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authorAlban Crequy <alban.crequy@collabora.co.uk>2011-01-18 06:39:15 +0000
committerDavid S. Miller <davem@davemloft.net>2011-01-18 21:33:05 -0800
commitd6ae3bae3d1bf7a8bf367e29f2cac0788dcd0db5 (patch)
tree726d5e4ceb62556d89a4548064acdace5319b1e4 /net/unix
parenta5db219f4cf9f67995eabd53b81a1232c82f5852 (diff)
downloadlwn-d6ae3bae3d1bf7a8bf367e29f2cac0788dcd0db5.tar.gz
lwn-d6ae3bae3d1bf7a8bf367e29f2cac0788dcd0db5.zip
af_unix: implement socket filter
Linux Socket Filters can already be successfully attached and detached on unix sockets with setsockopt(sockfd, SOL_SOCKET, SO_{ATTACH,DETACH}_FILTER, ...). See: Documentation/networking/filter.txt But the filter was never used in the unix socket code so it did not work. This patch uses sk_filter() to filter buffers before delivery. This short program demonstrates the problem on SOCK_DGRAM. int main(void) { int i, j, ret; int sv[2]; struct pollfd fds[2]; char *message = "Hello world!"; char buffer[64]; struct sock_filter ins[32] = {{0,},}; struct sock_fprog filter; socketpair(AF_UNIX, SOCK_DGRAM, 0, sv); for (i = 0 ; i < 2 ; i++) { fds[i].fd = sv[i]; fds[i].events = POLLIN; fds[i].revents = 0; } for(j = 1 ; j < 13 ; j++) { /* Set a socket filter to truncate the message */ memset(ins, 0, sizeof(ins)); ins[0].code = BPF_RET|BPF_K; ins[0].k = j; filter.len = 1; filter.filter = ins; setsockopt(sv[1], SOL_SOCKET, SO_ATTACH_FILTER, &filter, sizeof(filter)); /* send a message */ send(sv[0], message, strlen(message) + 1, 0); /* The filter should let the message pass but truncated. */ poll(fds, 2, 0); /* Receive the truncated message*/ ret = recv(sv[1], buffer, 64, 0); printf("received %d bytes, expected %d\n", ret, j); } for (i = 0 ; i < 2 ; i++) close(sv[i]); return 0; } Signed-off-by: Alban Crequy <alban.crequy@collabora.co.uk> Reviewed-by: Ian Molton <ian.molton@collabora.co.uk> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/unix')
-rw-r--r--net/unix/af_unix.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index dd419d286204..8d9bbba345a4 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1475,6 +1475,12 @@ restart:
goto out_free;
}
+ if (sk_filter(other, skb) < 0) {
+ /* Toss the packet but do not return any error to the sender */
+ err = len;
+ goto out_free;
+ }
+
unix_state_lock(other);
err = -EPERM;
if (!unix_may_send(sk, other))