Mercurial > hg > dhcpcd
changeset 5242:0dd9b7f7cf6b draft
privsep: Ensure we don't scribble garbage to BPF
Well, it's not garbage, it's a privsep IPC message telling us to
start BPF which the BPF process should not have recieved!
Add code to ensure this cannot happen.
| author | Roy Marples <roy@marples.name> |
|---|---|
| date | Wed, 20 May 2020 15:44:19 +0000 |
| parents | 989bcc6c8e70 |
| children | 0d5671483751 |
| files | src/privsep-bpf.c src/privsep-root.c |
| diffstat | 2 files changed, 22 insertions(+), 10 deletions(-) [+] |
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--- a/src/privsep-bpf.c Wed May 20 15:43:44 2020 +0000 +++ b/src/privsep-bpf.c Wed May 20 15:44:19 2020 +0000 @@ -92,11 +92,28 @@ } static ssize_t -ps_bpf_recvmsgcb(void *arg, __unused struct ps_msghdr *psm, struct msghdr *msg) +ps_bpf_recvmsgcb(void *arg, struct ps_msghdr *psm, struct msghdr *msg) { struct ps_process *psp = arg; struct iovec *iov = msg->msg_iov; +#ifdef PRIVSEP_DEBUG + logerrx("%s: IN cmd %x, psp %p", __func__, psm->ps_cmd, psp); +#endif + + switch(psm->ps_cmd) { +#ifdef ARP + case PS_BPF_ARP: /* FALLTHROUGH */ +#endif + case PS_BPF_BOOTP: + break; + default: + /* IPC failure, we should not be processing any commands + * at this point!/ */ + errno = EINVAL; + return -1; + } + return bpf_send(psp->psp_bpf, psp->psp_proto, iov->iov_base, iov->iov_len); } @@ -106,13 +123,6 @@ { struct ps_process *psp = arg; - /* - * OpenBSD-6.6 at least will return EPERM here for every - * BOOTP sent except for the first one. - * However with wih EPERM, the BOOTP message is *still* sent. - * This means the BPF write filter isn't working as it should. - * On FreeBSD it works fine. - */ if (ps_recvpsmsg(psp->psp_ctx, psp->psp_fd, ps_bpf_recvmsgcb, arg) == -1) logerr(__func__);
--- a/src/privsep-root.c Wed May 20 15:43:44 2020 +0000 +++ b/src/privsep-root.c Wed May 20 15:44:19 2020 +0000 @@ -409,8 +409,10 @@ ps_freeprocess(psp); return ret; - } - return ps_sendpsmmsg(ctx, psp->psp_fd, psm, msg); + } else if (!(psm->ps_cmd & PS_START)) + return ps_sendpsmmsg(ctx, psp->psp_fd, psm, msg); + /* Process has already started .... */ + return 0; } if (psm->ps_cmd & PS_STOP && psp == NULL)