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[PATCH] sanitize locate_fd()
* 'file' argument is unused; lose it. * move setting flags from the caller (dupfd()) to locate_fd(); pass cloexec flag as new argument. Note that files_fdtable() that used to be in dupfd() isn't needed in the place in locate_fd() where the moved code ends up - we know that ->file_lock hadn't been dropped since the last time we calculated fdt because we can get there only if expand_files() returns 0 and it doesn't drop/reacquire in that case. * move getting/dropping ->file_lock into locate_fd(). Now the caller doesn't need to do anything with files_struct *files anymore and we can move that inside locate_fd() as well, killing the struct files_struct * argument. At that point locate_fd() is extremely similar to get_unused_fd_flags() and the next patches will merge those two. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
parent
3b1253880b
commit
f8f95702f0
40
fs/fcntl.c
40
fs/fcntl.c
@ -55,14 +55,16 @@ static int get_close_on_exec(unsigned int fd)
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* file_lock held for write.
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*/
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static int locate_fd(struct files_struct *files,
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struct file *file, unsigned int orig_start)
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static int locate_fd(unsigned int orig_start, int cloexec)
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{
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struct files_struct *files = current->files;
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unsigned int newfd;
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unsigned int start;
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int error;
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struct fdtable *fdt;
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spin_lock(&files->file_lock);
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error = -EINVAL;
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if (orig_start >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
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goto out;
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@ -97,42 +99,28 @@ repeat:
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if (error)
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goto repeat;
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/*
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* We reacquired files_lock, so we are safe as long as
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* we reacquire the fdtable pointer and use it while holding
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* the lock, no one can free it during that time.
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*/
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if (start <= files->next_fd)
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files->next_fd = newfd + 1;
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FD_SET(newfd, fdt->open_fds);
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if (cloexec)
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FD_SET(newfd, fdt->close_on_exec);
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else
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FD_CLR(newfd, fdt->close_on_exec);
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error = newfd;
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out:
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spin_unlock(&files->file_lock);
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return error;
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}
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static int dupfd(struct file *file, unsigned int start, int cloexec)
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{
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struct files_struct * files = current->files;
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struct fdtable *fdt;
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int fd;
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spin_lock(&files->file_lock);
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fd = locate_fd(files, file, start);
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if (fd >= 0) {
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/* locate_fd() may have expanded fdtable, load the ptr */
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fdt = files_fdtable(files);
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FD_SET(fd, fdt->open_fds);
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if (cloexec)
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FD_SET(fd, fdt->close_on_exec);
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else
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FD_CLR(fd, fdt->close_on_exec);
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spin_unlock(&files->file_lock);
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int fd = locate_fd(start, cloexec);
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if (fd >= 0)
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fd_install(fd, file);
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} else {
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spin_unlock(&files->file_lock);
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else
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fput(file);
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}
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return fd;
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}
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