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[PATCH v2 5/5] net: slirp: allow CFI with libslirp >= 4.7
From: |
Paolo Bonzini |
Subject: |
[PATCH v2 5/5] net: slirp: allow CFI with libslirp >= 4.7 |
Date: |
Sun, 8 May 2022 11:31:20 +0200 |
slirp 4.7 introduces a new CFI-friendly timer callback that does
not pass function pointers within libslirp as callbacks for timers.
Check the version number and, if it is new enough, allow using CFI
even with a system libslirp.
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Reviewed-by: Marc-André Lureau <malureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
meson.build | 31 +++++++++++++++++--------------
1 file changed, 17 insertions(+), 14 deletions(-)
diff --git a/meson.build b/meson.build
index 264a5fb5ed..59ca709078 100644
--- a/meson.build
+++ b/meson.build
@@ -2637,10 +2637,25 @@ if have_system
slirp_opt = get_option('slirp')
if slirp_opt in ['enabled', 'auto', 'system']
have_internal = fs.exists(meson.current_source_dir() / 'slirp/meson.build')
+ slirp_dep_required = (slirp_opt == 'system' or
+ slirp_opt == 'enabled' and not have_internal)
slirp = dependency('slirp', kwargs: static_kwargs,
method: 'pkg-config', version: '>=4.1.0',
- required: slirp_opt == 'system' or
- slirp_opt == 'enabled' and not have_internal)
+ required: slirp_dep_required)
+ # slirp <4.7 is incompatible with CFI support in QEMU. This is because
+ # it passes function pointers within libslirp as callbacks for timers.
+ # When using a system-wide shared libslirp, the type information for the
+ # callback is missing and the timer call produces a false positive with
CFI.
+ # Do not use the "version" keyword argument to produce a better error.
+ # with control-flow integrity.
+ if get_option('cfi') and slirp.found() and
slirp.version().version_compare('<4.7')
+ if slirp_dep_required
+ error('Control-Flow Integrity requires libslirp 4.7.')
+ else
+ warning('Control-Flow Integrity requires libslirp 4.7, not using
system-wide libslirp.')
+ slirp = not_found
+ endif
+ endif
if slirp.found()
slirp_opt = 'system'
elif have_internal
@@ -2713,18 +2728,6 @@ if have_system
endif
endif
-# For CFI, we need to compile slirp as a static library together with qemu.
-# This is because we register slirp functions as callbacks for QEMU Timers.
-# When using a system-wide shared libslirp, the type information for the
-# callback is missing and the timer call produces a false positive with CFI.
-#
-# Now that slirp_opt has been defined, check if the selected slirp is
compatible
-# with control-flow integrity.
-if get_option('cfi') and slirp_opt == 'system'
- error('Control-Flow Integrity is not compatible with system-wide slirp.' \
- + ' Please configure with --enable-slirp=git')
-endif
-
fdt = not_found
if have_system
fdt_opt = get_option('fdt')
--
2.35.1