| Message ID | 20220221155311.166278-3-mic@digikod.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Minor Landlock fixes and new tests | expand |
Hi Mickaël, On 21/2/22 16:53, Mickaël Salaün wrote: > From: Mickaël Salaün <mic@linux.microsoft.com> > > 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/8a22a3c2-468c-e96c-6516-22a0f029aa34@gmail.com/ [1] > Reported-by: Alejandro Colomar <alx.manpages@gmail.com> > Cc: Nathan Chancellor <nathan@kernel.org> > Cc: Nick Desaulniers <ndesaulniers@google.com> > Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com> > Link: https://lore.kernel.org/r/20220221155311.166278-3-mic@digikod.net > --- > 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 <mic@linux.microsoft.com> >> >> 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/8a22a3c2-468c-e96c-6516-22a0f029aa34@gmail.com/ >> [1] >> Reported-by: Alejandro Colomar <alx.manpages@gmail.com> >> Cc: Nathan Chancellor <nathan@kernel.org> >> Cc: Nick Desaulniers <ndesaulniers@google.com> >> Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com> >> Link: https://lore.kernel.org/r/20220221155311.166278-3-mic@digikod.net >> --- >> 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; >
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;