passt/arp.c, branch 2023_03_21.1ee2f7c

arp, tap, util: Don't use perror() after seccomp filter is installed

2022-11-16T14:11:13+00:00

If stderr is closed, after we fork to background, glibc's
implementation of perror() will try to re-open it by calling dup(),
upon which the seccomp filter causes the process to terminate,
because dup() is not included in the list of allowed syscalls.

Replace perror() calls that might happen after isolation_postfork().
We could probably replace all of them, but early ones need a bit more
attention as we have to check whether log.c functions work in early
stages.

Signed-off-by: Stefano Brivio 
Reviewed-by: David Gibson

tap: Remove unhelpeful vnet_pre optimization from tap_send()

2022-10-19T01:34:43+00:00

Callers of tap_send() can optionally use a small optimization by adding
extra space for the 4 byte length header used on the qemu socket interface.
tap_ip_send() is currently the only user of this, but this is used only
for "slow path" ICMP and DHCP packets, so there's not a lot of value to
the optimization.

Worse, having the two paths here complicates the interface and makes future
cleanups difficult, so just remove it.  I have some plans to bring back the
optimization in a more general way in future, but for now it's just in the
way.

Signed-off-by: David Gibson 
Signed-off-by: Stefano Brivio

Make substructures for IPv4 and IPv6 specific context information

2022-07-30T20:14:07+00:00

The context structure contains a batch of fields specific to IPv4 and to
IPv6 connectivity.  Split those out into a sub-structure.

This allows the conf_ip4() and conf_ip6() functions, which take the
entire context but touch very little of it, to be given more specific
parameters, making it clearer what it affects without stepping through the
code.

Signed-off-by: David Gibson

treewide: Mark constant references as const

2022-03-29T13:35:38+00:00

Signed-off-by: Stefano Brivio

treewide: Packet abstraction with mandatory boundary checks

2022-03-29T13:35:38+00:00

Implement a packet abstraction providing boundary and size checks
based on packet descriptors: packets stored in a buffer can be queued
into a pool (without storage of its own), and data can be retrieved
referring to an index in the pool, specifying offset and length.

Checks ensure data is not read outside the boundaries of buffer and
descriptors, and that packets added to a pool are within the buffer
range with valid offset and indices.

This implies a wider rework: usage of the "queueing" part of the
abstraction mostly affects tap_handler_{passt,pasta}() functions and
their callees, while the "fetching" part affects all the guest or tap
facing implementations: TCP, UDP, ICMP, ARP, NDP, DHCP and DHCPv6
handlers.

Suggested-by: Stefan Hajnoczi 
Signed-off-by: Stefano Brivio

arp, dhcp: Fix strict aliasing warnings reported by gcc 4.9 with -Ofast

2022-02-28T21:17:32+00:00

Signed-off-by: Stefano Brivio

passt: Drop include, carry own ipv6hdr and opt_hdr definitions

2022-01-26T06:57:09+00:00

This is the only remaining Linux-specific include -- drop it to avoid
clang-tidy warnings and to make code more portable.

Signed-off-by: Stefano Brivio

passt: Fix build with gcc 7, use std=c99, enable some more Clang checkers

2021-10-21T02:26:08+00:00

Unions and structs, you all have names now.

Take the chance to enable bugprone-reserved-identifier,
cert-dcl37-c, and cert-dcl51-cpp checkers in clang-tidy.

Provide a ffsl() weak declaration using gcc built-in.

Start reordering includes, but that's not enough for the
llvm-include-order checker yet.

Signed-off-by: Stefano Brivio

arp: Don't resolve own, configured IPv4 address

2021-09-01T15:00:27+00:00

DHCP clients might try to resolve the assigned address to check if it's
already in use: don't resolve the configured IPv4 address.

Signed-off-by: Stefano Brivio

arp: Don't answer announcements from guest or namespace

2021-09-01T15:00:27+00:00

Depending on the configuration, the host might have the same address.
Don't answer them to avoid a duplicate IP address detection.

Signed-off-by: Stefano Brivio