Implement it as an inline function, and add restrict and ATTR_STRING()
and ATTR_ACCESS() as appropriate.
Reviewed-by: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
The variable declarations for the buffers have been aligned in this
commit, so that they appear in the diff, making it easier to review.
Some important but somewhat tangent changes included in this commit:
- lib/nss.c: The size was being defined as 65, but then used as 64.
That was a bug, although not an important one; we were just wasting
one byte. Fix that while we replace snprintf() by SNPRINTF(), which
will get the size from sizeof(), and thus will use the real size.
Signed-off-by: Alejandro Colomar <alx@kernel.org>
commonio.c: In function 'commonio_unlock':
commonio.c:487:49: warning: '.lock' directive output may be truncated writing 5 bytes into a region of size between 1 and 1024 [-Wformat-truncation=]
487 | snprintf (lock, sizeof lock, "%s.lock", db->filename);
| ^~~~~
commonio.c:487:17: note: 'snprintf' output between 6 and 1029 bytes into a destination of size 1024
487 | snprintf (lock, sizeof lock, "%s.lock", db->filename);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
asprintf(3) is non-standard, but is provided by GNU, the BSDs, and musl.
That makes it portable enough for us to use.
This function is much simpler than the burdensome code for allocating
the right size. Being simpler, it's thus safer.
I took the opportunity to fix the style to my preferred one in the
definitions of variables used in these calls, and also in the calls to
free(3) with these pointers. That isn't gratuituous, but has a reason:
it makes those appear in the diff for this patch, which helps review it.
Oh, well, I had an excuse :)
Reviewed-by: Iker Pedrosa <ipedrosa@redhat.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
commonio.c:522:15: warning: Although the value stored to 'cp' is used in the enclosing expression, the value is never actually read from 'cp' [deadcode.DeadStores]
Reviewed-by: Alejandro Colomar <alx@kernel.org>
Documentation:
- Correct the comment documenting the function:
write_full() doesn't write "up to" count bytes (which is write(2)'s
behavior, and exactly what this function is designed to avoid), but
rather exactly count bytes (on success).
- While fixing the documentation, take the time to add a man-page-like
comment as in other APIs. Especially, since we'll have to document
a few other changes from this patch, such as the modified return
values.
- Partial writes are still possible on error. It's the caller's
responsibility to handle that possibility.
API:
- In write(2), it's useful to know how many bytes were transferred,
since it can have short writes. In this API, since it either writes
it all or fails, that value is useless, and callers only want to know
if it succeeded or not. Thus, just return 0 or -1.
Implementation:
- Use `== -1` instead of `< 0` to check for write(2) syscall errors.
This is wisdom from Michael Kerrisk. This convention is useful
because it more explicitly tells maintainers that the only value
which can lead to that path is -1. Otherwise, a maintainer of the
code might be confused to think that other negative values are
possible. Keep it simple.
- The path under `if (res == 0)` was unreachable, since the loop
condition `while (count > 0)` precludes that possibility. Remove the
dead code.
- Use a temporary variable of type `const char *` to avoid a cast.
- Rename `res`, which just holds the result from write(2), to `w`,
which more clearly shows that it's just a very-short-lived variable
(by it's one-letter name), and also relates itself more to write(2).
I find it more readable.
- Move the definition of `w` to the top of the function. Now that the
function is significantly shorter, the lifetime of the variable is
clearer, and I find it more readable this way.
Use:
- Also use `== -1` to check errors.
Cc: Christian Göttsche <cgzones@googlemail.com>
Cc: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
If we consider simple objects as arrays of size 1, we can considerably
simplify these APIs, merging the *ARRAY and the non-array variants.
That will produce more readable code, since lines will be shorter (by
not having ARRAY in the macro names, as all macros will consistently
handle arrays), and the allocated size will be also more explicit.
The syntax will now be of the form:
p = MALLOC(42, foo_t); // allocate 42 elements of type foo_t.
p = MALLOC(1, bar_t); // allocate 1 element of type foo_t.
The _array() allocation functions should _never_ be called directly, and
instead these macros should be used.
The non-array functions (e.g., malloc(3)) still have their place, but
are limited to allocating structures with flexible array members. For
any other uses, the macros should be used.
Thus, we don't use any array or ARRAY variants in any code any more, and
they are only used as implementation details of these macros.
Link: <https://software.codidact.com/posts/285898/288023#answer-288023>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
The fcntl call to set FD_CLOEXEC can be performed directly with the
previously performed open call by using the O_CLOEXEC flag.
O_CLOEXEC is required by POSIX.1-2008.
Signed-off-by: Samanta Navarro <ferivoz@riseup.net>
Free the actual struct of the removed entry.
Example userdel report:
Direct leak of 40 byte(s) in 1 object(s) allocated from:
#0 0x55b230efe857 in reallocarray (./src/userdel+0xda857)
#1 0x55b230f6041f in mallocarray ./lib/./alloc.h:97:9
#2 0x55b230f6041f in commonio_open ./lib/commonio.c:563:7
#3 0x55b230f39098 in open_files ./src/userdel.c:555:6
#4 0x55b230f39098 in main ./src/userdel.c:1189:2
#5 0x7f9b48c64189 in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16
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>
Systems can suffer power interruptions whilst .lock files are in /etc,
preventing scripts and other automation tools from updating shadow's
files which persist across boots.
This commit replaces that mechanism with file locking to avoid problems
of power interruption/crashing.
Minor tweak to groupmems man page, requested by 'xx' on IRC.
Signed-off-by: ed neville <ed@s5h.net>
free(3) accepts NULL, since the oldest ISO C. I guess the
paranoid code was taking care of prehistoric implementations of
free(3). I've never known of an implementation that doesn't
conform to this, so let's simplify this.
Remove xfree(3), which was effectively an equivalent of free(3).
Signed-off-by: Alejandro Colomar <alx@kernel.org>
This tweaks the database locking logic so that failures in the
link-checking paths are more detailed.
The rationale for this is that I've experienced a non-deterministic
bug which seems to be coming from this logic, and I'd like to get
more details about the actual failing condition.
The build was failing with duplicate symbol errors with -fno-common.
This is the default in GCC 10 and later, and explicitly enabled in some
distributions to catch problems like this. There were two causes:
- Prog and shadow_logfd were defined in a header file that was included
in multiple other files. Fix this by defining them once in
shadowlog.c, and having extern declarations in the header.
- Most of the tools (except id/nologin) also define a Prog variable,
which is not intended to alias the one in the library. Fix
this by renaming Prog in the library to shadow_progname, which also
matches the new accessor functions for it.
Error: RESOURCE_LEAK (CWE-772): [#def1]
shadow-4.8.1/lib/commonio.c:320: alloc_fn: Storage is returned from allocation function "fopen_set_perms".
shadow-4.8.1/lib/commonio.c:320: var_assign: Assigning: "bkfp" = storage returned from "fopen_set_perms(backup, "w", &sb)".
shadow-4.8.1/lib/commonio.c:329: noescape: Resource "bkfp" is not freed or pointed-to in "putc".
shadow-4.8.1/lib/commonio.c:334: noescape: Resource "bkfp" is not freed or pointed-to in "fflush".
shadow-4.8.1/lib/commonio.c:339: noescape: Resource "bkfp" is not freed or pointed-to in "fileno".
shadow-4.8.1/lib/commonio.c:342: leaked_storage: Variable "bkfp" going out of scope leaks the storage it points to.
340| || (fclose (bkfp) != 0)) {
341| /* FIXME: unlink the backup file? */
342|-> return -1;
343| }
344|
Error: RESOURCE_LEAK (CWE-772): [#def2]
shadow-4.8.1/libmisc/addgrps.c:69: alloc_fn: Storage is returned from allocation function "malloc".
shadow-4.8.1/libmisc/addgrps.c:69: var_assign: Assigning: "grouplist" = storage returned from "malloc(i * 4UL)".
shadow-4.8.1/libmisc/addgrps.c:73: noescape: Resource "grouplist" is not freed or pointed-to in "getgroups". [Note: The source code implementation of the function has been overridden by a builtin model.]
shadow-4.8.1/libmisc/addgrps.c:126: leaked_storage: Variable "grouplist" going out of scope leaks the storage it points to.
124| }
125|
126|-> return 0;
127| }
128| #else /* HAVE_SETGROUPS && !USE_PAM */
Error: RESOURCE_LEAK (CWE-772): [#def3]
shadow-4.8.1/libmisc/chowntty.c:62: alloc_fn: Storage is returned from allocation function "getgr_nam_gid".
shadow-4.8.1/libmisc/chowntty.c:62: var_assign: Assigning: "grent" = storage returned from "getgr_nam_gid(getdef_str("TTYGROUP"))".
shadow-4.8.1/libmisc/chowntty.c:98: leaked_storage: Variable "grent" going out of scope leaks the storage it points to.
96| */
97| #endif
98|-> }
99|
Error: RESOURCE_LEAK (CWE-772): [#def4]
shadow-4.8.1/libmisc/copydir.c:742: open_fn: Returning handle opened by "open". [Note: The source code implementation of the function has been overridden by a user model.]
shadow-4.8.1/libmisc/copydir.c:742: var_assign: Assigning: "ifd" = handle returned from "open(src, 0)".
shadow-4.8.1/libmisc/copydir.c:748: leaked_handle: Handle variable "ifd" going out of scope leaks the handle.
746| #ifdef WITH_SELINUX
747| if (set_selinux_file_context (dst, NULL) != 0) {
748|-> return -1;
749| }
750| #endif /* WITH_SELINUX */
Error: RESOURCE_LEAK (CWE-772): [#def5]
shadow-4.8.1/libmisc/copydir.c:751: open_fn: Returning handle opened by "open". [Note: The source code implementation of the function has been overridden by a user model.]
shadow-4.8.1/libmisc/copydir.c:751: var_assign: Assigning: "ofd" = handle returned from "open(dst, 577, statp->st_mode & 0xfffU)".
shadow-4.8.1/libmisc/copydir.c:752: noescape: Resource "ofd" is not freed or pointed-to in "fchown_if_needed".
shadow-4.8.1/libmisc/copydir.c:775: leaked_handle: Handle variable "ofd" going out of scope leaks the handle.
773| ) {
774| (void) close (ifd);
775|-> return -1;
776| }
777|
Error: RESOURCE_LEAK (CWE-772): [#def7]
shadow-4.8.1/libmisc/idmapping.c:188: alloc_fn: Storage is returned from allocation function "xmalloc".
shadow-4.8.1/libmisc/idmapping.c:188: var_assign: Assigning: "buf" = storage returned from "xmalloc(bufsize)".
shadow-4.8.1/libmisc/idmapping.c:188: var_assign: Assigning: "pos" = "buf".
shadow-4.8.1/libmisc/idmapping.c:213: noescape: Resource "buf" is not freed or pointed-to in "write".
shadow-4.8.1/libmisc/idmapping.c:219: leaked_storage: Variable "pos" going out of scope leaks the storage it points to.
shadow-4.8.1/libmisc/idmapping.c:219: leaked_storage: Variable "buf" going out of scope leaks the storage it points to.
217| }
218| close(fd);
219|-> }
Error: RESOURCE_LEAK (CWE-772): [#def8]
shadow-4.8.1/libmisc/list.c:211: alloc_fn: Storage is returned from allocation function "xstrdup".
shadow-4.8.1/libmisc/list.c:211: var_assign: Assigning: "members" = storage returned from "xstrdup(comma)".
shadow-4.8.1/libmisc/list.c:217: var_assign: Assigning: "cp" = "members".
shadow-4.8.1/libmisc/list.c:218: noescape: Resource "cp" is not freed or pointed-to in "strchr".
shadow-4.8.1/libmisc/list.c:244: leaked_storage: Variable "cp" going out of scope leaks the storage it points to.
shadow-4.8.1/libmisc/list.c:244: leaked_storage: Variable "members" going out of scope leaks the storage it points to.
242| if ('\0' == *members) {
243| *array = (char *) 0;
244|-> return array;
245| }
246|
Error: RESOURCE_LEAK (CWE-772): [#def11]
shadow-4.8.1/libmisc/myname.c:61: alloc_fn: Storage is returned from allocation function "xgetpwnam".
shadow-4.8.1/libmisc/myname.c:61: var_assign: Assigning: "pw" = storage returned from "xgetpwnam(cp)".
shadow-4.8.1/libmisc/myname.c:67: leaked_storage: Variable "pw" going out of scope leaks the storage it points to.
65| }
66|
67|-> return xgetpwuid (ruid);
68| }
69|
Error: RESOURCE_LEAK (CWE-772): [#def12]
shadow-4.8.1/libmisc/user_busy.c:260: alloc_fn: Storage is returned from allocation function "opendir".
shadow-4.8.1/libmisc/user_busy.c:260: var_assign: Assigning: "task_dir" = storage returned from "opendir(task_path)".
shadow-4.8.1/libmisc/user_busy.c:262: noescape: Resource "task_dir" is not freed or pointed-to in "readdir".
shadow-4.8.1/libmisc/user_busy.c:278: leaked_storage: Variable "task_dir" going out of scope leaks the storage it points to.
276| _("%s: user %s is currently used by process %d\n"),
277| Prog, name, pid);
278|-> return 1;
279| }
280| }
Error: RESOURCE_LEAK (CWE-772): [#def20]
shadow-4.8.1/src/newgrp.c:162: alloc_fn: Storage is returned from allocation function "xgetspnam".
shadow-4.8.1/src/newgrp.c:162: var_assign: Assigning: "spwd" = storage returned from "xgetspnam(pwd->pw_name)".
shadow-4.8.1/src/newgrp.c:234: leaked_storage: Variable "spwd" going out of scope leaks the storage it points to.
232| }
233|
234|-> return;
235|
236| failure:
Error: RESOURCE_LEAK (CWE-772): [#def21]
shadow-4.8.1/src/passwd.c:530: alloc_fn: Storage is returned from allocation function "xstrdup".
shadow-4.8.1/src/passwd.c:530: var_assign: Assigning: "cp" = storage returned from "xstrdup(crypt_passwd)".
shadow-4.8.1/src/passwd.c:551: noescape: Resource "cp" is not freed or pointed-to in "strlen".
shadow-4.8.1/src/passwd.c:554: noescape: Resource "cp" is not freed or pointed-to in "strcat". [Note: The source code implementation of the function has been overridden by a builtin model.]
shadow-4.8.1/src/passwd.c:555: overwrite_var: Overwriting "cp" in "cp = newpw" leaks the storage that "cp" points to.
553| strcpy (newpw, "!");
554| strcat (newpw, cp);
555|-> cp = newpw;
556| }
557| return cp;
Closes#325
Add a new subid_init() function which can be used to specify the
stream on which error messages should be printed. (If you want to
get fancy you can redirect that to memory :) If subid_init() is
not called, use stderr. If NULL is passed, then /dev/null will
be used.
This patch also fixes up the 'Prog', which previously had to be
defined by any program linking against libsubid. Now, by default
in libsubid it will show (subid). Once subid_init() is called,
it will use the first variable passed to subid_init().
Signed-off-by: Serge Hallyn <serge@hallyn.com>
Search the SELinux selabel database for the file type to be created.
Not specifying the file mode can cause an incorrect file context to be
returned.
Also prepare contexts in commonio_close() for the generic database
filename, not with the backup suffix appended, to ensure the desired
file context after the final rename.
Closes: #322
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Acked-by: James Carter <jwcart2@gmail.com>
As the lockfiles have PID in the name, there can be no conflict
in the name with other process, so there is no point in using
O_EXCL and it only can fail if there is a stale lockfile from
previous execution that crashed for some reason.
The implementation of prefix option dropped the use of lckpwdf().
However that is incorrect as other tools manipulating the shadow passwords
such as PAM use lckpwdf() and do not know anything about the
shadow's own locking mechanism.
This reverts the implementation to use lckpwdf() if prefix option
is not used.
Some distributions, notably Fedora, have the following order of nsswitch
modules by default:
passwd: sss files
group: sss files
The advantage of serving local users through SSSD is that the nss_sss
module has a fast mmapped-cache that speeds up NSS lookups compared to
accessing the disk an opening the files on each NSS request.
Traditionally, this has been done with the help of nscd, but using nscd
in parallel with sssd is cumbersome, as both SSSD and nscd use their own
independent caching, so using nscd in setups where sssd is also serving
users from some remote domain (LDAP, AD, ...) can result in a bit of
unpredictability.
More details about why Fedora chose to use sss before files can be found
on e.g.:
https://fedoraproject.org//wiki/Changes/SSSDCacheForLocalUsers
or:
https://docs.pagure.org/SSSD.sssd/design_pages/files_provider.html
Now, even though sssd watches the passwd and group files with the help
of inotify, there can still be a small window where someone requests a
user or a group, finds that it doesn't exist, adds the entry and checks
again. Without some support in shadow-utils that would explicitly drop
the sssd caches, the inotify watch can fire a little late, so a
combination of commands like this:
getent passwd user || useradd user; getent passwd user
can result in the second getent passwd not finding the newly added user
as the racy behaviour might still return the cached negative hit from
the first getent passwd.
This patch more or less copies the already existing support that
shadow-utils had for dropping nscd caches, except using the "sss_cache"
tool that sssd ships.
