Hi,
On 29/03/2020 02:43, KP Singh wrote:
# How does it work?
The patchset introduces a new eBPF (https://docs.cilium.io/en/v1.6/bpf/)
program type BPF_PROG_TYPE_LSM which can only be attached to LSM hooks.
Loading and attachment of BPF programs requires CAP_SYS_ADMIN.
The new LSM registers nop functions (bpf_lsm_<hook_name>) as LSM hook
callbacks. Their purpose is to provide a definite point where BPF
programs can be attached as BPF_TRAMP_MODIFY_RETURN trampoline programs
for hooks that return an int, and BPF_TRAMP_FEXIT trampoline programs
for void LSM hooks.
I have two systems (a NUC and a qemu VM) that fail to boot if I enable
the BPF LSM without enabling SELinux first. Anything I might be missing
or are you able to trigger it too?
For instance, the following additional cmdline args: "lsm.debug=1
lsm="capability,apparmor,bpf" results in:
[ 1.251889] Call Trace:
[ 1.252344] dump_stack+0x57/0x7a
[ 1.252951] panic+0xe6/0x2a4
[ 1.253497] ? printk+0x43/0x45
[ 1.254075] mount_block_root+0x30c/0x31b
[ 1.254798] mount_root+0x78/0x7b
[ 1.255417] prepare_namespace+0x13a/0x16b
[ 1.256168] kernel_init_freeable+0x210/0x222
[ 1.257021] ? rest_init+0xa5/0xa5
[ 1.257639] kernel_init+0x9/0xfb
[ 1.258074] ret_from_fork+0x35/0x40
[ 1.258885] Kernel Offset: 0x11000000 from 0xffffffff81000000
(relocation range: 0xffffffff80000000-0xffffffffbfffffff)
[ 1.264046] ---[ end Kernel panic - not syncing: VFS: Unable to mount
root fs on unknown-block(253,3)
Taking out "bpf" or adding "selinux" before it boots OK. I've tried
with both 5.7-rc2 and -rc3.
LSM logs:
[ 0.267219] LSM: Security Framework initializing
[ 0.267844] LSM: first ordering: capability (enabled)
[ 0.267870] LSM: cmdline ignored: capability
[ 0.268869] LSM: cmdline ordering: apparmor (enabled)
[ 0.269508] LSM: cmdline ordering: bpf (enabled)
[ 0.269869] LSM: cmdline disabled: selinux
[ 0.270377] LSM: cmdline disabled: integrity
[ 0.270869] LSM: exclusive chosen: apparmor
[ 0.271869] LSM: cred blob size = 8
[ 0.272354] LSM: file blob size = 24
[ 0.272869] LSM: inode blob size = 0
[ 0.273362] LSM: ipc blob size = 0
[ 0.273869] LSM: msg_msg blob size = 0
[ 0.274352] LSM: task blob size = 32
[ 0.274873] LSM: initializing capability
[ 0.275381] LSM: initializing apparmor
[ 0.275880] AppArmor: AppArmor initialized
[ 0.276437] LSM: initializing bpf
[ 0.276871] LSM support for eBPF active
-- Regards, Mikko
