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bugtool: get bpffs mountpoint from /proc/self/mounts
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Rather then hardcoding the /sys/fs/bpf value in bugtool, use the
`mountinfo` package (which exposes the information in /proc/self/mounts)
to determine the correct mountpoint for the BPF filesystem.

Fixes: #13218

Signed-off-by: Gilberto Bertin <gilberto@isovalent.com>
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@jibi @borkmann
jibi authored and borkmann committed Oct 1, 2020
1 parent c0236a4 commit 57d3473
Showing 1 changed file with 51 additions and 18 deletions.
69 changes: 51 additions & 18 deletions bugtool/cmd/configuration.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@ import (

"github.com/cilium/cilium/pkg/components"
"github.com/cilium/cilium/pkg/defaults"
"github.com/cilium/cilium/pkg/mountinfo"
)

// BugtoolConfiguration creates and loads the configuration file used to run
Expand All @@ -39,6 +40,33 @@ func setupDefaultConfig(path string, k8sPods []string, confDir, cmdDir string) (
return &c, save(&c, path)
}

func bpffsMountpoint() string {
mountInfos, err := mountinfo.GetMountInfo()
if err != nil {
return ""
}

// To determine the mountpoint of the BPF fs we iterate through the list
// of mount info (i.e. /proc/self/mounts entries) and return the first
// one which has the "bpf" fs type and the "/" root.
//
// The root == "/" condition allows us to ignore all BPF fs which are
// sub mounts (such as for example /sys/fs/bpf/{xdp, ip, sk, sa}) of the
// one with the "/" root.
//
// Moreover, as Cilium will refuse to start if there are multiple BPF fs
// which have "/" as their root, we can assume there will be at most one
// mountpoint which matches the conditions and so we return it as soon
// as we find it.
for _, mountInfo := range mountInfos {
if mountInfo.FilesystemType == "bpf" && mountInfo.Root == "/" {
return mountInfo.MountPoint
}
}

return ""
}

func defaultCommands(confDir string, cmdDir string, k8sPods []string) []string {
var commands []string
// Not expecting all of the commands to be available
Expand All @@ -63,24 +91,6 @@ func defaultCommands(confDir string, cmdDir string, k8sPods []string) []string {
"sysctl -a",
"bpftool map show",
"bpftool prog show",
// LB and CT map for debugging services; using bpftool for a reliable dump
"bpftool map dump pinned /sys/fs/bpf/tc/globals/cilium_lb4_services_v2",
"bpftool map dump pinned /sys/fs/bpf/tc/globals/cilium_lb4_services",
"bpftool map dump pinned /sys/fs/bpf/tc/globals/cilium_lb4_backends",
"bpftool map dump pinned /sys/fs/bpf/tc/globals/cilium_lb4_reverse_nat",
"bpftool map dump pinned /sys/fs/bpf/tc/globals/cilium_ct4_global",
"bpftool map dump pinned /sys/fs/bpf/tc/globals/cilium_ct_any4_global",
"bpftool map dump pinned /sys/fs/bpf/tc/globals/cilium_lb4_affinity",
"bpftool map dump pinned /sys/fs/bpf/tc/globals/cilium_lb6_affinity",
"bpftool map dump pinned /sys/fs/bpf/tc/globals/cilium_lb_affinity_match",
"bpftool map dump pinned /sys/fs/bpf/tc/globals/cilium_lb6_services_v2",
"bpftool map dump pinned /sys/fs/bpf/tc/globals/cilium_lb6_services",
"bpftool map dump pinned /sys/fs/bpf/tc/globals/cilium_lb6_backends",
"bpftool map dump pinned /sys/fs/bpf/tc/globals/cilium_lb6_reverse_nat",
"bpftool map dump pinned /sys/fs/bpf/tc/globals/cilium_ct6_global",
"bpftool map dump pinned /sys/fs/bpf/tc/globals/cilium_ct_any6_global",
"bpftool map dump pinned /sys/fs/bpf/tc/globals/cilium_snat_v4_external",
"bpftool map dump pinned /sys/fs/bpf/tc/globals/cilium_snat_v6_external",
// iptables
"iptables-save -c",
"iptables -S",
Expand All @@ -102,6 +112,29 @@ func defaultCommands(confDir string, cmdDir string, k8sPods []string) []string {
fmt.Sprintf("ls -la /proc/$(pidof %s)/fd", components.CiliumAgentName),
}

if bpffsMountpoint := bpffsMountpoint(); bpffsMountpoint != "" {
commands = append(commands, []string{
// LB and CT map for debugging services; using bpftool for a reliable dump
fmt.Sprintf("bpftool map dump pinned %s/tc/globals/cilium_lb4_services_v2", bpffsMountpoint),
fmt.Sprintf("bpftool map dump pinned %s/tc/globals/cilium_lb4_services", bpffsMountpoint),
fmt.Sprintf("bpftool map dump pinned %s/tc/globals/cilium_lb4_backends", bpffsMountpoint),
fmt.Sprintf("bpftool map dump pinned %s/tc/globals/cilium_lb4_reverse_nat", bpffsMountpoint),
fmt.Sprintf("bpftool map dump pinned %s/tc/globals/cilium_ct4_global", bpffsMountpoint),
fmt.Sprintf("bpftool map dump pinned %s/tc/globals/cilium_ct_any4_global", bpffsMountpoint),
fmt.Sprintf("bpftool map dump pinned %s/tc/globals/cilium_lb4_affinity", bpffsMountpoint),
fmt.Sprintf("bpftool map dump pinned %s/tc/globals/cilium_lb6_affinity", bpffsMountpoint),
fmt.Sprintf("bpftool map dump pinned %s/tc/globals/cilium_lb_affinity_match", bpffsMountpoint),
fmt.Sprintf("bpftool map dump pinned %s/tc/globals/cilium_lb6_services_v2", bpffsMountpoint),
fmt.Sprintf("bpftool map dump pinned %s/tc/globals/cilium_lb6_services", bpffsMountpoint),
fmt.Sprintf("bpftool map dump pinned %s/tc/globals/cilium_lb6_backends", bpffsMountpoint),
fmt.Sprintf("bpftool map dump pinned %s/tc/globals/cilium_lb6_reverse_nat", bpffsMountpoint),
fmt.Sprintf("bpftool map dump pinned %s/tc/globals/cilium_ct6_global", bpffsMountpoint),
fmt.Sprintf("bpftool map dump pinned %s/tc/globals/cilium_ct_any6_global", bpffsMountpoint),
fmt.Sprintf("bpftool map dump pinned %s/tc/globals/cilium_snat_v4_external", bpffsMountpoint),
fmt.Sprintf("bpftool map dump pinned %s/tc/globals/cilium_snat_v6_external", bpffsMountpoint),
}...)
}

// Commands that require variables and / or more configuration are added
// separately below
commands = append(commands, catCommands()...)
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