| Message ID | 20181120052137.74317-2-joel@joelfernandes.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [-next,1/2] mm/memfd: make F_SEAL_FUTURE_WRITE seal more robust | expand |
On Mon, Nov 19, 2018 at 09:21:37PM -0800, Joel Fernandes (Google) wrote: > Modify the tests for F_SEAL_FUTURE_WRITE based on the changes > introduced in previous patch. > > Also add a test to make sure the reopen issue pointed by Jann Horn [1] > is fixed. > > [1] https://lore.kernel.org/lkml/CAG48ez1h=v-JYnDw81HaYJzOfrNhwYksxmc2r=cJvdQVgYM+NA@mail.gmail.com/ > > Cc: Jann Horn <jannh@google.com> > Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> > --- > tools/testing/selftests/memfd/memfd_test.c | 88 +++++++++++----------- > 1 file changed, 44 insertions(+), 44 deletions(-) Since we squashed [1] the mm/memfd patch modifications suggested by Andy into the original patch, I also squashed the selftests modifications and appended the patch inline below if you want to take this instead: [1] https://lore.kernel.org/lkml/20181122230906.GA198127@google.com/T/#m8ba68f67f3ec24913a977b62bcaeafc4b194b8c8 ---8<----------------------- From: "Joel Fernandes (Google)" <joel@joelfernandes.org> Subject: [PATCH v4] selftests/memfd: add tests for F_SEAL_FUTURE_WRITE seal Add tests to verify sealing memfds with the F_SEAL_FUTURE_WRITE works as expected. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> --- tools/testing/selftests/memfd/memfd_test.c | 74 ++++++++++++++++++++++ 1 file changed, 74 insertions(+) diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c index 10baa1652fc2..c67d32eeb668 100644 --- a/tools/testing/selftests/memfd/memfd_test.c +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -54,6 +54,22 @@ static int mfd_assert_new(const char *name, loff_t sz, unsigned int flags) return fd; } +static int mfd_assert_reopen_fd(int fd_in) +{ + int r, fd; + char path[100]; + + sprintf(path, "/proc/self/fd/%d", fd_in); + + fd = open(path, O_RDWR); + if (fd < 0) { + printf("re-open of existing fd %d failed\n", fd_in); + abort(); + } + + return fd; +} + static void mfd_fail_new(const char *name, unsigned int flags) { int r; @@ -255,6 +271,25 @@ static void mfd_assert_read(int fd) munmap(p, mfd_def_size); } +/* Test that PROT_READ + MAP_SHARED mappings work. */ +static void mfd_assert_read_shared(int fd) +{ + void *p; + + /* verify PROT_READ and MAP_SHARED *is* allowed */ + p = mmap(NULL, + mfd_def_size, + PROT_READ, + MAP_SHARED, + fd, + 0); + if (p == MAP_FAILED) { + printf("mmap() failed: %m\n"); + abort(); + } + munmap(p, mfd_def_size); +} + static void mfd_assert_write(int fd) { ssize_t l; @@ -692,6 +727,44 @@ static void test_seal_write(void) close(fd); } +/* + * Test SEAL_FUTURE_WRITE + * Test whether SEAL_FUTURE_WRITE actually prevents modifications. + */ +static void test_seal_future_write(void) +{ + int fd, fd2; + void *p; + + printf("%s SEAL-FUTURE-WRITE\n", memfd_str); + + fd = mfd_assert_new("kern_memfd_seal_future_write", + mfd_def_size, + MFD_CLOEXEC | MFD_ALLOW_SEALING); + + p = mfd_assert_mmap_shared(fd); + + mfd_assert_has_seals(fd, 0); + + mfd_assert_add_seals(fd, F_SEAL_FUTURE_WRITE); + mfd_assert_has_seals(fd, F_SEAL_FUTURE_WRITE); + + /* read should pass, writes should fail */ + mfd_assert_read(fd); + mfd_assert_read_shared(fd); + mfd_fail_write(fd); + + fd2 = mfd_assert_reopen_fd(fd); + /* read should pass, writes should still fail */ + mfd_assert_read(fd2); + mfd_assert_read_shared(fd2); + mfd_fail_write(fd2); + + munmap(p, mfd_def_size); + close(fd2); + close(fd); +} + /* * Test SEAL_SHRINK * Test whether SEAL_SHRINK actually prevents shrinking @@ -945,6 +1018,7 @@ int main(int argc, char **argv) test_basic(); test_seal_write(); + test_seal_future_write(); test_seal_shrink(); test_seal_grow(); test_seal_resize();
diff --git a/tools/testing/selftests/memfd/memfd_test.c b/tools/testing/selftests/memfd/memfd_test.c index 32b207ca7372..c67d32eeb668 100644 --- a/tools/testing/selftests/memfd/memfd_test.c +++ b/tools/testing/selftests/memfd/memfd_test.c @@ -54,6 +54,22 @@ static int mfd_assert_new(const char *name, loff_t sz, unsigned int flags) return fd; } +static int mfd_assert_reopen_fd(int fd_in) +{ + int r, fd; + char path[100]; + + sprintf(path, "/proc/self/fd/%d", fd_in); + + fd = open(path, O_RDWR); + if (fd < 0) { + printf("re-open of existing fd %d failed\n", fd_in); + abort(); + } + + return fd; +} + static void mfd_fail_new(const char *name, unsigned int flags) { int r; @@ -255,6 +271,25 @@ static void mfd_assert_read(int fd) munmap(p, mfd_def_size); } +/* Test that PROT_READ + MAP_SHARED mappings work. */ +static void mfd_assert_read_shared(int fd) +{ + void *p; + + /* verify PROT_READ and MAP_SHARED *is* allowed */ + p = mmap(NULL, + mfd_def_size, + PROT_READ, + MAP_SHARED, + fd, + 0); + if (p == MAP_FAILED) { + printf("mmap() failed: %m\n"); + abort(); + } + munmap(p, mfd_def_size); +} + static void mfd_assert_write(int fd) { ssize_t l; @@ -698,7 +733,7 @@ static void test_seal_write(void) */ static void test_seal_future_write(void) { - int fd; + int fd, fd2; void *p; printf("%s SEAL-FUTURE-WRITE\n", memfd_str); @@ -710,58 +745,23 @@ static void test_seal_future_write(void) p = mfd_assert_mmap_shared(fd); mfd_assert_has_seals(fd, 0); - /* Not adding grow/shrink seals makes the future write - * seal fail to get added - */ - mfd_fail_add_seals(fd, F_SEAL_FUTURE_WRITE); - - mfd_assert_add_seals(fd, F_SEAL_GROW); - mfd_assert_has_seals(fd, F_SEAL_GROW); - - /* Should still fail since shrink seal has - * not yet been added - */ - mfd_fail_add_seals(fd, F_SEAL_FUTURE_WRITE); - - mfd_assert_add_seals(fd, F_SEAL_SHRINK); - mfd_assert_has_seals(fd, F_SEAL_GROW | - F_SEAL_SHRINK); - /* Now should succeed, also verifies that the seal - * could be added with an existing writable mmap - */ mfd_assert_add_seals(fd, F_SEAL_FUTURE_WRITE); - mfd_assert_has_seals(fd, F_SEAL_SHRINK | - F_SEAL_GROW | - F_SEAL_FUTURE_WRITE); + mfd_assert_has_seals(fd, F_SEAL_FUTURE_WRITE); /* read should pass, writes should fail */ mfd_assert_read(fd); + mfd_assert_read_shared(fd); mfd_fail_write(fd); - munmap(p, mfd_def_size); - close(fd); - - /* Test adding all seals (grow, shrink, future write) at once */ - fd = mfd_assert_new("kern_memfd_seal_future_write2", - mfd_def_size, - MFD_CLOEXEC | MFD_ALLOW_SEALING); - - p = mfd_assert_mmap_shared(fd); - - mfd_assert_has_seals(fd, 0); - mfd_assert_add_seals(fd, F_SEAL_SHRINK | - F_SEAL_GROW | - F_SEAL_FUTURE_WRITE); - mfd_assert_has_seals(fd, F_SEAL_SHRINK | - F_SEAL_GROW | - F_SEAL_FUTURE_WRITE); - - /* read should pass, writes should fail */ - mfd_assert_read(fd); - mfd_fail_write(fd); + fd2 = mfd_assert_reopen_fd(fd); + /* read should pass, writes should still fail */ + mfd_assert_read(fd2); + mfd_assert_read_shared(fd2); + mfd_fail_write(fd2); munmap(p, mfd_def_size); + close(fd2); close(fd); }
Modify the tests for F_SEAL_FUTURE_WRITE based on the changes introduced in previous patch. Also add a test to make sure the reopen issue pointed by Jann Horn [1] is fixed. [1] https://lore.kernel.org/lkml/CAG48ez1h=v-JYnDw81HaYJzOfrNhwYksxmc2r=cJvdQVgYM+NA@mail.gmail.com/ Cc: Jann Horn <jannh@google.com> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> --- tools/testing/selftests/memfd/memfd_test.c | 88 +++++++++++----------- 1 file changed, 44 insertions(+), 44 deletions(-)