The only user of login_prompt is the login tool. This implies that the
first argument is always the same.
It is much easier to verify printf's format string and its argument if
both are next to each other.
Signed-off-by: Samanta Navarro <ferivoz@riseup.net>
Parsing optional environment variables after a login name is a feature
which is neither documented nor available in util-linux or busybox
login which are other wide spread login utilities used in Linux
distributions as reference.
Removing this feature resolves two issues:
- A memory leak exists if variables without an equal sign are used,
because set_env creates copies on its own. This could lead to OOM
situations in privileged part of login or may lead to heap spraying.
- Environment variables are not reset between login attempts. This
could lead to additional environment variables set for a user who
never intended to do so.
Proof of Concept on a system with shadow login without PAM and
util-linux agetty:
1. Provoke an invalid login, e.g. user `noone` and password `invalid`.
This starts shadow login and subsequent inputs are passed through
the function login_prompt.
2. Provoke an invalid login with environment variables, e.g.
user `noone HISTFILE=/tmp/owo` and password `invalid`.
3. Log in correctly with user `root`.
Now you can see with `echo $HISTFILE` that `/tmp/owo` has been set for
the root user.
This requires a malicious failed login attempt and a successful login
within the configured login timeout (default 60 seconds).
Signed-off-by: Samanta Navarro <ferivoz@riseup.net>
Use of these macros, apart from the benefits mentioned in the commit
that adds the macros, has some other good side effects:
- Consistency in getting the size of the object from sizeof(type),
instead of a mix of sizeof(type) sometimes and sizeof(*p) other
times.
- More readable code: no casts, and no sizeof(), so also shorter lines
that we don't need to cut.
- Consistency in using array allocation calls for allocations of arrays
of objects, even when the object size is 1.
Cc: Valentin V. Bartenev <vbartenev@gmail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
- Every non-const pointer converts automatically to void *.
- Every pointer converts automatically to void *.
- void * converts to any other pointer.
- const void * converts to any other const pointer.
- Integer variables convert to each other.
I changed the declaration of a few variables in order to allow removing
a cast.
However, I didn't attempt to edit casts inside comparisons, since they
are very delicate. I also kept casts in variadic functions, since they
are necessary, and in allocation functions, because I have other plans
for them.
I also changed a few casts to int that are better as ptrdiff_t.
This change has triggered some warnings about const correctness issues,
which have also been fixed in this patch (see for example src/login.c).
Signed-off-by: Alejandro Colomar <alx@kernel.org>
In variadic functions we still do the cast. In POSIX, it's not
necessary, since NULL is required to be of type 'void *', and 'void *'
is guaranteed to have the same alignment and representation as 'char *'.
However, since ISO C still doesn't mandate that, and moreover they're
doing dubious stuff by adding nullptr, let's be on the cautious side.
Also, C++ requires that NULL is _not_ 'void *', but either plain 0 or
some magic stuff.
Signed-off-by: Alejandro Colomar <alx@kernel.org>
C89 and POSIX.1-2001 define signal(2) as returning a pointer to a
function returning 'void'. K&R C signal(2) signature is obsolete.
Use 'void' directly.
Also, instead of writing the function pointer type explicitly, use
POSIX's 'sighandler_t'.
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
boolean.
* libmisc/basename.c: Avoid implicit conversion of pointer to
boolean.
* libmisc/basename.c, lib/prototypes.h (Basename): Return a
constant string.
* libmisc/basename.c, libmisc/obscure.c, lib/prototypes.h,
libmisc/xmalloc.c, libmisc/getdate.h, libmisc/system.c,
libmisc/getgr_nam_gid.c, libmisc/failure.c, libmisc/valid.c: Add
splint annotations.
* libmisc/chowndir.c: Avoid memory leak.
* libmisc/chowndir.c: Do not check *printf/*puts return value.
* libmisc/chowntty.c: Avoid implicit conversion between integer
types.
* libmisc/obscure.c: Return a bool when possible instead of int.
* libmisc/shell.c: Do not check *printf/*puts return value.
* libmisc/shell.c: Do not check execle return value.
* libmisc/setupenv.c: Avoid implicit conversion between integer
types.
* libmisc/xmalloc.c: size should not be zero to avoid returning
NULL pointers.
* libmisc/hushed.c: Do not check *printf/*puts return value.
* libmisc/system.c: Avoid implicit conversion of integer to
boolean. safe_system last argument is a boolean.
* libmisc/system.c: Check return value of dup2.
* libmisc/system.c: Do not check *printf/*puts return value.
* libmisc/system.c: Do not check execve return value.
* libmisc/salt.c: Do not check *printf/*puts return value.
* libmisc/loginprompt.c: Do not check gethostname return value.
* libmisc/find_new_gid.c, libmisc/find_new_uid.c: Do not check
gr_rewind/pw_rewind return value.
* libmisc/ttytype.c: Limit the number of parsed characters in the
sscanf format.
* libmisc/ttytype.c: Test if a type was really read.
* libmisc/sub.c: Do not check *printf/*puts return value.
* libmisc/sub.c: Avoid implicit conversion of integer to boolean.
* src/userdel.c: Fix typo in comment.
* src/userdel.c: Avoid implicit conversion of boolean to integer.
* src/userdel.c: safe_system last argument is a boolean.
* src/newusers.c: Avoid implicit conversion of boolean to integer.
* src/newusers.c: Avoid implicit conversion of integer to boolean.
* src/usermod.c: Add brackets.
* src/usermod.c: Avoid implicit conversion of characters or
integers to booleans.
* src/vipw.c: Avoid implicit conversion of integer to boolean.
* src/su.c: Avoid implicit conversion of integer to boolean.
* src/su.c: Add brackets.
* src/useradd.c: Avoid implicit conversion of characters or
integers to booleans.
libmisc/sulog.c, libmisc/hushed.c, libmisc/failure.c,
libmisc/loginprompt.c, libmisc/ttytype.c,
libmisc/pam_pass_non_interractive.c, src/userdel.c, src/login.c,
lib/commonio.c, lib/commonio.h: Fix some const issues.
* libmisc/motd.c: Avoid multi-statements lines.
* libmisc/motd.c: Support long MOTD_FILE.
* libmisc/list.c, lib/prototypes.h: Revert previous change.
dup_list and is_on_list are used with members as defined for the
group structure, and thus even if the list is not modified, the
list elements cannot be constant strings.
* libmisc/system.c: Avoid C++ comments.
* src/vipw.c: WITH_TCB cannot be tested inside a gettextized
string. Split the Usage string.
* lib/commonio.h: Re-indent.
no more used.
* lib/groupmem.c: Limit the scope of variable i.
* lib/shadow.c: Avoid implicit conversion of pointers and integers
to booleans.
* lib/shadow.c: Added brackets.
* libmisc/limits.c: Limit the scope of variable tmpmask.
* libmisc/copydir.c: Close opened file on failure.
* libmisc/loginprompt.c: Limit the scope of variable envc.
* libmisc/find_new_uid.c, libmisc/find_new_gid.c: Limit the scope
of variable id.
libmisc/loginprompt.c, libmisc/ttytype.c, libmisc/tz.c,
src/login_nopam.c, src/chpasswd.c, src/chgpasswd.c, lib/port.c:
The size argument of fgets is an int, not a size_t.
* libmisc/loginprompt.c: Ignore the return value from signal()
when the signal handlers are restored.
* src/chpasswd.c: Cast the return value of time() to a long
integer.
* src/chpasswd.c: Use the SCALE macro instead of (24L * 3600L)
for the values to be set in /etc/shadow.
* libmisc/loginprompt.c: Add brackets.
* libmisc/loginprompt.c: Avoid assignments in comparisons.
* libmisc/loginprompt.c: The return values of fclose and fflush are not checked on purpose.
Files with no license use the default 3-clauses BSD license. The copyright
were mostly not recorded; they were updated according to the Changelog.
"Julianne Frances Haugh and contributors" changed to "copyright holders
and contributors".
similar(), and simple() as unused.
* libmisc/loginprompt.c: Tag the `sig' parameter of login_exit()
as unused.
* src/expiry.c: Tag the `sig' parameter of catch_signals() as
unused.
* src/su.c: Tag the `sig' parameter of catch_signals() as unused.
* src/su.c: Add int parameter to the prototype of oldsig().
* src/login.c: Tag the `sig' parameter of alarm_handler() as
unused.
* src/sulogin.c: Tag the `sig' parameter of catch_signals() as
unused.
* libmisc/getdate.y: Tag the `string' parameter of yyerror() as
unused.
* libmisc/getdate.y: The string provided to yyerror() is const.
* libmisc/getdate.y: Fix the prototypes of yylex() and yyerror().
