fs: add do_faccessat() helper and ksys_access() wrapper; remove in-kernel calls to syscall

Using the fs-internal do_faccessat() helper allows us to get rid of
fs-internal calls to the sys_faccessat() syscall.

Introducing the ksys_access() wrapper allows us to avoid the in-kernel
calls to the sys_access() syscall. The ksys_ prefix denotes that this
function is meant as a drop-in replacement for the syscall. In
particular, it uses the same calling convention as sys_access().

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/[email protected]

Cc: Al Viro <[email protected]>
Cc: Andrew Morton <[email protected]>
Signed-off-by: Dominik Brodowski <[email protected]>
This commit is contained in:
Dominik Brodowski 2018-03-11 11:34:54 +01:00
commit cbfe20f565
4 changed files with 17 additions and 3 deletions

View file

@ -350,7 +350,7 @@ SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
* We do this by temporarily clearing all FS-related capabilities and
* switching the fsuid/fsgid around to the real ones.
*/
SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
long do_faccessat(int dfd, const char __user *filename, int mode)
{
const struct cred *old_cred;
struct cred *override_cred;
@ -426,9 +426,14 @@ out:
return res;
}
SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
{
return do_faccessat(dfd, filename, mode);
}
SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
{
return sys_faccessat(AT_FDCWD, filename, mode);
return do_faccessat(AT_FDCWD, filename, mode);
}
int ksys_chdir(const char __user *filename)