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Thu, 28 May 2026 18:52:39 -0700 (PDT) From: Justin Suess To: gnoack3000@gmail.com, mic@digikod.net Cc: linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, Justin Suess , Tingmao Wang Subject: [PATCH v8 08/10] samples/landlock: Add LANDLOCK_ADD_RULE_NO_INHERIT to landlock-sandboxer Date: Thu, 28 May 2026 21:52:07 -0400 Message-ID: <20260529015210.500291-9-utilityemal77@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260529015210.500291-1-utilityemal77@gmail.com> References: <20260529015210.500291-1-utilityemal77@gmail.com> Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add a new LL_FS_NO_INHERIT environment variable to the sandboxer. Paths listed in it are added with the LANDLOCK_ADD_RULE_NO_INHERIT flag, demonstrating how to set up a parent directory with broader access than its children. The flag is silently skipped on kernels older than ABI 10. Cc: Tingmao Wang Signed-off-by: Justin Suess --- Notes: v7..v8 changes: * Reworded commit message. * Updated the ABI fallthrough comment to mention 'quiet or no_inherit flags'. No code change beyond the comment update. samples/landlock/sandboxer.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c index 74ee53afed6a..b126ffd7cd4f 100644 --- a/samples/landlock/sandboxer.c +++ b/samples/landlock/sandboxer.c @@ -60,6 +60,7 @@ static inline int landlock_restrict_self(const int ruleset_fd, #define ENV_FS_RW_NAME "LL_FS_RW" #define ENV_FS_QUIET_NAME "LL_FS_QUIET" #define ENV_FS_QUIET_ACCESS_NAME "LL_FS_QUIET_ACCESS" +#define ENV_FS_NO_INHERIT_NAME "LL_FS_NO_INHERIT" #define ENV_TCP_BIND_NAME "LL_TCP_BIND" #define ENV_TCP_CONNECT_NAME "LL_TCP_CONNECT" #define ENV_NET_QUIET_NAME "LL_NET_QUIET" @@ -395,6 +396,7 @@ static const char help[] = "but to test audit we can set " ENV_FORCE_LOG_NAME "=1\n" ENV_FS_QUIET_NAME " and " ENV_NET_QUIET_NAME ", both optional, can then be used " "to make access to some denied paths or network ports not trigger audit logging.\n" + ENV_FS_NO_INHERIT_NAME " can be used to suppress access right propagation (ABI >= 10).\n" ENV_FS_QUIET_ACCESS_NAME " and " ENV_NET_QUIET_ACCESS_NAME " can be used to specify " "which accesses should be quieted (defaults to all):\n" "* " ENV_FS_QUIET_ACCESS_NAME ": file system accesses to quiet\n" @@ -447,6 +449,7 @@ int main(const int argc, char *const argv[], char *const *const envp) }; bool quiet_supported = true; + bool no_inherit_supported = true; int supported_restrict_flags = LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON; int set_restrict_flags = 0; @@ -538,8 +541,9 @@ int main(const int argc, char *const argv[], char *const *const envp) ~(LANDLOCK_ACCESS_NET_BIND_UDP | LANDLOCK_ACCESS_NET_CONNECT_SEND_UDP); __attribute__((fallthrough)); - /* Don't add quiet flags for ABI < 10 later on. */ + /* Don't add quiet or no_inherit flags for ABI < 10 later on. */ quiet_supported = false; + no_inherit_supported = false; /* Must be printed for any ABI < LANDLOCK_ABI_LAST. */ fprintf(stderr, @@ -644,6 +648,13 @@ int main(const int argc, char *const argv[], char *const *const envp) goto err_close_ruleset; } + /* Don't require this env to be present. */ + if (no_inherit_supported && getenv(ENV_FS_NO_INHERIT_NAME)) { + if (populate_ruleset_fs(ENV_FS_NO_INHERIT_NAME, ruleset_fd, 0, + LANDLOCK_ADD_RULE_NO_INHERIT)) + goto err_close_ruleset; + } + if (populate_ruleset_net(ENV_TCP_BIND_NAME, ruleset_fd, LANDLOCK_ACCESS_NET_BIND_TCP, 0)) { goto err_close_ruleset; -- 2.53.0