isisd: suppress maybe uninitialized warnings

[mirror_frr.git] / lib / privs.h

diff --git a/lib/privs.h b/lib/privs.h
index 9a5eb3bd6cec8c8723b44eb260291f88cd001033..b061370b753d2ce2bc88b39699ede003175cb645 100644 (file)
--- a/lib/privs.h
+++ b/lib/privs.h
@@ -1,4 +1,4 @@
-/* 
+/*
  * Zebra privileges header.
  *
  * Copyright (C) 2003 Paul Jakma.
@@ -24,66 +24,100 @@
 #define _ZEBRA_PRIVS_H
 
 /* list of zebra capabilities */
-typedef enum 
-{
-  ZCAP_SETID,
-  ZCAP_BIND,
-  ZCAP_NET_ADMIN,
-  ZCAP_SYS_ADMIN,
-  ZCAP_NET_RAW,
-  ZCAP_CHROOT,
-  ZCAP_NICE,
-  ZCAP_PTRACE,
-  ZCAP_DAC_OVERRIDE,
-  ZCAP_READ_SEARCH,
-  ZCAP_FOWNER,
-  ZCAP_MAX
+typedef enum {
+       ZCAP_SETID,
+       ZCAP_BIND,
+       ZCAP_NET_ADMIN,
+       ZCAP_SYS_ADMIN,
+       ZCAP_NET_RAW,
+       ZCAP_CHROOT,
+       ZCAP_NICE,
+       ZCAP_PTRACE,
+       ZCAP_DAC_OVERRIDE,
+       ZCAP_READ_SEARCH,
+       ZCAP_FOWNER,
+       ZCAP_MAX
 } zebra_capabilities_t;
 
-typedef enum
-{
-  ZPRIVS_LOWERED,
-  ZPRIVS_RAISED,
-  ZPRIVS_UNKNOWN,
+typedef enum {
+       ZPRIVS_LOWERED,
+       ZPRIVS_RAISED,
+       ZPRIVS_UNKNOWN,
 } zebra_privs_current_t;
 
-typedef enum
-{
-  ZPRIVS_RAISE,
-  ZPRIVS_LOWER,
+typedef enum {
+       ZPRIVS_RAISE,
+       ZPRIVS_LOWER,
 } zebra_privs_ops_t;
 
-struct zebra_privs_t
-{
-  zebra_capabilities_t *caps_p;       /* caps required for operation */
-  zebra_capabilities_t *caps_i;       /* caps to allow inheritance of */
-  int cap_num_p;                      /* number of caps in arrays */
-  int cap_num_i;                    
-  const char *user;                   /* user and group to run as */
-  const char *group;
-  const char *vty_group;              /* group to chown vty socket to */
-  /* methods */
-  int 
-    (*change) (zebra_privs_ops_t);    /* change privileges, 0 on success */
-  zebra_privs_current_t 
-    (*current_state) (void);          /* current privilege state */
+struct zebra_privs_t {
+       zebra_capabilities_t *caps_p; /* caps required for operation */
+       zebra_capabilities_t *caps_i; /* caps to allow inheritance of */
+       int cap_num_p;                /* number of caps in arrays */
+       int cap_num_i;
+       const char *user; /* user and group to run as */
+       const char *group;
+       const char *vty_group; /* group to chown vty socket to */
+       /* methods */
+       int (*change)(zebra_privs_ops_t); /* change privileges, 0 on success */
+       zebra_privs_current_t (*current_state)(
+               void); /* current privilege state */
+       const char *raised_in_funcname;
 };
 
-struct zprivs_ids_t
-{
-  /* -1 is undefined */
-  uid_t uid_priv;                     /* privileged uid */
-  uid_t uid_normal;                   /* normal uid */
-  gid_t gid_priv;                     /* privileged uid */
-  gid_t gid_normal;                   /* normal uid */
-  gid_t gid_vty;                      /* vty gid */
+struct zprivs_ids_t {
+       /* -1 is undefined */
+       uid_t uid_priv;   /* privileged uid */
+       uid_t uid_normal; /* normal uid */
+       gid_t gid_priv;   /* privileged uid */
+       gid_t gid_normal; /* normal uid */
+       gid_t gid_vty;    /* vty gid */
 };
 
-  /* initialise zebra privileges */
-extern void zprivs_init (struct zebra_privs_t *zprivs);
-  /* drop all and terminate privileges */ 
-extern void zprivs_terminate (struct zebra_privs_t *);
-  /* query for runtime uid's and gid's, eg vty needs this */
+/* initialise zebra privileges */
+extern void zprivs_preinit(struct zebra_privs_t *zprivs);
+extern void zprivs_init(struct zebra_privs_t *zprivs);
+/* drop all and terminate privileges */
+extern void zprivs_terminate(struct zebra_privs_t *);
+/* query for runtime uid's and gid's, eg vty needs this */
 extern void zprivs_get_ids(struct zprivs_ids_t *);
 
+/*
+ * Wrapper around zprivs, to be used as:
+ *   frr_elevate_privs(&privs) {
+ *     ... code ...
+ *     if (error)
+ *       break;         -- break can be used to get out of the block
+ *     ... code ...
+ *   }
+ *
+ * The argument to frr_elevate_privs() can be NULL to leave privileges as-is
+ * (mostly useful for conditional privilege-raising, i.e.:)
+ *   frr_elevate_privs(cond ? &privs : NULL) {}
+ *
+ * NB: The code block is always executed, regardless of whether privileges
+ * could be raised or not, or whether NULL was given or not.  This is fully
+ * intentional;  the user may have configured some RBAC or similar that we
+ * are not aware of, but that allows our code to proceed without privileges.
+ *
+ * The point of this wrapper is to prevent accidental bugs where privileges
+ * are elevated but then not dropped.  This can happen when, for example, a
+ * "return", "goto" or "break" in the middle of the elevated-privilege code
+ * skips past the privilege dropping call.
+ *
+ * The macro below uses variable cleanup to drop privileges as soon as the
+ * code block is left in any way (and thus the _privs variable goes out of
+ * scope.)  _once is just a trick to run the loop exactly once.
+ */
+extern struct zebra_privs_t *_zprivs_raise(struct zebra_privs_t *privs,
+                                          const char *funcname);
+extern void _zprivs_lower(struct zebra_privs_t **privs);
+
+#define frr_elevate_privs(privs)                                               \
+       for (struct zebra_privs_t *_once = NULL,                               \
+                                 *_privs __attribute__(                       \
+                                         (unused, cleanup(_zprivs_lower))) =  \
+                                         _zprivs_raise(privs, __func__);      \
+            _once == NULL; _once = (void *)1)
+
 #endif /* _ZEBRA_PRIVS_H */