rexec: remove needless /proc/cmdline parsing

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/src/lxc/rexec.c b/src/lxc/rexec.c
index 024728d855d484dacfdd9608d80bd9fe31da6429..17e1806fe58506eb24a838dfc4b2e28b8d45c038 100644 (file)
--- 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 @@ on_error:
        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 088ded932d451dfa65de1d55ed47ed9b7623bc3d..ba612d969f11e214c1717f78ec69d76d4846f9c9 100644 (file)
--- 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 d10b6ecc23847d23350bda58bc89859588e87a11..60b2ec64f29391e03096e46c098a61c7bc24f0c1 100644 (file)
--- 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);
        }