lkml.org 
[lkml]   [2018]   [Apr]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v3 1/7] kprobes: Make blacklist root user read only

    * Masami Hiramatsu <mhiramat@kernel.org> wrote:

    > Since the blacklist file indicates a sensitive address
    > information to reader, it should be restricted to the
    > root user.
    >
    > Suggested-by: Thomas Richter <tmricht@linux.ibm.com>
    > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
    > ---
    > kernel/kprobes.c | 2 +-
    > 1 file changed, 1 insertion(+), 1 deletion(-)
    >
    > diff --git a/kernel/kprobes.c b/kernel/kprobes.c
    > index ea619021d901..51096eece801 100644
    > --- a/kernel/kprobes.c
    > +++ b/kernel/kprobes.c
    > @@ -2621,7 +2621,7 @@ static int __init debugfs_kprobe_init(void)
    > if (!file)
    > goto error;
    >
    > - file = debugfs_create_file("blacklist", 0444, dir, NULL,
    > + file = debugfs_create_file("blacklist", 0400, dir, NULL,
    > &debugfs_kprobe_blacklist_ops);
    > if (!file)
    > goto error;

    Note that in a typical Linux distro debugfs is already root-only:

    fomalhaut:~> ls -ld /sys/kernel/debug
    drwx------ 28 root root 0 Apr 23 08:55 /sys/kernel/debug

    but this change might make sense if debugfs is mounted in some other fashion.

    But the patch looks incomplete, 'blacklist' is not the only word-readable file in
    the kprobes hierarchy. The kprobes directory itself, and the 'list' file is
    readable as well:

    [root@fomalhaut ~]# ls -ld /sys/kernel/debug/kprobes
    drwxr-xr-x 2 root root 0 Apr 23 08:55 /sys/kernel/debug/kprobes

    [root@fomalhaut ~]# ls -l /sys/kernel/debug/kprobes/

    -r--r--r-- 1 root root 0 Apr 23 08:55 blacklist
    -rw------- 1 root root 0 Apr 23 08:55 enabled
    -r--r--r-- 1 root root 0 Apr 23 08:55 list

    So not just the blacklist should be 400 but 'list' as well, and the main kprobes
    directory as well.

    Thanks,

    Ingo

    \
     
     \ /
      Last update: 2018-04-27 09:05    [W:4.299 / U:0.204 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site