[RFC][PATCH v2 1/9] ima: pass filename to ima_rdwr_violation_check()

[Mimi Zohar]

On Thu, 2017-11-30 at 11:56 +0100, Roberto Sassu wrote:
> ima_rdwr_violation_check() retrieves the full path of a measured file by
> calling ima_d_path(). If process_measurement() calls this function, it
> reuses the pointer and passes it to the functions to measure/appraise/audit
> an accessed file.
> 
> After commit bc15ed663e7e ("ima: fix ima_d_path() possible race with
> rename"), ima_d_path() first tries to retrieve the full path by calling
> d_absolute_path() and, if there is an error, copies the dentry name to the
> buffer passed as argument.
> 
> However, ima_rdwr_violation_check() passes to ima_d_path() the pointer of a
> local variable. process_measurement() might be reusing the pointer to an
> area in the stack which may have been already overwritten after
> ima_rdwr_violation_check() returned.
> 
> Correct this issue by passing to ima_rdwr_violation_check() the pointer of
> a buffer declared in process_measurement().
> 
> Fixes: bc15ed663e7e ("ima: fix ima_d_path() possible race with rename")
> Signed-off-by: Roberto Sassu <roberto.sassu at huawei.com>

Thanks!

> ---
>  security/integrity/ima/ima_main.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> index 294b2fe69334..5a7321bc325c 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -84,10 +84,10 @@ static void ima_rdwr_violation_check(struct file *file,
>  				     struct integrity_iint_cache *iint,
>  				     int must_measure,
>  				     char **pathbuf,
> -				     const char **pathname)
> +				     const char **pathname,
> +				     char *filename)
>  {
>  	struct inode *inode = file_inode(file);
> -	char filename[NAME_MAX];
>  	fmode_t mode = file->f_mode;
>  	bool send_tomtou = false, send_writers = false;
> 
> @@ -205,7 +205,7 @@ static int process_measurement(struct file *file, const struct cred *cred,
> 
>  	if (violation_check) {
>  		ima_rdwr_violation_check(file, iint, action & IMA_MEASURE,
> -					 &pathbuf, &pathname);
> +					 &pathbuf, &pathname, filename);
>  		if (!action) {
>  			rc = 0;
>  			goto out_free;

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