENDMSG));
+            RETURN_IF_NOT_OK(attachProgramToCgroup(CGROUP_UDP6_SENDMSG_PROG_PATH,
+                                        cg_fd, BPF_CGROUP_UDP6_SENDMSG));
+        }
 
         if (bpf::isAtLeastKernelVersion(5, 4, 0)) {
             RETURN_IF_NOT_OK(attachProgramToCgroup(CGROUP_GETSOCKOPT_PROG_PATH,
@@ -161,12 +165,16 @@
     }
 
     if (modules::sdklevel::IsAtLeastV()) {
-        if (bpf::queryProgram(cg_fd, BPF_CGROUP_INET4_CONNECT) <= 0) abort();
-        if (bpf::queryProgram(cg_fd, BPF_CGROUP_INET6_CONNECT) <= 0) abort();
-        if (bpf::queryProgram(cg_fd, BPF_CGROUP_UDP4_RECVMSG) <= 0) abort();
-        if (bpf::queryProgram(cg_fd, BPF_CGROUP_UDP6_RECVMSG) <= 0) abort();
-        if (bpf::queryProgram(cg_fd, BPF_CGROUP_UDP4_SENDMSG) <= 0) abort();
-        if (bpf::queryProgram(cg_fd, BPF_CGROUP_UDP6_SENDMSG) <= 0) abort();
+        // V requires 4.19+, so technically this 2nd 'if' is not required, but it
+        // doesn't hurt us to try to support AOSP forks that try to support older kernels.
+        if (bpf::isAtLeastKernelVersion(4, 19, 0)) {
+            if (bpf::queryProgram(cg_fd, BPF_CGROUP_INET4_CONNECT) <= 0) abort();
+            if (bpf::queryProgram(cg_fd, BPF_CGROUP_INET6_CONNECT) <= 0) abort();
+            if (bpf::queryProgram(cg_fd, BPF_CGROUP_UDP4_RECVMSG) <= 0) abort();
+            if (bpf::queryProgram(cg_fd, BPF_CGROUP_UDP6_RECVMSG) <= 0) abort();
+            if (bpf::queryProgram(cg_fd, BPF_CGROUP_UDP4_SENDMSG) <= 0) abort();
+            if (bpf::queryProgram(cg_fd, BPF_CGROUP_UDP6_SENDMSG) <= 0) abort();
+        }
 
         if (bpf::isAtLeastKernelVersion(5, 4, 0)) {
             if (bpf::queryProgram(cg_fd, BPF_CGROUP_GETSOCKOPT) <= 0) abort();