On Tue, 2023-01-31 at 19:00 -0500, Mimi Zohar wrote: > On Tue, 2023-01-31 at 18:42 +0100, Roberto Sassu wrote: > > From: Roberto Sassu <roberto.sassu@xxxxxxxxxx> > > > > Add tests to ensure that, after applying the kernel patch 'ima: Align > > ima_file_mmap() parameters with mmap_file LSM hook', the MMAP_CHECK hook > > checks the protections applied by the kernel and not those requested by the > > application. > > > > Also ensure that after applying 'ima: Introduce MMAP_CHECK_REQPROT hook', > > the MMAP_CHECK_REQPROT hook checks the protections requested by the > > application. > > > > Test both with the test_mmap application that by default requests the > > PROT_READ protection flag. Its syntax is: > > > > test_mmap <file> <mode> > > > > where mode can be: > > - exec: adds the PROT_EXEC protection flag to mmap() > > - read_implies_exec: calls the personality() system call with > > READ_IMPLIES_EXEC as the first argument before mmap() > > - mprotect: adds the PROT_EXEC protection flag to a memory area in addition > > to PROT_READ > > - exec_on_writable: calls mmap() with PROT_EXEC on a file which has a > > writable mapping > > > > Check the different combinations of hooks/modes and ensure that a > > measurement entry is found in the IMA measurement list only when it is > > expected. No measurement entry should be found when only the PROT_READ > > protection flag is requested or the matching policy rule has the > > MMAP_CHECK_REQPROT hook and the personality() system call was called with > > READ_IMPLIES_EXEC. > > > > mprotect() with PROT_EXEC on an existing memory area protected with > > PROT_READ should be denied (with an appraisal rule), regardless of the MMAP > > hook specified in the policy. The same applies for mmap() with PROT_EXEC on > > a file with a writable mapping. > > > > Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx> > > Nice! Including some comments, or at least the test assumption, would > help simplify reviewing the code. An example of a test assumption, or background information, for the "mprotect" test is described in the ima_file_mprotect() function comment: * Files can be mmap'ed read/write and later changed to execute to circumvent * IMA's mmap appraisal policy rules. Due to locking issues (mmap semaphore * would be taken before i_mutex), files can not be measured or appraised at * this point. Eliminate this integrity gap by denying the mprotect * PROT_EXECUTE change, if an mmap appraise policy rule exists. -- thanks, Mimi
