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switch mount_capable() to fs_context

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now both callers of mount_capable() have access to fs_context;
the only difference is that for sget_fc() we have the possibility
of fc->global being true, while for legacy_get_tree() it's guaranteed
to be impossible.  Unify to more generic variant...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2019-05-12 17:31:45 -04:00
parent fd912087f4
commit 20284ab742
3 changed files with 9 additions and 6 deletions
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2
fs/fs_context.c
View File

@ -663,7 +663,7 @@ static int legacy_get_tree(struct fs_context *fc)
struct dentry *root;
if (!(fc->sb_flags & (SB_KERNMOUNT|SB_SUBMOUNT))) {
if (!mount_capable(fc->fs_type, fc->user_ns))
if (!mount_capable(fc))
return -EPERM;
}

2
fs/internal.h
View File

@ -114,7 +114,7 @@ extern struct file *alloc_empty_file_noaccount(int, const struct cred *);
extern int reconfigure_super(struct fs_context *);
extern bool trylock_super(struct super_block *sb);
extern struct super_block *user_get_super(dev_t);
extern bool mount_capable(struct file_system_type *, struct user_namespace *);
extern bool mount_capable(struct fs_context *);
/*
* open.c

11
fs/super.c
View File

@ -476,12 +476,15 @@ void generic_shutdown_super(struct super_block *sb)
EXPORT_SYMBOL(generic_shutdown_super);
bool mount_capable(struct file_system_type *type, struct user_namespace *userns)
bool mount_capable(struct fs_context *fc)
{
if (!(type->fs_flags & FS_USERNS_MOUNT))
struct user_namespace *user_ns = fc->global ? &init_user_ns
: fc->user_ns;
if (!(fc->fs_type->fs_flags & FS_USERNS_MOUNT))
return capable(CAP_SYS_ADMIN);
else
return ns_capable(userns, CAP_SYS_ADMIN);
return ns_capable(user_ns, CAP_SYS_ADMIN);
}
/**
@ -513,7 +516,7 @@ struct super_block *sget_fc(struct fs_context *fc,
if (!(fc->sb_flags & SB_KERNMOUNT) &&
fc->purpose != FS_CONTEXT_FOR_SUBMOUNT) {
if (!mount_capable(fc->fs_type, user_ns))
if (!mount_capable(fc))
return ERR_PTR(-EPERM);
}