From: "Mickaël Salaün" <mic@digikod.net>
To: Casey Schaufler <casey@schaufler-ca.com>,
paul@paul-moore.com, linux-security-module@vger.kernel.org
Cc: jmorris@namei.org, keescook@chromium.org,
john.johansen@canonical.com, penguin-kernel@i-love.sakura.ne.jp,
stephen.smalley.work@gmail.com, linux-kernel@vger.kernel.org,
linux-api@vger.kernel.org
Subject: Re: [PATCH v7 07/11] LSM: Helpers for attribute names and filling an lsm_ctx
Date: Mon, 3 Apr 2023 11:47:08 +0200 [thread overview]
Message-ID: <544a4809-1a79-9dd7-61a5-5fce1f4a5f10@digikod.net> (raw)
In-Reply-To: <20230315224704.2672-8-casey@schaufler-ca.com>
On 15/03/2023 23:47, Casey Schaufler wrote:
> Add lsm_name_to_attr(), which translates a text string to a
> LSM_ATTR value if one is available.
>
> Add lsm_fill_user_ctx(), which fills a struct lsm_ctx, including
> the trailing attribute value.
>
> All are used in module specific components of LSM system calls.
>
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> ---
> include/linux/security.h | 13 ++++++++++
> security/lsm_syscalls.c | 51 ++++++++++++++++++++++++++++++++++++++++
> security/security.c | 31 ++++++++++++++++++++++++
> 3 files changed, 95 insertions(+)
[...]
> diff --git a/security/security.c b/security/security.c
> index 2c57fe28c4f7..f7b814a3940c 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -753,6 +753,37 @@ static int lsm_superblock_alloc(struct super_block *sb)
> return 0;
> }
>
> +/**
> + * lsm_fill_user_ctx - Fill a user space lsm_ctx structure
> + * @ctx: an LSM context to be filled
> + * @context: the new context value
> + * @context_size: the size of the new context value
> + * @id: LSM id
> + * @flags: LSM defined flags
> + *
> + * Fill all of the fields in a user space lsm_ctx structure.
> + * Caller is assumed to have verified that @ctx has enough space
> + * for @context.
> + * Returns 0 on success, -EFAULT on a copyout error.
> + */
> +int lsm_fill_user_ctx(struct lsm_ctx __user *ctx, void *context,
> + size_t context_size, u64 id, u64 flags)
> +{
> + struct lsm_ctx local;
> + void __user *vc = ctx;
> +
> + local.id = id;
> + local.flags = flags;
> + local.ctx_len = context_size;
> + local.len = context_size + sizeof(local);
> + vc += sizeof(local);
> + if (copy_to_user(ctx, &local, sizeof(local)))
> + return -EFAULT;
> + if (context_size > 0 && copy_to_user(vc, context, context_size))
> + return -EFAULT;
Can we do a single copy_to_user() call? That would avoid inconsistent
user space data, could speed up a bit the operation, and make the code
easier to understand. To use the stack, we need to know the maximum size
of context_size for all use cases, which seems reasonable and can be
checked at build time (on each LSM side, and potentially with specific
context type passed as enum instead of context_size) and run time (for
this generic helper).
> + return 0;
> +}
> +
> /*
> * The default value of the LSM hook is defined in linux/lsm_hook_defs.h and
> * can be accessed with:
next prev parent reply other threads:[~2023-04-03 9:47 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20230315224704.2672-1-casey.ref@schaufler-ca.com>
2023-03-15 22:46 ` [PATCH v7 00/11] LSM: Three basic syscalls Casey Schaufler
2023-03-15 22:46 ` [PATCH v7 01/11] LSM: Identify modules by more than name Casey Schaufler
2023-03-30 1:10 ` Paul Moore
2023-03-15 22:46 ` [PATCH v7 02/11] LSM: Maintain a table of LSM attribute data Casey Schaufler
2023-03-30 1:10 ` Paul Moore
2023-03-15 22:46 ` [PATCH v7 03/11] proc: Use lsmids instead of lsm names for attrs Casey Schaufler
2023-03-15 22:46 ` [PATCH v7 04/11] LSM: syscalls for current process attributes Casey Schaufler
2023-03-16 12:35 ` kernel test robot
2023-03-30 1:12 ` Paul Moore
2023-03-30 11:24 ` Paul Moore
2023-03-30 20:00 ` Casey Schaufler
2023-03-30 23:22 ` Paul Moore
2023-04-03 12:04 ` Mickaël Salaün
2023-04-03 17:36 ` Casey Schaufler
2023-04-03 18:04 ` Mickaël Salaün
2023-04-03 18:28 ` Casey Schaufler
2023-04-11 0:31 ` Paul Moore
2023-03-15 22:46 ` [PATCH v7 05/11] LSM: Create lsm_list_modules system call Casey Schaufler
2023-03-30 1:12 ` Paul Moore
2023-04-03 12:04 ` Mickaël Salaün
2023-04-10 23:37 ` Paul Moore
2023-04-10 23:38 ` Paul Moore
2023-04-13 11:55 ` Mickaël Salaün
2023-03-15 22:46 ` [PATCH v7 06/11] LSM: wireup Linux Security Module syscalls Casey Schaufler
2023-03-15 22:47 ` [PATCH v7 07/11] LSM: Helpers for attribute names and filling an lsm_ctx Casey Schaufler
2023-03-30 1:13 ` Paul Moore
2023-03-30 20:42 ` Casey Schaufler
2023-03-30 23:28 ` Paul Moore
2023-03-31 16:56 ` Casey Schaufler
2023-03-31 19:24 ` Paul Moore
2023-03-31 20:22 ` Casey Schaufler
2023-04-03 9:47 ` Mickaël Salaün [this message]
2023-04-03 9:54 ` Mickaël Salaün
2023-04-03 11:47 ` Mickaël Salaün
2023-04-03 18:04 ` Casey Schaufler
2023-04-03 18:03 ` Casey Schaufler
2023-04-03 18:06 ` Mickaël Salaün
2023-04-03 18:33 ` Casey Schaufler
2023-03-15 22:47 ` [PATCH v7 08/11] Smack: implement setselfattr and getselfattr hooks Casey Schaufler
2023-03-15 22:47 ` [PATCH v7 09/11] AppArmor: Add selfattr hooks Casey Schaufler
2023-03-15 22:47 ` [PATCH v7 10/11] SELinux: " Casey Schaufler
2023-03-30 1:13 ` Paul Moore
2023-03-30 20:55 ` Casey Schaufler
2023-03-30 23:32 ` Paul Moore
2023-03-15 22:47 ` [PATCH v7 11/11] LSM: selftests for Linux Security Module syscalls Casey Schaufler
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