LOGIN_CAP(3) BSD Programmer's Manual LOGIN_CAP(3)
login_getclass, login_getstyle, login_getcapbool, login_getcapnum,
login_getcapsize, login_getcapstr, login_getcaptime, login_close,
secure_path, setclasscontext, setusercontext - query login.conf database
about a user class
#include <sys/types.h>
#include <login_cap.h>
login_cap_t *
login_getclass(const char *class);
char *
login_getstyle(login_cap_t *lc, const char *style, char *type);
int
login_getcapbool(login_cap_t *lc, const char *cap, unsigned int def);
quad_t
login_getcapnum(login_cap_t *lc, const char *cap, quad_t def,
quad_t err);
quad_t
login_getcapsize(login_cap_t *lc, const char *cap, quad_t def,
quad_t err);
char *
login_getcapstr(login_cap_t *lc, const char *cap, char *def, char *err);
quad_t
login_getcaptime(login_cap_t *lc, const char *cap, quad_t def,
quad_t err);
void
login_close(login_cap_t *lc);
int
secure_path(const char *path);
int
setclasscontext(char *class, unsigned flags);
int
setusercontext(login_cap_t *lc, struct passwd *pwd, uid_t uid,
unsigned flags);
The login_getclass() function extracts the entry specified by class (or
default if class is NULL or the empty string) from /etc/login.conf (see
login.conf(5)). If the entry is found, a login_cap_t pointer is returned.
NULL is returned if the user class is not found. When the login_cap_t
structure is no longer needed, it should be freed by the login_close()
function.
Once lc has been returned by login_getclass(), any of the other login_*()
functions may be called. The login_getstyle() function is used to obtain
the style of authentication that should be used for this user class. The
style argument may either be NULL or the desired style of authentication.
If NULL, the first available authentication style will be used. The type
argument refers to the type of authentication being performed. This is
used to override the standard auth entry in the database. By convention
this should be of the form "auth-type". Future releases may remove the
requirement for the "auth-" prefix and add it if it is missing. If type
is NULL then only "auth" will be looked at (see login.conf(5)). The
login_getstyle() function will return NULL if the desired style of au-
thentication is not available, or if no style is available.
The login_getcapnum(), login_getcapsize(), login_getcapstr(), and
login_getcaptime() functions all query the database entry for a field
named cap. If the field is found, its value is returned. If the field is
not found, the value specified by def is returned. If an error is encoun-
tered while trying to find the field, err is returned. See login.conf(5)
for a discussion of the various textual forms the value may take. The
login_getcapbool() function is slightly different. It returns def if no
capabilities were found for this class (typically meaning that the de-
fault class was used and the /etc/login.conf file is missing). It returns
a non-zero value if cap, with no value, was found, zero otherwise.
The secure_path() function takes a path name and returns 0 if the path
name is secure, -1 if not. To be secure a path must exist, be a regular
file (and not a directory), owned by root, and only writable by the owner
(root).
The setclasscontext() function takes class, the name of a user class, and
sets the resources defined by that class according to flags. Only the
LOGIN_SETPATH, LOGIN_SETPRIORITY, LOGIN_SETRESOURCES, and LOGIN_SETUMASK
bits are used (see setusercontext() below). It returns 0 on success and
-1 on failure.
The setusercontext() function sets the resources according to flags. The
lc argument, if not NULL, contains the class information that should be
used. The pwd argument, if not NULL, provides information about the user.
Both lc and pwd cannot be NULL. The uid argument is used in place of the
user ID contained in the pwd structure when calling setuid(2). The
setusercontext() function returns 0 on success and -1 on failure. The
various bits available to be or-ed together to make up flags are:
LOGIN_SETENV Sets environment variables specified by the setenv
keyword.
LOGIN_SETGROUP Set the group ID and call initgroups(3). Requires
the pwd field be specified.
LOGIN_SETLOGIN Sets the login name by setlogin(2). Requires the
pwd field be specified.
LOGIN_SETPATH Sets the PATH environment variable.
LOGIN_SETPRIORITY Sets the priority by setpriority(2).
LOGIN_SETRESOURCES Sets the various system resources by setrlimit(2).
LOGIN_SETUMASK Sets the umask by umask(2).
LOGIN_SETUSER Sets the user ID to uid by setuid(2).
LOGIN_SETALL Sets all of the above.
setlogin(2), setpriority(2), setrlimit(2), setuid(2), umask(2),
initgroups(3), login.conf(5)
The login_getclass function first appeared in OpenBSD 2.8.
The string returned by login_getcapstr() is allocated via malloc(3) when
the specified capability is present and thus it is the responsibility of
the caller to free() this space. However, if the capability was not found
or an error occurred and def or err (whichever is relevant) are non-NULL
the returned value is simply what was passed in to login_getcapstr().
Therefore it is not possible to blindly free() the return value without
first checking it against def and err.
The same warnings set forth in setlogin(2) apply to setusercontext() when
the LOGIN_SETLOGIN flag is used. Specifically, changing the login name
affects all processes in the current session, not just the current pro-
cess. See setlogin(2) for more information.
MirBSD #10-current November 7, 2020 2