lib/chkname.c: Don't allow '$' in user/group names

[alejandro-colomar]

The dollar is dangerous. Require users to use --badname to allow it.

Cc: @zeha , @thesamesam , @jubalh , @Zugschlus , @stoeckmann

---

Revisions:

v1b

• Expand commit message.

$ git rd 
1:  91f74f912 ! 1:  895b1b420 lib/chkname.c: Don't allow '$' in user/group names
    @@ Metadata
      ## Commit message ##
         lib/chkname.c: Don't allow '$' in user/group names
     
    -    The dollar is dangerous.  Require users to use --badname to allow it.
    +    The dollar is dangerous.  Most languages use it as a special character,
    +    such as the shell --which uses it with many different meanings,
    +    depending on the context--.
    +
    +    Require users to use --badname to allow it.
     
         Signed-off-by: Alejandro Colomar <alx@kernel.org>
     

v1c

• Rebase

$ git rd 
1:  895b1b420 ! 1:  0d058ad4e lib/chkname.c: Don't allow '$' in user/group names
    @@ Commit message
     
      ## lib/chkname.c ##
     @@ lib/chkname.c: is_valid_name(const char *name)
    +    * User/group names must match BRE regex:
    +    *    [a-zA-Z0-9_.][a-zA-Z0-9_.-]*$\?
    +    *
    +-   * as a non-POSIX, extension, allow "$" as the last char for
    +-   * sake of Samba 3.x "add machine script"
    +-   *
    +    * Also do not allow fully numeric names or just "." or "..".
    +    */
      
    -   /*
    -          * User/group names must match BRE regex:
    --         *    [a-zA-Z0-9_.][a-zA-Z0-9_.-]*$\?
    --         *
    --         * as a non-POSIX, extension, allow "$" as the last char for
    --         * sake of Samba 3.x "add machine script"
    -+         *    [a-zA-Z0-9_.][a-zA-Z0-9_.-]*
    -          *
    -          * Also do not allow fully numeric names or just "." or "..".
    -          */
     @@ lib/chkname.c: is_valid_name(const char *name)
                      (*name >= '0' && *name <= '9') ||
                      *name == '_' ||

v1d

• Rebase

$ git rd 
1:  0d058ad4e ! 1:  54148256a lib/chkname.c: Don't allow '$' in user/group names
    @@ Commit message
     
      ## lib/chkname.c ##
     @@ lib/chkname.c: is_valid_name(const char *name)
    +   /*
         * User/group names must match BRE regex:
         *    [a-zA-Z0-9_.][a-zA-Z0-9_.-]*$\?
    -    *
    +-   *
     -   * as a non-POSIX, extension, allow "$" as the last char for
     -   * sake of Samba 3.x "add machine script"
    --   *
    -    * Also do not allow fully numeric names or just "." or "..".
         */
      
    +   if (!((*name >= 'a' && *name <= 'z') ||
     @@ lib/chkname.c: is_valid_name(const char *name)
                      (*name >= '0' && *name <= '9') ||
                      *name == '_' ||
    @@ lib/chkname.c: is_valid_name(const char *name)
     +                *name == '-'
                     ))
                {
    -                   errno = EINVAL;
    +                   errno = EILSEQ;

v1e

• Update regex in comment.

$ git rd 
1:  54148256a ! 1:  8ea2d9305 lib/chkname.c: Don't allow '$' in user/group names
    @@ Commit message
     
      ## lib/chkname.c ##
     @@ lib/chkname.c: is_valid_name(const char *name)
    + 
        /*
         * User/group names must match BRE regex:
    -    *    [a-zA-Z0-9_.][a-zA-Z0-9_.-]*$\?
    +-   *    [a-zA-Z0-9_.][a-zA-Z0-9_.-]*$\?
     -   *
     -   * as a non-POSIX, extension, allow "$" as the last char for
     -   * sake of Samba 3.x "add machine script"
    ++   *    [a-zA-Z0-9_.][a-zA-Z0-9_.-]*
         */
      
        if (!((*name >= 'a' && *name <= 'z') ||

v1f

• Rebase

$ git rd 
1:  8ea2d9305 = 1:  af9046e15 lib/chkname.c: Don't allow '$' in user/group names

v2

• Simplify code.

$ git rd 
1:  af9046e15 = 1:  af9046e15 lib/chkname.c: Don't allow '$' in user/group names
-:  --------- > 2:  7ec47ae50 lib/chkname.c: is_valid_name(): Remove redundant check

[zeha]

I'm in favour, but could the commit message spell out why it was deemed dangerous? Just to avoid re-ligitating this in the future.

[alejandro-colomar]

I'm in favour, but could the commit message spell out why it was deemed dangerous? Just to avoid re-ligitating this in the future.

Yup; I've expanded it. Please let me know if you'd add more to it. Thanks!