[PATCH v5 1/2] proc: pass file instead of inode to proc_mem_open

[Adrian Ratiu <adrian.ratiu@xxxxxxxxxxxxx>]

The file struct is required in proc_mem_open() so its
f_mode can be checked when deciding whether to allow or
deny /proc/*/mem open requests via the new read/write
and foll_force restriction mechanism.

Thus instead of directly passing the inode to the fun,
we pass the file and get the inode inside it.

Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: Jeff Xu <jeffxu@xxxxxxxxxx>
Signed-off-by: Adrian Ratiu <adrian.ratiu@xxxxxxxxxxxxx>
Reviewed-by: Kees Cook <kees@xxxxxxxxxx>
---
Changes in v5:
* Fixed task_nommu.c 0day build error
* Added Reviewed-by tag by Kees C. (thanks!)
* Rebased on next-20240605
---
 fs/proc/base.c       | 6 +++---
 fs/proc/internal.h   | 2 +-
 fs/proc/task_mmu.c   | 6 +++---
 fs/proc/task_nommu.c | 2 +-
 4 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 72a1acd03675c..4c607089f66ed 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -794,9 +794,9 @@ static const struct file_operations proc_single_file_operations = {
 };
 
 
-struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode)
+struct mm_struct *proc_mem_open(struct file  *file, unsigned int mode)
 {
-	struct task_struct *task = get_proc_task(inode);
+	struct task_struct *task = get_proc_task(file->f_inode);
 	struct mm_struct *mm = ERR_PTR(-ESRCH);
 
 	if (task) {
@@ -816,7 +816,7 @@ struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode)
 
 static int __mem_open(struct inode *inode, struct file *file, unsigned int mode)
 {
-	struct mm_struct *mm = proc_mem_open(inode, mode);
+	struct mm_struct *mm = proc_mem_open(file, mode);
 
 	if (IS_ERR(mm))
 		return PTR_ERR(mm);
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index a71ac5379584a..d38b2eea40d12 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -295,7 +295,7 @@ struct proc_maps_private {
 #endif
 } __randomize_layout;
 
-struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode);
+struct mm_struct *proc_mem_open(struct file *file, unsigned int mode);
 
 extern const struct file_operations proc_pid_maps_operations;
 extern const struct file_operations proc_pid_numa_maps_operations;
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index f8d35f993fe50..fe3b2182b0aae 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -210,7 +210,7 @@ static int proc_maps_open(struct inode *inode, struct file *file,
 		return -ENOMEM;
 
 	priv->inode = inode;
-	priv->mm = proc_mem_open(inode, PTRACE_MODE_READ);
+	priv->mm = proc_mem_open(file, PTRACE_MODE_READ);
 	if (IS_ERR(priv->mm)) {
 		int err = PTR_ERR(priv->mm);
 
@@ -1030,7 +1030,7 @@ static int smaps_rollup_open(struct inode *inode, struct file *file)
 		goto out_free;
 
 	priv->inode = inode;
-	priv->mm = proc_mem_open(inode, PTRACE_MODE_READ);
+	priv->mm = proc_mem_open(file, PTRACE_MODE_READ);
 	if (IS_ERR(priv->mm)) {
 		ret = PTR_ERR(priv->mm);
 
@@ -1754,7 +1754,7 @@ static int pagemap_open(struct inode *inode, struct file *file)
 {
 	struct mm_struct *mm;
 
-	mm = proc_mem_open(inode, PTRACE_MODE_READ);
+	mm = proc_mem_open(file, PTRACE_MODE_READ);
 	if (IS_ERR(mm))
 		return PTR_ERR(mm);
 	file->private_data = mm;
diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index bce6745330003..a8ab182a4ed14 100644
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -259,7 +259,7 @@ static int maps_open(struct inode *inode, struct file *file,
 		return -ENOMEM;
 
 	priv->inode = inode;
-	priv->mm = proc_mem_open(inode, PTRACE_MODE_READ);
+	priv->mm = proc_mem_open(file, PTRACE_MODE_READ);
 	if (IS_ERR(priv->mm)) {
 		int err = PTR_ERR(priv->mm);
 
-- 
2.30.2