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fs: introduce fsuidgid_has_mapping() helper

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Don't open-code the checks and instead move them into a clean little
helper we can call. This also reduces the risk that if we ever change
something we forget to change all locations.

Link: https://lore.kernel.org/r/[email protected]
Inspired-by: Vivek Goyal <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Al Viro <[email protected]>
Cc: [email protected]
Reviewed-by: Christoph Hellwig <[email protected]>
Signed-off-by: Christian Brauner <[email protected]>
This commit is contained in:
Christian Brauner committed 2021-03-23 11:15:24 +01:00
1 parent a65e58e791
commit 8e5389132a
2 files changed
+23 -8
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fs/namei.c
+3 -8
View File
@@ -2823,16 +2823,14 @@ static int may_delete(struct user_namespace *mnt_userns, struct inode *dir,
static inline int may_create(struct user_namespace *mnt_userns,
struct inode *dir, struct dentry *child)
{
struct user_namespace *s_user_ns;
audit_inode_child(dir, child, AUDIT_TYPE_CHILD_CREATE);
if (child->d_inode)
return -EEXIST;
if (IS_DEADDIR(dir))
return -ENOENT;
s_user_ns = dir->i_sb->s_user_ns;
if (!kuid_has_mapping(s_user_ns, mapped_fsuid(mnt_userns)) ||
!kgid_has_mapping(s_user_ns, mapped_fsgid(mnt_userns)))
if (!fsuidgid_has_mapping(dir->i_sb, mnt_userns))
return -EOVERFLOW;
return inode_permission(mnt_userns, dir, MAY_WRITE | MAY_EXEC);
}
@@ -3034,14 +3032,11 @@ static int may_o_create(struct user_namespace *mnt_userns,
const struct path *dir, struct dentry *dentry,
umode_t mode)
{
struct user_namespace *s_user_ns;
int error = security_path_mknod(dir, dentry, mode, 0);
if (error)
return error;
s_user_ns = dir->dentry->d_sb->s_user_ns;
if (!kuid_has_mapping(s_user_ns, mapped_fsuid(mnt_userns)) ||
!kgid_has_mapping(s_user_ns, mapped_fsgid(mnt_userns)))
if (!fsuidgid_has_mapping(dir->dentry->d_sb, mnt_userns))
return -EOVERFLOW;
error = inode_permission(mnt_userns, dir->dentry->d_inode,
include/linux/fs.h
+20
View File
@@ -1692,6 +1692,26 @@ static inline kgid_t mapped_fsgid(struct user_namespace *mnt_userns)
return kgid_from_mnt(mnt_userns, current_fsgid());
}
/**
* fsuidgid_has_mapping() - check whether caller's fsuid/fsgid is mapped
* @sb: the superblock we want a mapping in
* @mnt_userns: user namespace of the relevant mount
*
* Check whether the caller's fsuid and fsgid have a valid mapping in the
* s_user_ns of the superblock @sb. If the caller is on an idmapped mount map
* the caller's fsuid and fsgid according to the @mnt_userns first.
*
* Return: true if fsuid and fsgid is mapped, false if not.
*/
static inline bool fsuidgid_has_mapping(struct super_block *sb,
struct user_namespace *mnt_userns)
{
struct user_namespace *s_user_ns = sb->s_user_ns;
return kuid_has_mapping(s_user_ns, mapped_fsuid(mnt_userns)) &&
kgid_has_mapping(s_user_ns, mapped_fsgid(mnt_userns));
}
extern struct timespec64 current_time(struct inode *inode);
/*