On Sun, Sep 15, 2024 at 10:58 PM Kees Cook <kees@xxxxxxxxxx> wrote: > > On Sun, Sep 15, 2024 at 02:31:31PM +0000, Alice Ryhl wrote: > > Add an abstraction for viewing the string representation of a security > > context. > > Hm, this may collide with "LSM: Move away from secids" is going to happen. > https://lore.kernel.org/all/20240830003411.16818-1-casey@xxxxxxxxxxxxxxxx/ > > This series is not yet landed, but in the future, the API changes should > be something like this, though the "lsmblob" name is likely to change to > "lsmprop"? > security_cred_getsecid() -> security_cred_getlsmblob() > security_secid_to_secctx() -> security_lsmblob_to_secctx() Thanks for the heads up. I'll make sure to look into how this interacts with those changes. > > This is needed by Rust Binder because it has a feature where a process > > can view the string representation of the security context for incoming > > transactions. The process can use that to authenticate incoming > > transactions, and since the feature is provided by the kernel, the > > process can trust that the security context is legitimate. > > > > This abstraction makes the following assumptions about the C side: > > * When a call to `security_secid_to_secctx` is successful, it returns a > > pointer and length. The pointer references a byte string and is valid > > for reading for that many bytes. > > Yes. (len includes trailing C-String NUL character.) I suppose the NUL character implies that this API always returns a non-zero length? I could simplify the patch a little bit by not handling empty strings. It looks like the CONFIG_SECURITY=n case returns -EOPNOTSUPP, so we don't get an empty string from that case, at least. > > * The string may be referenced until `security_release_secctx` is > > called. > > Yes. > > > * If CONFIG_SECURITY is set, then the three methods mentioned in > > rust/helpers are available without a helper. (That is, they are not a > > #define or `static inline`.) > > Yes. > > > > > Reviewed-by: Benno Lossin <benno.lossin@xxxxxxxxx> > > Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@xxxxxxxxx> > > Reviewed-by: Trevor Gross <tmgross@xxxxxxxxx> > > Reviewed-by: Gary Guo <gary@xxxxxxxxxxx> > > Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx> > > Reviewed-by: Kees Cook <kees@xxxxxxxxxx> Thanks for the review! Alice
