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https://git.kernel.org/pub/scm/libs/libcap/libcap.git
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6baf268986
Other than the case of /dev/null, there is no situation in which pam_cap.so should act on world writable config files. There are legitimate local administration choices for the file being owned by non-root users, and similarly writable by a group of trusted users. So, we do not require any specific ownership for the file and do not check for writable access based on owner of group membership. Credit for finding this bug in pam_cap.so goes to X41 D-Sec GmbH (https://x41-dsec.de/) who performed a security audit of the libcap source code in April of 2023. The audit was sponsored by the Open Source Technology Improvement Fund (https://ostif.org/). Audit ref: LCAP-CR-23-101 Signed-off-by: Andrew G. Morgan <morgan@kernel.org>
94 lines
3.2 KiB
Makefile
94 lines
3.2 KiB
Makefile
# simple make file for the pam_cap module
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topdir=$(shell pwd)/..
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include ../Make.Rules
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# Always build pam_cap sources this way:
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CFLAGS += -fPIC
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all: pam_cap.so
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$(MAKE) testlink
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install: all
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mkdir -p -m 0755 $(FAKEROOT)$(LIBDIR)/security
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install -m 0755 pam_cap.so $(FAKEROOT)$(LIBDIR)/security
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../libcap/loader.txt:
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$(MAKE) -C ../libcap loader.txt
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execable.o: execable.c ../libcap/execable.h ../libcap/loader.txt
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$(CC) $(CFLAGS) $(CPPFLAGS) -DLIBCAP_VERSION=\"libcap-$(VERSION).$(MINOR)\" -DSHARED_LOADER=\"$(shell cat ../libcap/loader.txt)\" -c execable.c -o $@
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LIBCAP:
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$(MAKE) -C ../libcap all
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touch $@
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pam_cap.so: pam_cap.o execable.o pam_cap_linkopts LIBCAP
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cat pam_cap_linkopts | xargs -e $(LD) $(LDFLAGS) -o $@ pam_cap.o execable.o $(LIBCAPLIB)
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# Some distributions force link everything at compile time, and don't
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# take advantage of libpam's dlopen runtime options to resolve ill
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# defined symbols from its own linkage as needed. (As the original
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# author of that part of libpam, I consider this force linking
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# premature optimization.) We debugged its consequences to pam_cap.so
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# as part of:
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#
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# https://bugzilla.kernel.org/show_bug.cgi?id=214023
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#
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# If the current build environment is one of those, or we can't
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# reliably prove it isn't, extend the link options for pam_cap.so to
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# force linkage against libpam and the gazillion other things libpam
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# is linked against...
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#
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# If you want to force this behavior one way or the other, use the
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# make FORCELINKPAM=yes or FORCELINKPAM=no override.
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ifeq ($(FORCELINKPAM),yes)
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pam_cap_linkopts: Makefile
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echo "-Wl,-e,__so_start -lpam" > $@
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else
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ifeq ($(FORCELINKPAM),no)
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pam_cap_linkopts: Makefile
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echo "-Wl,-e,__so_start" > $@
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else
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pam_cap_linkopts: lazylink.so
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echo "-Wl,-e,__so_start" > $@
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./lazylink.so || echo "-lpam" >> $@
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lazylink.so: lazylink.c ../libcap/execable.h ../libcap/loader.txt
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$(LD) -o $@ $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) lazylink.c -DSHARED_LOADER=\"$(shell cat ../libcap/loader.txt)\" -Wl,-e,__so_start
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endif
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endif
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../libcap/libcap.a:
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$(MAKE) -C ../libcap libcap.a
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# Avoid $(LDFLAGS) here to avoid conflicts with --static for a in-tree
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# test binary.
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test_pam_cap: test_pam_cap.c pam_cap.c ../libcap/libcap.a
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$(CC) $(CFLAGS) $(CPPFLAGS) -o $@ test_pam_cap.c $(LIBCAPLIB) --static
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testlink: test.o pam_cap.o
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$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $+ -lpam -ldl $(LIBCAPLIB)
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incapable.conf:
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echo "^cap_setuid alpha" > $@ && chmod o+w $@
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test: testlink test_pam_cap pam_cap.so incapable.conf
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./test_pam_cap
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LD_LIBRARY_PATH=../libcap ./pam_cap.so
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LD_LIBRARY_PATH=../libcap ./pam_cap.so --help
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@echo "module can be run as an executable!"
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sudotest: test_pam_cap incapable.conf
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$(SUDO) ./test_pam_cap root 0x0 0x0 0x0 config=./capability.conf
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$(SUDO) ./test_pam_cap root 0x0 0x0 0x0 config=./sudotest.conf
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$(SUDO) ./test_pam_cap alpha 0x0 0x0 0x0 config=./capability.conf
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$(SUDO) ./test_pam_cap alpha 0x0 0x1 0x80 config=./sudotest.conf
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$(SUDO) ./test_pam_cap beta 0x0 0x1 0x0 config=./sudotest.conf
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$(SUDO) ./test_pam_cap gamma 0x0 0x0 0x81 config=./sudotest.conf
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$(SUDO) ./test_pam_cap delta 0x41 0x80 0x41 config=./sudotest.conf
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clean:
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rm -f *.o *.so testlink lazylink.so test_pam_cap pam_cap_linkopts *~
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rm -f LIBCAP incapable.conf
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