* [for-next][PATCH 13/31] tracing: Have syscall trace events use trace_event_buffer_lock_reserve()
[not found] <20220111173030.999527342@goodmis.org>
@ 2022-01-11 17:30 ` Steven Rostedt
2022-01-11 17:30 ` [for-next][PATCH 14/31] tracing: Add test for user space strings when filtering on string pointers Steven Rostedt
` (2 subsequent siblings)
3 siblings, 0 replies; 4+ messages in thread
From: Steven Rostedt @ 2022-01-11 17:30 UTC (permalink / raw)
To: linux-kernel
Cc: Ingo Molnar, Andrew Morton, stable, Tom Zanussi, Masami Hiramatsu
From: Steven Rostedt <rostedt@goodmis.org>
Currently, the syscall trace events call trace_buffer_lock_reserve()
directly, which means that it misses out on some of the filtering
optimizations provided by the helper function
trace_event_buffer_lock_reserve(). Have the syscall trace events call that
instead, as it was missed when adding the update to use the temp buffer
when filtering.
Link: https://lkml.kernel.org/r/20220107225839.823118570@goodmis.org
Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Fixes: 0fc1b09ff1ff4 ("tracing: Use temp buffer when filtering events")
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace_syscalls.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 8bfcd3b09422..f755bde42fd0 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -323,8 +323,7 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
trace_ctx = tracing_gen_ctx();
- buffer = tr->array_buffer.buffer;
- event = trace_buffer_lock_reserve(buffer,
+ event = trace_event_buffer_lock_reserve(&buffer, trace_file,
sys_data->enter_event->event.type, size, trace_ctx);
if (!event)
return;
@@ -367,8 +366,7 @@ static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
trace_ctx = tracing_gen_ctx();
- buffer = tr->array_buffer.buffer;
- event = trace_buffer_lock_reserve(buffer,
+ event = trace_event_buffer_lock_reserve(&buffer, trace_file,
sys_data->exit_event->event.type, sizeof(*entry),
trace_ctx);
if (!event)
--
2.33.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [for-next][PATCH 14/31] tracing: Add test for user space strings when filtering on string pointers
[not found] <20220111173030.999527342@goodmis.org>
2022-01-11 17:30 ` [for-next][PATCH 13/31] tracing: Have syscall trace events use trace_event_buffer_lock_reserve() Steven Rostedt
@ 2022-01-11 17:30 ` Steven Rostedt
2022-01-11 17:30 ` [for-next][PATCH 15/31] tracing/kprobes: nmissed not showed correctly for kretprobe Steven Rostedt
2022-01-11 17:31 ` [for-next][PATCH 31/31] tracing/osnoise: Properly unhook events if start_per_cpu_kthreads() fails Steven Rostedt
3 siblings, 0 replies; 4+ messages in thread
From: Steven Rostedt @ 2022-01-11 17:30 UTC (permalink / raw)
To: linux-kernel
Cc: Ingo Molnar, Andrew Morton, stable, Masami Hiramatsu,
Tom Zanussi, Pingfan Liu
From: Steven Rostedt <rostedt@goodmis.org>
Pingfan reported that the following causes a fault:
echo "filename ~ \"cpu\"" > events/syscalls/sys_enter_openat/filter
echo 1 > events/syscalls/sys_enter_at/enable
The reason is that trace event filter treats the user space pointer
defined by "filename" as a normal pointer to compare against the "cpu"
string. If the string is not loaded into memory yet, it will trigger a
fault in kernel space:
kvm-03-guest16 login: [72198.026181] BUG: unable to handle page fault for address: 00007fffaae8ef60
#PF: supervisor read access in kernel mode
#PF: error_code(0x0001) - permissions violation
PGD 80000001008b7067 P4D 80000001008b7067 PUD 2393f1067 PMD 2393ec067 PTE 8000000108f47867
Oops: 0001 [#1] PREEMPT SMP PTI
CPU: 1 PID: 1 Comm: systemd Kdump: loaded Not tainted 5.14.0-32.el9.x86_64 #1
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
RIP: 0010:strlen+0x0/0x20
Code: 48 89 f9 74 09 48 83 c1 01 80 39 00 75 f7 31 d2 44 0f b6 04 16 44 88 04 11
48 83 c2 01 45 84 c0 75 ee c3 0f 1f 80 00 00 00 00 <80> 3f 00 74 10 48 89 f8
48 83 c0 01 80 38 00 75 f7 48 29 f8 c3 31
RSP: 0018:ffffb5b900013e48 EFLAGS: 00010246
RAX: 0000000000000018 RBX: ffff8fc1c49ede00 RCX: 0000000000000000
RDX: 0000000000000020 RSI: ffff8fc1c02d601c RDI: 00007fffaae8ef60
RBP: 00007fffaae8ef60 R08: 0005034f4ddb8ea4 R09: 0000000000000000
R10: ffff8fc1c02d601c R11: 0000000000000000 R12: ffff8fc1c8a6e380
R13: 0000000000000000 R14: ffff8fc1c02d6010 R15: ffff8fc1c00453c0
FS: 00007fa86123db40(0000) GS:ffff8fc2ffd00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fffaae8ef60 CR3: 0000000102880001 CR4: 00000000007706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
filter_pred_pchar+0x18/0x40
filter_match_preds+0x31/0x70
ftrace_syscall_enter+0x27a/0x2c0
syscall_trace_enter.constprop.0+0x1aa/0x1d0
do_syscall_64+0x16/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fa861d88664
To be even more robust, test both kernel and user space strings. If the
string fails to read, then simply have the filter fail.
Link: https://lore.kernel.org/all/20220107044951.22080-1-kernelfans@gmail.com/
Link: https://lkml.kernel.org/r/20220110115532.536088fd@gandalf.local.home
Cc: stable@vger.kernel.org
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Tom Zanussi <zanussi@kernel.org>
Reported-by: Pingfan Liu <kernelfans@gmail.com>
Fixes: 87a342f5db69d ("tracing/filters: Support filtering for char * strings")
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
Documentation/trace/events.rst | 10 +++++
kernel/trace/trace_events_filter.c | 59 ++++++++++++++++++++++++++++--
2 files changed, 66 insertions(+), 3 deletions(-)
diff --git a/Documentation/trace/events.rst b/Documentation/trace/events.rst
index 8ddb9b09451c..45e66a60a816 100644
--- a/Documentation/trace/events.rst
+++ b/Documentation/trace/events.rst
@@ -230,6 +230,16 @@ Currently the caret ('^') for an error always appears at the beginning of
the filter string; the error message should still be useful though
even without more accurate position info.
+5.2.1 Filter limitations
+------------------------
+
+If a filter is placed on a string pointer ``(char *)`` that does not point
+to a string on the ring buffer, but instead points to kernel or user space
+memory, then, for safety reasons, at most 1024 bytes of the content is
+copied onto a temporary buffer to do the compare. If the copy of the memory
+faults (the pointer points to memory that should not be accessed), then the
+string compare will be treated as not matching.
+
5.3 Clearing filters
--------------------
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 996920ed1812..91352a64be09 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -5,6 +5,7 @@
* Copyright (C) 2009 Tom Zanussi <tzanussi@gmail.com>
*/
+#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/ctype.h>
#include <linux/mutex.h>
@@ -654,6 +655,40 @@ DEFINE_EQUALITY_PRED(32);
DEFINE_EQUALITY_PRED(16);
DEFINE_EQUALITY_PRED(8);
+/* user space strings temp buffer */
+#define USTRING_BUF_SIZE 1024
+
+struct ustring_buffer {
+ char buffer[USTRING_BUF_SIZE];
+};
+
+static __percpu struct ustring_buffer *ustring_per_cpu;
+
+static __always_inline char *test_string(char *str)
+{
+ struct ustring_buffer *ubuf;
+ char __user *ustr;
+ char *kstr;
+
+ if (!ustring_per_cpu)
+ return NULL;
+
+ ubuf = this_cpu_ptr(ustring_per_cpu);
+ kstr = ubuf->buffer;
+
+ if (likely((unsigned long)str >= TASK_SIZE)) {
+ /* For safety, do not trust the string pointer */
+ if (!strncpy_from_kernel_nofault(kstr, str, USTRING_BUF_SIZE))
+ return NULL;
+ } else {
+ /* user space address? */
+ ustr = (char __user *)str;
+ if (!strncpy_from_user_nofault(kstr, ustr, USTRING_BUF_SIZE))
+ return NULL;
+ }
+ return kstr;
+}
+
/* Filter predicate for fixed sized arrays of characters */
static int filter_pred_string(struct filter_pred *pred, void *event)
{
@@ -671,10 +706,16 @@ static int filter_pred_string(struct filter_pred *pred, void *event)
static int filter_pred_pchar(struct filter_pred *pred, void *event)
{
char **addr = (char **)(event + pred->offset);
+ char *str;
int cmp, match;
- int len = strlen(*addr) + 1; /* including tailing '\0' */
+ int len;
- cmp = pred->regex.match(*addr, &pred->regex, len);
+ str = test_string(*addr);
+ if (!str)
+ return 0;
+
+ len = strlen(str) + 1; /* including tailing '\0' */
+ cmp = pred->regex.match(str, &pred->regex, len);
match = cmp ^ pred->not;
@@ -1348,8 +1389,17 @@ static int parse_pred(const char *str, void *data,
pred->fn = filter_pred_strloc;
} else if (field->filter_type == FILTER_RDYN_STRING)
pred->fn = filter_pred_strrelloc;
- else
+ else {
+
+ if (!ustring_per_cpu) {
+ /* Once allocated, keep it around for good */
+ ustring_per_cpu = alloc_percpu(struct ustring_buffer);
+ if (!ustring_per_cpu)
+ goto err_mem;
+ }
+
pred->fn = filter_pred_pchar;
+ }
/* go past the last quote */
i++;
@@ -1415,6 +1465,9 @@ static int parse_pred(const char *str, void *data,
err_free:
kfree(pred);
return -EINVAL;
+err_mem:
+ kfree(pred);
+ return -ENOMEM;
}
enum {
--
2.33.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [for-next][PATCH 15/31] tracing/kprobes: nmissed not showed correctly for kretprobe
[not found] <20220111173030.999527342@goodmis.org>
2022-01-11 17:30 ` [for-next][PATCH 13/31] tracing: Have syscall trace events use trace_event_buffer_lock_reserve() Steven Rostedt
2022-01-11 17:30 ` [for-next][PATCH 14/31] tracing: Add test for user space strings when filtering on string pointers Steven Rostedt
@ 2022-01-11 17:30 ` Steven Rostedt
2022-01-11 17:31 ` [for-next][PATCH 31/31] tracing/osnoise: Properly unhook events if start_per_cpu_kthreads() fails Steven Rostedt
3 siblings, 0 replies; 4+ messages in thread
From: Steven Rostedt @ 2022-01-11 17:30 UTC (permalink / raw)
To: linux-kernel
Cc: Ingo Molnar, Andrew Morton, stable, Masami Hiramatsu, Xiangyang Zhang
From: Xiangyang Zhang <xyz.sun.ok@gmail.com>
The 'nmissed' column of the 'kprobe_profile' file for kretprobe is
not showed correctly, kretprobe can be skipped by two reasons,
shortage of kretprobe_instance which is counted by tk->rp.nmissed,
and kprobe itself is missed by some reason, so to show the sum.
Link: https://lkml.kernel.org/r/20220107150242.5019-1-xyz.sun.ok@gmail.com
Cc: stable@vger.kernel.org
Fixes: 4a846b443b4e ("tracing/kprobes: Cleanup kprobe tracer code")
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Xiangyang Zhang <xyz.sun.ok@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace_kprobe.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index f8c26ee72de3..3d85323278ed 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1170,15 +1170,18 @@ static int probes_profile_seq_show(struct seq_file *m, void *v)
{
struct dyn_event *ev = v;
struct trace_kprobe *tk;
+ unsigned long nmissed;
if (!is_trace_kprobe(ev))
return 0;
tk = to_trace_kprobe(ev);
+ nmissed = trace_kprobe_is_return(tk) ?
+ tk->rp.kp.nmissed + tk->rp.nmissed : tk->rp.kp.nmissed;
seq_printf(m, " %-44s %15lu %15lu\n",
trace_probe_name(&tk->tp),
trace_kprobe_nhit(tk),
- tk->rp.kp.nmissed);
+ nmissed);
return 0;
}
--
2.33.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [for-next][PATCH 31/31] tracing/osnoise: Properly unhook events if start_per_cpu_kthreads() fails
[not found] <20220111173030.999527342@goodmis.org>
` (2 preceding siblings ...)
2022-01-11 17:30 ` [for-next][PATCH 15/31] tracing/kprobes: nmissed not showed correctly for kretprobe Steven Rostedt
@ 2022-01-11 17:31 ` Steven Rostedt
3 siblings, 0 replies; 4+ messages in thread
From: Steven Rostedt @ 2022-01-11 17:31 UTC (permalink / raw)
To: linux-kernel
Cc: Ingo Molnar, Andrew Morton, stable, Daniel Bristot de Oliveira,
Nikita Yushchenko
From: Nikita Yushchenko <nikita.yushchenko@virtuozzo.com>
If start_per_cpu_kthreads() called from osnoise_workload_start() returns
error, event hooks are left in broken state: unhook_irq_events() called
but unhook_thread_events() and unhook_softirq_events() not called, and
trace_osnoise_callback_enabled flag not cleared.
On the next tracer enable, hooks get not installed due to
trace_osnoise_callback_enabled flag.
And on the further tracer disable an attempt to remove non-installed
hooks happened, hitting a WARN_ON_ONCE() in tracepoint_remove_func().
Fix the error path by adding the missing part of cleanup.
While at this, introduce osnoise_unhook_events() to avoid code
duplication between this error path and normal tracer disable.
Link: https://lkml.kernel.org/r/20220109153459.3701773-1-nikita.yushchenko@virtuozzo.com
Cc: stable@vger.kernel.org
Fixes: bce29ac9ce0b ("trace: Add osnoise tracer")
Acked-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Nikita Yushchenko <nikita.yushchenko@virtuozzo.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace_osnoise.c | 20 ++++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)
diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index 4719a848bf17..36d9d5be08b4 100644
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -2122,6 +2122,13 @@ static int osnoise_hook_events(void)
return -EINVAL;
}
+static void osnoise_unhook_events(void)
+{
+ unhook_thread_events();
+ unhook_softirq_events();
+ unhook_irq_events();
+}
+
/*
* osnoise_workload_start - start the workload and hook to events
*/
@@ -2154,7 +2161,14 @@ static int osnoise_workload_start(void)
retval = start_per_cpu_kthreads();
if (retval) {
- unhook_irq_events();
+ trace_osnoise_callback_enabled = false;
+ /*
+ * Make sure that ftrace_nmi_enter/exit() see
+ * trace_osnoise_callback_enabled as false before continuing.
+ */
+ barrier();
+
+ osnoise_unhook_events();
return retval;
}
@@ -2185,9 +2199,7 @@ static void osnoise_workload_stop(void)
stop_per_cpu_kthreads();
- unhook_irq_events();
- unhook_softirq_events();
- unhook_thread_events();
+ osnoise_unhook_events();
}
static void osnoise_tracer_start(struct trace_array *tr)
--
2.33.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
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2022-01-11 17:30 ` [for-next][PATCH 13/31] tracing: Have syscall trace events use trace_event_buffer_lock_reserve() Steven Rostedt
2022-01-11 17:30 ` [for-next][PATCH 14/31] tracing: Add test for user space strings when filtering on string pointers Steven Rostedt
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