Hi Mickaël,
On 11/10/21 20:06, Mickaël Salaün wrote:
diff --git a/fs/open.c b/fs/open.c
index f732fb94600c..96a80abec41b 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -480,6 +482,114 @@ SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
return do_faccessat(AT_FDCWD, filename, mode, 0);
}
+#define TRUST_POLICY_EXEC_MOUNT BIT(0)
+#define TRUST_POLICY_EXEC_FILE BIT(1)
+
+int sysctl_trusted_for_policy __read_mostly;
+
+/**
...
+ */
+SYSCALL_DEFINE3(trusted_for, const int, fd, const enum trusted_for_usage, usage,
Please, don't use enums for interfaces. They are implementation defined
types, and vary between compilers and within the same compiler also
depending on optimization flags.
C17::6.7.2.2.4:
[
Each enumerated type shall be compatible with char,
a signed integer type, or an unsigned integer type.
The choice of type is implementation-defined,130)
but shall be capable of representing the values of
all the members of the enumeration.
]
See also:
<https://stackoverflow.com/questions/366017/what-is-the-size-of-an-enum-in-c>
So, please use only standard integer types for interfaces.
And in the case of enums, since the language specifies that enumeration
constants (the macro-like identifiers) are of type int, it makes sense
for functions to use int.
C17::6.7.2.2.3:
[
The identifiers in an enumerator list are declared as constants
that have type int and may appear wherever such are permitted.
]
I'd use an int for the API/ABI, even if it's expected to be assigned
values of 'enum trusted_for_usage' (that should be specified in the
manual page in DESCRIPTION, but not in SYNOPSIS, which should specify int).
TL;DR:
ISO C specifies that for the following code:
enum foo {BAR};
enum foo foobar;
typeof(foo) shall be int
typeof(foobar) is implementation-defined
Since foobar = BAR; assigns an int, the best thing to do to avoid
implementation-defined behavior, is to declare foobar as int too.
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 528a478dbda8..c535e0e43cc8 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -462,6 +463,7 @@ asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len);
asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode);
asmlinkage long sys_faccessat2(int dfd, const char __user *filename, int mode,
int flags);
+asmlinkage long sys_trusted_for(int fd, enum trusted_for_usage usage, u32 flags);
Same here.
asmlinkage long sys_chdir(const char __user *filename);
asmlinkage long sys_fchdir(unsigned int fd);
asmlinkage long sys_chroot(const char __user *filename);
Thanks,
Alex
--
Alejandro Colomar
Linux man-pages comaintainer; http://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/
--
Alejandro Colomar
Linux man-pages comaintainer; http://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/
