Can't access exe symlinks in centos 6.6

I’m trying to access the /proc/< pid >/exe symlink on centos 6.6 but i’m geting

ls: cannot access /proc/57/exe: Permission denied

My Dockerfile is

FROM centos:6

# install base packages
RUN yum -y update
RUN yum -y groupinstall "Development Tools"
RUN yum -y install zlib-devel bzip2-devel openssl-devel ncurses-devel sqlite-    devel readline-devel tk-devel gdbm-devel db4-devel libpcap-devel xz-devel
RUN yum -y install wget
RUN wget
RUN yum -y install tar
RUN tar -xf  Python-2.7.6.tar.xz

RUN cd Python-2.7.6 && ./configure --prefix=/usr/local --enable-unicode=ucs4 --enable-shared LDFLAGS="-Wl,-rpath /usr/local/lib"
RUN cd Python-2.7.6 && make
RUN cd Python-2.7.6 && make altinstall

# First get the setup script for Setuptools:
RUN wget
# Then install it for Python 2.7 and/or Python 3.3:
RUN python2.7
# Now install pip using the newly installed setuptools:
RUN easy_install-2.7 pip

RUN yum -y install python-devel libxml2-devel libxslt-devel
RUN pip install lxml

RUN pip install pytest
RUN yum install -y gcc-c++
RUN pip install protobuf
RUN yum install -y rpm-build

This happens for any process.
Thanks in advance.