On 14/01/2021 04:21, Jann Horn wrote:
On Wed, Dec 9, 2020 at 8:29 PM Mickaël Salaün [off-list ref] wrote:
quoted
Add a basic sandbox tool to launch a command which can only access a
whitelist of file hierarchies in a read-only or read-write way.
I have to admit that I didn't really look at this closely before
because it's just sample code... but I guess I should. You can add
Reviewed-by: Jann Horn <jannh@google.com>
if you fix the following nits:
OK, I will!
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diff --git a/samples/Kconfig b/samples/Kconfig
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+config SAMPLE_LANDLOCK
+ bool "Build Landlock sample code"
+ depends on HEADERS_INSTALL
+ help
+ Build a simple Landlock sandbox manager able to launch a process
+ restricted by a user-defined filesystem access control.
nit: s/filesystem access control/filesystem access control policy/
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diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
[...]
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+/*
+ * Simple Landlock sandbox manager able to launch a process restricted by a
+ * user-defined filesystem access control.
nit: s/filesystem access control/filesystem access control policy/
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+int main(const int argc, char *const argv[], char *const *const envp)
+{
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+ if (argc < 2) {
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+ fprintf(stderr, "* %s: list of paths allowed to be used in a read-only way.\n",
+ ENV_FS_RO_NAME);
+ fprintf(stderr, "* %s: list of paths allowed to be used in a read-write way.\n",
+ ENV_FS_RO_NAME);
s/ENV_FS_RO_NAME/ENV_FS_RW_NAME/
quoted
+ fprintf(stderr, "\nexample:\n"
+ "%s=\"/bin:/lib:/usr:/proc:/etc:/dev/urandom\" "
+ "%s=\"/dev/null:/dev/full:/dev/zero:/dev/pts:/tmp\" "
+ "%s bash -i\n",
+ ENV_FS_RO_NAME, ENV_FS_RW_NAME, argv[0]);
+ return 1;
+ }
+
+ ruleset_fd = landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
+ if (ruleset_fd < 0) {
+ perror("Failed to create a ruleset");
+ switch (errno) {
(Just as a note: In theory perror() can change the value of errno, as
far as I know - so AFAIK you'd theoretically have to do something
like:
int errno_ = errno;
perror("...");
switch (errno_) {
...
}
Indeed :)
I'll almost certainly work fine as-is in practice though.)