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path: root/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
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Diffstat (limited to 'drivers/hwtracing/coresight/coresight-etm4x-sysfs.c')
-rw-r--r--drivers/hwtracing/coresight/coresight-etm4x-sysfs.c47
1 files changed, 38 insertions, 9 deletions
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
index 4eb8da785ce0..a0365e23678e 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c
@@ -4,6 +4,7 @@
* Author: Mathieu Poirier <mathieu.poirier@linaro.org>
*/
+#include <linux/pid_namespace.h>
#include <linux/pm_runtime.h>
#include <linux/sysfs.h>
#include "coresight-etm4x.h"
@@ -250,10 +251,8 @@ static ssize_t reset_store(struct device *dev,
}
config->ctxid_idx = 0x0;
- for (i = 0; i < drvdata->numcidc; i++) {
+ for (i = 0; i < drvdata->numcidc; i++)
config->ctxid_pid[i] = 0x0;
- config->ctxid_vpid[i] = 0x0;
- }
config->ctxid_mask0 = 0x0;
config->ctxid_mask1 = 0x0;
@@ -1637,9 +1636,16 @@ static ssize_t ctxid_pid_show(struct device *dev,
struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
struct etmv4_config *config = &drvdata->config;
+ /*
+ * Don't use contextID tracing if coming from a PID namespace. See
+ * comment in ctxid_pid_store().
+ */
+ if (task_active_pid_ns(current) != &init_pid_ns)
+ return -EINVAL;
+
spin_lock(&drvdata->spinlock);
idx = config->ctxid_idx;
- val = (unsigned long)config->ctxid_vpid[idx];
+ val = (unsigned long)config->ctxid_pid[idx];
spin_unlock(&drvdata->spinlock);
return scnprintf(buf, PAGE_SIZE, "%#lx\n", val);
}
@@ -1649,26 +1655,35 @@ static ssize_t ctxid_pid_store(struct device *dev,
const char *buf, size_t size)
{
u8 idx;
- unsigned long vpid, pid;
+ unsigned long pid;
struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
struct etmv4_config *config = &drvdata->config;
/*
+ * When contextID tracing is enabled the tracers will insert the
+ * value found in the contextID register in the trace stream. But if
+ * a process is in a namespace the PID of that process as seen from the
+ * namespace won't be what the kernel sees, something that makes the
+ * feature confusing and can potentially leak kernel only information.
+ * As such refuse to use the feature if @current is not in the initial
+ * PID namespace.
+ */
+ if (task_active_pid_ns(current) != &init_pid_ns)
+ return -EINVAL;
+
+ /*
* only implemented when ctxid tracing is enabled, i.e. at least one
* ctxid comparator is implemented and ctxid is greater than 0 bits
* in length
*/
if (!drvdata->ctxid_size || !drvdata->numcidc)
return -EINVAL;
- if (kstrtoul(buf, 16, &vpid))
+ if (kstrtoul(buf, 16, &pid))
return -EINVAL;
- pid = coresight_vpid_to_pid(vpid);
-
spin_lock(&drvdata->spinlock);
idx = config->ctxid_idx;
config->ctxid_pid[idx] = (u64)pid;
- config->ctxid_vpid[idx] = (u64)vpid;
spin_unlock(&drvdata->spinlock);
return size;
}
@@ -1682,6 +1697,13 @@ static ssize_t ctxid_masks_show(struct device *dev,
struct etmv4_drvdata *drvdata = dev_get_drvdata(dev->parent);
struct etmv4_config *config = &drvdata->config;
+ /*
+ * Don't use contextID tracing if coming from a PID namespace. See
+ * comment in ctxid_pid_store().
+ */
+ if (task_active_pid_ns(current) != &init_pid_ns)
+ return -EINVAL;
+
spin_lock(&drvdata->spinlock);
val1 = config->ctxid_mask0;
val2 = config->ctxid_mask1;
@@ -1699,6 +1721,13 @@ static ssize_t ctxid_masks_store(struct device *dev,
struct etmv4_config *config = &drvdata->config;
/*
+ * Don't use contextID tracing if coming from a PID namespace. See
+ * comment in ctxid_pid_store().
+ */
+ if (task_active_pid_ns(current) != &init_pid_ns)
+ return -EINVAL;
+
+ /*
* only implemented when ctxid tracing is enabled, i.e. at least one
* ctxid comparator is implemented and ctxid is greater than 0 bits
* in length