Use *at() functions to pin the directory operating in to avoid being
redirected by unprivileged users replacing parts of paths by symlinks to
privileged files.
Use *at() functions to pin the directory operating in to avoid being
redirected by unprivileged users replacing parts of paths by symlinks to
privileged files.
Allow the compiler to verify the format string against the supplied
arguments.
chage.c:239:51: warning: format not a string literal, format string not checked [-Wformat-nonliteral]
239 | (void) strftime (buf, sizeof buf, format, tp);
| ^~~~~~
salt.c:102:22: warning: type qualifiers ignored on function return type [-Wignored-qualifiers]
102 | static /*@observer@*/const unsigned long SHA_get_salt_rounds (/*@null@*/int *prefered_rounds);
| ^~~~~
salt.c:110:22: warning: type qualifiers ignored on function return type [-Wignored-qualifiers]
110 | static /*@observer@*/const unsigned long YESCRYPT_get_salt_cost (/*@null@*/int *prefered_cost);
| ^~~~~
subordinateio.c:160:8: warning: type qualifiers ignored on function return type [-Wignored-qualifiers]
160 | static const bool range_exists(struct commonio_db *db, const char *owner)
| ^~~~~
Compilers are free to ignore the indented hint and modern optimizations
should create good code by themself.
(As such it is for example deprecated in C++17.)
On systems with Linux kernel < 3.17, getentropy() and getrandom() may
exist but return ENOSYS. Use /dev/urandom as a fallback to avoid a hard
requirement on Linux kernel version.
Fixes#512.
Signed-off-by: Xi Ruoyao <xry111@xry111.site>
In order to remove some of the FIXMEs it was necessary to change the
code and call getulong() instead of getlong().
Signed-off-by: Iker Pedrosa <ipedrosa@redhat.com>
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 K&R C signal(2) signature is obsolete.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>
nss_init() does not modify its path argument, thus declare it const.
Also drop superfluous prototype.
nss.c:54:31: warning: assignment discards ‘const’ qualifier from pointer target type [-Wdiscarded-qualifiers]
54 | nsswitch_path = NSSWITCH;
| ^
Function declarations with no argument declare functions taking an
arbitrary number of arguments. Use the special type void to declare
functions taking no argument.
C89 defined isdigit as a function that tests for any decimal-digit
character, defining the decimal digits as 0 1 2 3 4 5 6 7 8 9.
I don't own a copy of C89 to check, but check in C17:
7.4.1.5
5.2.1
More specifically:
> In both the source and execution basic character sets, the value
> of each character after 0 in the above list of decimal digits
> shall be one greater than the value of the previous.
And since in ascii(7), the character after '9' is ':', it's highly
unlikely that any implementation will ever accept any
_decimal digit_ other than 0..9.
POSIX simply defers to the ISO C standard.
This is exactly what we wanted from ISDIGIT(c), so just use it.
Non-standard implementations might have been slower or considered
other characters as digits in the past, but let's assume
implementations available today conform to ISO C89.
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
It wasn't being used at all. Let's remove it.
Use isdigit(3) directly in comments that referenced it.
Also, in those comments, remove an outdated reference to the fact
that ISDIGIT_LOCALE(c) might evaluate its argument more than once,
which could be true a few commits ago, until
IN_CTYPE_DEFINITION(c) was removed. Previously, the definition
for ISDIGIT_LOCALE(c) was:
#if defined (STDC_HEADERS) || (!defined (isascii) && !defined (HAVE_ISASCII))
# define IN_CTYPE_DOMAIN(c) 1
#else
# define IN_CTYPE_DOMAIN(c) isascii(c)
#endif
#define ISDIGIT_LOCALE(c) (IN_CTYPE_DOMAIN (c) && isdigit (c))
Which could evaluate 'c' twice on pre-C89 systems (which I hope
don't exist nowadays).
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
Due to the recent removal of IN_CTYPE_DOMAIN(), the uppercase
macros that wrapped these standard calls are now defined to be
equivalent. Therefore, there's no need for the wrappers, and it
is much more readable to use the standard calls directly.
However, hold on with ISDIGIT*(), since it's not so obvious what
to do with it.
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
The recent removal of STDC_HEADERS made IN_CTYPE_DOMAIN be defined
to 1 unconditionally. Remove the now unnecessary definition, and
propagate its truthness to expressions where it was used.
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
We're in 2021. C89 is everywhere; in fact, there are many other
assumptions in the code that wouldn't probably hold on
pre-standard C environments. Let's simplify and assume that C89
is available.
The specific assumptions are that:
- <string.h>, and <stdlib.h> are available
- strchr(3), strrchr(3), and strtok(3) are available
- isalpha(3), isspace(3), isdigit(3), and isupper(3) are available
I think we can safely assume we have all of those.
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
memcpy(3) has been in standard C since C89. It is also in
POSIX.1-2001, in SVr4, and in 4.3BSD (see memcpy(3) and memcpy(3p)).
We can assume that this function is always available.
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
strftime(3) has been in standard C since C89. It is also in
POSIX.1-2001, and in SVr4 (see strftime(3) and strftime(3p)).
We can assume that this function is always available.
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.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>
When using groupdel with a prefix, groupdel will attempt to read a
passwd file to look for any user in the group. When the file does not
exist it cores with segmentation fault.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1986111
If a line in hushlogins file, e.g. /etc/hushlogins, starts with
'\0', then current code performs an out of boundary write.
If the line lacks a newline at the end, then another character is
overridden.
With strcspn both cases are solved.
Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
If SHA_CRYPT_MIN_ROUNDS and SHA_CRYPT_MAX_ROUNDS are both unspecified,
use SHA_ROUNDS_DEFAULT.
Previously, the code fell through, calling shadow_random(-1, -1). This
ultimately set rounds = (unsigned long) -1, which ends up being a very
large number! This then got capped to SHA_ROUNDS_MAX later in the
function.
The new behavior matches BCRYPT_get_salt_rounds().
Bug: https://bugs.gentoo.org/808195
Fixes: https://github.com/shadow-maint/shadow/issues/393
There's a better way to do this, and I hope to clean that up,
but this fixes out of tree builds for me right now.
Closes#386
Signed-off-by: Serge Hallyn <serge@hallyn.com>
In 9eb191edc4 I included a free() that
frees the members variable, which in turn causes the comma_to_list()
function to return an array of empty elements. The array variable holds
a list of pointers that point to offsets of the members variable. When
the function succeeds freeing members variable causes the elements of
the array variable to point to an empty string.
This is causing several regressions in our internal testing environment.
So, I'm reverting the change.
Signed-off-by: Iker Pedrosa <ipedrosa@redhat.com>
Most Linux distributions, including Fedora and RHEL 8, are shipping
with libxcrypt >= 4.0.
Since that version of libxcrypt the provided family of crypt_gensalt()
functions are able to use automatic entropy drawn from secure system
ressources, like arc4random(), getentropy() or getrandom().
Anyways, the settings generated by crypt_gensalt() are always
guaranteed to works with the crypt() function.
Using crypt_gensalt() is also needed to make proper use of newer
hashing methods, like yescrypt, provided by libxcrypt.
Signed-off-by: Björn Esser <besser82@fedoraproject.org>
In a previous commit we introduced /dev/urandom as a source to obtain
random bytes from. This may not be available on all systems, or when
operating inside of a chroot.
Almost all systems provide functions to obtain random bytes from
secure system ressources. Thus we should prefer to use these, and
fall back to /dev/urandom, if there is no such function present, as
a last resort.
Signed-off-by: Björn Esser <besser82@fedoraproject.org>
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;
Using the random() function to obtain pseudo-random bytes
for generating salt strings is considered to be dangerous.
See CWE-327.
We really should use a more reliable source for obtaining
pseudo-random bytes like /dev/urandom.
Fixes#376.
Signed-off-by: Björn Esser <besser82@fedoraproject.org>
In the previous commit we refactored the functions converting the
rounds number into a string for use with the crypt() function, to
not require any static buffer anymore.
Add some clarifying comments about how the minimum required buffer
length is computed inside of these functions.
Signed-off-by: Björn Esser <besser82@fedoraproject.org>
* Move all pre-processor defines to the top of the file.
* Unify the gensalt() function to be useable for all supported
hash methods.
* Drop the gensalt_{b,yes}crypt() functions in favor of the
previous change.
* Refactor the functions converting the rounds number into
a string for use with the crypt() function, to not require
any static buffer anymore.
* Clarify the comment about how crypt_make_salt() chooses the used
hash method from the settings in the login.defs file.
* Use memset() to fill static buffers with zero before using them.
* Use a fixed amount of 16 random base64-chars for the
sha{256,512}crypt hash methods, which is effectively still less
than the recommendation from NIST (>= 128 bits), but the maximum
those methods can effectively use (approx. 90 bits).
* Rename ROUNDS_{MIN,MAX} to SHA_ROUNDS_{MIN,MAX}.
* Bugfixes in the logic of setting rounds in BCRYPT_salt_rounds().
* Likewise for YESCRYPT_salt_cost().
* Fix formatting and white-space errors.
Signed-off-by: Björn Esser <besser82@fedoraproject.org>
The corresponding functions for the other hash methods all take
a pointer to an integer value as the only paramater, so this
particular function should do so as well.
Signed-off-by: Björn Esser <besser82@fedoraproject.org>
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>
When uid 0 maps host uid 0 into the child userns newer kernels require
CAP_SETFCAP be retained as this allows the caller to create fscaps that
are valid in the ancestor userns. This was a security issue (in very
rare circumstances). So whenever host uid 0 is mapped, retain
CAP_SETFCAP if the caller had it.
Userspace won't need to set CAP_SETFCAP on newuidmap as this is really
only a scenario that real root should be doing which always has
CAP_SETFCAP. And if they don't then they are in a locked-down userns.
(LXC sometimes maps host uid 0 during chown operations in a helper
userns but will not rely on newuidmap for that. But we don't want to
risk regressing callers that want to rely on this behavior.)
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.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>
Closes#154
When starting any operation to do with subuid delegation, check
nsswitch for a module to use. If none is specified, then use
the traditional /etc/subuid and /etc/subgid files.
Currently only one module is supported, and there is no fallback
to the files on errors. Several possibilities could be considered:
1. in case of connection error, fall back to files
2. in case of unknown user, also fall back to files
etc...
When non-files nss module is used, functions to edit the range
are not supported. It may make sense to support it, but it also
may make sense to require another tool to be used.
libsubordinateio also uses the nss_ helpers. This is how for instance
lxc could easily be converted to supporting nsswitch.
Add a set of test cases, including a dummy libsubid_zzz module. This
hardcodes values such that:
'ubuntu' gets 200000 - 300000
'user1' gets 100000 - 165536
'error' emulates an nss module error
'unknown' emulates a user unknown to the nss module
'conn' emulates a connection error ot the nss module
Changes to libsubid:
Change the list_owner_ranges api: return a count instead of making the array
null terminated.
This is a breaking change, so bump the libsubid abi major number.
Rename free_subuid_range and free_subgid_range to ungrant_subuid_range,
because otherwise it's confusing with free_subid_ranges which frees
memory.
Run libsubid tests in jenkins
Switch argument order in find_subid_owners
Move the db locking into subordinateio.c
Signed-off-by: Serge Hallyn <serge@hallyn.com>
Issue #297 reported seeing
*** Warning: Linking the shared library libsubid.la against the
*** static library ../libmisc/libmisc.a is not portable!
which commit b5fb1b38ee was supposed
to fix. But a few commits later it's back. So try to fix it
in the way the bug reporter suggested. This broke builds some
other ways, namely a few missing library specifications, so add
those.
Signed-off-by: Serge Hallyn <serge@hallyn.com>
Do not include <sys/prctl.h> we don't have <sys/capability.h>, we don't
need prctl in that case anyway.
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
In case there is a regular user with a process running on a system
with uid falling into a namespaced uid range of another user.
The user with the colliding namespaced uid range will not be
allowed to be deleted without forcing the action with -f.
The user_busy() is adjusted to check whether the suspected process
is really a namespaced process in a different namespace.
With this, it is possible for Linux distributors to store their
supplied default configuration files somewhere below /usr, while
/etc only contains the changes made by the user. The new option
--enable-vendordir defines where the shadow suite should additional
look for login.defs if this file is not in /etc.
libeconf is a key/value configuration file reading library, which
handles the split of configuration files in different locations
and merges them transparently for the application.
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.
From <https://github.com/shadow-maint/shadow/pull/71>:
```
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.
```
This updated PR adds some missing calls to gettime (). This was originally
filed by Johannes Schauer in Debian as #917773 [2].
[0] https://reproducible-builds.org/
[1] https://reproducible-builds.org/specs/source-date-epoch/
[2] https://bugs.debian.org/917773
simplify the condition for setting the euid of the process. Now it is
always set when we are running as root, the issue was introduced with
the commit 52c081b02c
Changelog: 2018-11-24 - seh - enforce that euid only gets set to ruid if
it currently == 0 (i.e. really was setuid-*root*).
Closes: https://github.com/genuinetools/img/issues/191
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
Signed-off-by: Serge Hallyn <shallyn@cisco.com>
Commit 1ecca8439d ("new[ug]idmap: not require CAP_SYS_ADMIN in the parent userNS")
does contain a wrong commit message, is lacking an explanation of the
issue, misses some simplifications and hardening features. This commit
tries to rectify this.
In (crazy) environment where all capabilities are dropped from the
capability bounding set apart from CAP_SET{G,U}ID setuid- and
fscaps-based new{g,u}idmap binaries behave differently when writing
complex mappings for an unprivileged user:
1. newuidmap is setuid
unshare -U sleep infinity &
newuidmap $? 0 100000 65536
First file_ns_capable(file, ns, CAP_SYS_ADMIN) is hit. This calls into
cap_capable() and hits the loop
for (;;) {
/* Do we have the necessary capabilities? */
if (ns == cred->user_ns)
return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
/*
* If we're already at a lower level than we're looking for,
* we're done searching.
*/
if (ns->level <= cred->user_ns->level)
return -EPERM;
/*
* The owner of the user namespace in the parent of the
* user namespace has all caps.
*/
if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid))
return 0;
/*
* If you have a capability in a parent user ns, then you have
* it over all children user namespaces as well.
*/
ns = ns->parent;
}
The first check fails and falls through to the end of the loop and
retrieves the parent user namespace and checks whether CAP_SYS_ADMIN is
available there which isn't.
2. newuidmap has CAP_SETUID as fscaps set
unshare -U sleep infinity &
newuidmap $? 0 100000 65536
The first file_ns_capable() check for CAP_SYS_ADMIN is passed since the
euid has not been changed:
if ((ns->parent == cred->user_ns) && uid_eq(ns->owner, cred->euid))
return 0;
Now new_idmap_permitted() is hit which calls ns_capable(ns->parent,
CAP_SET{G,U}ID). This check passes since CAP_SET{G,U}ID is available in
the parent user namespace.
Now file_ns_capable(file, ns->parent, CAP_SETUID) is hit and the
cap_capable() loop (see above) is entered again. This passes
if (ns == cred->user_ns)
return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
since CAP_SET{G,U}ID is available in the parent user namespace. Now the
mapping can be written.
There is no need for this descrepancy between setuid and fscaps based
new{g,u}idmap binaries. The solution is to do a
seteuid() back to the unprivileged uid and PR_SET_KEEPCAPS to keep
CAP_SET{G,U}ID. The seteuid() will cause the
file_ns_capable(file, ns, CAP_SYS_ADMIN) check to pass and the
PR_SET_KEEPCAPS for CAP_SET{G,U}ID will cause the CAP_SET{G,U}ID to
pass.
Fixes: 1ecca8439d ("new[ug]idmap: not require CAP_SYS_ADMIN in the parent userNS")
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
if the euid!=owner of the userns, the kernel returns EPERM when trying
to write the uidmap and there is no CAP_SYS_ADMIN in the parent
namespace.
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
This allows shadow-utils to build on systems like Adélie, which have no
<utmp.h> header or `struct utmp`. We use a <utmpx.h>-based daemon,
utmps[1], which uses `struct utmpx` only.
Tested both `login` and `logoutd` with utmps and both work correctly.
[1]: http://skarnet.org/software/utmps/
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>
Previously, the allocation was optimized for an outdated
deployment style (that of /etc/group alongside nss_db). The issue
here is that this results in extremely poor performance when using
SSSD, Winbind or nss_ldap.
There were actually two serious bugs here that have been addressed:
1) Running getgrent() loops won't work in most SSSD or Winbind
environments, as full group enumeration is disabled by default.
This could easily result in auto-allocating a group that was
already in use. (This might result in a security issue as well, if
the shared GID is a privileged group).
2) For system groups, the loop was always iterating through the
complete SYS_GID_MIN->SYS_GID_MAX range. On SSSD and Winbind, this
means hundreds of round-trips to LDAP (unless the GIDs were
specifically configured to be ignored by the SSSD or winbindd).
To a user with a slow connection to their LDAP server, this would
appear as if groupadd -r was hung. (Though it would eventually
complete).
This patch changes the algorithm to be more favorable for LDAP
environments, at the expense of some performance when using nss_db.
Given that the DB is a local service, this should have a negligible
effect from a user's perspective.
With the new algorithm, we simply first iterate through all entries
in the local database with gr_next(), recording the IDs that are in
use. We then start from the highest presumed-available entry and
call getgrgid() to see if it is available. We continue this until
we come to the first unused GID. We then select that and return it.
If we make it through all the remaining IDs without finding a free
one, we start over from the beginning of the range and try to find
room in one of the gaps in the range.
The patch was originally written by Stephen Gallagher and applied
identically also to the user allocation by Tomáš Mráz.
Signed-off-by: Serge Hallyn <serge@hallyn.com>
Catch up with Automake's [1], which was part of v1.6b, cut 2002-07-28
[2]. Avoids:
$ autoreconf -v -f --install
...
libmisc/Makefile.am:4: warning: 'INCLUDES' is the old name for 'AM_CPPFLAGS' (or '*_CPPFLAGS')
...
src/Makefile.am:10: warning: 'INCLUDES' is the old name for 'AM_CPPFLAGS' (or '*_CPPFLAGS')
...
Consolidating with the earlier AM_CPPFLAGS avoids:
$ autoreconf -v -f --install
src/Makefile.am:72: warning: AM_CPPFLAGS multiply defined in condition TRUE ...
src/Makefile.am:10: ... 'AM_CPPFLAGS' previously defined here
autoreconf-2.69: Leaving directory `.'
[1]: http://git.savannah.gnu.org/cgit/automake.git/commit/?id=1415d22f6203206bc393fc4ea233123ba579222d
Summary: automake.in (generate_makefile): Suggest using AM_CPPFLAGS instead of INCLUDES
Date: 2002-07-09
[2]: http://git.savannah.gnu.org/cgit/automake.git/tag/?id=Release-1-6b
- Use an allocation of 65536 uids and gids to allow for POSIX-compliant
user owned namespaces.
- Don't allocate a uid/gid map to system users.
Unfortunately checking for --system isn't quite enough as some
distribution wrappers always call useradd without --system and take care
of choosing a uid and gid themselves, so also check whether the
requested uid/gid is in the user range.
This is taken from a patch I wrote for Ubuntu a couple years ago and
which somehow didn't make it upstream.
Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
The number of ranges should be the ceiling of the number of arguments divided
by three.
Without this fix newuidmap and newgidmap always report and error and fail,
which is very much not what we want.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
* libmisc/find_new_sub_gids.c: Remove dead code.
find_new_sub_gids() is always called with *range_count set to 0.
It's more difficult to keep the subordinate GIDs and UIDs
synchronized, than for the user's UID/GId because the count of
subordinate IDs may differ.
* libmisc/find_new_sub_uids.c: Likewise.
* lib/subordinateio.h, lib/subordinateio.c: Remove APIs that are
no more needed: is_sub_uid_range_free(), is_sub_gid_range_free(),
is_range_free().
* libmisc/idmapping.h: Document what the upper and lower fields
are in struct map_range.
* man/newgidmap.1.xml: Document when the gid, gidlower and count
argument are.
* man/newuidmap.1.xml: Likewise for uid, uidlower and count.
* libmisc/salt.c (shadow_random): Use long instead of size_t.
Compatibility with size_t is easier to check since it's used for
smaller numbers (salt size).
* configure.in: Add configure options --enable-subordinate-ids /
--disable-subordinate-ids. Enabled by default.
* lib/prototypes.h: Include <config.h> before using its macros.
* lib/commonio.h, lib/commonio.c: Define commonio_append only when
ENABLE_SUBIDS is defined.
* lib/prototypes.h, libmisc/find_new_sub_gids.c,
libmisc/find_new_sub_uids.c: Likewise.
* lib/subordinateio.h, lib/subordinateio.c: Likewise.
* libmisc/user_busy.c: Only check if subordinate IDs are in use if
ENABLE_SUBIDS is defined.
* src/Makefile.am: Create newgidmap and newuidmap only if
ENABLE_SUBIDS is defined.
* src/newusers.c: Check for ENABLE_SUBIDS to enable support for
subordinate IDs.
* src/useradd.c: Likewise.
* src/userdel.c: Likewise.
* src/usermod.c: Likewise.
* man/Makefile.am: Install man1/newgidmap.1, man1/newuidmap.1,
man5/subgid.5, and man5/subuid.5 only if ENABLE_SUBIDS is defined.
* man/fr/Makefile.am: Install man1/newgidmap.1, man1/newuidmap.1,
man5/subgid.5, and man5/subuid.5 (not translated yet).
* man/generate_mans.mak: Add xsltproc conditionals
subids/no_subids.
* man/login.defs.d/SUB_GID_COUNT.xml: Add dependency on subids
condition.
* man/login.defs.d/SUB_UID_COUNT.xml: Likewise.
* man/usermod.8.xml: Document options for subordinate IDs and
reference subgid(5) / subuid(5) depending on the subids condition.
In find_new_sub_{u,g}ids, check for min, count and max values.
In idmapping.c:get_map_ranges(), make sure that the value passed
in for ranges did not overflow. Couldn't happen with the current
code, but this is a sanity check for any future potential mis-uses.
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
* libmisc/salt.c: random() max value is 2^31-1 (same as RAND_MAX
on GNU). As it is not clear whether on some systems the max value
can exceed this number and whether some systems have max values
which would be lower, we take this into account when defining the
salt size and number of rounds for SHA encrypted passwords. Higher
values are favored.
* libmisc/setupenv.c: xstrdup the static char* temp_pw_dir /
temp_pw_shell. That way we can continue to use pw_free() without
segving. Thanks to Serge Hallyn for the patch.
a salt that violates specs. On Linux, crypt() also fails with
DES/MD5 salts in FIPS140 mode. Rather than exit() on NULL returns
we send them back to the caller for appropriate handling.
enabled. This is not done by pam_lastlog. This was broken on
2011-07-23.
* NEWS, libmisc/utmp.c: Do not log in wtmp when PAM is enabled.
This is done by pam_lastlog.
libmisc/copydir.c, lib/selinux.c: Move set_selinux_file_context()
and reset_selinux_file_context() from libmisc/copydir.c to
lib/selinux.c.
* lib/commonio.c: Use set_selinux_file_context() and
reset_selinux_file_context() instead of using the existing
database SELinux context to set the context for the newly created
files.
annotations.
* src/pwconv.c, src/pwunconv.c, src/grpconv.c, src/grpunconv.c:
Ignore return value of spw_rewind, pw_rewind, sgr_rewind, and
gr_rewind.
* lib/commonio.h: Both head and tail cannot be owned. Set tail as
dependent.
* src/expiry.c: Ignore return value of expire ().
* src/expiry.c: The catch_signals function does not use its sig
parameter.
* src/userdel.c: Last audit_logger parameter is a
shadow_audit_result, use SHADOW_AUDIT_FAILURE instead of 0.
