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SubjectRe: [PATCH v3 08/12] ima: Shallow copy the args_p member of ima_rule_entry.lsm elements
Hi,

Found one glitch with this change, see below:

On Thu, Jul 9, 2020 at 9:22 AM Tyler Hicks <tyhicks@linux.microsoft.com> wrote:
>
> The args_p member is a simple string that is allocated by
> ima_rule_init(). Shallow copy it like other non-LSM references in
> ima_rule_entry structs.
>
> There are no longer any necessary error path cleanups to do in
> ima_lsm_copy_rule().
>
> Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com>
> ---
>
> * v3
> - No change
> * v2
> - Adjusted context to account for ima_lsm_copy_rule() directly calling
> ima_lsm_free_rule() and the lack of explicit reference ownership
> transfers
> - Added comment to ima_lsm_copy_rule() to document the args_p
> reference ownership transfer
>
> security/integrity/ima/ima_policy.c | 16 +++++++---------
> 1 file changed, 7 insertions(+), 9 deletions(-)
>
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index 9842e2e0bc6d..b02e1ffd10c9 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -300,10 +300,13 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
> continue;
>
> nentry->lsm[i].type = entry->lsm[i].type;
> - nentry->lsm[i].args_p = kstrdup(entry->lsm[i].args_p,
> - GFP_KERNEL);
> - if (!nentry->lsm[i].args_p)
> - goto out_err;
> + nentry->lsm[i].args_p = entry->lsm[i].args_p;
> + /*
> + * Remove the reference from entry so that the associated
> + * memory will not be freed during a later call to
> + * ima_lsm_free_rule(entry).
> + */
> + entry->lsm[i].args_p = NULL;

This assignment necessitates a change in the code below...

> security_filter_rule_init(nentry->lsm[i].type,
> Audit_equal,
> @@ -314,11 +317,6 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
> (char *)entry->lsm[i].args_p);

... you should refer to nentry->lsm[i].args_p here!

Other than that,

Reviewed-by: Konsta Karsisto <konsta.karsisto@gmail.com>


Konsta

> }
> return nentry;
> -
> -out_err:
> - ima_lsm_free_rule(nentry);
> - kfree(nentry);
> - return NULL;
> }
>
> static int ima_lsm_update_rule(struct ima_rule_entry *entry)
> --
> 2.25.1
>

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