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Message-Id: <1585441168-23444-1-git-send-email-rcombs@rcombs.me>
Date: Sat, 28 Mar 2020 19:19:25 -0500
From: rcombs <rcombs@...mbs.me>
To: musl@...ts.openwall.com
Subject: [PATCH 1/4] ldso: add option to rewrite the argv block
---
ldso/dynlink.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/ldso/dynlink.c b/ldso/dynlink.c
index 6468f20..c378f00 100644
--- a/ldso/dynlink.c
+++ b/ldso/dynlink.c
@@ -1698,6 +1698,7 @@ void __dls3(size_t *sp, size_t *auxv)
char **argv = (void *)(sp+1);
char **argv_orig = argv;
char **envp = argv+argc+1;
+ int replace_argv = 0;
/* Find aux vector just past environ[] and use it to initialize
* global data that may be needed before we can make syscalls. */
@@ -1771,6 +1772,8 @@ void __dls3(size_t *sp, size_t *auxv)
if (opt[5]=='=') replace_argv0 = opt+6;
else if (opt[5]) *argv = 0;
else if (*argv) replace_argv0 = *argv++;
+ } else if (!memcmp(opt, "replace-argv", 12)) {
+ replace_argv = 1;
} else {
argv[0] = 0;
}
@@ -1949,6 +1952,22 @@ void __dls3(size_t *sp, size_t *auxv)
debug.state = 0;
_dl_debug_state();
+ if (replace_argv) {
+ char *argv_end = argv_orig[0];
+ char *orig_ptr = argv_orig[0];
+ int i;
+ for (i = 0; i < (int)(argc - (argv-argv_orig)); i++) {
+ char *src = (i == 0 && replace_argv0) ? replace_argv0 : argv[i];
+ int len = strlen(src) + 1;
+ memmove(orig_ptr, src, len);
+ argv_end = argv[i] + strlen(argv[i]);
+ argv[i] = orig_ptr;
+ orig_ptr += len;
+ }
+ for (; orig_ptr < argv_end; orig_ptr++)
+ *orig_ptr = 0;
+ }
+
if (replace_argv0) argv[0] = replace_argv0;
errno = 0;
--
2.7.4
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