linux.git/fs/proc/inode.c, branch v5.14

proc: delete redundant subset=pid check

2021-05-07T02:24:11+00:00

Two checks in lookup and readdir code should be enough to not have third
check in open code.

Can't open what can't be looked up?

Link: https://lkml.kernel.org/r/YFYYwIBIkytqnkxP@localhost.localdomain
Signed-off-by: Alexey Dobriyan 
Acked-by: Alexey Gladkov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: mandate ->proc_lseek in "struct proc_ops"

2021-05-07T02:24:11+00:00

Now that proc_ops are separate from file_operations and other operations
it easy to check all instances to have ->proc_lseek hook and remove check
in main code.

Note:
nonseekable_open() files naturally don't require ->proc_lseek.

Garbage collect pde_lseek() function.

[adobriyan@gmail.com: smoke test lseek()]
  Link: https://lkml.kernel.org/r/YG4OIhChOrVTPgdN@localhost.localdomain

Link: https://lkml.kernel.org/r/YFYX0Bzwxlc7aBa/@localhost.localdomain
Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: wire up generic_file_splice_read for iter ops

2020-11-06T18:05:18+00:00

Wire up generic_file_splice_read for the iter based proxy ops, so
that splice reads from them work.

Signed-off-by: Christoph Hellwig 
Tested-by: Greg Kroah-Hartman 
Signed-off-by: Linus Torvalds

proc: add a read_iter method to proc proc_ops

2020-09-04T01:26:24+00:00

This will allow proc files to implement iter read semantics.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Al Viro

proc: cleanup the compat vs no compat file ops

2020-09-04T01:26:24+00:00

Instead of providing a special no-compat version provide a special
compat version for operations with ->compat_ioctl.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Al Viro

proc: remove a level of indentation in proc_get_inode

2020-09-04T01:26:24+00:00

Just return early on inode allocation failure.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Al Viro

proc: Use new_inode not new_inode_pseudo

2020-06-12T19:13:33+00:00

Recently syzbot reported that unmounting proc when there is an ongoing
inotify watch on the root directory of proc could result in a use
after free when the watch is removed after the unmount of proc
when the watcher exits.

Commit 69879c01a0c3 ("proc: Remove the now unnecessary internal mount
of proc") made it easier to unmount proc and allowed syzbot to see the
problem, but looking at the code it has been around for a long time.

Looking at the code the fsnotify watch should have been removed by
fsnotify_sb_delete in generic_shutdown_super.  Unfortunately the inode
was allocated with new_inode_pseudo instead of new_inode so the inode
was not on the sb->s_inodes list.  Which prevented
fsnotify_unmount_inodes from finding the inode and removing the watch
as well as made it so the "VFS: Busy inodes after unmount" warning
could not find the inodes to warn about them.

Make all of the inodes in proc visible to generic_shutdown_super,
and fsnotify_sb_delete by using new_inode instead of new_inode_pseudo.
The only functional difference is that new_inode places the inodes
on the sb->s_inodes list.

I wrote a small test program and I can verify that without changes it
can trigger this issue, and by replacing new_inode_pseudo with
new_inode the issues goes away.

Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/000000000000d788c905a7dfa3f4@google.com
Reported-by: syzbot+7d2debdcdb3cb93c1e5e@syzkaller.appspotmail.com
Fixes: 0097875bd415 ("proc: Implement /proc/thread-self to point at the directory of the current thread")
Fixes: 021ada7dff22 ("procfs: switch /proc/self away from proc_dir_entry")
Fixes: 51f0885e5415 ("vfs,proc: guarantee unique inodes in /proc")
Signed-off-by: "Eric W. Biederman"

proc: use named enums for better readability

2020-04-22T15:51:22+00:00

Signed-off-by: Alexey Gladkov 
Reviewed-by: Alexey Dobriyan 
Reviewed-by: Kees Cook 
Signed-off-by: Eric W. Biederman

proc: use human-readable values for hidepid

2020-04-22T15:51:22+00:00

The hidepid parameter values are becoming more and more and it becomes
difficult to remember what each new magic number means.

Backward compatibility is preserved since it is possible to specify
numerical value for the hidepid parameter. This does not break the
fsconfig since it is not possible to specify a numerical value through
it. All numeric values are converted to a string. The type
FSCONFIG_SET_BINARY cannot be used to indicate a numerical value.

Selftest has been added to verify this behavior.

Suggested-by: Andy Lutomirski 
Signed-off-by: Alexey Gladkov 
Reviewed-by: Alexey Dobriyan 
Reviewed-by: Kees Cook 
Signed-off-by: Eric W. Biederman

proc: add option to mount only a pids subset

2020-04-22T15:51:22+00:00

This allows to hide all files and directories in the procfs that are not
related to tasks.

Signed-off-by: Alexey Gladkov 
Reviewed-by: Alexey Dobriyan 
Reviewed-by: Kees Cook 
Signed-off-by: Eric W. Biederman