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    Subject[RFC PATCH 32/35] syscalls: do not call sys_{f,}access{,at}() within the kernel
    Date
    CC: Al Viro <viro@zeniv.linux.org.uk>
    CC: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
    ---
    fs/internal.h | 1 +
    fs/open.c | 9 +++++++--
    include/linux/syscalls.h | 6 ++++++
    init/main.c | 3 ++-
    4 files changed, 16 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 87feef73c077..ac4ba9439e52 100644
    --- a/include/linux/syscalls.h
    +++ b/include/linux/syscalls.h
    @@ -1016,4 +1016,10 @@ 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();
    }
    --
    2.16.2
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