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=== Description (from pull-request) ===
Signed-off-by: Christian Brauner <christian.brau...@ubuntu.com>
From 0c816b346788afa9d601766e31544fdcce67d780 Mon Sep 17 00:00:00 2001
From: Christian Brauner <christian.brau...@ubuntu.com>
Date: Wed, 13 Feb 2019 23:08:11 +0100
Subject: [PATCH] rexec: remove needless /proc/cmdline parsing
Signed-off-by: Christian Brauner <christian.brau...@ubuntu.com>
---
src/lxc/rexec.c | 70 +++-----------------------------------
src/lxc/rexec.h | 2 +-
src/lxc/tools/lxc_attach.c | 4 +--
3 files changed, 8 insertions(+), 68 deletions(-)
diff --git a/src/lxc/rexec.c b/src/lxc/rexec.c
index 024728d85..17e1806fe 100644
--- a/src/lxc/rexec.c
+++ b/src/lxc/rexec.c
@@ -25,6 +25,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
+#include <unistd.h>
#include "config.h"
#include "file_utils.h"
@@ -39,58 +40,6 @@
#define LXC_MEMFD_REXEC_SEALS \
(F_SEAL_SEAL | F_SEAL_SHRINK | F_SEAL_GROW | F_SEAL_WRITE)
-static int push_vargs(char *data, int data_length, char ***output)
-{
- int num = 0;
- char *cur = data;
-
- if (!data || *output)
- return -1;
-
- *output = must_realloc(NULL, sizeof(**output));
-
- while (cur < data + data_length) {
- num++;
- *output = must_realloc(*output, (num + 1) * sizeof(**output));
-
- (*output)[num - 1] = cur;
- cur += strlen(cur) + 1;
- }
- (*output)[num] = NULL;
- return num;
-}
-
-static int parse_exec_params(char ***argv, char ***envp)
-{
- int ret;
- char *cmdline = NULL, *env = NULL;
- size_t cmdline_size, env_size;
-
- cmdline = file_to_buf("/proc/self/cmdline", &cmdline_size);
- if (!cmdline)
- goto on_error;
-
- env = file_to_buf("/proc/self/environ", &env_size);
- if (!env)
- goto on_error;
-
- ret = push_vargs(cmdline, cmdline_size, argv);
- if (ret <= 0)
- goto on_error;
-
- ret = push_vargs(env, env_size, envp);
- if (ret <= 0)
- goto on_error;
-
- return 0;
-
-on_error:
- free(env);
- free(cmdline);
-
- return -1;
-}
-
static int is_memfd(void)
{
int fd, saved_errno, seals;
@@ -142,10 +91,9 @@ static void lxc_rexec_as_memfd(char **argv, char **envp,
const char *memfd_name)
errno = saved_errno;
}
-int lxc_rexec(const char *memfd_name)
+int lxc_rexec(char *argv[], const char *memfd_name)
{
int ret;
- char **argv = NULL, **envp = NULL;
ret = is_memfd();
if (ret < 0 && ret == -ENOTRECOVERABLE) {
@@ -157,15 +105,7 @@ int lxc_rexec(const char *memfd_name)
return 0;
}
- ret = parse_exec_params(&argv, &envp);
- if (ret < 0) {
- fprintf(stderr,
- "%s - Failed to parse command line parameters\n",
- strerror(errno));
- return -1;
- }
-
- lxc_rexec_as_memfd(argv, envp, memfd_name);
+ lxc_rexec_as_memfd(argv, environ, memfd_name);
fprintf(stderr, "%s - Failed to rexec as memfd\n", strerror(errno));
return -1;
}
@@ -177,9 +117,9 @@ int lxc_rexec(const char *memfd_name)
* container are in the same user namespace or have set up an identity id
* mapping: CVE-2019-5736.
*/
-__attribute__((constructor)) static void liblxc_rexec(void)
+__attribute__((constructor)) static void liblxc_rexec(int argc, char *argv[])
{
- if (getenv("LXC_MEMFD_REXEC") && lxc_rexec("liblxc")) {
+ if (getenv("LXC_MEMFD_REXEC") && lxc_rexec(argv, "liblxc")) {
fprintf(stderr, "Failed to re-execute liblxc via memory file
descriptor\n");
_exit(EXIT_FAILURE);
}
diff --git a/src/lxc/rexec.h b/src/lxc/rexec.h
index 088ded932..ba612d969 100644
--- a/src/lxc/rexec.h
+++ b/src/lxc/rexec.h
@@ -21,6 +21,6 @@
#ifndef __LXC_REXEC_H
#define __LXC_REXEC_H
-extern int lxc_rexec(const char *memfd_name);
+extern int lxc_rexec(char *argv[], const char *memfd_name);
#endif /* __LXC_REXEC_H */
diff --git a/src/lxc/tools/lxc_attach.c b/src/lxc/tools/lxc_attach.c
index d10b6ecc2..60b2ec64f 100644
--- a/src/lxc/tools/lxc_attach.c
+++ b/src/lxc/tools/lxc_attach.c
@@ -57,9 +57,9 @@ lxc_log_define(lxc_attach, lxc);
* mapping: CVE-2019-5736.
*/
#ifdef ENFORCE_MEMFD_REXEC
-__attribute__((constructor)) static void lxc_attach_rexec(void)
+__attribute__((constructor)) static void lxc_attach_rexec(int argc, char
*argv[])
{
- if (!getenv("LXC_MEMFD_REXEC") && lxc_rexec("lxc-attach")) {
+ if (!getenv("LXC_MEMFD_REXEC") && lxc_rexec(argv, "lxc-attach")) {
fprintf(stderr, "Failed to re-execute lxc-attach via memory
file descriptor\n");
_exit(EXIT_FAILURE);
}
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