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authorMickaël Salaün <mic@digikod.net>2022-09-23 17:42:05 +0200
committerMickaël Salaün <mic@digikod.net>2022-09-29 18:43:01 +0200
commit903cfe8a7aa8894ae60ef47a9c011e551d7bafef (patch)
treecbffd4ee51934be4d13666f819037843ff31cc84
parentf76349cf41451c5c42a99f18a9163377e4b364ff (diff)
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samples/landlock: Print hints about ABI versions
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
-rw-r--r--samples/landlock/sandboxer.c37
1 files changed, 29 insertions, 8 deletions
diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
index 3e404e51ec64..f29bb3c72230 100644
--- a/samples/landlock/sandboxer.c
+++ b/samples/landlock/sandboxer.c
@@ -162,11 +162,10 @@ out_free_name:
LANDLOCK_ACCESS_FS_MAKE_SYM | \
LANDLOCK_ACCESS_FS_REFER)
-#define ACCESS_ABI_2 ( \
- LANDLOCK_ACCESS_FS_REFER)
-
/* clang-format on */
+#define LANDLOCK_ABI_LAST 2
+
int main(const int argc, char *const argv[], char *const *const envp)
{
const char *cmd_path;
@@ -196,8 +195,12 @@ int main(const int argc, char *const argv[], char *const *const envp)
"\nexample:\n"
"%s=\"/bin:/lib:/usr:/proc:/etc:/dev/urandom\" "
"%s=\"/dev/null:/dev/full:/dev/zero:/dev/pts:/tmp\" "
- "%s bash -i\n",
+ "%s bash -i\n\n",
ENV_FS_RO_NAME, ENV_FS_RW_NAME, argv[0]);
+ fprintf(stderr,
+ "This sandboxer can use Landlock features "
+ "up to ABI version %d.\n",
+ LANDLOCK_ABI_LAST);
return 1;
}
@@ -225,12 +228,30 @@ int main(const int argc, char *const argv[], char *const *const envp)
}
return 1;
}
+
/* Best-effort security. */
- if (abi < 2) {
- ruleset_attr.handled_access_fs &= ~ACCESS_ABI_2;
- access_fs_ro &= ~ACCESS_ABI_2;
- access_fs_rw &= ~ACCESS_ABI_2;
+ switch (abi) {
+ case 1:
+ /* Removes LANDLOCK_ACCESS_FS_REFER for ABI < 2 */
+ ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_REFER;
+
+ fprintf(stderr,
+ "Hint: You should update the running kernel "
+ "to leverage Landlock features "
+ "provided by ABI version %d (instead of %d).\n",
+ LANDLOCK_ABI_LAST, abi);
+ __attribute__((fallthrough));
+ case LANDLOCK_ABI_LAST:
+ break;
+ default:
+ fprintf(stderr,
+ "Hint: You should update this sandboxer "
+ "to leverage Landlock features "
+ "provided by ABI version %d (instead of %d).\n",
+ abi, LANDLOCK_ABI_LAST);
}
+ access_fs_ro &= ruleset_attr.handled_access_fs;
+ access_fs_rw &= ruleset_attr.handled_access_fs;
ruleset_fd =
landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);