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/20180325162527.GA17492@xxxxxxxxxxxxxxxxxxxxxxxxxx Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx> --- fs/internal.h | 1 + fs/open.c | 9 +++++++-- include/linux/syscalls.h | 7 +++++++ init/main.c | 3 ++- 4 files changed, 17 insertions(+), 3 deletions(-) diff --git a/fs/internal.h b/fs/internal.h index 2474bf460f96..26f4f05b52ef 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -119,6 +119,7 @@ extern struct file *do_filp_open(int dfd, struct filename *pathname, extern struct file *do_file_open_root(struct dentry *, struct vfsmount *, const char *, const struct open_flags *); +long do_faccessat(int dfd, const char __user *filename, int mode); int do_fchmodat(int dfd, const char __user *filename, umode_t mode); extern int open_check_o_direct(struct file *f); diff --git a/fs/open.c b/fs/open.c index 6037f2bf418c..0fc8188be31a 100644 --- a/fs/open.c +++ b/fs/open.c @@ -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 @@ SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode) 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) diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index dd6c306f4f00..33f06de090ea 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -1014,4 +1014,11 @@ static inline int ksys_chmod(const char __user *filename, umode_t mode) return do_fchmodat(AT_FDCWD, filename, mode); } +extern long do_faccessat(int dfd, const char __user *filename, int mode); + +static inline long ksys_access(const char __user *filename, int mode) +{ + return do_faccessat(AT_FDCWD, filename, mode); +} + #endif diff --git a/init/main.c b/init/main.c index b8649d1466e1..d0ded4322c6b 100644 --- a/init/main.c +++ b/init/main.c @@ -1087,7 +1087,8 @@ static noinline void __init kernel_init_freeable(void) if (!ramdisk_execute_command) ramdisk_execute_command = "/init"; - if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) { + if (ksys_access((const char __user *) + ramdisk_execute_command, 0) != 0) { ramdisk_execute_command = NULL; prepare_namespace(); } -- 2.16.3
