[PATCH] Expand tilde for UNIX domain socket forwards.

[lauri]

Hello,

any updates on this? We're preparing for upgrade to Ubuntu 16.04 and I
was hoping I don't have to patch OpenSSH again :D

2015-08-19 5:31 GMT+03:00 Todd C. Miller <Todd.Miller at courtesan.com>:
> On Tue, 18 Aug 2015 09:41:47 +1000, Damien Miller wrote:
>
>> Yeah, we should refactor it into a version that returns a ssherr.h code
>> and (perhaps) leave the existing tilde_expand_filename() as a wrapper.
>
> We could do something like this.  The name stinks but...
>
>  - todd
>
> Index: misc.c
> ===================================================================
> RCS file: /cvs/src/usr.bin/ssh/misc.c,v
> retrieving revision 1.97
> diff -u -p -u -r1.97 misc.c
> --- misc.c      24 Apr 2015 01:36:00 -0000      1.97
> +++ misc.c      19 Aug 2015 02:28:18 -0000
> @@ -50,6 +50,7 @@
>  #include "xmalloc.h"
>  #include "misc.h"
>  #include "log.h"
> +#include "ssherr.h"
>  #include "ssh.h"
>
>  /* remove newline at end of string */
> @@ -499,29 +500,31 @@ freeargs(arglist *args)
>   * Expands tildes in the file name.  Returns data allocated by xmalloc.
>   * Warning: this calls getpw*.
>   */
> -char *
> -tilde_expand_filename(const char *filename, uid_t uid)
> +int
> +tilde_expand_filename2(const char *filename, char **expanded, uid_t uid)
>  {
>         const char *path, *sep;
>         char user[128], *ret;
>         struct passwd *pw;
> -       u_int len, slash;
> +       size_t len, slash;
>
> -       if (*filename != '~')
> -               return (xstrdup(filename));
> +       if (*filename != '~') {
> +               *expanded = xstrdup(filename);
> +               return SSH_ERR_SUCCESS;
> +       }
>         filename++;
>
>         path = strchr(filename, '/');
>         if (path != NULL && path > filename) {          /* ~user/path */
>                 slash = path - filename;
>                 if (slash > sizeof(user) - 1)
> -                       fatal("tilde_expand_filename: ~username too long");
> +                       return SSH_ERR_PATH_TOO_LONG;
>                 memcpy(user, filename, slash);
>                 user[slash] = '\0';
>                 if ((pw = getpwnam(user)) == NULL)
> -                       fatal("tilde_expand_filename: No such user %s", user);
> +                       return SSH_ERR_UNKNOWN_USER;
>         } else if ((pw = getpwuid(uid)) == NULL)        /* ~/path */
> -               fatal("tilde_expand_filename: No such uid %ld", (long)uid);
> +               return SSH_ERR_UNKNOWN_USER;
>
>         /* Make sure directory has a trailing '/' */
>         len = strlen(pw->pw_dir);
> @@ -534,10 +537,29 @@ tilde_expand_filename(const char *filena
>         if (path != NULL)
>                 filename = path + 1;
>
> -       if (xasprintf(&ret, "%s%s%s", pw->pw_dir, sep, filename) >= PATH_MAX)
> -               fatal("tilde_expand_filename: Path too long");
> +       if (xasprintf(ret, "%s%s%s", pw->pw_dir, sep, filename) >= PATH_MAX) {
> +               free(ret);
> +               return SSH_ERR_PATH_TOO_LONG;
> +       }
> +
> +       *expanded = ret;
> +       return SSH_ERR_SUCCESS;
> +}
> +
> +/*
> + * Expands tildes in the file name.  Returns data allocated by xmalloc.
> + * Warning: this calls getpw*.
> + */
> +char *
> +tilde_expand_filename(const char *filename, uid_t uid)
> +{
> +       char *ret;
> +       int rc;
>
> -       return (ret);
> +       rc = tilde_expand_filename2(filename, &ret, uid);
> +       if (rc != SSH_ERR_SUCCESS)
> +               fatal("%s: %s", __func__, ssh_err(rc));
> +       return ret;
>  }
>
>  /*
> Index: misc.h
> ===================================================================
> RCS file: /cvs/src/usr.bin/ssh/misc.h,v
> retrieving revision 1.54
> diff -u -p -u -r1.54 misc.h
> --- misc.h      15 Jul 2014 15:54:14 -0000      1.54
> +++ misc.h      19 Aug 2015 02:27:37 -0000
> @@ -49,6 +49,7 @@ char  *cleanhostname(char *);
>  char   *colon(char *);
>  long    convtime(const char *);
>  char   *tilde_expand_filename(const char *, uid_t);
> +int     tilde_expand_filename2(const char *, char **, uid_t);
>  char   *percent_expand(const char *, ...) __attribute__((__sentinel__));
>  char   *tohex(const void *, size_t);
>  void    sanitise_stdfd(void);
> Index: ssherr.c
> ===================================================================
> RCS file: /cvs/src/usr.bin/ssh/ssherr.c,v
> retrieving revision 1.4
> diff -u -p -u -r1.4 ssherr.c
> --- ssherr.c    16 Feb 2015 22:13:32 -0000      1.4
> +++ ssherr.c    19 Aug 2015 02:19:05 -0000
> @@ -135,6 +135,10 @@ ssh_err(int n)
>                 return "Connection corrupted";
>         case SSH_ERR_PROTOCOL_ERROR:
>                 return "Protocol error";
> +       case SSH_ERR_UNKNOWN_USER:
> +               return "Unknown user";
> +       case SSH_ERR_PATH_TOO_LONG:
> +               return "Path too long";
>         default:
>                 return "unknown error";
>         }
> Index: ssherr.h
> ===================================================================
> RCS file: /cvs/src/usr.bin/ssh/ssherr.h,v
> retrieving revision 1.3
> diff -u -p -u -r1.3 ssherr.h
> --- ssherr.h    30 Jan 2015 01:13:33 -0000      1.3
> +++ ssherr.h    19 Aug 2015 02:18:29 -0000
> @@ -77,6 +77,8 @@
>  #define SSH_ERR_CONN_TIMEOUT                   -53
>  #define SSH_ERR_CONN_CORRUPT                   -54
>  #define SSH_ERR_PROTOCOL_ERROR                 -55
> +#define SSH_ERR_UNKNOWN_USER                   -56
> +#define SSH_ERR_PATH_TOO_LONG                  -57
>
>  /* Translate a numeric error code to a human-readable error string */
>  const char *ssh_err(int n);



-- 
Lauri Võsandi
tel: +372 53329412
e-mail: lauri.vosandi at gmail.com
blog: http://lauri.vosandi.com/