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Peter Anvin" , Dan Williams Cc: Ira Weiny , Fenghua Yu , Rick Edgecombe , "Shankar, Ravi V" , linux-kernel@vger.kernel.org Subject: [PATCH V9 31/45] mm/pkeys: PKS testing, test pks_update_exception() Date: Thu, 10 Mar 2022 09:20:05 -0800 Message-Id: <20220310172019.850939-32-ira.weiny@intel.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220310172019.850939-1-ira.weiny@intel.com> References: <20220310172019.850939-1-ira.weiny@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ira Weiny A common use case for the custom fault callbacks will be for the callback to warn of the violation and relax the permissions rather than crash the kernel. pks_update_exception() was added for this purpose. Add a test which uses pks_update_exception() to clear the pkey permissions. Verify that the permissions are changed in the interrupted thread. Signed-off-by: Ira Weiny --- Changes for V9 Update the commit message Clean up test name Add test_pks support s/pks_mk_*/pks_set_*/ Simplify the use of globals for the faults From Rick Edgecombe Use WRITE_ONCE to protect against races with the fault handler s/RUN_FAULT_ABANDON/RUN_FAULT_CALLBACK Changes for V8 New test developed just to double check for regressions while reworking the code. --- lib/pks/pks_test.c | 60 ++++++++++++++++++++++++++ tools/testing/selftests/x86/test_pks.c | 5 ++- 2 files changed, 64 insertions(+), 1 deletion(-) diff --git a/lib/pks/pks_test.c b/lib/pks/pks_test.c index 762f4a19cb7d..a9cd2a49abfa 100644 --- a/lib/pks/pks_test.c +++ b/lib/pks/pks_test.c @@ -49,6 +49,7 @@ #define ARM_CTX_SWITCH 2 #define CHECK_CTX_SWITCH 3 #define RUN_EXCEPTION 4 +#define RUN_EXCEPTION_UPDATE 5 #define RUN_CRASH_TEST 9 DECLARE_PER_CPU(u32, pkrs_cache); @@ -64,6 +65,7 @@ struct pks_test_ctx { void *test_page; bool fault_seen; bool validate_exp_handling; + bool validate_update_exp; }; static bool check_pkey_val(u32 pk_reg, u8 pkey, u32 expected) @@ -164,6 +166,16 @@ static void validate_exception(struct pks_test_ctx *ctx, u32 thread_pkrs) } } +static bool handle_update_exception(struct pt_regs *regs, struct pks_test_ctx *ctx) +{ + pr_debug("Updating pkey %d during exception\n", ctx->pkey); + + ctx->fault_seen = true; + pks_update_exception(regs, ctx->pkey, 0); + + return true; +} + /* Global data protected by test_run_lock */ struct pks_test_ctx *g_ctx_under_test; @@ -190,6 +202,9 @@ bool pks_test_fault_callback(struct pt_regs *regs, unsigned long address, if (!g_ctx_under_test) return false; + if (g_ctx_under_test->validate_update_exp) + return handle_update_exception(regs, g_ctx_under_test); + if (g_ctx_under_test->validate_exp_handling) { validate_exception(g_ctx_under_test, pkrs); /* @@ -518,6 +533,47 @@ static void check_ctx_switch(struct pks_session_data *sd) } } +static bool run_exception_update(struct pks_session_data *sd) +{ + struct pks_test_ctx *ctx; + + ctx = alloc_ctx(PKS_KEY_TEST); + if (IS_ERR(ctx)) + return false; + + set_ctx_data(sd, ctx); + + ctx->fault_seen = false; + ctx->validate_update_exp = true; + pks_set_noaccess(ctx->pkey); + + set_context_for_fault(ctx); + + /* fault */ + memcpy(ctx->test_page, ctx->data, 8); + + if (!ctx->fault_seen) { + pr_err("Failed to see the callback\n"); + return false; + } + + ctx->fault_seen = false; + ctx->validate_update_exp = false; + + set_context_for_fault(ctx); + + /* no fault */ + memcpy(ctx->test_page, ctx->data, 8); + + if (ctx->fault_seen) { + pr_err("Pkey %d failed to be set RD/WR in the callback\n", + ctx->pkey); + return false; + } + + return true; +} + static ssize_t pks_read_file(struct file *file, char __user *user_buf, size_t count, loff_t *ppos) { @@ -584,6 +640,10 @@ static ssize_t pks_write_file(struct file *file, const char __user *user_buf, pr_debug("Exception checking\n"); sd->last_test_pass = run_exception_test(file->private_data); break; + case RUN_EXCEPTION_UPDATE: + pr_debug("Fault clear test\n"); + sd->last_test_pass = run_exception_update(file->private_data); + break; default: pr_debug("Unknown test\n"); sd->last_test_pass = false; diff --git a/tools/testing/selftests/x86/test_pks.c b/tools/testing/selftests/x86/test_pks.c index 817df7a14923..243347e48228 100644 --- a/tools/testing/selftests/x86/test_pks.c +++ b/tools/testing/selftests/x86/test_pks.c @@ -36,6 +36,7 @@ #define ARM_CTX_SWITCH "2" #define CHECK_CTX_SWITCH "3" #define RUN_EXCEPTION "4" +#define RUN_EXCEPTION_UPDATE "5" #define RUN_CRASH_TEST "9" time_t g_start_time; @@ -63,6 +64,7 @@ enum { TEST_SINGLE, TEST_CTX_SWITCH, TEST_EXCEPTION, + TEST_FAULT_CALLBACK, MAX_TESTS, } tests; @@ -77,7 +79,8 @@ struct test_item { { "check_defaults", CHECK_DEFAULTS, do_simple_test }, { "single", RUN_SINGLE, do_simple_test }, { "context_switch", ARM_CTX_SWITCH, do_context_switch }, - { "exception", RUN_EXCEPTION, do_simple_test } + { "exception", RUN_EXCEPTION, do_simple_test }, + { "exception_update", RUN_EXCEPTION_UPDATE, do_simple_test } }; static char *get_test_name(int test_num) -- 2.35.1