diff mbox series

[v3,4/4] Add system-wide tunables: Filters

Message ID 942ee8135bdc44add90fc98758574bdcbbc3771f.1728595809.git.dj@redhat.com
State New
Headers show
Series System-wide tunables | expand

Commit Message

DJ Delorie Oct. 10, 2024, 9:44 p.m. UTC
Add support for [prog] syntax where [prog] matches argv[0].
Tunables after such a line are limited to that prog.

Note that this filter is reset when including a file or at
end of file.
---
 csu/libc-start.c                        |  2 +-
 elf/Makefile                            |  4 +
 elf/cache.c                             |  3 +-
 elf/dl-tunables.c                       | 38 ++++++++--
 elf/dl-tunables.h                       |  2 +-
 elf/tst-tunconf1.c                      | 17 +++++
 elf/tst-tunconf1.root/etc/tunables.conf |  2 +
 elf/tst-tunconf1.root/ldconfig.run      |  0
 elf/tst-tunconf1.root/postclean.req     |  0
 elf/tunconf.c                           | 98 ++++++++++++++++++++++++-
 sysdeps/mach/hurd/dl-sysdep.c           |  2 +-
 sysdeps/unix/sysv/linux/dl-sysdep.c     |  2 +-
 12 files changed, 155 insertions(+), 15 deletions(-)
 create mode 100644 elf/tst-tunconf1.c
 create mode 100644 elf/tst-tunconf1.root/etc/tunables.conf
 create mode 100644 elf/tst-tunconf1.root/ldconfig.run
 create mode 100644 elf/tst-tunconf1.root/postclean.req
diff mbox series

Patch

diff --git a/csu/libc-start.c b/csu/libc-start.c
index d784de0f0b..8496b00622 100644
--- a/csu/libc-start.c
+++ b/csu/libc-start.c
@@ -264,7 +264,7 @@  LIBC_START_MAIN (int (*main) (int, char **, char ** MAIN_AUXVEC_DECL),
   _dl_aux_init (auxvec);
 # endif
 
-  __tunables_init (__environ);
+  __tunables_init (__environ, argv);
 
   ARCH_INIT_CPU_FEATURES ();
 
diff --git a/elf/Makefile b/elf/Makefile
index e27eed674f..36d1635cb5 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -323,6 +323,7 @@  tests := \
 tests-internal := \
   $(tests-static-internal) \
   tst-tls1 \
+  tst-tunconf1 \
   # tests-internal
 
 tests-static := $(tests-static-normal) $(tests-static-internal)
@@ -333,6 +334,8 @@  tests-static += \
   tst-tls9-static \
   # tests-static
 
+tst-tunconf1-ENV = GLIBC_TUNABLES=glibc.malloc.tcache_count=5
+
 static-dlopen-environment = \
   LD_LIBRARY_PATH=$(ld-library-path):$(common-objpfx)dlfcn
 tst-tls9-static-ENV = $(static-dlopen-environment)
@@ -532,6 +535,7 @@  tests-container += \
   tst-pldd \
   tst-preload-pthread-libc \
   tst-rootdir \
+  tst-tunconf1 \
   # tests-container
 
 test-srcs = \
diff --git a/elf/cache.c b/elf/cache.c
index 1146bba877..08557f8a5e 100644
--- a/elf/cache.c
+++ b/elf/cache.c
@@ -300,9 +300,10 @@  print_extensions (struct cache_extension_all_loaded *ext,
 	     thc->signature, thc->version, thc->num_tunables);
       for (i = 0; i < count; ++ i)
 	{
-	  printf("  [%d] %s : %s [flags 0x%08x",
+	  printf("  [%d] %s (%d) : %s [flags 0x%08x",
 		 i,
 		 cache_data + tec[i].name_offset,
+		 tec[i].tunable_id,
 		 cache_data + tec[i].value_offset,
 		 tec[i].flags);
 	  if (tec[i].flag_offset != 0)
diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
index fafd684115..31a0f8edba 100644
--- a/elf/dl-tunables.c
+++ b/elf/dl-tunables.c
@@ -318,13 +318,15 @@  dl_strlen(const char *s)
    ENV_ALIAS to find values.  Later we will also use the tunable names to find
    values.  */
 void
-__tunables_init (char **envp)
+__tunables_init (char **envp, char **argv)
 {
   char *envname = NULL;
   char *envval = NULL;
   char **prev_envp = envp;
-
 #ifdef SHARED
+  const char *prog_name = (argv && argv[0]) ? argv[0] : "";
+  int prog_name_len = -1;
+
   const struct tunable_header_cached *thc;
   const char *td;
 
@@ -357,9 +359,31 @@  __tunables_init (char **envp)
 	      if (tid == -1)
 		continue;
 	    }
-	  /* At this point, TID is valid for the tunable we want.  See
-	     if the parsed type matches the desired type.  */
-
+	  /* At this point, TID is valid for the tunable we want.  */
+
+	  /* Apply selected filter, if any.  */
+	  switch (tec->flags & TUNCONF_FLAG_FILTER) {
+	  case TUNCONF_FILTER_PERPROC:
+	    /* Perform one-time calculations that aren't needed if we
+	       don't use this filter.  */
+	    if (prog_name_len == -1 && prog_name != NULL)
+	      {
+		const char *slash = NULL, *cp;
+		for (cp = prog_name; *cp; ++ cp)
+		  if (*cp == '/')
+		    slash = cp;
+		if (slash)
+		  prog_name = slash + 1;
+		prog_name_len = dl_strlen (prog_name);
+	      }
+	    if (memcmp (prog_name, td + tec->flag_offset, prog_name_len) != 0)
+	      goto skip_due_to_filter;
+	    break;
+	  default:
+	    break;
+	  }
+
+	  /* See if the parsed type matches the desired type.  */
 	  if (tunable_list[tid].type.type_code == TUNABLE_TYPE_STRING)
 	    {
 	      /* This is a memory leak but there's no easy way around
@@ -379,9 +403,11 @@  __tunables_init (char **envp)
 	      else
 		{
 		  tunable_initialize (& tunable_list[tid],
-				      value, dl_strlen(value));
+				      value, dl_strlen (value));
 		}
 	    }
+
+	skip_due_to_filter:
 	}
     }
 #endif
diff --git a/elf/dl-tunables.h b/elf/dl-tunables.h
index d6d1ef94bd..6424ba970c 100644
--- a/elf/dl-tunables.h
+++ b/elf/dl-tunables.h
@@ -47,7 +47,7 @@  typedef void (*tunable_callback_t) (tunable_val_t *);
 
 #include "dl-tunable-list.h"
 
-extern void __tunables_init (char **);
+extern void __tunables_init (char **, 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);
diff --git a/elf/tst-tunconf1.c b/elf/tst-tunconf1.c
new file mode 100644
index 0000000000..37e8927fa7
--- /dev/null
+++ b/elf/tst-tunconf1.c
@@ -0,0 +1,17 @@ 
+#include <stdio.h>
+
+#include "dl-tunables.h"
+
+int
+main(void)
+{
+  printf("tst-tunconf1 !\n");
+  size_t tcache_count = TUNABLE_GET_FULL (glibc, malloc, tcache_count, size_t, NULL);
+  size_t tcache_max = TUNABLE_GET_FULL (glibc, malloc, tcache_max, size_t, NULL);
+  printf("tcache count is %ld (should be 5, from env)\n", (long)tcache_count);
+  printf("tcache max is %ld (should be 4, from /etc)\n", (long)tcache_max);
+
+  
+
+  return 0;
+}
diff --git a/elf/tst-tunconf1.root/etc/tunables.conf b/elf/tst-tunconf1.root/etc/tunables.conf
new file mode 100644
index 0000000000..c08b89b4f9
--- /dev/null
+++ b/elf/tst-tunconf1.root/etc/tunables.conf
@@ -0,0 +1,2 @@ 
+glibc.malloc.tcache_max=4
+glibc.malloc.tcache_count=3
diff --git a/elf/tst-tunconf1.root/ldconfig.run b/elf/tst-tunconf1.root/ldconfig.run
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/elf/tst-tunconf1.root/postclean.req b/elf/tst-tunconf1.root/postclean.req
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/elf/tunconf.c b/elf/tunconf.c
index 9ba35326f6..147ef2a7bb 100644
--- a/elf/tunconf.c
+++ b/elf/tunconf.c
@@ -65,12 +65,14 @@  typedef enum {
 struct tunable_entry_int {
   struct stringtable_entry *name;
   struct stringtable_entry *value;
+  struct stringtable_entry *filter;
   TOP top;
   int tunable_id;
   int value_is_negative:1;
   int value_was_parsed:1;
   unsigned long long value_ull;
   signed long long value_sll;
+  long filter_flags;
 
   struct tunable_entry_int *next;
 };
@@ -78,11 +80,80 @@  struct tunable_entry_int {
 struct tunable_entry_int *entry_list;
 struct tunable_entry_int **entry_list_next = &entry_list;
 
+static int filter_flags = 0;
+static char *filter_string = NULL;
+
 /*----------------------------------------------------------------------*/
 
 static void parse_tunconf_include (const char *tunconfig_file, unsigned int lineno,
 				   bool do_chroot, const char *pattern, const char *opt_chroot);
 
+
+static void
+clear_filter (void)
+{
+  free (filter_string);
+  filter_string = NULL;
+  filter_flags = 0;
+}
+
+/* Filters are lines the are bracketed, like
+   [prog:foo]
+*/
+static void
+parse_filter (char *line, const char *filename, int lineno)
+{
+  const char *colon = NULL;
+  const char *right_bracket = NULL;
+  const char *cp;
+
+  for (cp=line; *cp != 0; cp++)
+    {
+      if (*cp == ':')
+	colon = cp;
+      if (*cp == ']')
+	{
+	  right_bracket = cp;
+	  break;
+	}
+    }
+  /* Special case: [] means "no filter" */
+  if (right_bracket != NULL && right_bracket == line + 1)
+    {
+      clear_filter ();
+      return;
+    }
+  if (colon == NULL)
+    {
+      printf("%s:%d: syntax error, filter line ignored: `%s' (missing ':')\n",
+	     filename, lineno, line);
+      return;
+    }
+  if (right_bracket == NULL)
+    {
+      printf("%s:%d: syntax error, filter line ignored: `%s' (missing ']')\n",
+	     filename, lineno, line);
+      return;
+    }
+
+  if (filter_string != NULL)
+    {
+      clear_filter ();
+    }
+
+  if (memcmp ("proc", line + 1, colon - line - 1) == 0)
+    {
+      filter_string = (char *) malloc (right_bracket - colon);
+      memcpy (filter_string, colon + 1, right_bracket - colon - 1);
+      filter_string [right_bracket - colon] = 0;
+      filter_flags = TUNCONF_FILTER_PERPROC;
+    }
+
+  else
+    printf("%s:%d: unrecognized filter `%.*s', ignored\n", filename, lineno, (int)(colon - line - 1), line + 1);
+}
+
+
 static void
 add_tunable (char *line, const char *filename, int lineno)
 {
@@ -95,11 +166,10 @@  add_tunable (char *line, const char *filename, int lineno)
   int i, id;
 
   orig_line = line;
-  printf("%s:%d: `%s'\n", filename, lineno, line);
 
   // Leading whitespace has already been stripped.
 
-  if (*line == '!' || *line == '+' || *line == '-')
+  if (*line == '!' || *line == '+' || *line == '-' || *line == '[')
     {
       switch (*line)
 	{
@@ -112,8 +182,10 @@  add_tunable (char *line, const char *filename, int lineno)
 	case '-':
 	  top = TOP_DENY;
 	  break;
+	case '[':
+	  parse_filter (line, filename, lineno);
+	  return;
 	}
-      printf("TOP: %d\n", top);
       line ++;
       while (*line && isspace(*line))
 	line ++;
@@ -177,6 +249,12 @@  add_tunable (char *line, const char *filename, int lineno)
   entry->tunable_id = id;
   entry->top = top;
 
+  if (filter_flags)
+    {
+      entry->filter_flags = filter_flags;
+      entry->filter = cache_store_string (filter_string);
+    }
+
   *entry_list_next = entry;
   entry_list_next = & (entry->next);
 }
@@ -190,6 +268,9 @@  parse_tunconf (const char *filename, int do_chroot, char *opt_chroot)
   size_t len = 0;
   unsigned int lineno;
 
+  /* Filters do not live across file boundaries.  */
+  clear_filter ();
+
   if (do_chroot && opt_chroot)
     {
       canon = chroot_canon (opt_chroot, filename);
@@ -261,6 +342,7 @@  Warning: ignoring configuration file that cannot be opened: %s"),
   /* Free buffer and close file.  */
   free (line);
   fclose (file);
+  clear_filter ();
 }
 
 /* Handle one word in an `include' line, a glob pattern of additional
@@ -392,7 +474,15 @@  get_tunconf_ext (uint32_t string_table_offset)
       tec->tunable_id = tei->tunable_id;
       tec->name_offset = tei->name->offset + string_table_offset;
       tec->value_offset = tei->value->offset + string_table_offset;
-      tec->flag_offset = 0;
+
+      if (tei->filter_flags != 0)
+	{
+	  tec->flag_offset = tei->filter->offset + string_table_offset;
+	  tec->flags |= tei->filter_flags;
+	}
+      else
+	tec->flag_offset = 0;
+
       tec->unused_1 = 0;
       if (tei->value_is_negative)
 	tec->parsed_value = (uint64_t) tei->value_sll;
diff --git a/sysdeps/mach/hurd/dl-sysdep.c b/sysdeps/mach/hurd/dl-sysdep.c
index 6ba00e413d..c6bd8c58a4 100644
--- a/sysdeps/mach/hurd/dl-sysdep.c
+++ b/sysdeps/mach/hurd/dl-sysdep.c
@@ -99,7 +99,7 @@  _dl_sysdep_start (void **start_argptr,
 
       __libc_enable_secure = _dl_hurd_data->flags & EXEC_SECURE;
 
-      __tunables_init (_environ);
+      __tunables_init (_environ, _dl_argv);
 
       /* Initialize DSO sorting algorithm after tunables.  */
       _dl_sort_maps_init ();
diff --git a/sysdeps/unix/sysv/linux/dl-sysdep.c b/sysdeps/unix/sysv/linux/dl-sysdep.c
index a8ec2d7c18..ccb6114ab6 100644
--- a/sysdeps/unix/sysv/linux/dl-sysdep.c
+++ b/sysdeps/unix/sysv/linux/dl-sysdep.c
@@ -108,7 +108,7 @@  _dl_sysdep_start (void **start_argptr,
 
   dl_hwcap_check ();
 
-  __tunables_init (_environ);
+  __tunables_init (_environ, (char **) (start_argptr + 1));
 
   /* Initialize DSO sorting algorithm after tunables.  */
   _dl_sort_maps_init ();