From 02f92b3868a1b34ab98464e76b0e4e060474ba10 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Thu, 21 Jan 2021 14:19:22 +0100 Subject: fs: add file and path permissions helpers Add two simple helpers to check permissions on a file and path respectively and convert over some callers. It simplifies quite a few codepaths and also reduces the churn in later patches quite a bit. Christoph also correctly points out that this makes codepaths (e.g. ioctls) way easier to follow that would otherwise have to do more complex argument passing than necessary. Link: https://lore.kernel.org/r/20210121131959.646623-4-christian.brauner@ubuntu.com Cc: David Howells Cc: Al Viro Cc: linux-fsdevel@vger.kernel.org Suggested-by: Christoph Hellwig Reviewed-by: Christoph Hellwig Reviewed-by: James Morris Signed-off-by: Christian Brauner --- fs/udf/file.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/udf') diff --git a/fs/udf/file.c b/fs/udf/file.c index ad8eefad27d7..3671a40ed3c3 100644 --- a/fs/udf/file.c +++ b/fs/udf/file.c @@ -183,7 +183,7 @@ long udf_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) long old_block, new_block; int result; - if (inode_permission(inode, MAY_READ) != 0) { + if (file_permission(filp, MAY_READ) != 0) { udf_debug("no permission to access inode %lu\n", inode->i_ino); return -EPERM; } -- cgit v1.2.3 From 21cb47be6fb9ece7e6ee63f6780986faa384a77c Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Thu, 21 Jan 2021 14:19:25 +0100 Subject: 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 Cc: David Howells Cc: Al Viro Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig Reviewed-by: James Morris Signed-off-by: Christian Brauner --- fs/udf/ialloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/udf') diff --git a/fs/udf/ialloc.c b/fs/udf/ialloc.c index 84ed23edebfd..2ecf0e87660e 100644 --- a/fs/udf/ialloc.c +++ b/fs/udf/ialloc.c @@ -103,7 +103,7 @@ struct inode *udf_new_inode(struct inode *dir, umode_t mode) mutex_unlock(&sbi->s_alloc_mutex); } - inode_init_owner(inode, dir, mode); + inode_init_owner(&init_user_ns, inode, dir, mode); if (UDF_QUERY_FLAG(sb, UDF_FLAG_UID_SET)) inode->i_uid = sbi->s_uid; if (UDF_QUERY_FLAG(sb, UDF_FLAG_GID_SET)) -- cgit v1.2.3 From 2f221d6f7b881d95de1f356a3097d755ab1e47d4 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Thu, 21 Jan 2021 14:19:26 +0100 Subject: attr: handle idmapped mounts When file attributes are changed most filesystems rely on the setattr_prepare(), setattr_copy(), and notify_change() helpers for initialization and permission checking. Let them handle idmapped mounts. 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 mounts. If the initial user namespace is passed nothing changes so non-idmapped mounts will see identical behavior as before. Helpers that perform checks on the ia_uid and ia_gid fields in struct iattr assume that ia_uid and ia_gid are intended values and have already been mapped correctly at the userspace-kernelspace boundary as we already do today. 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/20210121131959.646623-8-christian.brauner@ubuntu.com Cc: Christoph Hellwig Cc: David Howells Cc: Al Viro Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig Signed-off-by: Christian Brauner --- fs/udf/file.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'fs/udf') diff --git a/fs/udf/file.c b/fs/udf/file.c index 3671a40ed3c3..7c7d161315c2 100644 --- a/fs/udf/file.c +++ b/fs/udf/file.c @@ -259,7 +259,7 @@ static int udf_setattr(struct dentry *dentry, struct iattr *attr) struct super_block *sb = inode->i_sb; int error; - error = setattr_prepare(dentry, attr); + error = setattr_prepare(&init_user_ns, dentry, attr); if (error) return error; @@ -282,7 +282,7 @@ static int udf_setattr(struct dentry *dentry, struct iattr *attr) if (attr->ia_valid & ATTR_MODE) udf_update_extra_perms(inode, attr->ia_mode); - setattr_copy(inode, attr); + setattr_copy(&init_user_ns, inode, attr); mark_inode_dirty(inode); return 0; } -- cgit v1.2.3 From 0d56a4518d5eaf595a24ab2202e171330bb2ed72 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Thu, 21 Jan 2021 14:19:30 +0100 Subject: stat: handle idmapped mounts The generic_fillattr() helper fills in the basic attributes associated with an inode. Enable it to handle idmapped mounts. If the inode is accessed through an idmapped mount map it into the mount's user namespace before we store the uid and gid. 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/20210121131959.646623-12-christian.brauner@ubuntu.com Cc: Christoph Hellwig Cc: David Howells Cc: Al Viro Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig Reviewed-by: James Morris Signed-off-by: Christian Brauner --- fs/udf/symlink.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/udf') diff --git a/fs/udf/symlink.c b/fs/udf/symlink.c index c973db239604..54a44d1f023c 100644 --- a/fs/udf/symlink.c +++ b/fs/udf/symlink.c @@ -159,7 +159,7 @@ static int udf_symlink_getattr(const struct path *path, struct kstat *stat, struct inode *inode = d_backing_inode(dentry); struct page *page; - generic_fillattr(inode, stat); + generic_fillattr(&init_user_ns, inode, stat); page = read_mapping_page(inode->i_mapping, 0, NULL); if (IS_ERR(page)) return PTR_ERR(page); -- cgit v1.2.3 From 549c7297717c32ee53f156cd949e055e601f67bb Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Thu, 21 Jan 2021 14:19:43 +0100 Subject: fs: make helpers idmap mount aware Extend some inode methods with an additional user namespace argument. A filesystem that is aware of idmapped mounts will receive the user namespace the mount has been marked with. This can be used for additional permission checking and also to enable filesystems to translate between uids and gids if they need to. We have implemented all relevant helpers in earlier patches. As requested we simply extend the exisiting inode method instead of introducing new ones. This is a little more code churn but it's mostly mechanical and doesnt't leave us with additional inode methods. Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com Cc: Christoph Hellwig Cc: David Howells Cc: Al Viro Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig Signed-off-by: Christian Brauner --- fs/udf/file.c | 3 ++- fs/udf/namei.c | 24 +++++++++++++----------- fs/udf/symlink.c | 5 +++-- 3 files changed, 18 insertions(+), 14 deletions(-) (limited to 'fs/udf') diff --git a/fs/udf/file.c b/fs/udf/file.c index 7c7d161315c2..2846dcd92197 100644 --- a/fs/udf/file.c +++ b/fs/udf/file.c @@ -253,7 +253,8 @@ const struct file_operations udf_file_operations = { .llseek = generic_file_llseek, }; -static int udf_setattr(struct dentry *dentry, struct iattr *attr) +static int udf_setattr(struct user_namespace *mnt_userns, struct dentry *dentry, + struct iattr *attr) { struct inode *inode = d_inode(dentry); struct super_block *sb = inode->i_sb; diff --git a/fs/udf/namei.c b/fs/udf/namei.c index e169d8fe35b5..f146b3089f3d 100644 --- a/fs/udf/namei.c +++ b/fs/udf/namei.c @@ -604,8 +604,8 @@ static int udf_add_nondir(struct dentry *dentry, struct inode *inode) return 0; } -static int udf_create(struct inode *dir, struct dentry *dentry, umode_t mode, - bool excl) +static int udf_create(struct user_namespace *mnt_userns, struct inode *dir, + struct dentry *dentry, umode_t mode, bool excl) { struct inode *inode = udf_new_inode(dir, mode); @@ -623,7 +623,8 @@ static int udf_create(struct inode *dir, struct dentry *dentry, umode_t mode, return udf_add_nondir(dentry, inode); } -static int udf_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) +static int udf_tmpfile(struct user_namespace *mnt_userns, struct inode *dir, + struct dentry *dentry, umode_t mode) { struct inode *inode = udf_new_inode(dir, mode); @@ -642,8 +643,8 @@ static int udf_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode) return 0; } -static int udf_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, - dev_t rdev) +static int udf_mknod(struct user_namespace *mnt_userns, struct inode *dir, + struct dentry *dentry, umode_t mode, dev_t rdev) { struct inode *inode; @@ -658,7 +659,8 @@ static int udf_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, return udf_add_nondir(dentry, inode); } -static int udf_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) +static int udf_mkdir(struct user_namespace *mnt_userns, struct inode *dir, + struct dentry *dentry, umode_t mode) { struct inode *inode; struct udf_fileident_bh fibh; @@ -877,8 +879,8 @@ out: return retval; } -static int udf_symlink(struct inode *dir, struct dentry *dentry, - const char *symname) +static int udf_symlink(struct user_namespace *mnt_userns, struct inode *dir, + struct dentry *dentry, const char *symname) { struct inode *inode = udf_new_inode(dir, S_IFLNK | 0777); struct pathComponent *pc; @@ -1065,9 +1067,9 @@ static int udf_link(struct dentry *old_dentry, struct inode *dir, /* Anybody can rename anything with this: the permission checks are left to the * higher-level routines. */ -static int udf_rename(struct inode *old_dir, struct dentry *old_dentry, - struct inode *new_dir, struct dentry *new_dentry, - unsigned int flags) +static int udf_rename(struct user_namespace *mnt_userns, struct inode *old_dir, + struct dentry *old_dentry, struct inode *new_dir, + struct dentry *new_dentry, unsigned int flags) { struct inode *old_inode = d_inode(old_dentry); struct inode *new_inode = d_inode(new_dentry); diff --git a/fs/udf/symlink.c b/fs/udf/symlink.c index 54a44d1f023c..9b223421a3c5 100644 --- a/fs/udf/symlink.c +++ b/fs/udf/symlink.c @@ -152,8 +152,9 @@ out_unmap: return err; } -static int udf_symlink_getattr(const struct path *path, struct kstat *stat, - u32 request_mask, unsigned int flags) +static int udf_symlink_getattr(struct user_namespace *mnt_userns, + const struct path *path, struct kstat *stat, + u32 request_mask, unsigned int flags) { struct dentry *dentry = path->dentry; struct inode *inode = d_backing_inode(dentry); -- cgit v1.2.3