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authorEric W. Biederman <ebiederm@xmission.com>2011-11-14 16:24:06 -0800
committerEric W. Biederman <ebiederm@xmission.com>2012-04-07 17:02:46 -0700
commit1a48e2ac034d47ed843081c4523b63c46b46888b (patch)
treed3a32ac7ffc47b075a64701a2fd74e00bbccf84d /fs/namei.c
parent973c5914260d75292f71a4729753086b9e863d57 (diff)
downloadlwn-1a48e2ac034d47ed843081c4523b63c46b46888b.tar.gz
lwn-1a48e2ac034d47ed843081c4523b63c46b46888b.zip
userns: Replace the hard to write inode_userns with inode_capable.
This represents a change in strategy of how to handle user namespaces. Instead of tagging everything explicitly with a user namespace and bulking up all of the comparisons of uids and gids in the kernel, all uids and gids in use will have a mapping to a flat kuid and kgid spaces respectively. This allows much more of the existing logic to be preserved and in general allows for faster code. In this new and improved world we allow someone to utiliize capabilities over an inode if the inodes owner mapps into the capabilities holders user namespace and the user has capabilities in their user namespace. Which is simple and efficient. Moving the fs uid comparisons to be comparisons in a flat kuid space follows in later patches, something that is only significant if you are using user namespaces. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'fs/namei.c')
-rw-r--r--fs/namei.c18
1 files changed, 5 insertions, 13 deletions
diff --git a/fs/namei.c b/fs/namei.c
index 701954d68ac7..941c4362e298 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -228,9 +228,6 @@ static int acl_permission_check(struct inode *inode, int mask)
{
unsigned int mode = inode->i_mode;
- if (current_user_ns() != inode_userns(inode))
- goto other_perms;
-
if (likely(current_fsuid() == inode->i_uid))
mode >>= 6;
else {
@@ -244,7 +241,6 @@ static int acl_permission_check(struct inode *inode, int mask)
mode >>= 3;
}
-other_perms:
/*
* If the DACs are ok we don't need any capability check.
*/
@@ -280,10 +276,10 @@ int generic_permission(struct inode *inode, int mask)
if (S_ISDIR(inode->i_mode)) {
/* DACs are overridable for directories */
- if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
+ if (inode_capable(inode, CAP_DAC_OVERRIDE))
return 0;
if (!(mask & MAY_WRITE))
- if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
+ if (inode_capable(inode, CAP_DAC_READ_SEARCH))
return 0;
return -EACCES;
}
@@ -293,7 +289,7 @@ int generic_permission(struct inode *inode, int mask)
* at least one exec bit set.
*/
if (!(mask & MAY_EXEC) || (inode->i_mode & S_IXUGO))
- if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))
+ if (inode_capable(inode, CAP_DAC_OVERRIDE))
return 0;
/*
@@ -301,7 +297,7 @@ int generic_permission(struct inode *inode, int mask)
*/
mask &= MAY_READ | MAY_WRITE | MAY_EXEC;
if (mask == MAY_READ)
- if (ns_capable(inode_userns(inode), CAP_DAC_READ_SEARCH))
+ if (inode_capable(inode, CAP_DAC_READ_SEARCH))
return 0;
return -EACCES;
@@ -1964,15 +1960,11 @@ static inline int check_sticky(struct inode *dir, struct inode *inode)
if (!(dir->i_mode & S_ISVTX))
return 0;
- if (current_user_ns() != inode_userns(inode))
- goto other_userns;
if (inode->i_uid == fsuid)
return 0;
if (dir->i_uid == fsuid)
return 0;
-
-other_userns:
- return !ns_capable(inode_userns(inode), CAP_FOWNER);
+ return !inode_capable(inode, CAP_FOWNER);
}
/*