The patch titled
Subject: procfs: add 'path' to /proc/<pid>/fdinfo/
has been added to the -mm mm-unstable branch. Its filename is
procfs-add-path-to-proc-pid-fdinfo.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/procfs-add-path-to-proc-pid-fdinfo.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Kalesh Singh <kaleshsingh@xxxxxxxxxx>
Subject: procfs: add 'path' to /proc/<pid>/fdinfo/
Date: Thu, 23 Jun 2022 15:06:07 -0700
In order to identify the type of memory a process has pinned through its
open fds, add the file path to fdinfo output. This allows identifying
memory types based on common prefixes: e.g. "/memfd...", "/dmabuf...",
"/dev/ashmem...".
To be cautious, only expose the paths for anonymous inodes, and this also
avoids printing path names with strange characters.
Access to /proc/<pid>/fdinfo is governed by PTRACE_MODE_READ_FSCREDS the
same as /proc/<pid>/maps which also exposes the file path of mappings; so
the security permissions for accessing path is consistent with that of
/proc/<pid>/maps.
Link: https://lkml.kernel.org/r/20220623220613.3014268-3-kaleshsingh@xxxxxxxxxx
Signed-off-by: Kalesh Singh <kaleshsingh@xxxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: Christoph Anton Mitterer <mail@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Colin Cross <ccross@xxxxxxxxxx>
Cc: David Laight <David.Laight@xxxxxxxxxx>
Cc: Ioannis Ilkos <ilkos@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Paul Gortmaker<paul.gortmaker@xxxxxxxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Stephen Brennan <stephen.s.brennan@xxxxxxxxxx>
Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: T.J. Mercier <tjmercier@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/filesystems/proc.rst | 10 ++++++++++
fs/libfs.c | 9 +++++++++
fs/proc/fd.c | 13 +++++++++++--
include/linux/fs.h | 1 +
4 files changed, 31 insertions(+), 2 deletions(-)
--- a/Documentation/filesystems/proc.rst~procfs-add-path-to-proc-pid-fdinfo
+++ a/Documentation/filesystems/proc.rst
@@ -1912,6 +1912,9 @@ All locks associated with a file descrip
lock: 1: FLOCK ADVISORY WRITE 359 00:13:11691 0 EOF
+Files with anonymous inodes have an additional 'path' field which represents
+the anonymous file path.
+
The files such as eventfd, fsnotify, signalfd, epoll among the regular pos/flags
pair provide additional information particular to the objects they represent.
@@ -1925,6 +1928,7 @@ Eventfd files
mnt_id: 9
ino: 63107
size: 0
+ path: anon_inode:[eventfd]
eventfd-count: 5a
where 'eventfd-count' is hex value of a counter.
@@ -1939,6 +1943,7 @@ Signalfd files
mnt_id: 9
ino: 63107
size: 0
+ path: anon_inode:[signalfd]
sigmask: 0000000000000200
where 'sigmask' is hex value of the signal mask associated
@@ -1954,6 +1959,7 @@ Epoll files
mnt_id: 9
ino: 63107
size: 0
+ path: anon_inode:[eventpoll]
tfd: 5 events: 1d data: ffffffffffffffff pos:0 ino:61af sdev:7
where 'tfd' is a target file descriptor number in decimal form,
@@ -1973,6 +1979,7 @@ For inotify files the format is the foll
mnt_id: 9
ino: 63107
size: 0
+ path: anon_inode:inotify
inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:7e9e0000640d1b6d
where 'wd' is a watch descriptor in decimal form, i.e. a target file
@@ -1997,6 +2004,7 @@ For fanotify files the format is::
mnt_id: 9
ino: 63107
size: 0
+ path: anon_inode:[fanotify]
fanotify flags:10 event-flags:0
fanotify mnt_id:12 mflags:40 mask:38 ignored_mask:40000003
fanotify ino:4f969 sdev:800013 mflags:0 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type:1 f_handle:69f90400c275b5b4
@@ -2023,6 +2031,7 @@ Timerfd files
mnt_id: 9
ino: 63107
size: 0
+ path: anon_inode:[timerfd]
clockid: 0
ticks: 0
settime flags: 01
@@ -2047,6 +2056,7 @@ DMA Buffer files
mnt_id: 9
ino: 63107
size: 32768
+ path: /dmabuf:
count: 2
exp_name: system-heap
--- a/fs/libfs.c~procfs-add-path-to-proc-pid-fdinfo
+++ a/fs/libfs.c
@@ -1217,6 +1217,15 @@ void kfree_link(void *p)
}
EXPORT_SYMBOL(kfree_link);
+static const struct address_space_operations anon_aops = {
+ .dirty_folio = noop_dirty_folio,
+};
+
+bool is_anon_inode(struct inode *inode)
+{
+ return inode->i_mapping->a_ops == &anon_aops;
+}
+
struct inode *alloc_anon_inode(struct super_block *s)
{
static const struct address_space_operations anon_aops = {
--- a/fs/proc/fd.c~procfs-add-path-to-proc-pid-fdinfo
+++ a/fs/proc/fd.c
@@ -23,6 +23,7 @@ static int seq_show(struct seq_file *m,
struct files_struct *files = NULL;
int f_flags = 0, ret = -ENOENT;
struct file *file = NULL;
+ struct inode *inode = NULL;
struct task_struct *task;
task = get_proc_task(m->private);
@@ -54,11 +55,19 @@ static int seq_show(struct seq_file *m,
if (ret)
return ret;
+ inode = file_inode(file);
+
seq_printf(m, "pos:\t%lli\n", (long long)file->f_pos);
seq_printf(m, "flags:\t0%o\n", f_flags);
seq_printf(m, "mnt_id:\t%i\n", real_mount(file->f_path.mnt)->mnt_id);
- seq_printf(m, "ino:\t%lu\n", file_inode(file)->i_ino);
- seq_printf(m, "size:\t%lli\n", (long long)file_inode(file)->i_size);
+ seq_printf(m, "ino:\t%lu\n", inode->i_ino);
+ seq_printf(m, "size:\t%lli\n", (long long)inode->i_size);
+
+ if (is_anon_inode(inode)) {
+ seq_puts(m, "path:\t");
+ seq_file_path(m, file, "\n");
+ seq_putc(m, '\n');
+ }
/* show_fd_locks() never deferences files so a stale value is safe */
show_fd_locks(m, file, files);
--- a/include/linux/fs.h~procfs-add-path-to-proc-pid-fdinfo
+++ a/include/linux/fs.h
@@ -3115,6 +3115,7 @@ extern void page_put_link(void *);
extern int page_symlink(struct inode *inode, const char *symname, int len);
extern const struct inode_operations page_symlink_inode_operations;
extern void kfree_link(void *);
+extern bool is_anon_inode(struct inode *inode);
void generic_fillattr(struct user_namespace *, struct inode *, struct kstat *);
void generic_fill_statx_attr(struct inode *inode, struct kstat *stat);
extern int vfs_getattr_nosec(const struct path *, struct kstat *, u32, unsigned int);
_
Patches currently in -mm which might be from kaleshsingh@xxxxxxxxxx are
procfs-add-size-to-proc-pid-fdinfo.patch
procfs-add-path-to-proc-pid-fdinfo.patch
