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The SO_ATTACH_FILTER option is set only. I propose to add the get ability by using SO_ATTACH_FILTER in getsockopt. To be less irritating to eyes the SO_GET_FILTER alias to it is declared. This ability is required by checkpoint-restore project to be able to save full state of a socket. There are two issues with getting filter back. First, kernel modifies the sock_filter->code on filter load, thus in order to return the filter element back to user we have to decode it into user-visible constants. Fortunately the modification in question is interconvertible. Second, the BPF_S_ALU_DIV_K code modifies the command argument k to speed up the run-time division by doing kernel_k = reciprocal(user_k). Bad news is that different user_k may result in same kernel_k, so we can't get the original user_k back. Good news is that we don't have to do it. What we need to is calculate a user2_k so, that reciprocal(user2_k) == reciprocal(user_k) == kernel_k i.e. if it's re-loaded back the compiled again value will be exactly the same as it was. That said, the user2_k can be calculated like this user2_k = reciprocal(kernel_k) with an exception, that if kernel_k == 0, then user2_k == 1. The optlen argument is treated like this -- when zero, kernel returns the amount of sock_fprog elements in filter, otherwise it should be large enough for the sock_fprog array. changes since v1: * Declared SO_GET_FILTER in all arch headers * Added decode of vlan-tag codes Signed-off-by: Pavel Emelyanov <xemul@parallels.com> Signed-off-by: David S. Miller <davem@davemloft.net> |
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| .. | ||
| auxvec.h | ||
| bitsperlong.h | ||
| byteorder.h | ||
| errno.h | ||
| fcntl.h | ||
| ioctl.h | ||
| ioctls.h | ||
| ipcbuf.h | ||
| Kbuild | ||
| kvm_para.h | ||
| mman.h | ||
| msgbuf.h | ||
| param.h | ||
| poll.h | ||
| posix_types.h | ||
| ptrace.h | ||
| registers.h | ||
| resource.h | ||
| sembuf.h | ||
| setup.h | ||
| shmbuf.h | ||
| sigcontext.h | ||
| siginfo.h | ||
| signal.h | ||
| socket.h | ||
| sockios.h | ||
| stat.h | ||
| statfs.h | ||
| swab.h | ||
| termbits.h | ||
| termios.h | ||
| types.h | ||
| unistd.h | ||