[PATCH -mm] coredump: add support for %d=__get_dumpable() in corename

From: Oleg Nesterov
Date: Thu Sep 13 2012 - 13:26:22 EST


Some coredump handlers want to create a core file in a way compatible
with standard behavior. Standard behavior with fs.suid_dumpable = 2
is to create core file with uid=gid=0. However, there was no way for
coredump handler to know that the process being dumped was suid'ed.

This patch adds the new %d specifier for format_corename() which
simply reports __get_dumpable(mm->flags), this is compatible with
/proc/sys/fs/suid_dumpable we already have.

By-discussion-with: Denys Vlasenko <vda.linux@xxxxxxxxxxxxxx>
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
fs/coredump.c | 10 +++++++---
1 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/coredump.c b/fs/coredump.c
index 1935b4d..aad8715 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -149,7 +149,7 @@ put_exe_file:
* name into corename, which must have space for at least
* CORENAME_MAX_SIZE bytes plus one byte for the zero terminator.
-static int format_corename(struct core_name *cn, long signr)
+static int format_corename(struct core_name *cn, struct coredump_params *cprm)
const struct cred *cred = current_cred();
const char *pat_ptr = core_pattern;
@@ -194,9 +194,13 @@ static int format_corename(struct core_name *cn, long signr)
case 'g':
err = cn_printf(cn, "%d", cred->gid);
+ case 'd':
+ err = cn_printf(cn, "%d",
+ __get_dumpable(cprm->mm_flags));
+ break;
/* signal that caused the coredump */
case 's':
- err = cn_printf(cn, "%ld", signr);
+ err = cn_printf(cn, "%ld", cprm->signr);
/* UNIX time of coredump */
case 't': {
@@ -524,7 +528,7 @@ void do_coredump(long signr, int exit_code, struct pt_regs *regs)

- ispipe = format_corename(&cn, signr);
+ ispipe = format_corename(&cn, &cprm);

if (ispipe) {
int dump_count;

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