Re: [PATCH 1/3] libsemanage: remove access() check to make setuid programs work

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On Fri, 2017-05-05 at 14:49 +0200, Vit Mojzis wrote:
> access() uses real UID instead of effective UID which causes false
> negative checks in setuid programs (except for F_OK which works
> properly). fopen() return values are always checked, which makes
> access() checks redundant.
> 
> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431
> ---
>  libsemanage/src/direct_api.c     |  3 ---
>  libsemanage/src/semanage_store.c | 17 ++++++++---------
>  2 files changed, 8 insertions(+), 12 deletions(-)
> 
> diff --git a/libsemanage/src/direct_api.c
> b/libsemanage/src/direct_api.c
> index f4b0416..dc46f8f 100644
> --- a/libsemanage/src/direct_api.c
> +++ b/libsemanage/src/direct_api.c
> @@ -146,9 +146,6 @@ int semanage_direct_connect(semanage_handle_t *
> sh)
>  		if (semanage_create_store(sh, 1))
>  			goto err;
>  
> -	if (semanage_access_check(sh) < SEMANAGE_CAN_READ)
> -		goto err;
> -
>  	sh->u.direct.translock_file_fd = -1;
>  	sh->u.direct.activelock_file_fd = -1;
>  
> diff --git a/libsemanage/src/semanage_store.c
> b/libsemanage/src/semanage_store.c
> index 6b75002..0a10032 100644
> --- a/libsemanage/src/semanage_store.c
> +++ b/libsemanage/src/semanage_store.c
> @@ -535,7 +535,6 @@ char *semanage_conf_path(void)
>  int semanage_create_store(semanage_handle_t * sh, int create)
>  {
>  	struct stat sb;
> -	int mode_mask = R_OK | W_OK | X_OK;
>  	const char *path = semanage_files[SEMANAGE_ROOT];
>  	int fd;
>  
> @@ -554,9 +553,9 @@ int semanage_create_store(semanage_handle_t * sh,
> int create)
>  			return -1;
>  		}
>  	} else {
> -		if (!S_ISDIR(sb.st_mode) || access(path, mode_mask)
> == -1) {
> +		if (!S_ISDIR(sb.st_mode)) {
>  			ERR(sh,
> -			    "Could not access module store at %s, or
> it is not a directory.",
> +			    "Module store at %s is not a
> directory.",
>  			    path);
>  			return -1;
>  		}
> @@ -577,9 +576,9 @@ int semanage_create_store(semanage_handle_t * sh,
> int create)
>  			return -1;
>  		}
>  	} else {
> -		if (!S_ISDIR(sb.st_mode) || access(path, mode_mask)
> == -1) {
> +		if (!S_ISDIR(sb.st_mode)) {
>  			ERR(sh,
> -			    "Could not access module store active
> subdirectory at %s, or it is not a directory.",
> +			    "Module store active subdirectory at %s
> is not a directory.",
>  			    path);
>  			return -1;
>  		}
> @@ -600,9 +599,9 @@ int semanage_create_store(semanage_handle_t * sh,
> int create)
>  			return -1;
>  		}
>  	} else {
> -		if (!S_ISDIR(sb.st_mode) || access(path, mode_mask)
> == -1) {
> +		if (!S_ISDIR(sb.st_mode)) {
>  			ERR(sh,
> -			    "Could not access module store active
> modules subdirectory at %s, or it is not a directory.",
> +			    "Module store active modules
> subdirectory at %s is not a directory.",
>  			    path);
>  			return -1;
>  		}
> @@ -621,8 +620,8 @@ int semanage_create_store(semanage_handle_t * sh,
> int create)
>  			return -1;
>  		}
>  	} else {
> -		if (!S_ISREG(sb.st_mode) || access(path, R_OK |
> W_OK) == -1) {
> -			ERR(sh, "Could not access lock file at %s.",
> path);
> +		if (!S_ISREG(sb.st_mode)) {
> +			ERR(sh, "Lock file at %s missing.", path);

It can't be missing or the stat() would have failed.
Lock file is not a regular file?
Not sure how useful these tests are though...

>  			return -1;
>  		}
>  	}



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