Clarify the distinction between filesystem variables (mandatory)
and all others (optional).
For optional variables, explain the difference between unset variables
(no access check performed) and empty variables (nothing allowed for
lists of allowed paths/ports, or no effect for lists of scopes).
List the known LL_SCOPED values and their effect.
Signed-off-by: Matthieu Buffet <matthieu@buffet.re>
Link: https://lore.kernel.org/r/20241019151534.1400605-4-matthieu@buffet.re
[mic: Add a missing colon]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Help message is getting larger with each new supported feature (scopes,
and soon UDP). Also the large number of calls to fprintf with
environment variables make it hard to read. Refactor it away into a
single simpler constant format string.
Signed-off-by: Matthieu Buffet <matthieu@buffet.re>
Link: https://lore.kernel.org/r/20241019151534.1400605-3-matthieu@buffet.re
[mic: Move the small cleanups in the next commit]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
If you want to specify that no port can be bind()ed, you would think
(looking quickly at both help message and code) that setting
LL_TCP_BIND="" would do it.
However the code splits on ":" then applies atoi(), which does not allow
checking for errors. Passing an empty string returns 0, which is
interpreted as "allow bind(0)", which means bind to any ephemeral port.
This bug occurs whenever passing an empty string or when leaving a
trailing/leading colon, making it impossible to completely deny bind().
To reproduce:
export LL_FS_RO="/" LL_FS_RW="" LL_TCP_BIND=""
./sandboxer strace -e bind nc -n -vvv -l -p 0
Executing the sandboxed command...
bind(3, {sa_family=AF_INET, sin_port=htons(0),
sin_addr=inet_addr("0.0.0.0")}, 16) = 0
Listening on 0.0.0.0 37629
Use strtoull(3) instead, which allows error checking. Check that the
entire string has been parsed correctly without overflows/underflows,
but not that the __u64 (the type of struct landlock_net_port_attr.port)
is a valid __u16 port: that is already done by the kernel.
Fixes: 5e990dcef1 ("samples/landlock: Support TCP restrictions")
Signed-off-by: Matthieu Buffet <matthieu@buffet.re>
Link: https://lore.kernel.org/r/20241019151534.1400605-2-matthieu@buffet.re
Signed-off-by: Mickaël Salaün <mic@digikod.net>
The sandboxer can receive the character "s" as input from the
environment variable LL_SCOPE to restrict sandboxed processes from
sending signals to processes outside of the sandbox.
Example
=======
Create a sandboxed shell and pass the character "s" to LL_SCOPED:
LL_FS_RO=/ LL_FS_RW=. LL_SCOPED="s" ./sandboxer /bin/bash
Try to send a SIGTRAP to a process with process ID <PID> through:
kill -SIGTRAP <PID>
The sandboxed process should not be able to send the signal.
Signed-off-by: Tahera Fahimi <fahimitahera@gmail.com>
Link: https://lore.kernel.org/r/1f3f1992b2abeb8e5d7aa61b854e1b0721978b9a.1725657728.git.fahimitahera@gmail.com
[mic: Improve commit message, simplify code, rebase on previous sample
change]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
The sandboxer can receive the character "a" as input from the
environment variable LL_SCOPE to restrict sandboxed processes from
connecting to an abstract UNIX socket created by a process outside of
the sandbox.
Example
=======
Create an abstract UNIX socket to listen with socat(1):
socat abstract-listen:mysocket -
Create a sandboxed shell and pass the character "a" to LL_SCOPED:
LL_FS_RO=/ LL_FS_RW=. LL_SCOPED="a" ./sandboxer /bin/bash
Note that any other form of input (e.g. "a:a", "aa", etc) is not
acceptable.
If the sandboxed process tries to connect to the listening socket, the
connection will fail:
socat - abstract-connect:mysocket
Signed-off-by: Tahera Fahimi <fahimitahera@gmail.com>
Link: https://lore.kernel.org/r/d8af908f00b77415caa3eb0f4de631c3794e4909.1725494372.git.fahimitahera@gmail.com
[mic: Improve commit message, simplify check_ruleset_scope() with
inverted error code and only one scoped change, always unset environment
variable]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Add IOCTL support to the Landlock sample tool.
The IOCTL right is grouped with the read-write rights in the sample
tool, as some IOCTL requests provide features that mutate state.
Signed-off-by: Günther Noack <gnoack@google.com>
Link: https://lore.kernel.org/r/20240419161122.2023765-9-gnoack@google.com
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Pointer env_port_name changes after strsep(). Memory allocated via
strdup() will not be freed if landlock_add_rule() returns non-zero value.
Fixes: 5e990dcef1 ("samples/landlock: Support TCP restrictions")
Signed-off-by: Ivanov Mikhail <ivanov.mikhail1@huawei-partners.com>
Reviewed-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
Link: https://lore.kernel.org/r/20240326095625.3576164-1-ivanov.mikhail1@huawei-partners.com
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Instead of creating a hard error and aborting the sandbox creation,
accept file path not usable in the LL_FS_RO and LL_FS_RW environment
variables but only print a warning. This makes it easier to test, for
instance with LL_FS_RO="${PATH}:/usr/lib:/lib"
Print that we are going to execute the command in the sandbox before
doing so.
Rename "launch" to "execute", and improve header description.
Reviewed-by: Günther Noack <gnoack@google.com>
Link: https://lore.kernel.org/r/20240307143849.1517218-1-mic@digikod.net
[mic: Improve header description as suggested by Günther]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Add TCP restrictions to the sandboxer demo. It's possible to allow a
sandboxer to bind/connect to a list of specified ports restricting
network actions to the rest of them. This is controlled with the new
LL_TCP_BIND and LL_TCP_CONNECT environment variables.
Rename ENV_PATH_TOKEN to ENV_DELIMITER.
Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
Link: https://lore.kernel.org/r/20231026014751.414649-12-konstantin.meskhidze@huawei.com
[mic: Extend commit message]
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Add a comment to clarify how to handle best-effort backwards
compatibility for LANDLOCK_ACCESS_FS_REFER.
The "refer" access is special because these operations are always
forbidden in ABI 1, unlike most other operations, which are permitted
when using Landlock ABI levels where they are not supported yet.
Signed-off-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20221107181651.4555-1-gnoack3000@gmail.com
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Update the sandboxer sample to restrict truncate actions. This is
automatically enabled by default if the running kernel supports
LANDLOCK_ACCESS_FS_TRUNCATE, except for the paths listed in the
LL_FS_RW environment variable.
Signed-off-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20221018182216.301684-11-gnoack3000@gmail.com
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Extend the help with the latest Landlock ABI version supported by the
sandboxer.
Inform users about the sandboxer or the kernel not being up-to-date.
Make the version check code easier to update and harder to misuse.
Cc: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Reviewed-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20220923154207.3311629-2-mic@digikod.net
Add LANDLOCK_ACCESS_FS_REFER to the "roughly write" access rights and
leverage the Landlock ABI version to only try to enforce it if it is
supported by the running kernel.
Reviewed-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20220506161102.525323-10-mic@digikod.net
Let's follow a consistent and documented coding style. Everything may
not be to our liking but it is better than tacit knowledge. Moreover,
this will help maintain style consistency between different developers.
This contains only whitespace changes.
Automatically formatted with:
clang-format-14 -i samples/landlock/*.[ch]
Link: https://lore.kernel.org/r/20220506160513.523257-8-mic@digikod.net
Cc: stable@vger.kernel.org
Signed-off-by: Mickaël Salaün <mic@digikod.net>
In preparation to a following commit, add clang-format on and
clang-format off stanzas around constant definitions. This enables to
keep aligned values, which is much more readable than packed
definitions.
Link: https://lore.kernel.org/r/20220506160513.523257-7-mic@digikod.net
Cc: stable@vger.kernel.org
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Clang static analysis reports this error
sandboxer.c:134:8: warning: Potential leak of memory
pointed to by 'path_list'
ret = 0;
^
path_list is allocated in parse_path() but never freed.
Signed-off-by: Tom Rix <trix@redhat.com>
Link: https://lore.kernel.org/r/20210428213852.2874324-1-trix@redhat.com
Cc: stable@vger.kernel.org
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
Add a basic sandbox tool to launch a command which can only access a
list of file hierarchies in a read-only or read-write way.
Cc: James Morris <jmorris@namei.org>
Cc: Serge E. Hallyn <serge@hallyn.com>
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210422154123.13086-12-mic@digikod.net
Signed-off-by: James Morris <jamorris@linux.microsoft.com>
