Re: [RFC][PATCH v2] procfs: Always expose /proc/<pid>/map_files/ and make it readable
From: Kirill A. Shutemov <hidden>
Date: 2015-01-26 12:48:08
Also in:
lkml
On Fri, Jan 23, 2015 at 07:15:44PM -0800, Calvin Owens wrote:
Currently, /proc/<pid>/map_files/ is restricted to CAP_SYS_ADMIN, and is only exposed if CONFIG_CHECKPOINT_RESTORE is set. This interface is very useful for enumerating the files mapped into a process when the more verbose information in /proc/<pid>/maps is not needed. This patch moves the folder out from behind CHECKPOINT_RESTORE, and removes the CAP_SYS_ADMIN restrictions. Following the links requires the ability to ptrace the process in question, so this doesn't allow an attacker to do anything they couldn't already do before. Signed-off-by: Calvin Owens <redacted>
Cc +linux-api@
quoted hunk
--- Changes in v2: Removed the follow_link() stub that returned -EPERM if the caller didn't have CAP_SYS_ADMIN, since the caller in my chroot() scenario gets -EACCES anyway. fs/proc/base.c | 18 ------------------ 1 file changed, 18 deletions(-)diff --git a/fs/proc/base.c b/fs/proc/base.c index 3f3d7ae..67b15ac 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c@@ -1632,8 +1632,6 @@ end_instantiate: return dir_emit(ctx, name, len, 1, DT_UNKNOWN); } -#ifdef CONFIG_CHECKPOINT_RESTORE - /* * dname_to_vma_addr - maps a dentry name into two unsigned longs * which represent vma start and end addresses.@@ -1660,11 +1658,6 @@ static int map_files_d_revalidate(struct dentry *dentry, unsigned int flags) if (flags & LOOKUP_RCU) return -ECHILD; - if (!capable(CAP_SYS_ADMIN)) { - status = -EPERM; - goto out_notask; - } - inode = dentry->d_inode; task = get_proc_task(inode); if (!task)@@ -1792,10 +1785,6 @@ static struct dentry *proc_map_files_lookup(struct inode *dir, int result; struct mm_struct *mm; - result = -EPERM; - if (!capable(CAP_SYS_ADMIN)) - goto out; - result = -ENOENT; task = get_proc_task(dir); if (!task)@@ -1849,10 +1838,6 @@ proc_map_files_readdir(struct file *file, struct dir_context *ctx) struct map_files_info *p; int ret; - ret = -EPERM; - if (!capable(CAP_SYS_ADMIN)) - goto out; - ret = -ENOENT; task = get_proc_task(file_inode(file)); if (!task)@@ -2040,7 +2025,6 @@ static const struct file_operations proc_timers_operations = { .llseek = seq_lseek, .release = seq_release_private, }; -#endif /* CONFIG_CHECKPOINT_RESTORE */ static int proc_pident_instantiate(struct inode *dir, struct dentry *dentry, struct task_struct *task, const void *ptr)@@ -2537,9 +2521,7 @@ static const struct inode_operations proc_task_inode_operations; static const struct pid_entry tgid_base_stuff[] = { DIR("task", S_IRUGO|S_IXUGO, proc_task_inode_operations, proc_task_operations), DIR("fd", S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations), -#ifdef CONFIG_CHECKPOINT_RESTORE DIR("map_files", S_IRUSR|S_IXUSR, proc_map_files_inode_operations, proc_map_files_operations), -#endif DIR("fdinfo", S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fdinfo_operations), DIR("ns", S_IRUSR|S_IXUGO, proc_ns_dir_inode_operations, proc_ns_dir_operations), #ifdef CONFIG_NET-- 1.8.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
-- Kirill A. Shutemov