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authorChristian Brauner <christian.brauner@ubuntu.com>2021-01-21 14:19:25 +0100
committerChristian Brauner <christian.brauner@ubuntu.com>2021-01-24 14:27:16 +0100
commit21cb47be6fb9ece7e6ee63f6780986faa384a77c (patch)
tree986aa824a8b3aa45487b26364dbde88dbc853ff4 /mm/madvise.c
parent47291baa8ddfdae10663624ff0a15ab165952708 (diff)
inode: make init and permission helpers idmapped mount aware
The inode_owner_or_capable() helper determines whether the caller is the owner of the inode or is capable with respect to that inode. Allow it to handle idmapped mounts. If the inode is accessed through an idmapped mount it according to the mount's user namespace. Afterwards the checks are identical to non-idmapped mounts. If the initial user namespace is passed nothing changes so non-idmapped mounts will see identical behavior as before. Similarly, allow the inode_init_owner() helper to handle idmapped mounts. It initializes a new inode on idmapped mounts by mapping the fsuid and fsgid of the caller from the mount's user namespace. If the initial user namespace is passed nothing changes so non-idmapped mounts will see identical behavior as before. Link: https://lore.kernel.org/r/20210121131959.646623-7-christian.brauner@ubuntu.com Cc: Christoph Hellwig <hch@lst.de> Cc: David Howells <dhowells@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: James Morris <jamorris@linux.microsoft.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Diffstat (limited to 'mm/madvise.c')
-rw-r--r--mm/madvise.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/madvise.c b/mm/madvise.c
index 175c5582d8a9..d4f5eece9d56 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -539,7 +539,8 @@ static inline bool can_do_pageout(struct vm_area_struct *vma)
* otherwise we'd be including shared non-exclusive mappings, which
* opens a side channel.
*/
- return inode_owner_or_capable(file_inode(vma->vm_file)) ||
+ return inode_owner_or_capable(&init_user_ns,
+ file_inode(vma->vm_file)) ||
file_permission(vma->vm_file, MAY_WRITE) == 0;
}