From: Marc Dionne <[email protected]>
[ Upstream commit 29be9100aca2915fab54b5693309bc42956542e5 ]
Don't cross a mountpoint that explicitly specifies a backup volume
(target is <vol>.backup) when starting from a backup volume.
It it not uncommon to mount a volume's backup directly in the volume
itself. This can cause tools that are not paying attention to get
into a loop mounting the volume onto itself as they attempt to
traverse the tree, leading to a variety of problems.
This doesn't prevent the general case of loops in a sequence of
mountpoints, but addresses a common special case in the same way
as other afs clients.
Reported-by: Jan Henrik Sylvester <[email protected]>
Link: http://lists.infradead.org/pipermail/linux-afs/2024-May/008454.html
Reported-by: Markus Suvanto <[email protected]>
Link: http://lists.infradead.org/pipermail/linux-afs/2024-February/008074.html
Signed-off-by: Marc Dionne <[email protected]>
Signed-off-by: David Howells <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Jeffrey Altman <[email protected]>
cc: [email protected]
Signed-off-by: Christian Brauner <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
---
fs/afs/mntpt.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/fs/afs/mntpt.c b/fs/afs/mntpt.c
index bbb2c210d139d..fa8a6543142d5 100644
--- a/fs/afs/mntpt.c
+++ b/fs/afs/mntpt.c
@@ -146,6 +146,11 @@ static int afs_mntpt_set_params(struct fs_context *fc, struct dentry *mntpt)
put_page(page);
if (ret < 0)
return ret;
+
+ /* Don't cross a backup volume mountpoint from a backup volume */
+ if (src_as->volume && src_as->volume->type == AFSVL_BACKVOL &&
+ ctx->type == AFSVL_BACKVOL)
+ return -ENODEV;
}
return 0;
--
2.43.0