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fix: make maps compatible with kernel <= 4.14

In kernel 4.15 and additional parameter was added to allow maps to have
names but using this breaks on older kernels.

This change makes it so the name is only added on kernels 4.15 and
newer.
Dan Everton 3 jaren geleden
bovenliggende
commit
fc0861105a
1 gewijzigde bestanden met toevoegingen van 11 en 5 verwijderingen
  1. 11 5
      aya/src/sys/bpf.rs

+ 11 - 5
aya/src/sys/bpf.rs

@@ -14,7 +14,7 @@ use crate::{
     generated::{bpf_attach_type, bpf_attr, bpf_cmd, bpf_insn, bpf_prog_info, bpf_prog_type},
     maps::PerCpuValues,
     programs::VerifierLog,
-    sys::SysResult,
+    sys::{kernel_version, SysResult},
     Pod, BPF_OBJ_NAME_LEN,
 };
 
@@ -30,10 +30,16 @@ pub(crate) fn bpf_create_map(name: &CStr, def: &bpf_map_def) -> SysResult {
     u.max_entries = def.max_entries;
     u.map_flags = def.map_flags;
 
-    // u.map_name is 16 bytes max and must be NULL terminated
-    let name_len = cmp::min(name.to_bytes().len(), BPF_OBJ_NAME_LEN - 1);
-    u.map_name[..name_len]
-        .copy_from_slice(unsafe { slice::from_raw_parts(name.as_ptr(), name_len) });
+    // https://github.com/torvalds/linux/commit/ad5b177bd73f5107d97c36f56395c4281fb6f089
+    // The map name was added as a parameter in kernel 4.15+ so we skip adding it on
+    // older kernels for compatibility 
+    let k_ver = kernel_version().unwrap();
+    if k_ver >= (4, 15, 0) {
+        // u.map_name is 16 bytes max and must be NULL terminated
+        let name_len = cmp::min(name.to_bytes().len(), BPF_OBJ_NAME_LEN - 1);
+        u.map_name[..name_len]
+            .copy_from_slice(unsafe { slice::from_raw_parts(name.as_ptr(), name_len) });
+    }
 
     sys_bpf(bpf_cmd::BPF_MAP_CREATE, &attr)
 }