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authorStefano Brivio <sbrivio@redhat.com>2023-06-04 06:51:47 +0200
committerStefano Brivio <sbrivio@redhat.com>2023-06-23 10:15:10 +0200
commitd072ac243407df464d0e0c74268631e39c5f1251 (patch)
tree3e842b2c267bf3279f3d3c242aad0e701fd47a20
parent429e1a7e71ad9020f0e53bc467986c55bf5c0e38 (diff)
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tap: With pasta, don't reset on tap errors, handle write failures
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@yawnt.com> Reported-by: Chris Kuhn <kuhnchris@kuhnchris.eu> Fixes: 0515adceaa8f ("passt, pasta: Namespace-based sandboxing, defer seccomp policy application") Signed-off-by: Stefano Brivio <sbrivio@redhat.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
-rw-r--r--tap.c24
1 files 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);
}
}