On 21 Feb 2022, at 15:46, Eric van Gyzen <[email protected]> wrote: > > The branch main has been updated by vangyzen: > > URL: > https://cgit.FreeBSD.org/src/commit/?id=766c2466ff465b3c7c1a46be729b42a6da47de03 > > commit 766c2466ff465b3c7c1a46be729b42a6da47de03 > Author: Arka Sharma <[email protected]> > AuthorDate: 2022-02-18 15:34:15 +0000 > Commit: Eric van Gyzen <[email protected]> > CommitDate: 2022-02-21 15:43:42 +0000 > > mmap map_at_zero test: handle W^X > > Use kern.elfXX.allow_wx to decide whether to map W+X or W-only memory. > > Future work could expand this test to add an "allow_wx" axis to the > test matrix, but I would argue that a separate test should be written, > since that's orthogonal to map_at_zero. > > MFC after: 1 week > Sponsored by: Dell EMC Isilon > --- > tests/sys/vm/mmap_test.c | 27 +++++++++++++++++++++++++-- > 1 file changed, 25 insertions(+), 2 deletions(-) > > diff --git a/tests/sys/vm/mmap_test.c b/tests/sys/vm/mmap_test.c > index 61ede96fc49b..dc01a23fff21 100644 > --- a/tests/sys/vm/mmap_test.c > +++ b/tests/sys/vm/mmap_test.c > @@ -34,6 +34,7 @@ > #include <errno.h> > #include <fcntl.h> > #include <stdarg.h> > +#include <stdbool.h> > #include <stdio.h> > #include <stdlib.h> > > @@ -54,6 +55,12 @@ static const struct { > > #define MAP_AT_ZERO "security.bsd.map_at_zero" > > +#ifdef __LP64__ > +#define ALLOW_WX "kern.elf64.allow_wx" > +#else > +#define ALLOW_WX "kern.elf32.allow_wx" > +#endif > + > ATF_TC_WITHOUT_HEAD(mmap__map_at_zero); > ATF_TC_BODY(mmap__map_at_zero, tc) > { > @@ -61,6 +68,8 @@ ATF_TC_BODY(mmap__map_at_zero, tc) > size_t len; > unsigned int i; > int map_at_zero; > + bool allow_wx; > + int prot_flags; > > len = sizeof(map_at_zero); > if (sysctlbyname(MAP_AT_ZERO, &map_at_zero, &len, NULL, 0) == -1) { > @@ -69,13 +78,27 @@ ATF_TC_BODY(mmap__map_at_zero, tc) > return; > } > > + len = sizeof(allow_wx); > + if (sysctlbyname(ALLOW_WX, &allow_wx, &len, NULL, 0) == -1) { > + if (errno == ENOENT) { > + /* Allow W+X if sysctl isn't present */ > + allow_wx = true; > + } else { > + atf_tc_skip("sysctl for %s failed: %s\n", ALLOW_WX, > + strerror(errno)); > + return; > + } > + } > + > /* Normalize to 0 or 1 for array access. */ > map_at_zero = !!map_at_zero; > > for (i = 0; i < nitems(map_at_zero_tests); i++) { > + prot_flags = PROT_READ | PROT_WRITE; > + if (allow_wx) > + prot_flags |= PROT_EXEC; > p = mmap((void *)map_at_zero_tests[i].addr, PAGE_SIZE, > - PROT_READ | PROT_WRITE | PROT_EXEC, MAP_ANON | MAP_FIXED, > - -1, 0); > + prot_flags, MAP_ANON | MAP_FIXED, -1, 0); > if (p == MAP_FAILED) { > ATF_CHECK_MSG(map_at_zero_tests[i].ok[map_at_zero] == 0, > "mmap(%p, ...) failed", map_at_zero_tests[i].addr);
If the test is just as legitimate without PROT_EXEC, what’s the justification for not just removing PROT_EXEC entirely rather than making its behaviour depend on the sysctl, which could become confusing (and complicates the test)? IMO either the test should be skipped for !allow_wx or it should always just make a RW mapping; this choice is rather odd. Jess
