sel_ldr_seccomp: block open(2) calls.
sel_ldr_seccomp: block open(2) calls.

If sel_ldr_seccomp would try to open a file, the kernel will block this attempt and send SIGSYS.
The SIGSYS handler will complain about a blocked call to stderr and return -1 as a result.

Example output:

$ scons-out/opt-linux-x86-64/staging/nacl_helper_bootstrap scons-out/opt-linux-x86-64/staging/sel_ldr_seccomp --r_debug=0xXXXXXXXXXXXXXXXX --reserved_at_zero=0xXXXXXXXXXXXXXXXX -- scons-out/nacl-x86-64/staging/hello_world.nexe
[26585,2760836928:14:07:38.175453] Native Client module will be loaded at base address 0x0000747200000000
[SECCOMP BPF] Blocked open('/sys/devices/system/cpu/online')
[SECCOMP BPF] Blocked open('/sys/devices/system/cpu/online')
[SECCOMP BPF] Blocked open('/proc/stat')
[SECCOMP BPF] Blocked open('/proc/stat')
[SECCOMP BPF] Blocked open('/proc/cpuinfo')
[SECCOMP BPF] Blocked open('/proc/cpuinfo')
Hello, World!


BUG=https://code.google.com/p/nativeclient/issues/detail?id=3098
Review URL: https://codereview.chromium.org/12262053

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@10816 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client