From 975d6b3932d43b87a48d2107264ed0c9a7541d8d Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Sun, 13 Nov 2011 12:16:43 -0800 Subject: vfs: Don't allow a user namespace root to make device nodes Safely making device nodes in a container is solvable but simply having the capability in a user namespace is not sufficient to make this work. Acked-by: Serge Hallyn Signed-off-by: Eric W. Biederman --- fs/namei.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'fs/namei.c') diff --git a/fs/namei.c b/fs/namei.c index 1898198abc3d..701954d68ac7 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2560,8 +2560,7 @@ int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) if (error) return error; - if ((S_ISCHR(mode) || S_ISBLK(mode)) && - !ns_capable(inode_userns(dir), CAP_MKNOD)) + if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) return -EPERM; if (!dir->i_op->mknod) -- cgit v1.2.3 From 1a48e2ac034d47ed843081c4523b63c46b46888b Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Mon, 14 Nov 2011 16:24:06 -0800 Subject: 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 Signed-off-by: Eric W. Biederman --- fs/namei.c | 18 +++++------------- 1 file changed, 5 insertions(+), 13 deletions(-) (limited to 'fs/namei.c') 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); } /* -- cgit v1.2.3 From 8e96e3b7b8407be794ab1fd8e4b332818a358e78 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Sat, 3 Mar 2012 21:17:15 -0800 Subject: userns: Use uid_eq gid_eq helpers when comparing kuids and kgids in the vfs Acked-by: Serge Hallyn Signed-off-by: Eric W. Biederman --- fs/namei.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'fs/namei.c') diff --git a/fs/namei.c b/fs/namei.c index 941c4362e298..86512b4d38fd 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -228,7 +228,7 @@ static int acl_permission_check(struct inode *inode, int mask) { unsigned int mode = inode->i_mode; - if (likely(current_fsuid() == inode->i_uid)) + if (likely(uid_eq(current_fsuid(), inode->i_uid))) mode >>= 6; else { if (IS_POSIXACL(inode) && (mode & S_IRWXG)) { @@ -1956,13 +1956,13 @@ static int user_path_parent(int dfd, const char __user *path, */ static inline int check_sticky(struct inode *dir, struct inode *inode) { - uid_t fsuid = current_fsuid(); + kuid_t fsuid = current_fsuid(); if (!(dir->i_mode & S_ISVTX)) return 0; - if (inode->i_uid == fsuid) + if (uid_eq(inode->i_uid, fsuid)) return 0; - if (dir->i_uid == fsuid) + if (uid_eq(dir->i_uid, fsuid)) return 0; return !inode_capable(inode, CAP_FOWNER); } -- cgit v1.2.3