On 09/08, Pu Lehui wrote:
From: Pu Lehui <pulehui@xxxxxxxxxx>
When root-cgroup attach multi progs and sub-cgroup attach a override prog, bpftool will display incorrectly for the attach flags of the sub-cgroup’s effective progs:
$ bpftool cgroup tree /sys/fs/cgroup effective CgroupPath ID AttachType AttachFlags Name /sys/fs/cgroup 6 cgroup_sysctl multi sysctl_tcp_mem 13 cgroup_sysctl multi sysctl_tcp_mem /sys/fs/cgroup/cg1 20 cgroup_sysctl override sysctl_tcp_mem 6 cgroup_sysctl override sysctl_tcp_mem <- wrong 13 cgroup_sysctl override sysctl_tcp_mem <- wrong /sys/fs/cgroup/cg1/cg2 20 cgroup_sysctl sysctl_tcp_mem 6 cgroup_sysctl sysctl_tcp_mem 13 cgroup_sysctl sysctl_tcp_mem
For cg1, obviously, the attach flags of prog6 and prog13 can not be OVERRIDE, and the attach flags of prog6 and prog13 is meaningless for cg1. We only need to care the attach flags of prog which attached to cg1, other progs attach flags should be omit. After these patches, the above situation will show as bellow:
$ bpftool cgroup tree /sys/fs/cgroup effective CgroupPath ID AttachType AttachFlags Name /sys/fs/cgroup 6 cgroup_sysctl multi sysctl_tcp_mem 13 cgroup_sysctl multi sysctl_tcp_mem /sys/fs/cgroup/cg1 20 cgroup_sysctl override sysctl_tcp_mem 6 cgroup_sysctl sysctl_tcp_mem 13 cgroup_sysctl sysctl_tcp_mem /sys/fs/cgroup/cg1/cg2 20 cgroup_sysctl sysctl_tcp_mem 6 cgroup_sysctl sysctl_tcp_mem 13 cgroup_sysctl sysctl_tcp_mem
v2: - Limit prog_cnt to avoid overflow. (John) - Add more detail message.
John also raised a good question in v1: the flags don't seem to make sense when requesting effective list. So maybe not export them at all?
v1: https://lore.kernel.org/bpf/20220820120234.2121044-1-pulehui@xxxxxxxxxx
Pu Lehui (2): bpf, cgroup: Fix attach flags being assigned to effective progs bpftool: Fix cgroup attach flags being assigned to effective progs
kernel/bpf/cgroup.c | 5 ++++- tools/bpf/bpftool/cgroup.c | 9 +++------ 2 files changed, 7 insertions(+), 7 deletions(-)
-- 2.25.1
