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Diffstat (limited to 'plugins/sudoers/auth/API')
| -rw-r--r-- | plugins/sudoers/auth/API | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/plugins/sudoers/auth/API b/plugins/sudoers/auth/API new file mode 100644 index 0000000..b38a1c4 --- /dev/null +++ b/plugins/sudoers/auth/API @@ -0,0 +1,148 @@ +NOTE: the Sudo auth API is subject to change + +Purpose: to provide a simple API for authentication methods that + encapsulates things nicely without turning into a maze + of #ifdef's + +The sudo_auth struct looks like this: + +typedef struct sudo_auth { + unsigned int flags; /* various flags, see below */ + int status; /* status from verify routine */ + char *name; /* name of the method in string form */ + void *data; /* method-specific data pointer */ + + int (*init)(struct passwd *pw, sudo_auth *auth); + int (*setup)(struct passwd *pw, char **prompt, sudo_auth *auth); + int (*verify)(struct passwd *pw, const char *p, sudo_auth *auth, struct sudo_conv_callback *callback); + int (*approval)(struct passwd *pw, sudo_auth *auth); + int (*cleanup)(struct passwd *pw, sudo_auth *auth, bool force); + int (*begin_session)(struct passwd *pw, char **user_env[], struct sudo_auth *auth); + int (*end_session)(struct passwd *pw, struct sudo_auth *auth); +} sudo_auth; + +The variables in the struct are as follows: + flags Bitwise binary flags, see below. + + status Contains the return value from the last run of + the "verify" function. Starts out as AUTH_FAILURE. + + name The name of the authentication method as a C string. + + data A pointer to method-specific data. This is passed to + all the functions of an auth method and is usually + initialized in the "init" or "setup" routines. + +Possible values of sudo_auth.flags: + FLAG_DISABLED Set if an "init" or "setup" function fails. + + FLAG_STANDALONE If set, this indicates that the method must + be the only auth method configured, and that + it will prompt for the password itself. + + FLAG_ONEANDONLY If set, this indicates that the method is the + only one in use. Can be used by auth functions + to determine whether to return a fatal or nonfatal + error. + + FLAG_NONINTERACTIVE If set, this indicates that the user invoked + sudo with the -n option and no user interaction + is allowed. + +The member functions can return the following values: + AUTH_SUCCESS Function succeeded. For a ``verify'' function + this means the user correctly authenticated. + + AUTH_FAILURE Function failed. If this is an ``init'' or + ``setup'' routine, the auth method will be + marked as !configured. + + AUTH_ERROR A fatal error occurred. The routine should have + written an error message to stderr and optionally + sent mail to the administrator. When verify_user() + receives AUTH_ERROR from an auth function it stops + authenticating and returns an error. + + AUTH_INTR An attempt to read the password read was interrupted. + Usually this means the user entered ^C at the + password prompt. + + AUTH_NONINTERACTIVE Function failed because user interaction was + required but sudo was run in non-interactive + mode. + +The functions in the struct are as follows: + + int init(struct passwd *pw, sudo_auth *auth) + Function to do any one-time initialization for the auth + method. All of the "init" functions are run before anything + else. + + int setup(struct passwd *pw, char **prompt, sudo_auth *auth) + Function to do method-specific setup. All the "setup" + routines are run before any of the "verify" routines. A + pointer to the prompt string may be used to add method-specific + info to the prompt. + + int verify(struct passwd *pw, char *p, sudo_auth *auth, struct sudo_conv_callback *callback) + Function to do user verification for this auth method. For + standalone auth methods ``p'' is the prompt string. For + normal auth methods, ``p'' is the password the user entered. + The callback should be passed to auth_getpass() to allow sudoers + to unlock the ticket file when sudo is suspended. + Note that standalone auth methods are responsible for + rerading the password themselves. + + int approval(struct passwd *pw, struct sudo_auth *auth) + Function to perform account management and approval *after* + the user has authenticated successfully. This function may + check for expired accounts, perform time of day restrictions, etc. + For PAM, this calls pam_acct_mgmt(). For BSD auth, it calls + auth_approval(). + + int cleanup(struct passwd *pw, sudo_auth *auth, bool force) + Function to do per-auth method cleanup. This is only run + at the end of the authentication process, after the user + has completely failed or succeeded to authenticate. + The ``auth->status'' variable contains the result of the + last authentication attempt which may be interesting. + If the force flag is set, cleanup should happen immediately. + + int begin_session(struct passwd *pw, char **user_env[], struct sudo_auth *auth) + Function to begin a user session. This is used for session handling + in PAM and SIA. + + int end_session(struct passwd *pw, struct sudo_auth *auth) + Function to end a user session. This is used for session handling + in PAM and SIA. + +A note about standalone methods. Some authentication methods can't +coexist with any others. This may be because they encapsulate other +methods (pam, sia) or because they have a special way of interacting +with the user (securid). + +Adding a new authentication method: + +Each method should live in its own file. Add prototypes for the functions +in sudo_auth.h. + +Add the method to the ``auth_switch'' in sudo_auth.c. Note that +standalone methods must go first. If ``fooauth'' is a normal auth +method, its entry would look like: + +#ifdef HAVE_FOOAUTH +AUTH_ENTRY("foo", 0, foo_init, foo_setup, foo_verify, + foo_cleanup, foo_begin_session, foo_end_session) +#endif + +If this is a standalone method, it would be: + +#ifdef HAVE_FOOAUTH +AUTH_ENTRY("foo", FLAG_STANDALONE, foo_init, foo_setup, foo_verify, + foo_cleanup, foo_begin_session, foo_end_session) +#endif + +If the method needs to run as the user, not root, add FLAG_USER to +the second argument in the AUTH_ENTRY line. If you don't have an +init/setup/cleanup/begin/end routine, just use a NULL for that +field. |