我正在编写一个 pam 模块，让用户针对链接到 Django 站点的 PostreSQL 数据库进行身份验证。当我让 sshd 使用它时，它工作正常，但每当我尝试使用 vsftpd 时，我都会在 /var/log/auth.log 中收到以下几行：
Jul 7 23:32:31 jeeves vsftpd: PAM unable to dlopen(pam_django.so): libsqlite3.so.0: failed to map segment from shared object: Cannot allocate memory
Jul 7 23:32:31 jeeves vsftpd: PAM adding faulty module: pam_django.so
在客户端，我收到一个意外的 TLS 数据包，连接失败。当我改用 pam_pwdfile.so 时，vsftpd 运行良好。唯一的区别是 pam 模块。
由于错误消息与分配内存有关，因此我在两个 .so 文件上都运行了 ldd，而 pam_django 确实比 pam_pwdfile 拖慢了不少时间：
pam_django.so:
linux-vdso.so.1 => (0x00007fff90b12000)
libpq.so.5 => /usr/lib/libpq.so.5 (0x00007f35b969c000)
libpam.so.0 => /lib/x86_64-linux-gnu/libpam.so.0 (0x00007f35b948e000)
libcrypto.so.1.0.0 => /lib/x86_64-linux-gnu/libcrypto.so.1.0.0 (0x00007f35b90b2000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f35b8db6000)
libconfuse.so.0 => /usr/lib/x86_64-linux-gnu/libconfuse.so.0 (0x00007f35b8baa000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f35b87ea000)
libssl.so.1.0.0 => /lib/x86_64-linux-gnu/libssl.so.1.0.0 (0x00007f35b858c000)
libkrb5.so.3 => /usr/lib/x86_64-linux-gnu/libkrb5.so.3 (0x00007f35b82be000)
libcom_err.so.2 => /lib/x86_64-linux-gnu/libcom_err.so.2 (0x00007f35b80b9000)
libgssapi_krb5.so.2 => /usr/lib/x86_64-linux-gnu/libgssapi_krb5.so.2 (0x00007f35b7e7b000)
libldap_r-2.4.so.2 => /usr/lib/x86_64-linux-gnu/libldap_r-2.4.so.2 (0x00007f35b7c2c000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f35b7a0e000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f35b780a000)
libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f35b75f3000)
/lib64/ld-linux-x86-64.so.2 (0x00007f35b9ae0000)
libk5crypto.so.3 => /usr/lib/x86_64-linux-gnu/libk5crypto.so.3 (0x00007f35b73ca000)
libkrb5support.so.0 => /usr/lib/x86_64-linux-gnu/libkrb5support.so.0 (0x00007f35b71c2000)
libkeyutils.so.1 => /lib/x86_64-linux-gnu/libkeyutils.so.1 (0x00007f35b6fbe000)
libresolv.so.2 => /lib/x86_64-linux-gnu/libresolv.so.2 (0x00007f35b6da1000)
liblber-2.4.so.2 => /usr/lib/x86_64-linux-gnu/liblber-2.4.so.2 (0x00007f35b6b93000)
libsasl2.so.2 => /usr/lib/x86_64-linux-gnu/libsasl2.so.2 (0x00007f35b6978000)
libgssapi.so.3 => /usr/lib/x86_64-linux-gnu/libgssapi.so.3 (0x00007f35b6739000)
libgnutls.so.26 => /usr/lib/x86_64-linux-gnu/libgnutls.so.26 (0x00007f35b647d000)
libgcrypt.so.11 => /lib/x86_64-linux-gnu/libgcrypt.so.11 (0x00007f35b61ff000)
libheimntlm.so.0 => /usr/lib/x86_64-linux-gnu/libheimntlm.so.0 (0x00007f35b5ff7000)
libkrb5.so.26 => /usr/lib/x86_64-linux-gnu/libkrb5.so.26 (0x00007f35b5d71000)
libasn1.so.8 => /usr/lib/x86_64-linux-gnu/libasn1.so.8 (0x00007f35b5ad1000)
libhcrypto.so.4 => /usr/lib/x86_64-linux-gnu/libhcrypto.so.4 (0x00007f35b589c000)
libroken.so.18 => /usr/lib/x86_64-linux-gnu/libroken.so.18 (0x00007f35b5687000)
libtasn1.so.3 => /usr/lib/x86_64-linux-gnu/libtasn1.so.3 (0x00007f35b5476000)
libp11-kit.so.0 => /usr/lib/x86_64-linux-gnu/libp11-kit.so.0 (0x00007f35b5263000)
libgpg-error.so.0 => /lib/x86_64-linux-gnu/libgpg-error.so.0 (0x00007f35b505f000)
libwind.so.0 => /usr/lib/x86_64-linux-gnu/libwind.so.0 (0x00007f35b4e36000)
libheimbase.so.1 => /usr/lib/x86_64-linux-gnu/libheimbase.so.1 (0x00007f35b4c26000)
libhx509.so.5 => /usr/lib/x86_64-linux-gnu/libhx509.so.5 (0x00007f35b49dc000)
libsqlite3.so.0 => /usr/lib/x86_64-linux-gnu/libsqlite3.so.0 (0x00007f35b4739000)
libcrypt.so.1 => /lib/x86_64-linux-gnu/libcrypt.so.1 (0x00007f35b44ff000)
pam_pwdfile.so:
linux-vdso.so.1 => (0x00007fffc41ff000)
libcrypt.so.1 => /lib/x86_64-linux-gnu/libcrypt.so.1 (0x00007ff57bad5000)
libpam.so.0 => /lib/x86_64-linux-gnu/libpam.so.0 (0x00007ff57b8c7000)
libpam_misc.so.0 => /lib/x86_64-linux-gnu/libpam_misc.so.0 (0x00007ff57b6c2000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007ff57b303000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007ff57b0ff000)
/lib64/ld-linux-x86-64.so.2 (0x00007ff57bf28000)
所以我的问题是：vsftpd 可以从其 pam 模块处理的共享库数量是否有限制？这与 vsftpd 对某些任务进行沙盒处理的方式有什么关系吗？还是问题完全是其他原因？