From: Linus Torvalds Date: Wed, 9 Nov 2011 23:16:00 +0000 (-0500) Subject: Revert "proc: fix races against execve() of /proc/PID/fd**" X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=5e442a493fc59fa536c76db1fff5b49ca36a88c5;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git Revert "proc: fix races against execve() of /proc/PID/fd**" This reverts commit aa6afca5bcaba8101f3ea09d5c3e4100b2b9f0e5. It escalates of some of the google-chrome SELinux problems with ptrace ("Check failed: pid_ > 0. Did not find zygote process"), and Andrew says that it is also causing mystery lockdep reports. Reported-by: Alex Villacís Lasso Requested-by: James Morris Requested-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/proc/base.c b/fs/proc/base.c index 2db1bd3173b2..851ba3dcdc29 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1652,46 +1652,12 @@ out: return error; } -static int proc_pid_fd_link_getattr(struct vfsmount *mnt, struct dentry *dentry, - struct kstat *stat) -{ - struct inode *inode = dentry->d_inode; - struct task_struct *task = get_proc_task(inode); - int rc; - - if (task == NULL) - return -ESRCH; - - rc = -EACCES; - if (lock_trace(task)) - goto out_task; - - generic_fillattr(inode, stat); - unlock_trace(task); - rc = 0; -out_task: - put_task_struct(task); - return rc; -} - static const struct inode_operations proc_pid_link_inode_operations = { .readlink = proc_pid_readlink, .follow_link = proc_pid_follow_link, .setattr = proc_setattr, }; -static const struct inode_operations proc_fdinfo_link_inode_operations = { - .setattr = proc_setattr, - .getattr = proc_pid_fd_link_getattr, -}; - -static const struct inode_operations proc_fd_link_inode_operations = { - .readlink = proc_pid_readlink, - .follow_link = proc_pid_follow_link, - .setattr = proc_setattr, - .getattr = proc_pid_fd_link_getattr, -}; - /* building an inode */ @@ -1923,61 +1889,49 @@ out: static int proc_fd_info(struct inode *inode, struct path *path, char *info) { - struct task_struct *task; - struct files_struct *files; + struct task_struct *task = get_proc_task(inode); + struct files_struct *files = NULL; struct file *file; int fd = proc_fd(inode); - int rc; - - task = get_proc_task(inode); - if (!task) - return -ENOENT; - - rc = -EACCES; - if (lock_trace(task)) - goto out_task; - - rc = -ENOENT; - files = get_files_struct(task); - if (files == NULL) - goto out_unlock; - /* - * We are not taking a ref to the file structure, so we must - * hold ->file_lock. - */ - spin_lock(&files->file_lock); - file = fcheck_files(files, fd); - if (file) { - unsigned int f_flags; - struct fdtable *fdt; - - fdt = files_fdtable(files); - f_flags = file->f_flags & ~O_CLOEXEC; - if (FD_ISSET(fd, fdt->close_on_exec)) - f_flags |= O_CLOEXEC; - - if (path) { - *path = file->f_path; - path_get(&file->f_path); + if (task) { + files = get_files_struct(task); + put_task_struct(task); + } + if (files) { + /* + * We are not taking a ref to the file structure, so we must + * hold ->file_lock. + */ + spin_lock(&files->file_lock); + file = fcheck_files(files, fd); + if (file) { + unsigned int f_flags; + struct fdtable *fdt; + + fdt = files_fdtable(files); + f_flags = file->f_flags & ~O_CLOEXEC; + if (FD_ISSET(fd, fdt->close_on_exec)) + f_flags |= O_CLOEXEC; + + if (path) { + *path = file->f_path; + path_get(&file->f_path); + } + if (info) + snprintf(info, PROC_FDINFO_MAX, + "pos:\t%lli\n" + "flags:\t0%o\n", + (long long) file->f_pos, + f_flags); + spin_unlock(&files->file_lock); + put_files_struct(files); + return 0; } - if (info) - snprintf(info, PROC_FDINFO_MAX, - "pos:\t%lli\n" - "flags:\t0%o\n", - (long long) file->f_pos, - f_flags); - rc = 0; - } else - rc = -ENOENT; - spin_unlock(&files->file_lock); - put_files_struct(files); - -out_unlock: - unlock_trace(task); -out_task: - put_task_struct(task); - return rc; + spin_unlock(&files->file_lock); + put_files_struct(files); + } + return -ENOENT; } static int proc_fd_link(struct inode *inode, struct path *path) @@ -2072,7 +2026,7 @@ static struct dentry *proc_fd_instantiate(struct inode *dir, spin_unlock(&files->file_lock); put_files_struct(files); - inode->i_op = &proc_fd_link_inode_operations; + inode->i_op = &proc_pid_link_inode_operations; inode->i_size = 64; ei->op.proc_get_link = proc_fd_link; d_set_d_op(dentry, &tid_fd_dentry_operations); @@ -2104,12 +2058,7 @@ static struct dentry *proc_lookupfd_common(struct inode *dir, if (fd == ~0U) goto out; - result = ERR_PTR(-EACCES); - if (lock_trace(task)) - goto out; - result = instantiate(dir, dentry, task, &fd); - unlock_trace(task); out: put_task_struct(task); out_no_task: @@ -2129,28 +2078,23 @@ static int proc_readfd_common(struct file * filp, void * dirent, retval = -ENOENT; if (!p) goto out_no_task; - - retval = -EACCES; - if (lock_trace(p)) - goto out; - retval = 0; fd = filp->f_pos; switch (fd) { case 0: if (filldir(dirent, ".", 1, 0, inode->i_ino, DT_DIR) < 0) - goto out_unlock; + goto out; filp->f_pos++; case 1: ino = parent_ino(dentry); if (filldir(dirent, "..", 2, 1, ino, DT_DIR) < 0) - goto out_unlock; + goto out; filp->f_pos++; default: files = get_files_struct(p); if (!files) - goto out_unlock; + goto out; rcu_read_lock(); for (fd = filp->f_pos-2; fd < files_fdtable(files)->max_fds; @@ -2174,9 +2118,6 @@ static int proc_readfd_common(struct file * filp, void * dirent, rcu_read_unlock(); put_files_struct(files); } - -out_unlock: - unlock_trace(p); out: put_task_struct(p); out_no_task: @@ -2254,7 +2195,6 @@ static struct dentry *proc_fdinfo_instantiate(struct inode *dir, ei->fd = fd; inode->i_mode = S_IFREG | S_IRUSR; inode->i_fop = &proc_fdinfo_file_operations; - inode->i_op = &proc_fdinfo_link_inode_operations; d_set_d_op(dentry, &tid_fd_dentry_operations); d_add(dentry, inode); /* Close the race of the process dying before we return the dentry */