The patch titled Subject: proc: use task_access_lock() instead of ptrace_may_access() has been removed from the -mm tree. Its filename was proc-use-task_access_lock-instead-of-ptrace_may_access.patch This patch was dropped because it was withdrawn The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ From: Cong Wang <xiyou.wangcong@xxxxxxxxx> Subject: proc: use task_access_lock() instead of ptrace_may_access() There are several places in fs/proc/base.c still use ptrace_may_access() directly to check the permission, actually this just gets a snapshot of the permission, nothing prevents the target task from raising the priviledges itself, it is better to use task_access_lock() for these places, to hold the priviledges. Signed-off-by: Cong Wang <xiyou.wangcong@xxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/proc/base.c | 74 ++++++++++++++++++++--------------------------- 1 file changed, 33 insertions(+), 41 deletions(-) diff -puN fs/proc/base.c~proc-use-task_access_lock-instead-of-ptrace_may_access fs/proc/base.c --- a/fs/proc/base.c~proc-use-task_access_lock-instead-of-ptrace_may_access +++ a/fs/proc/base.c @@ -253,6 +253,23 @@ static int proc_pid_auxv(struct task_str return res; } +static int task_access_lock(struct task_struct *task, unsigned int mode) + +{ + int err = mutex_lock_killable(&task->signal->cred_guard_mutex); + if (err) + return err; + if (!ptrace_may_access(task, mode)) { + mutex_unlock(&task->signal->cred_guard_mutex); + return -EPERM; + } + return 0; +} + +static void task_access_unlock(struct task_struct *task) +{ + mutex_unlock(&task->signal->cred_guard_mutex); +} #ifdef CONFIG_KALLSYMS /* @@ -264,35 +281,18 @@ static int proc_pid_wchan(struct task_st unsigned long wchan; char symname[KSYM_NAME_LEN]; + if (task_access_lock(task, PTRACE_MODE_READ)) + return 0; wchan = get_wchan(task); + task_access_unlock(task); if (lookup_symbol_name(wchan, symname) < 0) - if (!ptrace_may_access(task, PTRACE_MODE_READ)) - return 0; - else - return sprintf(buffer, "%lu", wchan); + return sprintf(buffer, "%lu", wchan); else return sprintf(buffer, "%s", symname); } #endif /* CONFIG_KALLSYMS */ -static int task_access_lock(struct task_struct *task, unsigned int mode) -{ - int err = mutex_lock_killable(&task->signal->cred_guard_mutex); - if (err) - return err; - if (!ptrace_may_access(task, mode)) { - mutex_unlock(&task->signal->cred_guard_mutex); - return -EPERM; - } - return 0; -} - -static void task_access_unlock(struct task_struct *task) -{ - mutex_unlock(&task->signal->cred_guard_mutex); -} - #ifdef CONFIG_STACKTRACE #define MAX_STACK_TRACE_DEPTH 64 @@ -512,23 +512,6 @@ static int proc_pid_syscall(struct task_ /* Here the fs part begins */ /************************************************************************/ -/* permission checks */ -static int proc_fd_access_allowed(struct inode *inode) -{ - struct task_struct *task; - int allowed = 0; - /* Allow access to a task's file descriptors if it is us or we - * may use ptrace attach to the process and find out that - * information. - */ - task = get_proc_task(inode); - if (task) { - allowed = ptrace_may_access(task, PTRACE_MODE_READ); - put_task_struct(task); - } - return allowed; -} - int proc_setattr(struct dentry *dentry, struct iattr *attr) { int error; @@ -1425,17 +1408,21 @@ static int proc_exe_link(struct dentry * static void *proc_pid_follow_link(struct dentry *dentry, struct nameidata *nd) { struct inode *inode = dentry->d_inode; + struct task_struct *task = get_proc_task(inode); int error = -EACCES; /* We don't need a base pointer in the /proc filesystem */ path_put(&nd->path); /* Are we allowed to snoop on the tasks file descriptors? */ - if (!proc_fd_access_allowed(inode)) + error = task_access_lock(task, PTRACE_MODE_READ); + if (error) goto out; error = PROC_I(inode)->op.proc_get_link(dentry, &nd->path); + task_access_unlock(task); out: + put_task_struct(task); return ERR_PTR(error); } @@ -1467,19 +1454,24 @@ static int proc_pid_readlink(struct dent { int error = -EACCES; struct inode *inode = dentry->d_inode; + struct task_struct *task = get_proc_task(inode); struct path path; /* Are we allowed to snoop on the tasks file descriptors? */ - if (!proc_fd_access_allowed(inode)) + error = task_access_lock(task, PTRACE_MODE_READ); + if (error) goto out; error = PROC_I(inode)->op.proc_get_link(dentry, &path); if (error) - goto out; + goto out_unlock; error = do_proc_readlink(&path, buffer, buflen); path_put(&path); +out_unlock: + task_access_unlock(task); out: + put_task_struct(task); return error; } _ Patches currently in -mm which might be from xiyou.wangcong@xxxxxxxxx are linux-next.patch cris-select-generic_atomic64.patch proc-clean-up-proc-pid-environ-handling.patch proc-clean-up-proc-pid-environ-handling-checkpatch-fixes.patch proc-unify-ptrace_may_access-locking-code.patch proc-remove-mm_for_maps.patch proc-use-mm_access-instead-of-ptrace_may_access.patch proc-use-is_err_or_null.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html