rootless: fix usage with hidepid=1
when /proc is mounted with hidepid=1 a process doesn't see processes
from the outer user namespace.  This causes an issue reading the
cmdline from the parent process.
To address it, always read the command line from /proc/self instead of
using /proc/PARENT_PID.
@@ -108,10 +108,9 @@ do_pause ()
}
static char **
-get_cmd_line_args (pid_t pid)
+get_cmd_line_args ()
{
int fd;
- char path[PATH_MAX];
char *buffer;
size_t allocated;
size_t used = 0;
@@ -119,11 +118,7 @@ get_cmd_line_args (pid_t pid)
int i, argc = 0;
char **argv;
- if (pid)
- sprintf (path, "/proc/%d/cmdline", pid);
- else
- strcpy (path, "/proc/self/cmdline");
- fd = open (path, O_RDONLY);
+ fd = open ("/proc/self/cmdline", O_RDONLY);
if (fd < 0)
return NULL;
@@ -196,7 +191,7 @@ can_use_shortcut ()
return false;
#endif
- argv = get_cmd_line_args (0);
+ argv = get_cmd_line_args ();
if (argv == NULL)
return false;
@@ -542,7 +537,6 @@ create_pause_process (const char *pause_pid_file_path, char **argv)
int
reexec_userns_join (int userns, int mountns, char *pause_pid_file_path)
{
- pid_t ppid = getpid ();
char uid[16];
char gid[16];
char **argv;
@@ -559,7 +553,7 @@ reexec_userns_join (int userns, int mountns, char *pause_pid_file_path)
sprintf (uid, "%d", geteuid ());
sprintf (gid, "%d", getegid ());
- argv = get_cmd_line_args (ppid);
+ argv = get_cmd_line_args ();
if (argv == NULL)
{
fprintf (stderr, "cannot read argv: %s\n", strerror (errno));
@@ -724,7 +718,6 @@ reexec_in_user_namespace (int ready, char *pause_pid_file_path, char *file_to_re
int ret;
pid_t pid;
char b;
- pid_t ppid = getpid ();
char **argv;
char uid[16];
char gid[16];
@@ -801,7 +794,7 @@ reexec_in_user_namespace (int ready, char *pause_pid_file_path, char *file_to_re
_exit (EXIT_FAILURE);
}
- argv = get_cmd_line_args (ppid);
+ argv = get_cmd_line_args ();
if (argv == NULL)
{
fprintf (stderr, "cannot read argv: %s\n", strerror (errno));
