File 59de05ba-libxl-userlookup_helper_getpwnam.patch of Package xen

Overview Repositories Revisions Requests Users Attributes Meta

File 59de05ba-libxl-userlookup_helper_getpwnam.patch of Package xen (Revision 32c66e2a7e6b1648f2747f3d0ae55290)

Currently displaying revision 32c66e2a7e6b1648f2747f3d0ae55290 , Show latest

# Commit c9616d74b7f672ceaa383226531a4965228b13f1
# Date 2017-10-11 12:51:22 +0100
# Author Ian Jackson <ian.jackson@eu.citrix.com>
# Committer Ian Jackson <Ian.Jackson@eu.citrix.com>
libxl: userlookup_helper_getpwnam rename and turn into a macro

We are going to want versions of getpwuid, too.  And maybe in the
future getgr*.

This is most sanely achieved with a macro, as otherwise the types are
a mess.

Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>

# Commit 6cde84a81b157828ec421f84b8c7fb1b649a7306
# Date 2017-10-13 11:31:59 +0100
# Author Ian Jackson <ian.jackson@eu.citrix.com>
# Committer Ian Jackson <Ian.Jackson@eu.citrix.com>
libxl: dm_restrict: DEFINE_USERLOOKUP_HELPER returned a pointer to an auto

When I converted the previous open-coded user lookup functionality
into DEFINE_USERLOOKUP_HELPER, I moved the struct passwd buffer into
the function generated by the macro.  This is wrong because that
buffer is used by get{pw,gr}* for its return value, so the helper
function would contrive to return a pointer to the buffer on its own
stack.

Fix this by adding a buffer parameter to the generated helpers, that
the caller must supply, and updating all the call sites.

Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>

--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -729,39 +729,49 @@ libxl__detect_gfx_passthru_kind(libxl__g
     return LIBXL_GFX_PASSTHRU_KIND_DEFAULT;
 }
 
-/* return 1 if the user was found, 0 if it was not, -1 on error */
-static int libxl__dm_runas_helper(libxl__gc *gc, const char *username,
-                                       struct passwd **pwd_r)
-{
-    struct passwd pwd, *user = NULL;
-    char *buf = NULL;
-    long buf_size;
-    int ret;
-
-    buf_size = sysconf(_SC_GETPW_R_SIZE_MAX);
-    if (buf_size < 0) {
-        buf_size = 2048;
-        LOG(DEBUG,
-"sysconf(_SC_GETPW_R_SIZE_MAX) failed, setting the initial buffer size to %ld",
-            buf_size);
-    }
-
-    while (1) {
-        buf = libxl__realloc(gc, buf, buf_size);
-        ret = getpwnam_r(username, &pwd, buf, buf_size, &user);
-        if (ret == ERANGE) {
-            buf_size += 128;
-            continue;
-        }
-        if (ret != 0)
-            return ERROR_FAIL;
-        if (user != NULL) {
-            if (pwd_r) *pwd_r = pwd;
-            return 1;
-        }
-        return 0;
+/*
+ *  userlookup_helper_getpwnam(libxl__gc*, const char *user,
+ *                             struct passwd **pwd_r);
+ *
+ *  returns 1 if the user was found, 0 if it was not, -1 on error
+ */
+#define DEFINE_USERLOOKUP_HELPER(NAME,SPEC_TYPE,STRUCTNAME,SYSCONF)     \
+    static int userlookup_helper_##NAME(libxl__gc *gc,                  \
+                                        SPEC_TYPE spec,                 \
+                                        struct STRUCTNAME *resultbuf,   \
+                                        struct STRUCTNAME **out)        \
+    {                                                                   \
+        struct STRUCTNAME *resultp = NULL;                              \
+        char *buf = NULL;                                               \
+        long buf_size;                                                  \
+        int ret;                                                        \
+                                                                        \
+        buf_size = sysconf(SYSCONF);                                    \
+        if (buf_size < 0) {                                             \
+            buf_size = 2048;                                            \
+            LOG(DEBUG,                                                  \
+    "sysconf failed, setting the initial buffer size to %ld",           \
+                buf_size);                                              \
+        }                                                               \
+                                                                        \
+        while (1) {                                                     \
+            buf = libxl__realloc(gc, buf, buf_size);                    \
+            ret = NAME##_r(spec, resultbuf, buf, buf_size, &resultp);   \
+            if (ret == ERANGE) {                                        \
+                buf_size += 128;                                        \
+                continue;                                               \
+            }                                                           \
+            if (ret != 0)                                               \
+                return ERROR_FAIL;                                      \
+            if (resultp != NULL) {                                      \
+                if (out) *out = resultp;                                \
+                return 1;                                               \
+            }                                                           \
+            return 0;                                                   \
+        }                                                               \
     }
-}
+
+DEFINE_USERLOOKUP_HELPER(getpwnam, const char*, passwd, _SC_GETPW_R_SIZE_MAX);
 
 /* colo mode */
 enum {
@@ -926,6 +936,7 @@ static int libxl__build_device_model_arg
     uint64_t ram_size;
     const char *path, *chardev;
     char *user = NULL;
+    struct passwd user_pwbuf;
 
     dm_args = flexarray_make(gc, 16, 1);
     dm_envs = flexarray_make(gc, 16, 1);
@@ -1620,14 +1631,14 @@ static int libxl__build_device_model_arg
         }
 
         user = GCSPRINTF("%s%d", LIBXL_QEMU_USER_BASE, guest_domid);
-        ret = libxl__dm_runas_helper(gc, user, 0);
+        ret = userlookup_helper_getpwnam(gc, user, &user_pwbuf, 0);
         if (ret < 0)
             return ret;
         if (ret > 0)
             goto end_search;
 
         user = LIBXL_QEMU_USER_SHARED;
-        ret = libxl__dm_runas_helper(gc, user, 0);
+        ret = userlookup_helper_getpwnam(gc, user, &user_pwbuf, 0);
         if (ret < 0)
             return ret;
         if (ret > 0) {

Places

File 59de05ba-libxl-userlookup_helper_getpwnam.patch of Package xen (Revision 32c66e2a7e6b1648f2747f3d0ae55290)

Places