From: Mickaël Salaün <[email protected]>
Replace the enum landlock_rule_type with an int in the syscall signature
of landlock_add_rule to avoid an implementation-defined size. In
practice an enum type is like an int (at least with GCC and clang), but
compilers may accept options (e.g. -fshort-enums) that would have an
impact on that [1]. This change is mostly a cosmetic fix according to
the current kernel compilers and used options.
Link: https://lore.kernel.org/r/[email protected]/ [1]
Reported-by: Alejandro Colomar <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Signed-off-by: Mickaël Salaün <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
include/linux/syscalls.h | 3 +--
security/landlock/syscalls.c | 7 ++++---
2 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 819c0cb00b6d..a5956f91caf2 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -71,7 +71,6 @@ struct clone_args;
struct open_how;
struct mount_attr;
struct landlock_ruleset_attr;
-enum landlock_rule_type;
#include <linux/types.h>
#include <linux/aio_abi.h>
@@ -1053,7 +1052,7 @@ asmlinkage long sys_pidfd_send_signal(int pidfd, int sig,
asmlinkage long sys_pidfd_getfd(int pidfd, int fd, unsigned int flags);
asmlinkage long sys_landlock_create_ruleset(const struct landlock_ruleset_attr __user *attr,
size_t size, __u32 flags);
-asmlinkage long sys_landlock_add_rule(int ruleset_fd, enum landlock_rule_type rule_type,
+asmlinkage long sys_landlock_add_rule(int ruleset_fd, int rule_type,
const void __user *rule_attr, __u32 flags);
asmlinkage long sys_landlock_restrict_self(int ruleset_fd, __u32 flags);
asmlinkage long sys_memfd_secret(unsigned int flags);
diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
index fd4b24022a06..3b40fc5d0216 100644
--- a/security/landlock/syscalls.c
+++ b/security/landlock/syscalls.c
@@ -277,8 +277,9 @@ static int get_path_from_fd(const s32 fd, struct path *const path)
*
* @ruleset_fd: File descriptor tied to the ruleset that should be extended
* with the new rule.
- * @rule_type: Identify the structure type pointed to by @rule_attr (only
- * LANDLOCK_RULE_PATH_BENEATH for now).
+ * @rule_type: Identify the structure type pointed to by @rule_attr as defined
+ * by enum landlock_rule_type (only LANDLOCK_RULE_PATH_BENEATH for
+ * now).
* @rule_attr: Pointer to a rule (only of type &struct
* landlock_path_beneath_attr for now).
* @flags: Must be 0.
@@ -301,7 +302,7 @@ static int get_path_from_fd(const s32 fd, struct path *const path)
* - EFAULT: @rule_attr inconsistency.
*/
SYSCALL_DEFINE4(landlock_add_rule,
- const int, ruleset_fd, const enum landlock_rule_type, rule_type,
+ const int, ruleset_fd, const int, rule_type,
const void __user *const, rule_attr, const __u32, flags)
{
struct landlock_path_beneath_attr path_beneath_attr;
--
2.35.1
Hi Mickaël,
On 21/2/22 16:53, Mickaël Salaün wrote:
> From: Mickaël Salaün <[email protected]>
>
> Replace the enum landlock_rule_type with an int in the syscall signature
> of landlock_add_rule to avoid an implementation-defined size. In
> practice an enum type is like an int (at least with GCC and clang), but
> compilers may accept options (e.g. -fshort-enums) that would have an
> impact on that [1]. This change is mostly a cosmetic fix according to
> the current kernel compilers and used options.
There are two proposals for C2x that might bring C++ syntax to C for
enums, i.e., being able to specify the underlying type of an enum.
See:
<http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2904.htm>
<http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2908.htm>
Since the current kernel is safe from that enum problem, it may be
better to wait and see what the standard decides to do with enum. I
guess they'll add this feature sooner or later.
Regards,
Alex
>
> Link: https://lore.kernel.org/r/[email protected]/ [1]
> Reported-by: Alejandro Colomar <[email protected]>
> Cc: Nathan Chancellor <[email protected]>
> Cc: Nick Desaulniers <[email protected]>
> Signed-off-by: Mickaël Salaün <[email protected]>
> Link: https://lore.kernel.org/r/[email protected]
> ---
> include/linux/syscalls.h | 3 +--
> security/landlock/syscalls.c | 7 ++++---
> 2 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> index 819c0cb00b6d..a5956f91caf2 100644
> --- a/include/linux/syscalls.h
> +++ b/include/linux/syscalls.h
> @@ -71,7 +71,6 @@ struct clone_args;
> struct open_how;
> struct mount_attr;
> struct landlock_ruleset_attr;
> -enum landlock_rule_type;
>
> #include <linux/types.h>
> #include <linux/aio_abi.h>
> @@ -1053,7 +1052,7 @@ asmlinkage long sys_pidfd_send_signal(int pidfd, int sig,
> asmlinkage long sys_pidfd_getfd(int pidfd, int fd, unsigned int flags);
> asmlinkage long sys_landlock_create_ruleset(const struct landlock_ruleset_attr __user *attr,
> size_t size, __u32 flags);
> -asmlinkage long sys_landlock_add_rule(int ruleset_fd, enum landlock_rule_type rule_type,
> +asmlinkage long sys_landlock_add_rule(int ruleset_fd, int rule_type,
> const void __user *rule_attr, __u32 flags);
> asmlinkage long sys_landlock_restrict_self(int ruleset_fd, __u32 flags);
> asmlinkage long sys_memfd_secret(unsigned int flags);
> diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
> index fd4b24022a06..3b40fc5d0216 100644
> --- a/security/landlock/syscalls.c
> +++ b/security/landlock/syscalls.c
> @@ -277,8 +277,9 @@ static int get_path_from_fd(const s32 fd, struct path *const path)
> *
> * @ruleset_fd: File descriptor tied to the ruleset that should be extended
> * with the new rule.
> - * @rule_type: Identify the structure type pointed to by @rule_attr (only
> - * LANDLOCK_RULE_PATH_BENEATH for now).
> + * @rule_type: Identify the structure type pointed to by @rule_attr as defined
> + * by enum landlock_rule_type (only LANDLOCK_RULE_PATH_BENEATH for
> + * now).
> * @rule_attr: Pointer to a rule (only of type &struct
> * landlock_path_beneath_attr for now).
> * @flags: Must be 0.
> @@ -301,7 +302,7 @@ static int get_path_from_fd(const s32 fd, struct path *const path)
> * - EFAULT: @rule_attr inconsistency.
> */
> SYSCALL_DEFINE4(landlock_add_rule,
> - const int, ruleset_fd, const enum landlock_rule_type, rule_type,
> + const int, ruleset_fd, const int, rule_type,
> const void __user *const, rule_attr, const __u32, flags)
> {
> struct landlock_path_beneath_attr path_beneath_attr;
On 26/02/2022 22:26, Alejandro Colomar (man-pages) wrote:
> Hi Mickaël,
>
> On 21/2/22 16:53, Mickaël Salaün wrote:
>> From: Mickaël Salaün <[email protected]>
>>
>> Replace the enum landlock_rule_type with an int in the syscall signature
>> of landlock_add_rule to avoid an implementation-defined size. In
>> practice an enum type is like an int (at least with GCC and clang), but
>> compilers may accept options (e.g. -fshort-enums) that would have an
>> impact on that [1]. This change is mostly a cosmetic fix according to
>> the current kernel compilers and used options.
>
> There are two proposals for C2x that might bring C++ syntax to C for
> enums, i.e., being able to specify the underlying type of an enum.
>
> See:
> <http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2904.htm>
> <http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2908.htm>
>
> Since the current kernel is safe from that enum problem, it may be
> better to wait and see what the standard decides to do with enum. I
> guess they'll add this feature sooner or later.
Ok, interesting, I'll remove this patch then. I'd be curious to know
when this will impact Linux though.
Thanks!
>
> Regards,
> Alex
>
>>
>> Link:
>> https://lore.kernel.org/r/[email protected]/
>> [1]
>> Reported-by: Alejandro Colomar <[email protected]>
>> Cc: Nathan Chancellor <[email protected]>
>> Cc: Nick Desaulniers <[email protected]>
>> Signed-off-by: Mickaël Salaün <[email protected]>
>> Link: https://lore.kernel.org/r/[email protected]
>> ---
>> include/linux/syscalls.h | 3 +--
>> security/landlock/syscalls.c | 7 ++++---
>> 2 files changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
>> index 819c0cb00b6d..a5956f91caf2 100644
>> --- a/include/linux/syscalls.h
>> +++ b/include/linux/syscalls.h
>> @@ -71,7 +71,6 @@ struct clone_args;
>> struct open_how;
>> struct mount_attr;
>> struct landlock_ruleset_attr;
>> -enum landlock_rule_type;
>> #include <linux/types.h>
>> #include <linux/aio_abi.h>
>> @@ -1053,7 +1052,7 @@ asmlinkage long sys_pidfd_send_signal(int pidfd,
>> int sig,
>> asmlinkage long sys_pidfd_getfd(int pidfd, int fd, unsigned int flags);
>> asmlinkage long sys_landlock_create_ruleset(const struct
>> landlock_ruleset_attr __user *attr,
>> size_t size, __u32 flags);
>> -asmlinkage long sys_landlock_add_rule(int ruleset_fd, enum
>> landlock_rule_type rule_type,
>> +asmlinkage long sys_landlock_add_rule(int ruleset_fd, int rule_type,
>> const void __user *rule_attr, __u32 flags);
>> asmlinkage long sys_landlock_restrict_self(int ruleset_fd, __u32
>> flags);
>> asmlinkage long sys_memfd_secret(unsigned int flags);
>> diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
>> index fd4b24022a06..3b40fc5d0216 100644
>> --- a/security/landlock/syscalls.c
>> +++ b/security/landlock/syscalls.c
>> @@ -277,8 +277,9 @@ static int get_path_from_fd(const s32 fd, struct
>> path *const path)
>> *
>> * @ruleset_fd: File descriptor tied to the ruleset that should be
>> extended
>> * with the new rule.
>> - * @rule_type: Identify the structure type pointed to by @rule_attr
>> (only
>> - * LANDLOCK_RULE_PATH_BENEATH for now).
>> + * @rule_type: Identify the structure type pointed to by @rule_attr
>> as defined
>> + * by enum landlock_rule_type (only
>> LANDLOCK_RULE_PATH_BENEATH for
>> + * now).
>> * @rule_attr: Pointer to a rule (only of type &struct
>> * landlock_path_beneath_attr for now).
>> * @flags: Must be 0.
>> @@ -301,7 +302,7 @@ static int get_path_from_fd(const s32 fd, struct
>> path *const path)
>> * - EFAULT: @rule_attr inconsistency.
>> */
>> SYSCALL_DEFINE4(landlock_add_rule,
>> - const int, ruleset_fd, const enum landlock_rule_type, rule_type,
>> + const int, ruleset_fd, const int, rule_type,
>> const void __user *const, rule_attr, const __u32, flags)
>> {
>> struct landlock_path_beneath_attr path_beneath_attr;
>