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authorChristian Brauner <christian.brauner@ubuntu.com>2021-01-21 16:19:23 +0300
committerChristian Brauner <christian.brauner@ubuntu.com>2021-01-24 16:27:16 +0300
commit0558c1bf5a0811bf5e3753eed911a15b9bd08271 (patch)
treebbaad2c11479beaac5328c5c3eb33241f9b3cc45 /security
parent02f92b3868a1b34ab98464e76b0e4e060474ba10 (diff)
downloadlinux-0558c1bf5a0811bf5e3753eed911a15b9bd08271.tar.xz
capability: handle idmapped mounts
In order to determine whether a caller holds privilege over a given inode the capability framework exposes the two helpers privileged_wrt_inode_uidgid() and capable_wrt_inode_uidgid(). The former verifies that the inode has a mapping in the caller's user namespace and the latter additionally verifies that the caller has the requested capability in their current user namespace. If the inode is accessed through an idmapped mount map it into the mount's user namespace. Afterwards the checks are identical to non-idmapped inodes. If the initial user namespace is passed all operations are a nop so non-idmapped mounts will not see a change in behavior. Link: https://lore.kernel.org/r/20210121131959.646623-5-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> Acked-by: Serge Hallyn <serge@hallyn.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Diffstat (limited to 'security')
-rw-r--r--security/commoncap.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/security/commoncap.c b/security/commoncap.c
index bacc1111d871..88ee345f7bfa 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -489,7 +489,7 @@ int cap_convert_nscap(struct dentry *dentry, const void **ivalue, size_t size)
return -EINVAL;
if (!validheader(size, cap))
return -EINVAL;
- if (!capable_wrt_inode_uidgid(inode, CAP_SETFCAP))
+ if (!capable_wrt_inode_uidgid(&init_user_ns, inode, CAP_SETFCAP))
return -EPERM;
if (size == XATTR_CAPS_SZ_2)
if (ns_capable(inode->i_sb->s_user_ns, CAP_SETFCAP))
@@ -956,7 +956,8 @@ int cap_inode_removexattr(struct dentry *dentry, const char *name)
struct inode *inode = d_backing_inode(dentry);
if (!inode)
return -EINVAL;
- if (!capable_wrt_inode_uidgid(inode, CAP_SETFCAP))
+ if (!capable_wrt_inode_uidgid(&init_user_ns, inode,
+ CAP_SETFCAP))
return -EPERM;
return 0;
}