On Sun, Jun 04, 2023 at 07:49:57AM +0200, Stefano Brivio wrote:Since commit 0515adceaa8f ("passt, pasta: Namespace-based sandboxing, defer seccomp policy application"), it makes no sense to close and reopen the tap device on error: we don't have access to /dev/net/tun after the initial setup phase. If we hit ENOBUFS while writing (as reported: in one case because the kernel actually ran out of memory, with another case under investigation), or ENOSPC, we're supposed to drop whatever data we were trying to send: there's no room for it. Handle EINTR just like we handled EAGAIN/EWOULDBLOCK: there's no particular reason why sending the same data should fail again. Anything else I can think of would be an unrecoverable error: exit with failure then. While at it, drop a useless cast on the write() call: it takes a const void * anyway. Reported-by: Gianluca Stivan <me(a)yawnt.com> Reported-by: Chris Kuhn <kuhnchris(a)kuhnchris.eu> Fixes: 0515adceaa8f ("passt, pasta: Namespace-based sandboxing, defer seccomp policy application") Signed-off-by: Stefano Brivio <sbrivio(a)redhat.com>Reviewed-by: David Gibson <david(a)gibson.dropbear.id.au>--- tap.c | 24 +++++++++++++++++++----- 1 file changed, 19 insertions(+), 5 deletions(-) diff --git a/tap.c b/tap.c index c0b7f33..e323529 100644 --- a/tap.c +++ b/tap.c @@ -320,12 +320,23 @@ static size_t tap_send_frames_pasta(struct ctx *c, size_t i; for (i = 0; i < n; i++) { - if (write(c->fd_tap, (char *)iov[i].iov_base, - iov[i].iov_len) < 0) { + if (write(c->fd_tap, iov[i].iov_base, iov[i].iov_len) < 0) { debug("tap write: %s", strerror(errno)); - if (errno != EAGAIN && errno != EWOULDBLOCK) - tap_handler(c, c->fd_tap, EPOLLERR, NULL); - i--; + + switch (errno) { + case EAGAIN: +#if EAGAIN != EWOULDBLOCK + case EWOULDBLOCK: +#endif + case EINTR: + i--; + break; + case ENOBUFS: + case ENOSPC: + break; + default: + die("Write error on tap device, exiting"); + } } } @@ -1237,6 +1248,9 @@ void tap_handler(struct ctx *c, int fd, uint32_t events, exit(EXIT_SUCCESS); } + if (c->mode == MODE_PASTA) + die("Error on tap device, exiting"); + tap_sock_init(c); } }-- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson