[PATCH 03/10] proc: Pass file mode to proc_pid_make_inode

Wen Yang
2020-12-03T18:33:40Z

From: Andreas Gruenbacher <agruenba@redhat.com>

[ Upstream commit db978da8fa1d0819b210c137d31a339149b88875 ]

Pass the file mode of the proc inode to be created to
proc_pid_make_inode. In proc_pid_make_inode, initialize inode->i_mode
before calling security_task_to_inode. This allows selinux to set
isec->sclass right away without introducing "half-initialized" inode
security structs.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Cc: <stable@vger.kernel.org> # 4.9.x
Signed-off-by: Wen Yang <wenyang@linux.alibaba.com>
---
fs/proc/base.c | 23 +++++++++--------------
fs/proc/fd.c | 6 ++----
fs/proc/internal.h | 2 +-
fs/proc/namespaces.c | 3 +--
security/selinux/hooks.c | 1 +
5 files changed, 14 insertions(+), 21 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index b9e4183..ee2e0ec 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1676,7 +1676,8 @@ static int proc_pid_readlink(struct dentry * dentry, char __user * buffer, int b

/* building an inode */

-struct inode *proc_pid_make_inode(struct super_block * sb, struct task_struct *task)
+struct inode *proc_pid_make_inode(struct super_block * sb,
+ struct task_struct *task, umode_t mode)
{
struct inode * inode;
struct proc_inode *ei;
@@ -1690,6 +1691,7 @@ struct inode *proc_pid_make_inode(struct super_block * sb, struct task_struct *t

/* Common stuff */
ei = PROC_I(inode);
+ inode->i_mode = mode;
inode->i_ino = get_next_ino();
inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
inode->i_op = &proc_def_inode_operations;
@@ -2041,7 +2043,9 @@ struct map_files_info {
struct proc_inode *ei;
struct inode *inode;

- inode = proc_pid_make_inode(dir->i_sb, task);
+ inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK |
+ ((mode & FMODE_READ ) ? S_IRUSR : 0) |
+ ((mode & FMODE_WRITE) ? S_IWUSR : 0));
if (!inode)
return -ENOENT;

@@ -2050,12 +2054,6 @@ struct map_files_info {

inode->i_op = &proc_map_files_link_inode_operations;
inode->i_size = 64;
- inode->i_mode = S_IFLNK;
-
- if (mode & FMODE_READ)
- inode->i_mode |= S_IRUSR;
- if (mode & FMODE_WRITE)
- inode->i_mode |= S_IWUSR;

d_set_d_op(dentry, &tid_map_files_dentry_operations);
d_add(dentry, inode);
@@ -2409,12 +2407,11 @@ static int proc_pident_instantiate(struct inode *dir,
struct inode *inode;
struct proc_inode *ei;

- inode = proc_pid_make_inode(dir->i_sb, task);
+ inode = proc_pid_make_inode(dir->i_sb, task, p->mode);
if (!inode)
goto out;

ei = PROC_I(inode);
- inode->i_mode = p->mode;
if (S_ISDIR(inode->i_mode))
set_nlink(inode, 2); /* Use getattr to fix if necessary */
if (p->iop)
@@ -3096,11 +3093,10 @@ static int proc_pid_instantiate(struct inode *dir,
{
struct inode *inode;

- inode = proc_pid_make_inode(dir->i_sb, task);
+ inode = proc_pid_make_inode(dir->i_sb, task, S_IFDIR | S_IRUGO | S_IXUGO);
if (!inode)
goto out;

- inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
inode->i_op = &proc_tgid_base_inode_operations;
inode->i_fop = &proc_tgid_base_operations;
inode->i_flags|=S_IMMUTABLE;
@@ -3391,11 +3387,10 @@ static int proc_task_instantiate(struct inode *dir,
struct dentry *dentry, struct task_struct *task, const void *ptr)
{
struct inode *inode;
- inode = proc_pid_make_inode(dir->i_sb, task);
+ inode = proc_pid_make_inode(dir->i_sb, task, S_IFDIR | S_IRUGO | S_IXUGO);

if (!inode)
goto out;
- inode->i_mode = S_IFDIR|S_IRUGO|S_IXUGO;
inode->i_op = &proc_tid_base_inode_operations;
inode->i_fop = &proc_tid_base_operations;
inode->i_flags|=S_IMMUTABLE;
diff --git a/fs/proc/fd.c b/fs/proc/fd.c
index d21dafe..4274f83 100644
--- a/fs/proc/fd.c
+++ b/fs/proc/fd.c
@@ -183,14 +183,13 @@ static int proc_fd_link(struct dentry *dentry, struct path *path)
struct proc_inode *ei;
struct inode *inode;

- inode = proc_pid_make_inode(dir->i_sb, task);
+ inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK);
if (!inode)
goto out;

ei = PROC_I(inode);
ei->fd = fd;

- inode->i_mode = S_IFLNK;
inode->i_op = &proc_pid_link_inode_operations;
inode->i_size = 64;

@@ -322,14 +321,13 @@ int proc_fd_permission(struct inode *inode, int mask)
struct proc_inode *ei;
struct inode *inode;

- inode = proc_pid_make_inode(dir->i_sb, task);
+ inode = proc_pid_make_inode(dir->i_sb, task, S_IFREG | S_IRUSR);
if (!inode)
goto out;

ei = PROC_I(inode);
ei->fd = fd;

- inode->i_mode = S_IFREG | S_IRUSR;
inode->i_fop = &proc_fdinfo_file_operations;

d_set_d_op(dentry, &tid_fd_dentry_operations);
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index c0bdece..5bc057b 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -163,7 +163,7 @@ extern int proc_pid_statm(struct seq_file *, struct pid_namespace *,
extern const struct dentry_operations pid_dentry_operations;
extern int pid_getattr(struct vfsmount *, struct dentry *, struct kstat *);
extern int proc_setattr(struct dentry *, struct iattr *);
-extern struct inode *proc_pid_make_inode(struct super_block *, struct task_struct *);
+extern struct inode *proc_pid_make_inode(struct super_block *, struct task_struct *, umode_t);
extern int pid_revalidate(struct dentry *, unsigned int);
extern int pid_delete_dentry(const struct dentry *);
extern int proc_pid_readdir(struct file *, struct dir_context *);
diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index 51b8b0a..766f0c6 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -92,12 +92,11 @@ static int proc_ns_instantiate(struct inode *dir,
struct inode *inode;
struct proc_inode *ei;

- inode = proc_pid_make_inode(dir->i_sb, task);
+ inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK | S_IRWXUGO);
if (!inode)
goto out;

ei = PROC_I(inode);
- inode->i_mode = S_IFLNK|S_IRWXUGO;
inode->i_op = &proc_ns_link_inode_operations;
ei->ns_ops = ns_ops;

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index a2b63a6..98b5f40 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3967,6 +3967,7 @@ static void selinux_task_to_inode(struct task_struct *p,
struct inode_security_struct *isec = inode->i_security;
u32 sid = task_sid(p);

+ isec->sclass = inode_mode_to_security_class(inode->i_mode);
isec->sid = sid;
isec->initialized = LABEL_INITIALIZED;
}
--
1.8.3.1