Changes in v6:
- Move la57 check to using mmap().
- Merge kernel_has_lam() and cpu_has_lam() into lam_is_available() since
the syscall (if CONFIG_ADDRESS_MASKING is set) and cpuid check
provides the same information.
Recent change in how get_user() handles pointers [1] has a specific case
for LAM. It assigns a different bitmask that's later used to check
whether a pointer comes from userland in get_user().
While currently commented out (until LASS [2] is merged into the kernel)
it's worth making changes to the LAM selftest ahead of time.
Modify cpu_has_la57() so it provides current paging level information
instead of the cpuid one.
Add test case to LAM that utilizes a ioctl (FIOASYNC) syscall which uses
get_user() in its implementation. Execute the syscall with differently
tagged pointers to verify that valid user pointers are passing through
and invalid kernel/non-canonical pointers are not.
Also to avoid unhelpful test failures add a check in main() to skip
running tests if LAM was not compiled into the kernel.
Code was tested on a Sierra Forest Xeon machine that's LAM capable. The
test was ran without issues with both the LAM lines from [1] untouched
and commented out. The test was also ran without issues with LAM_SUP
both enabled and disabled.
4/5 level pagetables code paths were also successfully tested in Simics
on a 5-level capable machine.
[1] https://lore.kernel.org/all/20241024013214.129639-1-torvalds@linux-foundati…
[2] https://lore.kernel.org/all/20241028160917.1380714-1-alexander.shishkin@lin…
Previous series entries:
[v1] https://lore.kernel.org/all/20241029141421.715686-1-maciej.wieczor-retman@i…
[v2] https://lore.kernel.org/all/20241121090651.254054-1-maciej.wieczor-retman@i…
[v3] https://lore.kernel.org/all/20241122085521.270802-1-maciej.wieczor-retman@i…
[v4] https://lore.kernel.org/all/cover.1732627541.git.maciej.wieczor-retman@inte…
[v5] https://lore.kernel.org/all/cover.1732728879.git.maciej.wieczor-retman@inte…
Maciej Wieczor-Retman (3):
selftests/lam: Move cpu_has_la57() to use cpuinfo flag
selftests/lam: Skip test if LAM is disabled
selftests/lam: Test get_user() LAM pointer handling
tools/testing/selftests/x86/lam.c | 147 +++++++++++++++++++++++++++---
1 file changed, 136 insertions(+), 11 deletions(-)
--
2.47.1
From: Kumar Kartikeya Dwivedi <memxor(a)gmail.com>
[ Upstream commit cbd8730aea8d79cda6b0f3c18b406dfdef0c1b80 ]
The verifier log when leaking resources on BPF_EXIT may be a bit
confusing, as it's a problem only when finally existing from the main
prog, not from any of the subprogs. Hence, update the verifier error
string and the corresponding selftests matching on it.
Acked-by: Eduard Zingerman <eddyz87(a)gmail.com>
Suggested-by: Eduard Zingerman <eddyz87(a)gmail.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor(a)gmail.com>
Link: https://lore.kernel.org/r/20241204030400.208005-6-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast(a)kernel.org>
Signed-off-by: Sasha Levin <sashal(a)kernel.org>
---
kernel/bpf/verifier.c | 2 +-
.../testing/selftests/bpf/progs/exceptions_fail.c | 4 ++--
tools/testing/selftests/bpf/progs/preempt_lock.c | 14 +++++++-------
.../selftests/bpf/progs/verifier_spin_lock.c | 2 +-
4 files changed, 11 insertions(+), 11 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 77f56674aaa99..4f02345b764fd 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -18803,7 +18803,7 @@ static int do_check(struct bpf_verifier_env *env)
* match caller reference state when it exits.
*/
err = check_resource_leak(env, exception_exit, !env->cur_state->curframe,
- "BPF_EXIT instruction");
+ "BPF_EXIT instruction in main prog");
if (err)
return err;
diff --git a/tools/testing/selftests/bpf/progs/exceptions_fail.c b/tools/testing/selftests/bpf/progs/exceptions_fail.c
index fe0f3fa5aab68..8a0fdff899271 100644
--- a/tools/testing/selftests/bpf/progs/exceptions_fail.c
+++ b/tools/testing/selftests/bpf/progs/exceptions_fail.c
@@ -131,7 +131,7 @@ int reject_subprog_with_lock(void *ctx)
}
SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_rcu_read_lock-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_rcu_read_lock-ed region")
int reject_with_rcu_read_lock(void *ctx)
{
bpf_rcu_read_lock();
@@ -147,7 +147,7 @@ __noinline static int throwing_subprog(struct __sk_buff *ctx)
}
SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_rcu_read_lock-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_rcu_read_lock-ed region")
int reject_subprog_with_rcu_read_lock(void *ctx)
{
bpf_rcu_read_lock();
diff --git a/tools/testing/selftests/bpf/progs/preempt_lock.c b/tools/testing/selftests/bpf/progs/preempt_lock.c
index 885377e836077..5269571cf7b57 100644
--- a/tools/testing/selftests/bpf/progs/preempt_lock.c
+++ b/tools/testing/selftests/bpf/progs/preempt_lock.c
@@ -6,7 +6,7 @@
#include "bpf_experimental.h"
SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")
int preempt_lock_missing_1(struct __sk_buff *ctx)
{
bpf_preempt_disable();
@@ -14,7 +14,7 @@ int preempt_lock_missing_1(struct __sk_buff *ctx)
}
SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")
int preempt_lock_missing_2(struct __sk_buff *ctx)
{
bpf_preempt_disable();
@@ -23,7 +23,7 @@ int preempt_lock_missing_2(struct __sk_buff *ctx)
}
SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")
int preempt_lock_missing_3(struct __sk_buff *ctx)
{
bpf_preempt_disable();
@@ -33,7 +33,7 @@ int preempt_lock_missing_3(struct __sk_buff *ctx)
}
SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")
int preempt_lock_missing_3_minus_2(struct __sk_buff *ctx)
{
bpf_preempt_disable();
@@ -55,7 +55,7 @@ static __noinline void preempt_enable(void)
}
SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")
int preempt_lock_missing_1_subprog(struct __sk_buff *ctx)
{
preempt_disable();
@@ -63,7 +63,7 @@ int preempt_lock_missing_1_subprog(struct __sk_buff *ctx)
}
SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")
int preempt_lock_missing_2_subprog(struct __sk_buff *ctx)
{
preempt_disable();
@@ -72,7 +72,7 @@ int preempt_lock_missing_2_subprog(struct __sk_buff *ctx)
}
SEC("?tc")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_preempt_disable-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_preempt_disable-ed region")
int preempt_lock_missing_2_minus_1_subprog(struct __sk_buff *ctx)
{
preempt_disable();
diff --git a/tools/testing/selftests/bpf/progs/verifier_spin_lock.c b/tools/testing/selftests/bpf/progs/verifier_spin_lock.c
index 3f679de73229f..25599eac9a702 100644
--- a/tools/testing/selftests/bpf/progs/verifier_spin_lock.c
+++ b/tools/testing/selftests/bpf/progs/verifier_spin_lock.c
@@ -187,7 +187,7 @@ l0_%=: r6 = r0; \
SEC("cgroup/skb")
__description("spin_lock: test6 missing unlock")
-__failure __msg("BPF_EXIT instruction cannot be used inside bpf_spin_lock-ed region")
+__failure __msg("BPF_EXIT instruction in main prog cannot be used inside bpf_spin_lock-ed region")
__failure_unpriv __msg_unpriv("")
__naked void spin_lock_test6_missing_unlock(void)
{
--
2.39.5