Управление списками доступа POSIX ACL (Access Control Lists).

http://savannah.nongnu.org/projects/acl/

Access Control Lists in Linux

Использование в Samba

Графический интерфейс: Eiciel

Может ли пользователь выполнить действие над файлом или папкой определяются следующим образом: -

1. Используются права владельца, если пользователь им является.
2. Используются права, указанные конкретно для этого пользователя.
3. Если действие разрешено хотя бы для одной из группы в которую входит пользователь.
4. Если пользователь не входит ни в одну группу описанную в ACL, то используются права для other.

apt-get install acl

Для того, чтобы проверить поддерживаются ли списки доступа (ACL) нужно выполнить команду:

tune2fs -l /dev/sdaX |grep acl

/dev/sdaX имя устройства.

Если ACL поддерживаются то в выводе команды будет примерно это:

Default mount options:    user_xattr acl

Установка прав доступа

SETFACL(1)                                         Access Control Lists                                         SETFACL(1)

NAME
       setfacl - set file access control lists

SYNOPSIS
       setfacl [-bkndRLPvh] [{-m|-x} acl_spec] [{-M|-X} acl_file] file ...

       setfacl --restore=file

DESCRIPTION
       This  utility  sets  Access Control Lists (ACLs) of files and directories.  On the command line, a sequence of com‐
       mands is followed by a sequence of files (which in turn can be followed by another sequence of commands, ...).

       The options -m, and -x expect an ACL on the command line. Multiple ACL entries are separated  by  comma  characters
       (`,').  The options -M, and -X read an ACL from a file or from standard input. The ACL entry format is described in
       Section ACL ENTRIES.

       The --set and --set-file options set the ACL of a file or a directory. The previous ACL is replaced.   ACL  entries
       for this operation must include permissions.

       The -m (--modify) and -M (--modify-file) options modify the ACL of a file or directory.  ACL entries for this oper‐
       ation must include permissions.

       The -x (--remove) and -X (--remove-file) options remove ACL entries. It is not an error to remove  an  entry  which
       does  not  exist.   Only  ACL entries without the perms field are accepted as parameters, unless POSIXLY_CORRECT is
       defined.

       When reading from files using the -M, and -X options, setfacl accepts the output getfacl  produces.   There  is  at
       most  one  ACL  entry per line. After a Pound sign (`#'), everything up to the end of the line is treated as a com‐
       ment.

       If setfacl is used on a file system which does not support ACLs, setfacl operates on the file mode permission bits.
       If  the  ACL  does  not  fit  completely  in the permission bits, setfacl modifies the file mode permission bits to
       reflect the ACL as closely as possible, writes an error message to standard error, and returns with an exit  status
       greater than 0.

   PERMISSIONS
       The  file  owner and processes capable of CAP_FOWNER are granted the right to modify ACLs of a file. This is analo‐
       gous to the permissions required for accessing the file mode. (On current Linux systems, root is the only user with
       the CAP_FOWNER capability.)

OPTIONS
       -b, --remove-all
           Remove all extended ACL entries. The base ACL entries of the owner, group and others are retained.

       -k, --remove-default
           Remove the Default ACL. If no Default ACL exists, no warnings are issued.

       -n, --no-mask
           Do  not  recalculate  the effective rights mask. The default behavior of setfacl is to recalculate the ACL mask
           entry, unless a mask entry was explicitly given.  The mask entry is set to the union of all permissions of  the
           owning group, and all named user and group entries. (These are exactly the entries affected by the mask entry).

       --mask
           Do recalculate the effective rights mask, even if an ACL mask entry was explicitly given. (See the -n option.)

       -d, --default
           All  operations  apply  to  the  Default  ACL. Regular ACL entries in the input set are promoted to Default ACL
           entries. Default ACL entries in the input set are discarded. (A warning is issued if that happens).

       --restore=file
           Restore a permission backup created by `getfacl -R' or similar. All permissions of a complete directory subtree
           are  restored using this mechanism. If the input contains owner comments or group comments, setfacl attempts to
           restore the owner and owning group. If the input contains flags comments (which define the setuid, setgid,  and
           sticky bits), setfacl sets those three bits accordingly; otherwise, it clears them. This option cannot be mixed
           with other options except `--test'.

       --test
           Test mode. Instead of changing the ACLs of any files, the resulting ACLs are listed.

       -R, --recursive
           Apply operations to all files and directories recursively. This option cannot be mixed with `--restore'.

       -L, --logical
           Logical walk, follow symbolic links to directories. The default behavior is to follow symbolic link  arguments,
           and  skip  symbolic  links  encountered in subdirectories.  Only effective in combination with -R.  This option
           cannot be mixed with `--restore'.

       -P, --physical
           Physical walk, do not follow symbolic links to directories.  This also skips  symbolic  link  arguments.   Only
           effective in combination with -R.  This option cannot be mixed with `--restore'.

       -v, --version
           Print the version of setfacl and exit.

       -h, --help
           Print help explaining the command line options.

       --  End  of command line options. All remaining parameters are interpreted as file names, even if they start with a
           dash.

       -   If the file name parameter is a single dash, setfacl reads a list of files from standard input.

   ACL ENTRIES
       The setfacl utility recognizes the following ACL entry formats (blanks inserted for clarity):

       [d[efault]:] [u[ser]:]uid [:perms]
              Permissions of a named user. Permissions of the file owner if uid is empty.

       [d[efault]:] g[roup]:gid [:perms]
              Permissions of a named group. Permissions of the owning group if gid is empty.

       [d[efault]:] m[ask][:] [:perms]
              Effective rights mask

       [d[efault]:] o[ther][:] [:perms]
              Permissions of others.

       Whitespace between delimiter characters and non-delimiter characters is ignored.

       Proper ACL entries including permissions are used in modify and set operations. (options -m, -M, --set  and  --set-
       file).  Entries without the perms field are used for deletion of entries (options -x and -X).

       For uid and gid you can specify either a name or a number.

       The  perms  field  is  a combination of characters that indicate the permissions: read (r), write (w), execute (x),
       execute only if the file is a directory or already has execute permission for some user  (X).   Alternatively,  the
       perms field can be an octal digit (0-7).

   AUTOMATICALLY CREATED ENTRIES
       Initially,  files  and  directories  contain  only the three base ACL entries for the owner, the group, and others.
       There are some rules that need to be satisfied in order for an ACL to be valid:

       *   The three base entries cannot be removed. There must be exactly one entry of each of these base entry types.

       *   Whenever an ACL contains named user entries or named group objects, it must also contain  an  effective  rights
           mask.

       *   Whenever  an  ACL  contains any Default ACL entries, the three Default ACL base entries (default owner, default
           group, and default others) must also exist.

       *   Whenever a Default ACL contains named user entries or named group objects,  it  must  also  contain  a  default
           effective rights mask.

       To help the user ensure these rules, setfacl creates entries from existing entries under the following conditions:

       *   If  an  ACL  contains  named user or named group entries, and no mask entry exists, a mask entry containing the
           same permissions as the group entry is created. Unless the -n option is given,  the  permissions  of  the  mask
           entry  are  further  adjusted  to  include the union of all permissions affected by the mask entry. (See the -n
           option description).

       *   If a Default ACL entry is created, and the Default ACL contains no owner, owning group, or others entry, a copy
           of the ACL owner, owning group, or others entry is added to the Default ACL.

       *   If  a  Default  ACL  contains named user entries or named group entries, and no mask entry exists, a mask entry
           containing the same permissions as the default Default ACL's group entry is added.  Unless  the  -n  option  is
           given, the permissions of the mask entry are further adjusted to inclu de the union of all permissions affected
           by the mask entry. (See the -n option description).

EXAMPLES
       Granting an additional user read access
              setfacl -m u:lisa:r file

       Revoking write access from all groups and all named users (using the effective rights mask)
              setfacl -m m::rx file

       Removing a named group entry from a file's ACL
              setfacl -x g:staff file

       Copying the ACL of one file to another
              getfacl file1 | setfacl --set-file=- file2

       Copying the access ACL into the Default ACL
              getfacl --access dir | setfacl -d -M- dir

CONFORMANCE TO POSIX 1003.1e DRAFT STANDARD 17
       If the environment variable POSIXLY_CORRECT is defined, the default behavior of setfacl  changes  as  follows:  All
       non-standard options are disabled.  The ``default:'' prefix is disabled.  The -x and -X options also accept permis‐
       sion fields (and ignore them).

AUTHOR
       Andreas Gruenbacher, <a.gruenbacher@bestbits.at>.

       Please send your bug reports, suggested features and comments to the above address.

SEE ALSO
       getfacl(1), chmod(1), umask(1), acl(5)

May 2000                                            ACL File Utilities                                          SETFACL(1)

Пример:

setfacl -R -b -m g:Group_F:rwx,g:Group_R:rx,default:g:Group_F:rwx,default:g:Group_R:rx,default:other:--- /srv/share01

Рекурсивно -R удаляем существующие права -b и добавляем заданные права, устанавливаем умолчания.

• Group_F полные права
• Group_R только чтение
• other = нет доступа

GETFACL(1)                                         Access Control Lists                                         GETFACL(1)

NAME
       getfacl - get file access control lists

SYNOPSIS
       getfacl [-aceEsRLPtpndvh] file ...

       getfacl [-aceEsRLPtpndvh] -

DESCRIPTION
       For  each file, getfacl displays the file name, owner, the group, and the Access Control List (ACL). If a directory
       has a default ACL, getfacl also displays the default ACL. Non-directories cannot have default ACLs.

       If getfacl is used on a file system that does not support ACLs, getfacl displays the access permissions defined  by
       the traditional file mode permission bits.

       The output format of getfacl is as follows:
               1:  # file: somedir/
               2:  # owner: lisa
               3:  # group: staff
               4:  # flags: -s-
               5:  user::rwx
               6:  user:joe:rwx               #effective:r-x
               7:  group::rwx                 #effective:r-x
               8:  group:cool:r-x
               9:  mask::r-x
              10:  other::r-x
              11:  default:user::rwx
              12:  default:user:joe:rwx       #effective:r-x
              13:  default:group::r-x
              14:  default:mask::r-x
              15:  default:other::---

       Lines 1--3 indicate the file name, owner, and owning group.

       Line 4 indicates the setuid (s), setgid (s), and sticky (t) bits: either the letter representing the bit, or else a
       dash (-). This line is included if any of those bits is set and left out otherwise, so it will  not  be  shown  for
       most files. (See CONFORMANCE TO POSIX 1003.1e DRAFT STANDARD 17 below.)

       Lines  5, 7 and 10 correspond to the user, group and other fields of the file mode permission bits. These three are
       called the base ACL entries. Lines 6 and 8 are named user and named group entries. Line 9 is the  effective  rights
       mask.  This  entry limits the effective rights granted to all groups and to named users. (The file owner and others
       permissions are not affected by the effective rights mask; all  other  entries  are.)   Lines  11--15  display  the
       default  ACL associated with this directory. Directories may have a default ACL. Regular files never have a default
       ACL.

       The default behavior for getfacl is to display both the ACL and the default ACL, and to include an effective rights
       comment for lines where the rights of the entry differ from the effective rights.

       If output is to a terminal, the effective rights comment is aligned to column 40. Otherwise, a single tab character
       separates the ACL entry and the effective rights comment.

       The ACL listings of multiple files are separated by blank lines.  The output of getfacl can also be used  as  input
       to setfacl.

   PERMISSIONS
       Process  with  search access to a file (i.e., processes with read access to the containing directory of a file) are
       also granted read access to the file's ACLs.  This is analogous to the permissions required for accessing the  file
       mode.

OPTIONS
       -a, --access
           Display the file access control list.

       -d, --default
           Display the default access control list.

       -c, --omit-header
           Do not display the comment header (the first three lines of each file's output).

       -e, --all-effective
           Print all effective rights comments, even if identical to the rights defined by the ACL entry.

       -E, --no-effective
           Do not print effective rights comments.

       -s, --skip-base
           Skip files that only have the base ACL entries (owner, group, others).

       -R, --recursive
           List the ACLs of all files and directories recursively.

       -L, --logical
           Logical  walk, follow symbolic links to directories. The default behavior is to follow symbolic link arguments,
           and skip symbolic links encountered in subdirectories.  Only effective in combination with -R.

       -P, --physical
           Physical walk, do not follow symbolic links to directories. This also  skips  symbolic  link  arguments.   Only
           effective in combination with -R.

       -t, --tabular
           Use  an  alternative tabular output format. The ACL and the default ACL are displayed side by side. Permissions
           that are ineffective due to the ACL mask  entry  are  displayed  capitalized.  The  entry  tag  names  for  the
           ACL_USER_OBJ  and  ACL_GROUP_OBJ  entries  are also displayed in capital letters, which helps in spotting those
           entries.

       -p, --absolute-names
           Do not strip leading slash characters (`/'). The default behavior is to strip leading slash characters.

       -n, --numeric
           List numeric user and group IDs

       -v, --version
           Print the version of getfacl and exit.

       -h, --help
           Print help explaining the command line options.

       --  End of command line options. All remaining parameters are interpreted as file names, even if they start with  a
           dash character.

       -   If the file name parameter is a single dash character, getfacl reads a list of files from standard input.

CONFORMANCE TO POSIX 1003.1e DRAFT STANDARD 17
       If  the  environment  variable POSIXLY_CORRECT is defined, the default behavior of getfacl changes in the following
       ways: Unless otherwise specified, only the ACL is printed. The default ACL is only printed  if  the  -d  option  is
       given. If no command line parameter is given, getfacl behaves as if it was invoked as ``getfacl -''.  No flags com‐
       ments indicating the setuid, setgit, and sticky bits are generated.

AUTHOR
       Andreas Gruenbacher, <a.gruenbacher@bestbits.at>.

       Please send your bug reports and comments to the above address.

SEE ALSO
       setfacl(1), acl(5)

May 2000                                            ACL File Utilities                                          GETFACL(1)

Настройка прав доступа ACL

Access Control List - списки контроля доступа

File Permissions ACLs

Библиотека сайта rus-linux.net: Фундаментальные основы Linux. Часть VIII. Механизмы безопасной работы с файлами

Linux getfacl command

Linux setfacl command