Re: [PATCH v1 2/7] landlock: Fix landlock_add_rule(2) signature
From: Alejandro Colomar (man-pages) <hidden>
Date: 2022-02-26 21:27:03
Also in:
linux-security-module, lkml
Hi Mickaël, On 21/2/22 16:53, Mickaël Salaün wrote:
From: Mickaël Salaün <redacted> 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
quoted hunk ↗ jump to hunk
Link: https://lore.kernel.org/r/8a22a3c2-468c-e96c-6516-22a0f029aa34@gmail.com/ (local) [1] Reported-by: Alejandro Colomar <redacted> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Nick Desaulniers <redacted> Signed-off-by: Mickaël Salaün <redacted> Link: https://lore.kernel.org/r/20220221155311.166278-3-mic@digikod.net (local) --- 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;