The branch main has been updated by kevans:
URL:
https://cgit.FreeBSD.org/src/commit/?id=3ce3b342db7e5c987e5eee039f7b290a3919ca37
commit 3ce3b342db7e5c987e5eee039f7b290a3919ca37
Author: Kyle Evans <kev...@freebsd.org>
AuthorDate: 2025-07-22 16:49:52 +0000
Commit: Kyle Evans <kev...@freebsd.org>
CommitDate: 2025-07-26 21:31:42 +0000
kern: add some better error messages for coredump() failures
After debugging with a user on discord why their process is not
generating coredumps, it became clear that we can use better error
messages -- particularly to distinguish between the different EFAULT
cases. For those that are denied by system policies, include some
more specific pointers to the relevant knob.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D51465
---
sys/kern/kern_ucoredump.c | 57 ++++++++++++++++++++++++++++-------------------
1 file changed, 34 insertions(+), 23 deletions(-)
diff --git a/sys/kern/kern_ucoredump.c b/sys/kern/kern_ucoredump.c
index a2412bf06441..d425596b5f24 100644
--- a/sys/kern/kern_ucoredump.c
+++ b/sys/kern/kern_ucoredump.c
@@ -51,7 +51,7 @@
#include <sys/ucoredump.h>
#include <sys/wait.h>
-static int coredump(struct thread *td);
+static int coredump(struct thread *td, const char **);
int compress_user_cores = 0;
@@ -135,7 +135,6 @@ void
sigexit(struct thread *td, int sig)
{
struct proc *p = td->td_proc;
- const char *coreinfo;
int rv;
bool logexit;
@@ -158,6 +157,8 @@ sigexit(struct thread *td, int sig)
* (e.g. via fork()), we won't get a dump at all.
*/
if (sig_do_core(sig) && thread_single(p, SINGLE_NO_EXIT) == 0) {
+ const char *err = NULL;
+
p->p_sig = sig;
/*
* Log signals which would cause core dumps
@@ -166,32 +167,34 @@ sigexit(struct thread *td, int sig)
* XXX : Todo, as well as euid, write out ruid too
* Note that coredump() drops proc lock.
*/
- rv = coredump(td);
- switch (rv) {
- case 0:
+ rv = coredump(td, &err);
+ if (rv == 0) {
+ MPASS(err == NULL);
sig |= WCOREFLAG;
- coreinfo = " (core dumped)";
- break;
- case EFAULT:
- coreinfo = " (no core dump - bad address)";
- break;
- case EINVAL:
- coreinfo = " (no core dump - invalid argument)";
- break;
- case EFBIG:
- coreinfo = " (no core dump - too large)";
- break;
- default:
- coreinfo = " (no core dump - other error)";
- break;
+ } else if (err == NULL) {
+ switch (rv) {
+ case EFAULT:
+ err = "bad address";
+ break;
+ case EINVAL:
+ err = "invalild argument";
+ break;
+ case EFBIG:
+ err = "too large";
+ break;
+ default:
+ err = "other error";
+ break;
+ }
}
if (logexit)
log(LOG_INFO,
"pid %d (%s), jid %d, uid %d: exited on "
- "signal %d%s\n", p->p_pid, p->p_comm,
+ "signal %d (%s%s)\n", p->p_pid, p->p_comm,
p->p_ucred->cr_prison->pr_id,
- td->td_ucred->cr_uid,
- sig &~ WCOREFLAG, coreinfo);
+ td->td_ucred->cr_uid, sig &~ WCOREFLAG,
+ err != NULL ? "no core dump - " : "core dumped",
+ err != NULL ? err : "");
} else
PROC_UNLOCK(p);
exit1(td, 0, sig);
@@ -207,7 +210,7 @@ sigexit(struct thread *td, int sig)
* ENOSYS; otherwise it returns the error from the process-specific routine.
*/
static int
-coredump(struct thread *td)
+coredump(struct thread *td, const char **errmsg)
{
struct coredumper *iter, *chosen;
struct proc *p = td->td_proc;
@@ -221,6 +224,13 @@ coredump(struct thread *td)
if (!do_coredump || (!sugid_coredump && (p->p_flag & P_SUGID) != 0) ||
(p->p_flag2 & P2_NOTRACE) != 0) {
PROC_UNLOCK(p);
+
+ if (!do_coredump)
+ *errmsg = "denied by kern.coredump";
+ else if ((p->p_flag2 & P2_NOTRACE) != 0)
+ *errmsg = "process has trace disabled";
+ else
+ *errmsg = "sugid process denied by kern.sugid_coredump";
return (EFAULT);
}
@@ -235,6 +245,7 @@ coredump(struct thread *td)
limit = (off_t)lim_cur(td, RLIMIT_CORE);
if (limit == 0 || racct_get_available(p, RACCT_CORE) == 0) {
PROC_UNLOCK(p);
+ *errmsg = "coredumpsize limit is 0";
return (EFBIG);
}
