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common: explain why mlock() failed instead of a bare abort #9438

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common: explain why mlock() failed instead of a bare abort #9438

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18 changes: 17 additions & 1 deletion common/utils.c
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,8 @@
#include <errno.h>
#include <locale.h>
#include <sodium.h>
#include <stdio.h>
#include <string.h>

const tal_t *wally_tal_ctx = NULL;
secp256k1_context *secp256k1_ctx;
Expand Down Expand Up @@ -100,8 +102,22 @@ static void destroy_munlock(const tal_t *ptr)

void mlock_tal_memory(const tal_t *ptr)
{
if (sodium_mlock((void *)ptr, tal_bytelen(ptr)) != 0)

@Andezion Andezion Aug 20, 2026

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daemon_setup() already calls err_set_progname(argv0) (via common_setup) before mlock_tal_memory() can run. Did you consider using ccan warn()/warnx() instead of a hand-rolled fprintf + strerror, so the message gets the daemon-name prefix for free and matches the warnx() call in crashdump() that immediately follows it on the same failure path?

if (sodium_mlock((void *)ptr, tal_bytelen(ptr)) != 0) {
fprintf(stderr,
"FATAL: could not lock %zu bytes of sensitive memory"
" into RAM: %s\n"
"Memory locking is required to keep secrets out of"
" swap.\n"
"If you are running in a container or jail, the"
" privilege must be granted:\n"
" FreeBSD jail: set allow.mlock=1 for the jail\n"
" Linux: raise RLIMIT_MEMLOCK (ulimit -l), or grant"
" the CAP_IPC_LOCK capability\n"
" Docker/Podman: --ulimit memlock=-1:-1 or"
" --cap-add=IPC_LOCK\n",
tal_bytelen(ptr), strerror(errno));
abort();
}
tal_add_destructor(ptr, destroy_munlock);
}

Expand Down