On Wed, Nov 13, 2019 at 12:22 AM Christian Brauner <christian.brauner@xxxxxxxxxx> wrote: > On Sun, Nov 03, 2019 at 04:55:48PM +0200, Topi Miettinen wrote: > > Several items in /proc/sys need not be accessible to unprivileged > > tasks. Let the system administrator change the permissions, but only > > to more restrictive modes than what the sysctl tables allow. > > > > Signed-off-by: Topi Miettinen <toiwoton@xxxxxxxxx> > > --- > > fs/proc/proc_sysctl.c | 41 +++++++++++++++++++++++++++++++---------- > > 1 file changed, 31 insertions(+), 10 deletions(-) > > > > diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c > > index d80989b6c344..88c4ca7d2782 100644 > > --- a/fs/proc/proc_sysctl.c > > +++ b/fs/proc/proc_sysctl.c > > @@ -818,6 +818,10 @@ static int proc_sys_permission(struct inode *inode, int > > mask) > > if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) > > return -EACCES; > > > > + error = generic_permission(inode, mask); > > + if (error) > > + return error; In kernel/ucount.c, the ->permissions handler set_permissions() grants access based on whether the caller has CAP_SYS_RESOURCE. And in net/sysctl_net.c, the handler net_ctl_permissions() grants access based on whether the caller has CAP_NET_ADMIN. This added check is going to break those, right?
