Re: [PATCH] ls: show SMACK label of a file when available

[Pádraig Brady]

On 05/13/2013 11:27 AM, Jarkko Sakkinen wrote:
> Read security.SMACK64 and display it when '-Z' option is given
> to the ls command.
> ---
>  src/local.mk |    1 +
>  src/ls.c     |   73 
> ++++++++++++++++++++++++++++++++++++++++++++++------------
>  2 files changed, 59 insertions(+), 15 deletions(-)
> 
> diff --git a/src/local.mk b/src/local.mk
> index 0570d73..95c0672 100644
> --- a/src/local.mk
> +++ b/src/local.mk
> @@ -230,6 +230,7 @@ src_ginstall_LDADD += $(LIB_SELINUX)
>  src_id_LDADD += $(LIB_SELINUX)
>  src_id_LDADD += $(LIB_SMACK)
>  src_ls_LDADD += $(LIB_SELINUX)
> +src_ls_LDADD += $(LIB_SMACK)
>  src_mkdir_LDADD += $(LIB_SELINUX)
>  src_mkfifo_LDADD += $(LIB_SELINUX)
>  src_mknod_LDADD += $(LIB_SELINUX)
> diff --git a/src/ls.c b/src/ls.c
> index f1ed43b..5b0c190 100644
> --- a/src/ls.c
> +++ b/src/ls.c
> @@ -115,6 +115,11 @@
>  # include <sys/capability.h>
>  #endif
>  
> +#ifdef HAVE_SMACK
> +# include <sys/smack.h>
> +# include <attr/xattr.h>
> +#endif
> +
>  #define PROGRAM_NAME (ls_mode == LS_LS ? "ls" \
>                        : (ls_mode == LS_MULTI_COL \
>                           ? "dir" : "vdir"))
> @@ -350,7 +355,16 @@ static struct pending *pending_dirs;
>  
>  static struct timespec current_time;
>  
> -static bool print_scontext;
> +enum scontext_type
> +  {
> +  no_context,
> +  selinux_context,
> +#ifdef HAVE_SMACK
> +  smack_context,
> +#endif
> +  };
> +
> +static enum scontext_type print_scontext;
>  static char UNKNOWN_SECURITY_CONTEXT[] = "?";
>  
>  /* Whether any of the files has an ACL.  This affects the width of the
> @@ -1363,7 +1377,7 @@ main (int argc, char **argv)
>  
>    format_needs_stat = sort_type == sort_time || sort_type == sort_size
>      || format == long_format
> -    || print_scontext
> +    || print_scontext != no_context
>      || print_block_size;
>    format_needs_type = (! format_needs_stat
>                         && (recursive
> @@ -1565,7 +1579,7 @@ decode_switches (int argc, char **argv)
>    ignore_mode = IGNORE_DEFAULT;
>    ignore_patterns = NULL;
>    hide_patterns = NULL;
> -  print_scontext = false;
> +  print_scontext = no_context;
>  
>    /* FIXME: put this in a function.  */
>    {
> @@ -1941,7 +1955,11 @@ decode_switches (int argc, char **argv)
>            break;
>  
>          case 'Z':
> -          print_scontext = true;
> +          print_scontext = selinux_context;
> +#ifdef HAVE_SMACK
> +          if (smack_smackfs_path ())
> +            print_scontext = smack_context;
> +#endif
>            break;
>  
>          case_GETOPT_HELP_CHAR;
> @@ -2995,17 +3013,20 @@ gobble_file (char const *name, enum filetype type, 
> ino_t inode,
>            && print_with_color && is_colored (C_CAP))
>          f->has_capability = has_capability_cache (absolute_name, f);
>  
> -      if (format == long_format || print_scontext)
> +      if (format == long_format || print_scontext != no_context)
>          {
>            bool have_selinux = false;
>            bool have_acl = false;
> -          int attr_len = getfilecon_cache (absolute_name, f, do_deref);
> -          err = (attr_len < 0);
>  
> -          if (err == 0)
> -            have_selinux = ! STREQ ("unlabeled", f->scontext);
> -          else
> +          if (print_scontext == selinux_context)
>              {
> +            int attr_len = getfilecon_cache (absolute_name, f, do_deref);
> +            err = (attr_len < 0);

Indentation is off here.
You need to indent 2 more after a {

> +
> +            if (err == 0)
> +              have_selinux = ! STREQ ("unlabeled", f->scontext);
> +            else
> +              {
>                f->scontext = UNKNOWN_SECURITY_CONTEXT;
>  
>                /* When requesting security context information, don't make
> @@ -3014,7 +3035,29 @@ gobble_file (char const *name, enum filetype type, 
> ino_t inode,
>                   failure isn't in the same class as a stat failure.  */
>                if (errno == ENOTSUP || errno == EOPNOTSUPP || errno == 
> ENODATA)
>                  err = 0;
> +              }
> +            }
> +#ifdef HAVE_SMACK
> +          else

This needs to be 'else if (print_scontext == smack_context)'
otherwise the smack context would be printed with just -l ?

> +            {
> +            ssize_t ret = 0;
> +
> +            ret = getxattr (absolute_name, "security.SMACK64", NULL, 0);
> +            if (ret < 0)

This check looks wrong, and should also include errno == ERANGE probably.

> +              goto done_xattr;
> +            f->scontext = xmalloc (ret + 1);
> +            ret = getxattr (absolute_name, "security.SMACK64", f->scontext, 
> ret);
> +done_xattr:

So smack has no equiv to getfilecon, and uses the lower level getxattr?
That's fair enough, but it would be good to encapsulate that
in a getsmackcon_cache(). I.E. have the equivalent to getfilecon_cache()
which would have the advantage of better structure, honoring of do_deref,
and avoiding redundant calls on unsupported file systems.

> +            if (ret < 0)
> +              {
> +              f->scontext = UNKNOWN_SECURITY_CONTEXT;
> +              if (err == ENOTSUP || err == ENOATTR)
> +                err = 0;
> +              }
> +            else
> +              have_selinux = (ret > 0 && !STREQ ("_", f->scontext));
>              }
> +#endif
>  
>            if (err == 0 && format == long_format)
>              {
> @@ -3111,7 +3154,7 @@ gobble_file (char const *name, enum filetype type, 
> ino_t inode,
>              }
>          }

All the following changes aren't strictly required.
I'd change the enum def to explicitly set no_context = 0,
and then it would be fine to drop all the following I think.

thanks,
Pádraig.

>  
> -      if (print_scontext)
> +      if (print_scontext != no_context)
>          {
>            int len = strlen (f->scontext);
>            if (scontext_width < len)
> @@ -3846,7 +3889,7 @@ print_long_format (const struct fileinfo *f)
>  
>    DIRED_INDENT ();
>  
> -  if (print_owner || print_group || print_author || print_scontext)
> +  if (print_owner || print_group || print_author || print_scontext != 
> no_context)
>      {
>        DIRED_FPUTS (buf, stdout, p - buf);
>  
> @@ -3859,7 +3902,7 @@ print_long_format (const struct fileinfo *f)
>        if (print_author)
>          format_user (f->stat.st_author, author_width, f->stat_ok);
>  
> -      if (print_scontext)
> +      if (print_scontext != no_context)
>          format_user_or_group (f->scontext, 0, scontext_width);
>  
>        p = buf;
> @@ -4207,7 +4250,7 @@ print_file_name_and_frills (const struct fileinfo *f, 
> size_t start_col)
>              : human_readable (ST_NBLOCKS (f->stat), buf, human_output_opts,
>                                ST_NBLOCKSIZE, output_block_size));
>  
> -  if (print_scontext)
> +  if (print_scontext != no_context)
>      printf ("%*s ", format == with_commas ? 0 : scontext_width, f->scontext);
>  
>    size_t width = print_name_with_quoting (f, false, NULL, start_col);
> @@ -4417,7 +4460,7 @@ length_of_file_name_and_frills (const struct fileinfo 
> *f)
>                                              output_block_size))
>                  : block_size_width);
>  
> -  if (print_scontext)
> +  if (print_scontext != no_context)
>      len += 1 + (format == with_commas ? strlen (f->scontext) : 
> scontext_width);
>  
>    quote_name (NULL, f->name, filename_quoting_options, &name_width);
>