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>
alloca(3) fails silently if not enough memory can be allocated on the
stack. Use checked dynamic allocation instead.
Also drop unnecessary manual NUL assignment, ensured by snprintf(3).
Co-developed-by: Alejandro Colomar <alx@kernel.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Allocate enough memory for the strings, two slashes and the NUL
terminator.
Reported-by: Alejandro Colomar <alx@kernel.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
The --gid option accepts a group name or id. When a name is provided, it
is resolved to an id by looking up the name in the group database
(/etc/group).
The --prefix option overides the location of the passwd and group
databases. I suspect the --gid option was overlooked when wiring up the
--prefix option.
useradd --gid already respects --prefix; this change makes usermod
behave the same way.
Fixes: b6b2c756c9
Signed-off-by: Mike Gilbert <floppym@gentoo.org>
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>
Report error if usermod asked for moving homedir and it does not exist.
Signed-off-by: Tomáš Mráz <tm@t8m.info>
Signed-off-by: Iker Pedrosa <ipedrosa@redhat.com>
PARAMETERS:
According to the C2x charter, I reordered the parameters 'size'
and 'buf' from previously existing date_to_str() definitions.
C2x charter:
> 15. Application Programming Interfaces (APIs) should be
> self-documenting when possible. In particular, the order of
> parameters in function declarations should be arranged such that
> the size of an array appears before the array. The purpose is to
> allow Variable-Length Array (VLA) notation to be used. This not
> only makes the code's purpose clearer to human readers, but also
> makes static analysis easier. Any new APIs added to the Standard
> should take this into consideration.
I used 'long' for the date parameter, as some uses of the function
need to pass a negative value meaning "never".
FUNCTION BODY:
I didn't check '#ifdef HAVE_STRFTIME', which old definitions did,
since strftime(3) is guaranteed by the C89 standard, and all of
the conversion specifiers that we use are also specified by that
standard, so we don't need any extensions at all.
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
The only way of removing a group from the supplementary list is to use
-G option, and list all groups that the user is a member of except for
the one that wants to be removed. The problem lies when there's a user
that contains both local and remote groups, and the group to be removed
is a local one. As we need to include the remote group with -G option
the command will fail.
This reverts commit 140510de9d. This way,
it would be possible to remove the remote groups from the supplementary
list.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1967641
Resolves: https://github.com/shadow-maint/shadow/issues/338
Signed-off-by: Iker Pedrosa <ipedrosa@redhat.com>
Error: RESOURCE_LEAK (CWE-772): [#def31]
shadow-4.8.1/src/usermod.c:813: alloc_fn: Storage is returned from allocation function "__gr_dup".
shadow-4.8.1/src/usermod.c:813: var_assign: Assigning: "ngrp" = storage returned from "__gr_dup(grp)".
shadow-4.8.1/src/usermod.c:892: leaked_storage: Variable "ngrp" going out of scope leaks the storage it points to.
890| }
891| }
892|-> }
893|
894| #ifdef SHADOWGRP
Error: RESOURCE_LEAK (CWE-772): [#def32]
shadow-4.8.1/src/usermod.c:933: alloc_fn: Storage is returned from allocation function "__sgr_dup".
shadow-4.8.1/src/usermod.c:933: var_assign: Assigning: "nsgrp" = storage returned from "__sgr_dup(sgrp)".
shadow-4.8.1/src/usermod.c:1031: leaked_storage: Variable "nsgrp" going out of scope leaks the storage it points to.
1029| }
1030| }
1031|-> }
1032| #endif /* SHADOWGRP */
1033|
Error: RESOURCE_LEAK (CWE-772): [#def34]
shadow-4.8.1/src/usermod.c:1161: alloc_fn: Storage is returned from allocation function "getgr_nam_gid".
shadow-4.8.1/src/usermod.c:1161: var_assign: Assigning: "grp" = storage returned from "getgr_nam_gid(optarg)".
shadow-4.8.1/src/usermod.c:1495: leaked_storage: Variable "grp" going out of scope leaks the storage it points to.
1493| }
1494| #endif /* ENABLE_SUBIDS */
1495|-> }
1496|
1497| /*
Error: RESOURCE_LEAK (CWE-772): [#def35]
shadow-4.8.1/src/usermod.c:1991: 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/src/usermod.c:1991: var_assign: Assigning: "fd" = handle returned from "open("/var/log/lastlog", 2)".
shadow-4.8.1/src/usermod.c:2000: noescape: Resource "fd" is not freed or pointed-to in "lseek".
shadow-4.8.1/src/usermod.c:2000: noescape: Resource "fd" is not freed or pointed-to in "read". [Note: The source code implementation of the function has been overridden by a builtin model.]
shadow-4.8.1/src/usermod.c:2003: noescape: Resource "fd" is not freed or pointed-to in "lseek".
shadow-4.8.1/src/usermod.c:2032: leaked_handle: Handle variable "fd" going out of scope leaks the handle.
2030| }
2031| }
2032|-> }
2033|
2034| /*
Error: RESOURCE_LEAK (CWE-772): [#def36]
shadow-4.8.1/src/usermod.c:2052: 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/src/usermod.c:2052: var_assign: Assigning: "fd" = handle returned from "open("/var/log/faillog", 2)".
shadow-4.8.1/src/usermod.c:2061: noescape: Resource "fd" is not freed or pointed-to in "lseek".
shadow-4.8.1/src/usermod.c:2061: noescape: Resource "fd" is not freed or pointed-to in "read". [Note: The source code implementation of the function has been overridden by a builtin model.]
shadow-4.8.1/src/usermod.c:2064: noescape: Resource "fd" is not freed or pointed-to in "lseek".
shadow-4.8.1/src/usermod.c:2092: leaked_handle: Handle variable "fd" going out of scope leaks the handle.
2090| }
2091| }
2092|-> }
2093|
2094| #ifndef NO_MOVE_MAILBOX
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>
new switch added to useradd command, --btrfs-subvolume-home. When
specified *and* the filesystem is detected as btrfs, it will create a
subvolume for user's home instead of a plain directory. This is done via
`btrfs subvolume` command. Specifying the new switch while trying to
create home on non-btrfs will result in an error.
userdel -r will handle and remove this subvolume transparently via
`btrfs subvolume` command. Previosuly this failed as you can't rmdir a
subvolume.
usermod, when moving user's home across devices, will detect if the home
is a subvolume and issue an error messages instead of copying it. Moving
user's home (as subvolume) on same btrfs works transparently.
In case the home directory is not a real home directory
(owned by the user) but things like / or /var or similar,
it is unsafe to change ownership of home directory content.
The test checks whether the home directory is owned by the
user him/herself, if not no ownership modification of contents
is performed.
As the large uids are usually provided by remote user identity and
authentication service, which also provide user login tracking,
there is no need to create a huge sparse file for them on every local
machine.
fixup! login.defs: Add LASTLOG_UID_MAX variable to limit lastlog to small uids.
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.
The third field in the /etc/shadow file (sp_lstchg) contains the date of
the last password change expressed as the number of days since Jan 1, 1970.
As this is a relative time, creating a user today will result in:
username:17238:0:99999:7:::
whilst creating the same user tomorrow will result in:
username:17239:0:99999:7:::
This has an impact for the Reproducible Builds[0] project where we aim to
be independent of as many elements the build environment as possible,
including the current date.
This patch changes the behaviour to use the SOURCE_DATE_EPOCH[1]
environment variable (instead of Jan 1, 1970) if valid.
[0] https://reproducible-builds.org/
[1] https://reproducible-builds.org/specs/source-date-epoch/
Signed-off-by: Chris Lamb <lamby@debian.org>
Alejandro Colomar
Christian Göttsche
Iker Pedrosa
Martin Kletzander
Mike Gilbert
xyz
Jeremy Whiting
Matheus Marques
Serge Hallyn
Alejandro Colomar
ed neville
Andy Zaugg
a1346054
Geert Ijewski
Stanislav Brabec
Adam Majer
Tomas Mraz
Jakub Hrozek
fariouche
WheresAlice
Chris Lamb