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From 7bd77a63f226a572946f30db3e76f23f971f46d5 Mon Sep 17 00:00:00 2001
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From: Jakub Filak <jfilak@redhat.com>
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Date: Wed, 20 May 2015 06:07:15 +0200
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Subject: [ABRT PATCH] ccpp: do not unlink failed and big user cores
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* We might end up deleting an already existing file.
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* Kernel does not delete nor truncate core files. Admittedly, kernel
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  knows how process's memory is structured, dumps it per logical
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  segments and checks whether a next segment can be written.
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* 'ulimit -c' does not seem to be a hard limit. Kernel wrote 8192 bytes
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  despite $(ulimit -c) == 6.
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Related: #1212818
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Signed-off-by: Jakub Filak <jfilak@redhat.com>
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---
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 src/hooks/abrt-hook-ccpp.c | 70 +++++++++++++++++++---------------------------
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 1 file changed, 29 insertions(+), 41 deletions(-)
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diff --git a/src/hooks/abrt-hook-ccpp.c b/src/hooks/abrt-hook-ccpp.c
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index fdd9b06..9b38ed7 100644
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--- a/src/hooks/abrt-hook-ccpp.c
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+++ b/src/hooks/abrt-hook-ccpp.c
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@@ -129,8 +129,8 @@ static off_t copyfd_sparse(int src_fd, int dst_fd1, int dst_fd2, off_t size2)
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 		size2 -= rd;
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 		if (size2 < 0)
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 			dst_fd2 = -1;
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-//TODO: truncate to 0 or even delete the second file
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-//(currently we delete the file later)
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+// truncate to 0 or even delete the second file?
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+// No, kernel does not delete nor truncate core files.
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 	}
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  out:
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@@ -502,13 +502,20 @@ static int open_user_core(uid_t uid, uid_t fsuid, pid_t pid, char **percent_valu
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 user_core_fail:
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     if (user_core_fd >= 0)
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-    {
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         close(user_core_fd);
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-        unlinkat(dirfd(proc_cwd), core_basename, /*unlink file*/0);
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-    }
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     return -1;
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 }
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+static int close_user_core(int user_core_fd, off_t core_size)
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+{
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+    if (user_core_fd >= 0 && (fsync(user_core_fd) != 0 || close(user_core_fd) != 0 || core_size < 0))
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+    {
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+        perror_msg("Error writing '%s' at '%s'", core_basename, user_pwd);
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+        return -1;
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+    }
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+    return 0;
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+}
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+
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 static bool dump_fd_info(const char *dest_filename, char *source_filename, int source_base_ofs, uid_t uid, gid_t gid)
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 {
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     FILE *fp = fopen(dest_filename, "wx");
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@@ -569,7 +576,7 @@ static int create_or_die(const char *filename)
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     if (dd)
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         dd_delete(dd);
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     if (user_core_fd >= 0)
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-        unlinkat(dirfd(proc_cwd), core_basename, /*unlink file*/0);
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+        close(user_core_fd);
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     errno = sv_errno;
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     perror_msg_and_die("Can't open '%s'", filename);
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@@ -577,6 +584,7 @@ static int create_or_die(const char *filename)
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 int main(int argc, char** argv)
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 {
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+    int err = 1;
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     /* Kernel starts us with all fd's closed.
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      * But it's dangerous:
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      * fprintf(stderr) can dump messages into random fds, etc.
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@@ -778,9 +786,8 @@ int main(int argc, char** argv)
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             error_msg_and_die("Error saving '%s'", path);
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         }
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         log("Saved core dump of pid %lu (%s) to %s (%llu bytes)", (long)pid, executable, path, (long long)core_size);
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-        if (proc_cwd != NULL)
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-            closedir(proc_cwd);
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-        return 0;
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+        err = 0;
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+        goto finito;
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     }
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     unsigned path_len = snprintf(path, sizeof(path), "%s/ccpp-%s-%lu.new",
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@@ -895,26 +902,17 @@ int main(int argc, char** argv)
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          * ls: cannot access core*: No such file or directory <=== BAD
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          */
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         off_t core_size = copyfd_sparse(STDIN_FILENO, abrt_core_fd, user_core_fd, ulimit_c);
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+
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+        close_user_core(user_core_fd, core_size);
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+
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         if (fsync(abrt_core_fd) != 0 || close(abrt_core_fd) != 0 || core_size < 0)
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         {
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             unlink(path);
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             dd_delete(dd);
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-            if (user_core_fd >= 0)
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-                unlinkat(dirfd(proc_cwd), core_basename, /*unlink file*/0);
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             /* copyfd_sparse logs the error including errno string,
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              * but it does not log file name */
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             error_msg_and_die("Error writing '%s'", path);
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         }
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-        if (user_core_fd >= 0
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-            /* error writing user coredump? */
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-         && (fsync(user_core_fd) != 0 || close(user_core_fd) != 0
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-            /* user coredump is too big? */
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-            || (ulimit_c == 0 /* paranoia */ || core_size > ulimit_c)
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-            )
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-        ) {
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-            /* nuke it (silently) */
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-            unlinkat(dirfd(proc_cwd), core_basename, /*unlink file*/0);
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-        }
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 /* Because of #1211835 and #1126850 */
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 #if 0
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@@ -984,9 +982,9 @@ int main(int argc, char** argv)
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         }
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         free(rootdir);
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-        if (proc_cwd != NULL)
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-            closedir(proc_cwd);
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-        return 0;
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+
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+        err = 0;
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+        goto finito;
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     }
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     /* We didn't create abrt dump, but may need to create compat coredump */
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@@ -994,26 +992,16 @@ int main(int argc, char** argv)
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     if (user_core_fd >= 0)
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     {
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         off_t core_size = copyfd_size(STDIN_FILENO, user_core_fd, ulimit_c, COPYFD_SPARSE);
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-        if (fsync(user_core_fd) != 0 || close(user_core_fd) != 0 || core_size < 0)
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-        {
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-            /* perror first, otherwise unlink may trash errno */
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-            perror_msg("Error writing '%s' at '%s'", core_basename, user_pwd);
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-            unlinkat(dirfd(proc_cwd), core_basename, /*unlink file*/0);
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-            if (proc_cwd != NULL)
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-                closedir(proc_cwd);
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-            return 1;
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-        }
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-        if (ulimit_c == 0 || core_size > ulimit_c)
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-        {
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-            unlinkat(dirfd(proc_cwd), core_basename, /*unlink file*/0);
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-            if (proc_cwd != NULL)
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-                closedir(proc_cwd);
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-            return 1;
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-        }
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+        if (close_user_core(user_core_fd, core_size) != 0)
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+            goto finito;
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+
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+        err = 0;
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         log("Saved core dump of pid %lu to %s at %s (%llu bytes)", (long)pid, core_basename, user_pwd, (long long)core_size);
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     }
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+ finito:
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     if (proc_cwd != NULL)
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         closedir(proc_cwd);
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-    return 0;
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+
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+    return err;
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 }
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-- 
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1.8.3.1
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