From 23ed36735af09c258e542266aaed92cdd8571c6c Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Thu, 16 Jul 2020 16:21:28 +0200
Subject: nss_compat: Do not use mmap to read database files (bug 26258)

This avoids crashes in case the files are truncated for some reason.
For typically file sizes, it is also going to be slightly faster.
Using __nss_files_fopen instead mirrors what nss_files does.

Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
---
 nss/nss_compat/compat-grp.c        | 6 ++----
 nss/nss_compat/compat-initgroups.c | 6 ++----
 nss/nss_compat/compat-pwd.c        | 6 ++----
 nss/nss_compat/compat-spwd.c       | 6 ++----
 4 files changed, 8 insertions(+), 16 deletions(-)

(limited to 'nss')

diff --git a/nss/nss_compat/compat-grp.c b/nss/nss_compat/compat-grp.c
index d4f750b95c..510d49e8c7 100644
--- a/nss/nss_compat/compat-grp.c
+++ b/nss/nss_compat/compat-grp.c
@@ -26,6 +26,7 @@
 #include <string.h>
 #include <libc-lock.h>
 #include <kernel-features.h>
+#include <nss_files.h>
 
 NSS_DECLARE_MODULE_FUNCTIONS (compat)
 
@@ -108,13 +109,10 @@ internal_setgrent (ent_t *ent, int stayopen, int needent)
 
   if (ent->stream == NULL)
     {
-      ent->stream = fopen ("/etc/group", "rme");
+      ent->stream = __nss_files_fopen ("/etc/group");
 
       if (ent->stream == NULL)
 	status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;
-      else
-	/* We take care of locking ourself.  */
-	__fsetlocking (ent->stream, FSETLOCKING_BYCALLER);
     }
   else
     rewind (ent->stream);
diff --git a/nss/nss_compat/compat-initgroups.c b/nss/nss_compat/compat-initgroups.c
index 3671bef48b..c0dcdf839d 100644
--- a/nss/nss_compat/compat-initgroups.c
+++ b/nss/nss_compat/compat-initgroups.c
@@ -29,6 +29,7 @@
 #include <libc-lock.h>
 #include <kernel-features.h>
 #include <scratch_buffer.h>
+#include <nss_files.h>
 
 NSS_DECLARE_MODULE_FUNCTIONS (compat)
 
@@ -122,13 +123,10 @@ internal_setgrent (ent_t *ent)
   else
     ent->blacklist.current = 0;
 
-  ent->stream = fopen ("/etc/group", "rme");
+  ent->stream = __nss_files_fopen ("/etc/group");
 
   if (ent->stream == NULL)
     status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;
-  else
-    /* We take care of locking ourself.  */
-    __fsetlocking (ent->stream, FSETLOCKING_BYCALLER);
 
   return status;
 }
diff --git a/nss/nss_compat/compat-pwd.c b/nss/nss_compat/compat-pwd.c
index 394e39b811..3a212a0dab 100644
--- a/nss/nss_compat/compat-pwd.c
+++ b/nss/nss_compat/compat-pwd.c
@@ -27,6 +27,7 @@
 #include <string.h>
 #include <libc-lock.h>
 #include <kernel-features.h>
+#include <nss_files.h>
 
 #include "netgroup.h"
 #include "nisdomain.h"
@@ -223,13 +224,10 @@ internal_setpwent (ent_t *ent, int stayopen, int needent)
 
   if (ent->stream == NULL)
     {
-      ent->stream = fopen ("/etc/passwd", "rme");
+      ent->stream = __nss_files_fopen ("/etc/passwd");
 
       if (ent->stream == NULL)
 	status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;
-      else
-	/* We take care of locking ourself.  */
-	__fsetlocking (ent->stream, FSETLOCKING_BYCALLER);
     }
   else
     rewind (ent->stream);
diff --git a/nss/nss_compat/compat-spwd.c b/nss/nss_compat/compat-spwd.c
index ec5bf283cd..d802ee0302 100644
--- a/nss/nss_compat/compat-spwd.c
+++ b/nss/nss_compat/compat-spwd.c
@@ -27,6 +27,7 @@
 #include <string.h>
 #include <libc-lock.h>
 #include <kernel-features.h>
+#include <nss_files.h>
 
 #include "netgroup.h"
 #include "nisdomain.h"
@@ -179,13 +180,10 @@ internal_setspent (ent_t *ent, int stayopen, int needent)
 
   if (ent->stream == NULL)
     {
-      ent->stream = fopen ("/etc/shadow", "rme");
+      ent->stream = __nss_files_fopen ("/etc/shadow");
 
       if (ent->stream == NULL)
 	status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;
-      else
-	/* We take care of locking ourself.  */
-	__fsetlocking (ent->stream, FSETLOCKING_BYCALLER);
     }
   else
     rewind (ent->stream);
-- 
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