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net: slirp: allow CFI with libslirp >= 4.7

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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>
This commit is contained in:
Paolo Bonzini 2022-04-11 09:41:27 +02:00
parent 6222e55d13
commit bf2f69d08b
1 changed files with 17 additions and 14 deletions
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31
meson.build
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@ -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')