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glibc/SOURCES/glibc-RHEL-25531-1.patch

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From a4c3f5f46e850c977cda81c251036475aab8313c Mon Sep 17 00:00:00 2001
From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Thu, 23 Nov 2023 14:29:14 -0300
Subject: [PATCH] elf: Add a way to check if tunable is set (BZ 27069)
Content-type: text/plain; charset=UTF-8
The patch adds two new macros, TUNABLE_GET_DEFAULT and TUNABLE_IS_INITIALIZED,
here the former get the default value with a signature similar to
TUNABLE_GET, while the later returns whether the tunable was set by
the environment variable.
Checked on x86_64-linux-gnu.
Reviewed-by: DJ Delorie <dj@redhat.com>
Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Conflicts:
elf/Versions
(removed to preserve ABI)
elf/dl-tunable-types.h
(line numbers)
scripts/gen-tunables.awk
(account for missing TUNABLE_SECLEVEL patch)
---
elf/dl-tunable-types.h | 1 +
elf/dl-tunables.c | 40 ++++++++++++++++++++++++++++++++++++++++
elf/dl-tunables.h | 28 ++++++++++++++++++++++++++++
elf/dl-tunables.list | 1 +
scripts/gen-tunables.awk | 4 ++--
6 files changed, 73 insertions(+), 2 deletions(-)
diff -rup a/elf/dl-tunable-types.h b/elf/dl-tunable-types.h
--- a/elf/dl-tunable-types.h 2021-08-01 21:33:43.000000000 -0400
+++ b/elf/dl-tunable-types.h 2024-03-26 18:23:22.211504813 -0400
@@ -61,6 +61,7 @@ struct _tunable
{
const char name[TUNABLE_NAME_MAX]; /* Internal name of the tunable. */
tunable_type_t type; /* Data type of the tunable. */
+ const tunable_val_t def; /* The value. */
tunable_val_t val; /* The value. */
bool initialized; /* Flag to indicate that the tunable is
initialized. */
diff -rup a/elf/dl-tunables.c b/elf/dl-tunables.c
--- a/elf/dl-tunables.c 2024-03-26 18:21:10.090681748 -0400
+++ b/elf/dl-tunables.c 2024-03-26 18:23:22.214504923 -0400
@@ -152,6 +152,13 @@ tunable_initialize (tunable_t *cur, cons
do_tunable_update_val (cur, &val, NULL, NULL);
}
+bool
+__tunable_is_initialized (tunable_id_t id)
+{
+ return tunable_list[id].initialized;
+}
+rtld_hidden_def (__tunable_is_initialized)
+
void
__tunable_set_val (tunable_id_t id, tunable_val_t *valp, tunable_num_t *minp,
tunable_num_t *maxp)
@@ -399,6 +406,39 @@ __tunables_print (void)
}
}
+void
+__tunable_get_default (tunable_id_t id, void *valp)
+{
+ tunable_t *cur = &tunable_list[id];
+
+ switch (cur->type.type_code)
+ {
+ case TUNABLE_TYPE_UINT_64:
+ {
+ *((uint64_t *) valp) = (uint64_t) cur->def.numval;
+ break;
+ }
+ case TUNABLE_TYPE_INT_32:
+ {
+ *((int32_t *) valp) = (int32_t) cur->def.numval;
+ break;
+ }
+ case TUNABLE_TYPE_SIZE_T:
+ {
+ *((size_t *) valp) = (size_t) cur->def.numval;
+ break;
+ }
+ case TUNABLE_TYPE_STRING:
+ {
+ *((const char **)valp) = cur->def.strval;
+ break;
+ }
+ default:
+ __builtin_unreachable ();
+ }
+}
+rtld_hidden_def (__tunable_get_default)
+
/* Set the tunable value. This is called by the module that the tunable exists
in. */
void
diff -rup a/elf/dl-tunables.h b/elf/dl-tunables.h
--- a/elf/dl-tunables.h 2021-08-01 21:33:43.000000000 -0400
+++ b/elf/dl-tunables.h 2024-03-26 18:23:22.217505032 -0400
@@ -53,18 +53,26 @@ typedef void (*tunable_callback_t) (tuna
extern void __tunables_init (char **);
extern void __tunables_print (void);
+extern bool __tunable_is_initialized (tunable_id_t);
extern void __tunable_get_val (tunable_id_t, void *, tunable_callback_t);
extern void __tunable_set_val (tunable_id_t, tunable_val_t *, tunable_num_t *,
tunable_num_t *);
+extern void __tunable_get_default (tunable_id_t id, void *valp);
rtld_hidden_proto (__tunables_init)
rtld_hidden_proto (__tunables_print)
+rtld_hidden_proto (__tunable_is_initialized)
rtld_hidden_proto (__tunable_get_val)
rtld_hidden_proto (__tunable_set_val)
+rtld_hidden_proto (__tunable_get_default)
/* Define TUNABLE_GET and TUNABLE_SET in short form if TOP_NAMESPACE and
TUNABLE_NAMESPACE are defined. This is useful shorthand to get and set
tunables within a module. */
#if defined TOP_NAMESPACE && defined TUNABLE_NAMESPACE
+# define TUNABLE_IS_INITIALIZED(__id) \
+ TUNABLE_IS_INITIALIZED_FULL(TOP_NAMESPACE, TUNABLE_NAMESPACE, __id)
+# define TUNABLE_GET_DEFAULT(__id, __type) \
+ TUNABLE_GET_DEFAULT_FULL(TOP_NAMESPACE, TUNABLE_NAMESPACE,__id, __type)
# define TUNABLE_GET(__id, __type, __cb) \
TUNABLE_GET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __cb)
# define TUNABLE_SET(__id, __val) \
@@ -73,6 +81,10 @@ rtld_hidden_proto (__tunable_set_val)
TUNABLE_SET_WITH_BOUNDS_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, \
__val, __min, __max)
#else
+# define TUNABLE_IS_INITIALIZED(__top, __ns, __id) \
+ TUNABLE_IS_INITIALIZED_FULL(__top, __ns, __id)
+# define TUNABLE_GET_DEFAULT(__top, __ns, __type) \
+ TUNABLE_GET_DEFAULT_FULL(__top, __ns, __id, __type)
# define TUNABLE_GET(__top, __ns, __id, __type, __cb) \
TUNABLE_GET_FULL (__top, __ns, __id, __type, __cb)
# define TUNABLE_SET(__top, __ns, __id, __val) \
@@ -81,6 +93,22 @@ rtld_hidden_proto (__tunable_set_val)
TUNABLE_SET_WITH_BOUNDS_FULL (__top, __ns, __id, __val, __min, __max)
#endif
+/* Return whether the tunable was initialized by the environment variable. */
+#define TUNABLE_IS_INITIALIZED_FULL(__top, __ns, __id) \
+({ \
+ tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \
+ __tunable_is_initialized (id); \
+})
+
+/* Return the default value of the tunable. */
+#define TUNABLE_GET_DEFAULT_FULL(__top, __ns, __id, __type) \
+({ \
+ tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \
+ __type __ret; \
+ __tunable_get_default (id, &__ret); \
+ __ret; \
+})
+
/* Get and return a tunable value. If the tunable was set externally and __CB
is defined then call __CB before returning the value. */
# define TUNABLE_GET_FULL(__top, __ns, __id, __type, __cb) \
diff -rup a/elf/dl-tunables.list b/elf/dl-tunables.list
--- a/elf/dl-tunables.list 2024-03-26 18:21:09.664666196 -0400
+++ b/elf/dl-tunables.list 2024-03-26 18:23:22.220505142 -0400
@@ -20,6 +20,7 @@
# type: Defaults to STRING
# minval: Optional minimum acceptable value
# maxval: Optional maximum acceptable value
+# default: Optional default value (if not specified it will be 0 or "")
# env_alias: An alias environment variable
# security_level: Specify security level of the tunable for AT_SECURE binaries.
# Valid values are:
diff -rup a/scripts/gen-tunables.awk b/scripts/gen-tunables.awk
--- a/scripts/gen-tunables.awk 2024-03-26 18:21:09.523661049 -0400
+++ b/scripts/gen-tunables.awk 2024-03-26 18:34:45.385462341 -0400
@@ -236,8 +236,8 @@ END {
n = indices[2];
m = indices[3];
printf (" {TUNABLE_NAME_S(%s, %s, %s)", t, n, m)
- printf (", {TUNABLE_TYPE_%s, %s, %s}, {%s}, NULL, TUNABLE_SECLEVEL_%s, %s},\n",
- types[t,n,m], minvals[t,n,m], maxvals[t,n,m],
+ printf (", {TUNABLE_TYPE_%s, %s, %s}, {%s}, {%s}, NULL, TUNABLE_SECLEVEL_%s, %s},\n",
+ types[t,n,m], minvals[t,n,m], maxvals[t,n,m],default_val[t,n,m],
default_val[t,n,m], security_level[t,n,m], env_alias[t,n,m]);
}
print "};"
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