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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v4 1/4] xen: add hypercall for reading runtime parameters
Add a sysctl hypercall to support reading hypervisor runtime parameters.
Limitations:
- Custom runtime parameters (OPT_CUSTOM) are not supported yet.
- For integer parameters (OPT_UINT), only unsigned parameters are printed
correctly.
- The implementation only reads runtime parameters, but it can be changed
to read all hypervisor parameters if needed.
Signed-off-by: Vasilis Liaskovitis <vliaskovitis@xxxxxxxx>
---
tools/flask/policy/modules/dom0.te | 2 +-
xen/common/kernel.c | 118 ++++++++++++++++++++++++++++
xen/common/sysctl.c | 52 +++++++++++-
xen/include/public/sysctl.h | 18 +++++
xen/include/xen/lib.h | 1 +
xen/xsm/flask/hooks.c | 3 +
xen/xsm/flask/policy/access_vectors | 2 +
7 files changed, 193 insertions(+), 3 deletions(-)
diff --git a/tools/flask/policy/modules/dom0.te
b/tools/flask/policy/modules/dom0.te
index a347d664f8..681d1a101b 100644
--- a/tools/flask/policy/modules/dom0.te
+++ b/tools/flask/policy/modules/dom0.te
@@ -16,7 +16,7 @@ allow dom0_t xen_t:xen {
allow dom0_t xen_t:xen2 {
resource_op psr_cmt_op psr_alloc pmu_ctrl get_symbol
get_cpu_levelling_caps get_cpu_featureset livepatch_op
- coverage_op set_parameter
+ coverage_op set_parameter get_parameter
};
# Allow dom0 to use all XENVER_ subops that have checks.
diff --git a/xen/common/kernel.c b/xen/common/kernel.c
index 612575430f..6695ffc372 100644
--- a/xen/common/kernel.c
+++ b/xen/common/kernel.c
@@ -12,6 +12,7 @@
#include <xen/paging.h>
#include <xen/guest_access.h>
#include <xen/hypercall.h>
+#include <xen/ctype.h>
#include <xsm/xsm.h>
#include <asm/current.h>
#include <public/version.h>
@@ -52,6 +53,123 @@ static int assign_integer_param(const struct kernel_param
*param, uint64_t val)
return 0;
}
+static int get_integer_param(const struct kernel_param *param, uint64_t *val)
+{
+ switch ( param->len )
+ {
+ case sizeof(uint8_t):
+ *val = *(uint8_t *)param->par.var;
+ break;
+
+ case sizeof(uint16_t):
+ *val = *(uint16_t *)param->par.var;
+ break;
+
+ case sizeof(uint32_t):
+ *val = *(uint32_t *)param->par.var;
+ break;
+
+ case sizeof(uint64_t):
+ *val = *(uint64_t *)param->par.var;
+ break;
+
+ default:
+ BUG();
+ break;
+ }
+
+ return 0;
+}
+
+int runtime_get_params(const char *cmdline, char *values,
+ size_t maxlen)
+{
+ char opt[128], *optkey, *q, *val = values;
+ const char *p = cmdline;
+ const struct kernel_param *param;
+ int rc = 0, len = 0;
+ size_t bufpos = 0;
+ uint64_t param_int;
+
+ while ( !rc )
+ {
+ /* Skip whitespace. */
+ while ( isspace(*p) )
+ p++;
+ if ( *p == '\0' )
+ break;
+
+ /* Grab the next whitespace-delimited option. */
+ q = optkey = opt;
+ while ( !isspace(*p) && (*p != '\0') )
+ {
+ if ( (q - opt) < (sizeof(opt) - 1) ) /* avoid overflow */
+ *q++ = *p;
+ else return -ENOMEM;
+ p++;
+ }
+ *q = '\0';
+
+ for ( param = __param_start; param < __param_end; param++ )
+ {
+ if ( strcmp(param->name, optkey) )
+ continue;
+
+ switch ( param->type )
+ {
+ case OPT_STR:
+ len = snprintf(val + bufpos, maxlen - bufpos, "%s ",
+ (char*)param->par.var);
+ break;
+
+ case OPT_UINT:
+ case OPT_SIZE:
+ /* Signed integer parameters are not supported yet.
+ * While there are no runtime signed integer parameters
+ * at the moment, adding one and trying to get its value
+ * with the current implementation will output the wrong
+ * value.
+ */
+ get_integer_param(param, ¶m_int);
+ len = snprintf(val + bufpos, maxlen - bufpos,
+ "%"PRIu64" ", param_int);
+ break;
+
+ case OPT_BOOL:
+ get_integer_param(param, ¶m_int);
+ len = snprintf(val + bufpos, maxlen - bufpos, "%s ",
+ param_int ? "true" : "false");
+ break;
+
+ case OPT_CUSTOM:
+ /* Custom parameters are not supported yet. */
+ rc = -EINVAL;
+ break;
+
+ default:
+ BUG();
+ break;
+ }
+
+ if ( len < 0 )
+ rc = len;
+ else if ( len < maxlen - bufpos )
+ /* if output was not truncated update buffer position. */
+ bufpos += len;
+ else if ( len > 0 )
+ rc = -ENOMEM;
+
+ break;
+ }
+
+ /* no parameter was matched */
+ if ( param >= __param_end )
+ rc = -EINVAL;
+ }
+
+ return rc;
+}
+
static int parse_params(const char *cmdline, const struct kernel_param *start,
const struct kernel_param *end)
{
diff --git a/xen/common/sysctl.c b/xen/common/sysctl.c
index c0aa6bde4e..20be6a6d8d 100644
--- a/xen/common/sysctl.c
+++ b/xen/common/sysctl.c
@@ -466,9 +466,9 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t)
u_sysctl)
copyback = 1;
break;
+#define XEN_PARAMETER_MAX_SIZE 1023
case XEN_SYSCTL_set_parameter:
{
-#define XEN_SET_PARAMETER_MAX_SIZE 1023
char *params;
if ( op->u.set_parameter.pad[0] || op->u.set_parameter.pad[1] ||
@@ -477,7 +477,7 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t)
u_sysctl)
ret = -EINVAL;
break;
}
- if ( op->u.set_parameter.size > XEN_SET_PARAMETER_MAX_SIZE )
+ if ( op->u.set_parameter.size > XEN_PARAMETER_MAX_SIZE )
{
ret = -E2BIG;
break;
@@ -501,6 +501,54 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t)
u_sysctl)
break;
}
+ case XEN_SYSCTL_get_parameter:
+ {
+ char *params, *values;
+
+ if ( op->u.get_parameter.pad[0] || op->u.get_parameter.pad[1] ||
+ op->u.get_parameter.pad[2] )
+ {
+ ret = -EINVAL;
+ break;
+ }
+ if ( op->u.get_parameter.size > XEN_PARAMETER_MAX_SIZE )
+ {
+ ret = -E2BIG;
+ break;
+ }
+ params = xmalloc_bytes(op->u.get_parameter.size + 1);
+ if ( !params )
+ {
+ ret = -ENOMEM;
+ break;
+ }
+
+ values = xmalloc_bytes(XEN_PARAMETER_MAX_SIZE);
+ if ( !values )
+ {
+ xfree(params);
+ ret = -ENOMEM;
+ break;
+ }
+
+ if ( copy_from_guest(params, op->u.get_parameter.params,
+ op->u.get_parameter.size) )
+ ret = -EFAULT;
+ else
+ {
+ params[op->u.set_parameter.size] = 0;
+ ret = runtime_get_params(params, values, XEN_PARAMETER_MAX_SIZE);
+
+ if ( !ret && copy_to_guest(op->u.get_parameter.values, values,
+ strlen(values)) )
+ ret = -EFAULT;
+ }
+
+ xfree(params);
+ xfree(values);
+
+ break;
+ }
default:
ret = arch_do_sysctl(op, u_sysctl);
diff --git a/xen/include/public/sysctl.h b/xen/include/public/sysctl.h
index c49b4dcc99..7d77d57115 100644
--- a/xen/include/public/sysctl.h
+++ b/xen/include/public/sysctl.h
@@ -1100,6 +1100,22 @@ typedef struct xen_sysctl_cpu_policy
xen_sysctl_cpu_policy_t;
DEFINE_XEN_GUEST_HANDLE(xen_sysctl_cpu_policy_t);
#endif
+/*
+ * XEN_SYSCTL_get_parameter
+ *
+ * Read hypervisor parameters at runtime.
+ * Parameters are a single string terminated by a NUL byte of max. size
+ * characters. Multiple settings can be specified by separating them
+ * with blanks.
+ */
+
+struct xen_sysctl_get_parameter {
+ XEN_GUEST_HANDLE_64(char) params; /* IN: pointer to parameters. */
+ XEN_GUEST_HANDLE_64(char) values; /* OUT: pointer to output values.
*/
+ uint16_t size; /* IN: size of parameters. */
+ uint16_t pad[3]; /* IN: MUST be zero. */
+};
+
struct xen_sysctl {
uint32_t cmd;
#define XEN_SYSCTL_readconsole 1
@@ -1130,6 +1146,7 @@ struct xen_sysctl {
#define XEN_SYSCTL_livepatch_op 27
#define XEN_SYSCTL_set_parameter 28
#define XEN_SYSCTL_get_cpu_policy 29
+#define XEN_SYSCTL_get_parameter 30
uint32_t interface_version; /* XEN_SYSCTL_INTERFACE_VERSION */
union {
struct xen_sysctl_readconsole readconsole;
@@ -1162,6 +1179,7 @@ struct xen_sysctl {
#if defined(__i386__) || defined(__x86_64__)
struct xen_sysctl_cpu_policy cpu_policy;
#endif
+ struct xen_sysctl_get_parameter get_parameter;
uint8_t pad[128];
} u;
};
diff --git a/xen/include/xen/lib.h b/xen/include/xen/lib.h
index e0b7bcb6b7..6e6367bb7a 100644
--- a/xen/include/xen/lib.h
+++ b/xen/include/xen/lib.h
@@ -71,6 +71,7 @@ struct domain;
void cmdline_parse(const char *cmdline);
int runtime_parse(const char *line);
int parse_bool(const char *s, const char *e);
+int runtime_get_params(const char *cmdline, char *values, size_t maxlen);
/**
* Given a specific name, parses a string of the form:
diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c
index 3d00c747f6..1b832e9a4c 100644
--- a/xen/xsm/flask/hooks.c
+++ b/xen/xsm/flask/hooks.c
@@ -830,6 +830,9 @@ static int flask_sysctl(int cmd)
case XEN_SYSCTL_set_parameter:
return avc_current_has_perm(SECINITSID_XEN, SECCLASS_XEN2,
XEN2__SET_PARAMETER, NULL);
+ case XEN_SYSCTL_get_parameter:
+ return avc_current_has_perm(SECINITSID_XEN, SECCLASS_XEN2,
+ XEN2__GET_PARAMETER, NULL);
default:
return avc_unknown_permission("sysctl", cmd);
diff --git a/xen/xsm/flask/policy/access_vectors
b/xen/xsm/flask/policy/access_vectors
index e00448b776..c5ee21d852 100644
--- a/xen/xsm/flask/policy/access_vectors
+++ b/xen/xsm/flask/policy/access_vectors
@@ -103,6 +103,8 @@ class xen2
coverage_op
# XEN_SYSCTL_set_parameter
set_parameter
+# XEN_SYSCTL_get_parameter
+ get_parameter
}
# Classes domain and domain2 consist of operations that a domain performs on
--
2.20.1
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