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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
commit | 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch) | |
tree | a94efe259b9009378be6d90eb30d2b019d95c194 /tools/testing/selftests/arm64/pauth/pac.c | |
parent | Initial commit. (diff) | |
download | linux-430c2fc249ea5c0536abd21c23382884005c9093.tar.xz linux-430c2fc249ea5c0536abd21c23382884005c9093.zip |
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'tools/testing/selftests/arm64/pauth/pac.c')
-rw-r--r-- | tools/testing/selftests/arm64/pauth/pac.c | 370 |
1 files changed, 370 insertions, 0 deletions
diff --git a/tools/testing/selftests/arm64/pauth/pac.c b/tools/testing/selftests/arm64/pauth/pac.c new file mode 100644 index 000000000..b743daa77 --- /dev/null +++ b/tools/testing/selftests/arm64/pauth/pac.c @@ -0,0 +1,370 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (C) 2020 ARM Limited + +#define _GNU_SOURCE + +#include <sys/auxv.h> +#include <sys/types.h> +#include <sys/wait.h> +#include <signal.h> +#include <setjmp.h> +#include <sched.h> + +#include "../../kselftest_harness.h" +#include "helper.h" + +#define PAC_COLLISION_ATTEMPTS 10 +/* + * The kernel sets TBID by default. So bits 55 and above should remain + * untouched no matter what. + * The VA space size is 48 bits. Bigger is opt-in. + */ +#define PAC_MASK (~0xff80ffffffffffff) +#define ARBITRARY_VALUE (0x1234) +#define ASSERT_PAUTH_ENABLED() \ +do { \ + unsigned long hwcaps = getauxval(AT_HWCAP); \ + /* data key instructions are not in NOP space. This prevents a SIGILL */ \ + if (!(hwcaps & HWCAP_PACA)) \ + SKIP(return, "PAUTH not enabled"); \ +} while (0) +#define ASSERT_GENERIC_PAUTH_ENABLED() \ +do { \ + unsigned long hwcaps = getauxval(AT_HWCAP); \ + /* generic key instructions are not in NOP space. This prevents a SIGILL */ \ + if (!(hwcaps & HWCAP_PACG)) \ + SKIP(return, "Generic PAUTH not enabled"); \ +} while (0) + +void sign_specific(struct signatures *sign, size_t val) +{ + sign->keyia = keyia_sign(val); + sign->keyib = keyib_sign(val); + sign->keyda = keyda_sign(val); + sign->keydb = keydb_sign(val); +} + +void sign_all(struct signatures *sign, size_t val) +{ + sign->keyia = keyia_sign(val); + sign->keyib = keyib_sign(val); + sign->keyda = keyda_sign(val); + sign->keydb = keydb_sign(val); + sign->keyg = keyg_sign(val); +} + +int n_same(struct signatures *old, struct signatures *new, int nkeys) +{ + int res = 0; + + res += old->keyia == new->keyia; + res += old->keyib == new->keyib; + res += old->keyda == new->keyda; + res += old->keydb == new->keydb; + if (nkeys == NKEYS) + res += old->keyg == new->keyg; + + return res; +} + +int n_same_single_set(struct signatures *sign, int nkeys) +{ + size_t vals[nkeys]; + int same = 0; + + vals[0] = sign->keyia & PAC_MASK; + vals[1] = sign->keyib & PAC_MASK; + vals[2] = sign->keyda & PAC_MASK; + vals[3] = sign->keydb & PAC_MASK; + + if (nkeys >= 4) + vals[4] = sign->keyg & PAC_MASK; + + for (int i = 0; i < nkeys - 1; i++) { + for (int j = i + 1; j < nkeys; j++) { + if (vals[i] == vals[j]) + same += 1; + } + } + return same; +} + +int exec_sign_all(struct signatures *signed_vals, size_t val) +{ + int new_stdin[2]; + int new_stdout[2]; + int status; + int i; + ssize_t ret; + pid_t pid; + cpu_set_t mask; + + ret = pipe(new_stdin); + if (ret == -1) { + perror("pipe returned error"); + return -1; + } + + ret = pipe(new_stdout); + if (ret == -1) { + perror("pipe returned error"); + return -1; + } + + /* + * pin this process and all its children to a single CPU, so it can also + * guarantee a context switch with its child + */ + sched_getaffinity(0, sizeof(mask), &mask); + + for (i = 0; i < sizeof(cpu_set_t); i++) + if (CPU_ISSET(i, &mask)) + break; + + CPU_ZERO(&mask); + CPU_SET(i, &mask); + sched_setaffinity(0, sizeof(mask), &mask); + + pid = fork(); + // child + if (pid == 0) { + dup2(new_stdin[0], STDIN_FILENO); + if (ret == -1) { + perror("dup2 returned error"); + exit(1); + } + + dup2(new_stdout[1], STDOUT_FILENO); + if (ret == -1) { + perror("dup2 returned error"); + exit(1); + } + + close(new_stdin[0]); + close(new_stdin[1]); + close(new_stdout[0]); + close(new_stdout[1]); + + ret = execl("exec_target", "exec_target", (char *)NULL); + if (ret == -1) { + perror("exec returned error"); + exit(1); + } + } + + close(new_stdin[0]); + close(new_stdout[1]); + + ret = write(new_stdin[1], &val, sizeof(size_t)); + if (ret == -1) { + perror("write returned error"); + return -1; + } + + /* + * wait for the worker to finish, so that read() reads all data + * will also context switch with worker so that this function can be used + * for context switch tests + */ + waitpid(pid, &status, 0); + if (WIFEXITED(status) == 0) { + fprintf(stderr, "worker exited unexpectedly\n"); + return -1; + } + if (WEXITSTATUS(status) != 0) { + fprintf(stderr, "worker exited with error\n"); + return -1; + } + + ret = read(new_stdout[0], signed_vals, sizeof(struct signatures)); + if (ret == -1) { + perror("read returned error"); + return -1; + } + + return 0; +} + +sigjmp_buf jmpbuf; +void pac_signal_handler(int signum, siginfo_t *si, void *uc) +{ + if (signum == SIGSEGV || signum == SIGILL) + siglongjmp(jmpbuf, 1); +} + +/* check that a corrupted PAC results in SIGSEGV or SIGILL */ +TEST(corrupt_pac) +{ + struct sigaction sa; + + ASSERT_PAUTH_ENABLED(); + if (sigsetjmp(jmpbuf, 1) == 0) { + sa.sa_sigaction = pac_signal_handler; + sa.sa_flags = SA_SIGINFO | SA_RESETHAND; + sigemptyset(&sa.sa_mask); + + sigaction(SIGSEGV, &sa, NULL); + sigaction(SIGILL, &sa, NULL); + + pac_corruptor(); + ASSERT_TRUE(0) TH_LOG("SIGSEGV/SIGILL signal did not occur"); + } +} + +/* + * There are no separate pac* and aut* controls so checking only the pac* + * instructions is sufficient + */ +TEST(pac_instructions_not_nop) +{ + size_t keyia = 0; + size_t keyib = 0; + size_t keyda = 0; + size_t keydb = 0; + + ASSERT_PAUTH_ENABLED(); + + for (int i = 0; i < PAC_COLLISION_ATTEMPTS; i++) { + keyia |= keyia_sign(i) & PAC_MASK; + keyib |= keyib_sign(i) & PAC_MASK; + keyda |= keyda_sign(i) & PAC_MASK; + keydb |= keydb_sign(i) & PAC_MASK; + } + + ASSERT_NE(0, keyia) TH_LOG("keyia instructions did nothing"); + ASSERT_NE(0, keyib) TH_LOG("keyib instructions did nothing"); + ASSERT_NE(0, keyda) TH_LOG("keyda instructions did nothing"); + ASSERT_NE(0, keydb) TH_LOG("keydb instructions did nothing"); +} + +TEST(pac_instructions_not_nop_generic) +{ + size_t keyg = 0; + + ASSERT_GENERIC_PAUTH_ENABLED(); + + for (int i = 0; i < PAC_COLLISION_ATTEMPTS; i++) + keyg |= keyg_sign(i) & PAC_MASK; + + ASSERT_NE(0, keyg) TH_LOG("keyg instructions did nothing"); +} + +TEST(single_thread_different_keys) +{ + int same = 10; + int nkeys = NKEYS; + int tmp; + struct signatures signed_vals; + unsigned long hwcaps = getauxval(AT_HWCAP); + + /* generic and data key instructions are not in NOP space. This prevents a SIGILL */ + ASSERT_PAUTH_ENABLED(); + if (!(hwcaps & HWCAP_PACG)) { + TH_LOG("WARNING: Generic PAUTH not enabled. Skipping generic key checks"); + nkeys = NKEYS - 1; + } + + /* + * In Linux the PAC field can be up to 7 bits wide. Even if keys are + * different, there is about 5% chance for PACs to collide with + * different addresses. This chance rapidly increases with fewer bits + * allocated for the PAC (e.g. wider address). A comparison of the keys + * directly will be more reliable. + * All signed values need to be different at least once out of n + * attempts to be certain that the keys are different + */ + for (int i = 0; i < PAC_COLLISION_ATTEMPTS; i++) { + if (nkeys == NKEYS) + sign_all(&signed_vals, i); + else + sign_specific(&signed_vals, i); + + tmp = n_same_single_set(&signed_vals, nkeys); + if (tmp < same) + same = tmp; + } + + ASSERT_EQ(0, same) TH_LOG("%d keys clashed every time", same); +} + +/* + * fork() does not change keys. Only exec() does so call a worker program. + * Its only job is to sign a value and report back the resutls + */ +TEST(exec_changed_keys) +{ + struct signatures new_keys; + struct signatures old_keys; + int ret; + int same = 10; + int nkeys = NKEYS; + unsigned long hwcaps = getauxval(AT_HWCAP); + + /* generic and data key instructions are not in NOP space. This prevents a SIGILL */ + ASSERT_PAUTH_ENABLED(); + if (!(hwcaps & HWCAP_PACG)) { + TH_LOG("WARNING: Generic PAUTH not enabled. Skipping generic key checks"); + nkeys = NKEYS - 1; + } + + for (int i = 0; i < PAC_COLLISION_ATTEMPTS; i++) { + ret = exec_sign_all(&new_keys, i); + ASSERT_EQ(0, ret) TH_LOG("failed to run worker"); + + if (nkeys == NKEYS) + sign_all(&old_keys, i); + else + sign_specific(&old_keys, i); + + ret = n_same(&old_keys, &new_keys, nkeys); + if (ret < same) + same = ret; + } + + ASSERT_EQ(0, same) TH_LOG("exec() did not change %d keys", same); +} + +TEST(context_switch_keep_keys) +{ + int ret; + struct signatures trash; + struct signatures before; + struct signatures after; + + ASSERT_PAUTH_ENABLED(); + + sign_specific(&before, ARBITRARY_VALUE); + + /* will context switch with a process with different keys at least once */ + ret = exec_sign_all(&trash, ARBITRARY_VALUE); + ASSERT_EQ(0, ret) TH_LOG("failed to run worker"); + + sign_specific(&after, ARBITRARY_VALUE); + + ASSERT_EQ(before.keyia, after.keyia) TH_LOG("keyia changed after context switching"); + ASSERT_EQ(before.keyib, after.keyib) TH_LOG("keyib changed after context switching"); + ASSERT_EQ(before.keyda, after.keyda) TH_LOG("keyda changed after context switching"); + ASSERT_EQ(before.keydb, after.keydb) TH_LOG("keydb changed after context switching"); +} + +TEST(context_switch_keep_keys_generic) +{ + int ret; + struct signatures trash; + size_t before; + size_t after; + + ASSERT_GENERIC_PAUTH_ENABLED(); + + before = keyg_sign(ARBITRARY_VALUE); + + /* will context switch with a process with different keys at least once */ + ret = exec_sign_all(&trash, ARBITRARY_VALUE); + ASSERT_EQ(0, ret) TH_LOG("failed to run worker"); + + after = keyg_sign(ARBITRARY_VALUE); + + ASSERT_EQ(before, after) TH_LOG("keyg changed after context switching"); +} + +TEST_HARNESS_MAIN |