lkml.org 
[lkml]   [2018]   [Apr]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Subject[PATCH 22/24] bpf: Restrict kernel image access functions when the kernel is locked down
    From
    Date
    There are some bpf functions can be used to read kernel memory:
    bpf_probe_read, bpf_probe_write_user and bpf_trace_printk. These allow
    private keys in kernel memory (e.g. the hibernation image signing key) to
    be read by an eBPF program.

    Completely prohibit the use of BPF when the kernel is locked down.

    Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
    Signed-off-by: David Howells <dhowells@redhat.com>
    cc: netdev@vger.kernel.org
    cc: Chun-Yi Lee <jlee@suse.com>
    cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
    ---

    kernel/bpf/syscall.c | 3 +++
    1 file changed, 3 insertions(+)

    diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
    index 0244973ee544..7457f2676c6d 100644
    --- a/kernel/bpf/syscall.c
    +++ b/kernel/bpf/syscall.c
    @@ -2031,6 +2031,9 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
    if (sysctl_unprivileged_bpf_disabled && !capable(CAP_SYS_ADMIN))
    return -EPERM;

    + if (kernel_is_locked_down("BPF"))
    + return -EPERM;
    +
    err = check_uarg_tail_zero(uattr, sizeof(attr), size);
    if (err)
    return err;
    \
     
     \ /
      Last update: 2018-04-11 18:27    [W:4.067 / U:0.036 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site