it's a SELinux issue
tail /var/log/audit/audit.log
type=AVC msg=audit(1399879586.183:2081199): avc: denied { search } for pid=26495 comm="nginx" name="dev" dev="dm-1" ino=269277 scontext=system_u:system_r:httpd_t:s0 tcontext=unconfined_u:object_r:user_home_dir_t:s0 tclass=dir
type=SYSCALL msg=audit(1399879586.183:2081199): arch=c000003e syscall=2 success=no exit=-13 a0=7fdd65ed2219 a1=800 a2=0 a3=0 items=0 ppid=26494 pid=26495 auid=4294967295 uid=996 gid=1000 euid=996 suid=996 fsuid=996 egid=1000 sgid=1000 fsgid=1000 ses=4294967295 tty=(none) comm="nginx" exe="/usr/sbin/nginx" subj=system_u:system_r:httpd_t:s0 key=(null)
detailed explanation and resolution can be found here