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-rw-r--r--fs/open.c73
1 files changed, 72 insertions, 1 deletions
diff --git a/fs/open.c b/fs/open.c
index b47aab39c057..d05e18c60bae 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -890,15 +890,86 @@ void fd_install(unsigned int fd, struct file *file)
EXPORT_SYMBOL(fd_install);
+static inline int build_open_flags(int flags, int mode, struct open_flags *op)
+{
+ int lookup_flags = 0;
+ int acc_mode;
+
+ if (!(flags & O_CREAT))
+ mode = 0;
+ op->mode = mode;
+
+ /* Must never be set by userspace */
+ flags &= ~FMODE_NONOTIFY;
+
+ /*
+ * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
+ * check for O_DSYNC if the need any syncing at all we enforce it's
+ * always set instead of having to deal with possibly weird behaviour
+ * for malicious applications setting only __O_SYNC.
+ */
+ if (flags & __O_SYNC)
+ flags |= O_DSYNC;
+
+ op->open_flag = flags;
+
+ acc_mode = MAY_OPEN | ACC_MODE(flags);
+
+ /* O_TRUNC implies we need access checks for write permissions */
+ if (flags & O_TRUNC)
+ acc_mode |= MAY_WRITE;
+
+ /* Allow the LSM permission hook to distinguish append
+ access from general write access. */
+ if (flags & O_APPEND)
+ acc_mode |= MAY_APPEND;
+
+ op->acc_mode = acc_mode;
+
+ op->intent = LOOKUP_OPEN;
+ if (flags & O_CREAT) {
+ op->intent |= LOOKUP_CREATE;
+ if (flags & O_EXCL)
+ op->intent |= LOOKUP_EXCL;
+ }
+
+ if (flags & O_DIRECTORY)
+ lookup_flags |= LOOKUP_DIRECTORY;
+ if (!(flags & O_NOFOLLOW))
+ lookup_flags |= LOOKUP_FOLLOW;
+ return lookup_flags;
+}
+
+/**
+ * filp_open - open file and return file pointer
+ *
+ * @filename: path to open
+ * @flags: open flags as per the open(2) second argument
+ * @mode: mode for the new file if O_CREAT is set, else ignored
+ *
+ * This is the helper to open a file from kernelspace if you really
+ * have to. But in generally you should not do this, so please move
+ * along, nothing to see here..
+ */
+struct file *filp_open(const char *filename, int flags, int mode)
+{
+ struct open_flags op;
+ int lookup = build_open_flags(flags, mode, &op);
+ return do_filp_open(AT_FDCWD, filename, &op, lookup);
+}
+EXPORT_SYMBOL(filp_open);
+
long do_sys_open(int dfd, const char __user *filename, int flags, int mode)
{
+ struct open_flags op;
+ int lookup = build_open_flags(flags, mode, &op);
char *tmp = getname(filename);
int fd = PTR_ERR(tmp);
if (!IS_ERR(tmp)) {
fd = get_unused_fd_flags(flags);
if (fd >= 0) {
- struct file *f = do_filp_open(dfd, tmp, flags, mode, 0);
+ struct file *f = do_filp_open(dfd, tmp, &op, lookup);
if (IS_ERR(f)) {
put_unused_fd(fd);
fd = PTR_ERR(f);