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@xxxxxxxxx>
---
samples/landlock/sandboxer.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
index f29bb3c72230..fd4237c64fb2 100644
--- a/samples/landlock/sandboxer.c
+++ b/samples/landlock/sandboxer.c
@@ -76,7 +76,8 @@ static int parse_path(char *env_path, const char ***const path_list)
#define ACCESS_FILE ( \
LANDLOCK_ACCESS_FS_EXECUTE | \
LANDLOCK_ACCESS_FS_WRITE_FILE | \
- LANDLOCK_ACCESS_FS_READ_FILE)
+ LANDLOCK_ACCESS_FS_READ_FILE | \
+ LANDLOCK_ACCESS_FS_TRUNCATE)
/* clang-format on */
@@ -160,11 +161,12 @@ static int populate_ruleset(const char *const env_var, const int ruleset_fd,
LANDLOCK_ACCESS_FS_MAKE_FIFO | \
LANDLOCK_ACCESS_FS_MAKE_BLOCK | \
LANDLOCK_ACCESS_FS_MAKE_SYM | \
- LANDLOCK_ACCESS_FS_REFER)
+ LANDLOCK_ACCESS_FS_REFER | \
+ LANDLOCK_ACCESS_FS_TRUNCATE)
/* clang-format on */
-#define LANDLOCK_ABI_LAST 2
+#define LANDLOCK_ABI_LAST 3
int main(const int argc, char *const argv[], char *const *const envp)
{
@@ -234,6 +236,10 @@ int main(const int argc, char *const argv[], char *const *const envp)
case 1:
/* Removes LANDLOCK_ACCESS_FS_REFER for ABI < 2 */
ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_REFER;
+ __attribute__((fallthrough));
+ case 2:
+ /* Removes LANDLOCK_ACCESS_FS_TRUNCATE for ABI < 3 */
+ ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_TRUNCATE;
fprintf(stderr,
"Hint: You should update the running kernel "
--
2.38.0
