From 0516cbbb356ca0bfd3faf7accb36c60fc5da89d7 Mon Sep 17 00:00:00 2001

From: Jakub Filak <jfilak@redhat.com>

Date: Fri, 17 Apr 2015 14:36:45 +0200

Subject: [PATCH] ccpp: do not override existing files by compat cores

Implement all checks used in kernel's do_coredump() and require

non-relative path if suid_dumpable is 2.

Related: #1212818

Signed-off-by: Jakub Filak <jfilak@redhat.com>

---

 src/hooks/abrt-hook-ccpp.c | 20 ++++++++++++++++----

 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/src/hooks/abrt-hook-ccpp.c b/src/hooks/abrt-hook-ccpp.c

index f77a23f..b481421 100644

--- a/src/hooks/abrt-hook-ccpp.c

+++ b/src/hooks/abrt-hook-ccpp.c

@@ -26,6 +26,8 @@

 #include <satyr/utils.h>

 #endif /* ENABLE_DUMP_TIME_UNWIND */

+static int g_user_core_flags;

+static int g_need_nonrelative;

 /* I want to use -Werror, but gcc-4.4 throws a curveball:

  * "warning: ignoring return value of 'ftruncate', declared with attribute warn_unused_result"

@@ -227,7 +229,14 @@ static int open_user_core(uid_t uid, uid_t fsuid, pid_t pid, char **percent_valu

     full_core_basename = core_basename;

     if (core_basename[0] != '/')

+    {

+        if (g_need_nonrelative)

+        {

+            error_msg("Current suid_dumpable policy prevents from saving core dumps according to relative core_pattern");

+            return -1;

+        }

         core_basename = concat_path_file(user_pwd, core_basename);

+    }

     /* Open (create) compat core file.

      * man core:

@@ -262,19 +271,19 @@ static int open_user_core(uid_t uid, uid_t fsuid, pid_t pid, char **percent_valu

     struct stat sb;

     errno = 0;

     /* Do not O_TRUNC: if later checks fail, we do not want to have file already modified here */

-    int user_core_fd = open(core_basename, O_WRONLY | O_CREAT | O_NOFOLLOW, 0600); /* kernel makes 0600 too */

+    int user_core_fd = open(core_basename, O_WRONLY | O_CREAT | O_NOFOLLOW | g_user_core_flags, 0600); /* kernel makes 0600 too */

     xsetegid(0);

     xseteuid(0);

     if (user_core_fd < 0

      || fstat(user_core_fd, &sb) != 0

      || !S_ISREG(sb.st_mode)

      || sb.st_nlink != 1

-    /* kernel internal dumper checks this too: if (inode->i_uid != current->fsuid) <fail>, need to mimic? */

+     || sb.st_uid != fsuid

     ) {

         if (user_core_fd < 0)

             perror_msg("Can't open '%s'", full_core_basename);

         else

-            perror_msg("'%s' is not a regular file with link count 1", full_core_basename);

+            perror_msg("'%s' is not a regular file with link count 1 owned by UID(%d)", full_core_basename, fsuid);

         return -1;

     }

     if (ftruncate(user_core_fd, 0) != 0) {

@@ -518,8 +527,11 @@ int main(int argc, char** argv)

         /* use root for suided apps unless it's explicitly set to UNSAFE */

         fsuid = 0;

         if (suid_policy == DUMP_SUID_UNSAFE)

-        {

             fsuid = tmp_fsuid;

+        else

+        {

+            g_user_core_flags = O_EXCL;

+            g_need_nonrelative = 1;

         }

     }

-- 

2.1.0