[PATCH] integrity: Annotate struct ima_rule_opt_list with __counted_by

[PATCH] integrity: Annotate struct ima_rule_opt_list with __counted_by

[Kees Cook]

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct ima_rule_opt_list.
Additionally, since the element count member must be set before accessing
the annotated flexible array member, move its initialization earlier.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Mimi Zohar <zohar@linux.ibm.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: linux-integrity@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 security/integrity/ima/ima_policy.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 69452b79686b..f69062617754 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -68,7 +68,7 @@ enum policy_rule_list { IMA_DEFAULT_POLICY = 1, IMA_CUSTOM_POLICY };
 
 struct ima_rule_opt_list {
 	size_t count;
-	char *items[];
+	char *items[] __counted_by(count);
 };
 
 /*
@@ -342,6 +342,7 @@ static struct ima_rule_opt_list *ima_alloc_rule_opt_list(const substring_t *src)
 		kfree(src_copy);
 		return ERR_PTR(-ENOMEM);
 	}
+	opt_list->count = count;
 
 	/*
 	 * strsep() has already replaced all instances of '|' with '\0',
@@ -357,7 +358,6 @@ static struct ima_rule_opt_list *ima_alloc_rule_opt_list(const substring_t *src)
 		opt_list->items[i] = cur;
 		cur = strchr(cur, '\0') + 1;
 	}
-	opt_list->count = count;
 
 	return opt_list;
 }
-- 
2.34.1

Re: [PATCH] integrity: Annotate struct ima_rule_opt_list with __counted_by

[Gustavo A. R. Silva]

On 8/17/23 15:03, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
> 
> As found with Coccinelle[1], add __counted_by for struct ima_rule_opt_list.
> Additionally, since the element count member must be set before accessing
> the annotated flexible array member, move its initialization earlier.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Mimi Zohar <zohar@linux.ibm.com>
> Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
> Cc: Paul Moore <paul@paul-moore.com>
> Cc: James Morris <jmorris@namei.org>
> Cc: "Serge E. Hallyn" <serge@hallyn.com>
> Cc: linux-integrity@vger.kernel.org
> Cc: linux-security-module@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks
--
Gustavo

> ---
>   security/integrity/ima/ima_policy.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index 69452b79686b..f69062617754 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -68,7 +68,7 @@ enum policy_rule_list { IMA_DEFAULT_POLICY = 1, IMA_CUSTOM_POLICY };
>   
>   struct ima_rule_opt_list {
>   	size_t count;
> -	char *items[];
> +	char *items[] __counted_by(count);
>   };
>   
>   /*
> @@ -342,6 +342,7 @@ static struct ima_rule_opt_list *ima_alloc_rule_opt_list(const substring_t *src)
>   		kfree(src_copy);
>   		return ERR_PTR(-ENOMEM);
>   	}
> +	opt_list->count = count;
>   
>   	/*
>   	 * strsep() has already replaced all instances of '|' with '\0',
> @@ -357,7 +358,6 @@ static struct ima_rule_opt_list *ima_alloc_rule_opt_list(const substring_t *src)
>   		opt_list->items[i] = cur;
>   		cur = strchr(cur, '\0') + 1;
>   	}
> -	opt_list->count = count;
>   
>   	return opt_list;
>   }

Re: [PATCH] integrity: Annotate struct ima_rule_opt_list with __counted_by

[Jarkko Sakkinen]

On Fri Aug 18, 2023 at 12:03 AM EEST, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
>
> As found with Coccinelle[1], add __counted_by for struct ima_rule_opt_list.
> Additionally, since the element count member must be set before accessing
> the annotated flexible array member, move its initialization earlier.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Mimi Zohar <zohar@linux.ibm.com>
> Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
> Cc: Paul Moore <paul@paul-moore.com>
> Cc: James Morris <jmorris@namei.org>
> Cc: "Serge E. Hallyn" <serge@hallyn.com>
> Cc: linux-integrity@vger.kernel.org
> Cc: linux-security-module@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  security/integrity/ima/ima_policy.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index 69452b79686b..f69062617754 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -68,7 +68,7 @@ enum policy_rule_list { IMA_DEFAULT_POLICY = 1, IMA_CUSTOM_POLICY };
>  
>  struct ima_rule_opt_list {
>  	size_t count;
> -	char *items[];
> +	char *items[] __counted_by(count);
>  };
>  
>  /*
> @@ -342,6 +342,7 @@ static struct ima_rule_opt_list *ima_alloc_rule_opt_list(const substring_t *src)
>  		kfree(src_copy);
>  		return ERR_PTR(-ENOMEM);
>  	}
> +	opt_list->count = count;
>  
>  	/*
>  	 * strsep() has already replaced all instances of '|' with '\0',
> @@ -357,7 +358,6 @@ static struct ima_rule_opt_list *ima_alloc_rule_opt_list(const substring_t *src)
>  		opt_list->items[i] = cur;
>  		cur = strchr(cur, '\0') + 1;
>  	}
> -	opt_list->count = count;
>  
>  	return opt_list;
>  }
> -- 
> 2.34.1

Acked-by: Jarkko Sakkinen <jarkko@kernel.org>

BR, Jarkko

Re: [PATCH] integrity: Annotate struct ima_rule_opt_list with __counted_by

[Mimi Zohar]

On Thu, 2023-08-17 at 14:03 -0700, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
> 
> As found with Coccinelle[1], add __counted_by for struct ima_rule_opt_list.
> Additionally, since the element count member must be set before accessing
> the annotated flexible array member, move its initialization earlier.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Mimi Zohar <zohar@linux.ibm.com>
> Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
> Cc: Paul Moore <paul@paul-moore.com>
> Cc: James Morris <jmorris@namei.org>
> Cc: "Serge E. Hallyn" <serge@hallyn.com>
> Cc: linux-integrity@vger.kernel.org
> Cc: linux-security-module@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Acked-by: Mimi Zohar <zohar@linux.ibm.com>

-- 
thanks,

Mimi

Re: [PATCH] integrity: Annotate struct ima_rule_opt_list with __counted_by

[Kees Cook]

On Thu, 17 Aug 2023 14:03:28 -0700, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
> 
> As found with Coccinelle[1], add __counted_by for struct ima_rule_opt_list.
> Additionally, since the element count member must be set before accessing
> the annotated flexible array member, move its initialization earlier.
> 
> [...]

Applied to for-next/hardening, thanks!

[1/1] integrity: Annotate struct ima_rule_opt_list with __counted_by
      https://git.kernel.org/kees/c/a4b35d4d05b9

Take care,

-- 
Kees Cook