BPF: Start with the EOF marker set

This will allow us to abort any BPF read loop if it's reset.
While here, delay restarting DHCP slightly to allow privsep builds
to recover the same error.

Fixes #481.

diff --git a/src/bpf.c b/src/bpf.c
index 47375a3da08ff787edfa06704b85f35dede42741..7c52126187a1a855ff94e7532e4b49eb6fc47330 100644 (file)
--- a/src/bpf.c
+++ b/src/bpf.c
@@ -170,6 +170,7 @@ bpf_open(const struct interface *ifp,
        if (bpf == NULL)
                return NULL;
        bpf->bpf_ifp = ifp;
+       bpf->bpf_flags = BPF_EOF;
 
        /* /dev/bpf is a cloner on modern kernels */
        bpf->bpf_fd = open("/dev/bpf", BPF_OPEN_FLAGS);
@@ -218,10 +219,12 @@ bpf_open(const struct interface *ifp,
        /* Get the required BPF buffer length from the kernel. */
        if (ioctl(bpf->bpf_fd, BIOCGBLEN, &ibuf_len) == -1)
                goto eexit;
+
        bpf->bpf_size = (size_t)ibuf_len;
        bpf->bpf_buffer = malloc(bpf->bpf_size);
        if (bpf->bpf_buffer == NULL)
                goto eexit;
+
        return bpf;
 
 eexit:

diff --git a/src/dhcp.c b/src/dhcp.c
index f6db1a7c213b9cecf476925cd347e5eb411da188..436399cb017d33e1d87c47db7644d203adca2599 100644 (file)
--- a/src/dhcp.c
+++ b/src/dhcp.c
@@ -2236,12 +2236,18 @@ dhcp_arp_defend_failed(struct arp_state *astate)
 {
        struct interface *ifp = astate->iface;
        struct dhcp_state *state = D_STATE(ifp);
+       unsigned int delay;
 
        if (!(ifp->options->options & (DHCPCD_INFORM | DHCPCD_STATIC)))
                dhcp_decline(ifp);
        dhcp_drop(ifp, "EXPIRED");
        dhcp_unlink(ifp->ctx, state->leasefile);
-       dhcp_start1(ifp);
+
+       // Delay restarting to give time for the BPF ARP process to exit
+       // as we may spawn a new one with a different filter fairly quickly
+       delay = MSEC_PER_SEC +
+               (arc4random_uniform(MSEC_PER_SEC * 2) - MSEC_PER_SEC);
+       eloop_timeout_add_msec(ifp->ctx->eloop, delay, dhcp_start1, ifp);
 }
 #endif
 

diff --git a/src/if-linux.c b/src/if-linux.c
index 2e519f2a22d01e139bb19825030e83f27a65407d..b9082505a5453c6600e75f68a48ad552204e2b2d 100644 (file)
--- a/src/if-linux.c
+++ b/src/if-linux.c
@@ -1850,6 +1850,7 @@ bpf_open(const struct interface *ifp,
        if (bpf == NULL)
                return NULL;
        bpf->bpf_ifp = ifp;
+       bpf->bpf_flags = BPF_EOF;
 
        /* Allocate a suitably large buffer for a single packet. */
        bpf->bpf_size = ETH_FRAME_LEN;