Unverified Commit 9f111059 authored by Eric Sandeen's avatar Eric Sandeen Committed by Christian Brauner
Browse files

fs_parse: add uid & gid option option parsing helpers 

Multiple filesystems take uid and gid as options, and the code to
create the ID from an integer and validate it is standard boilerplate
that can be moved into common helper functions, so do that for
consistency and less cut&paste.

This also helps avoid the buggy pattern noted by Seth Jenkins at
https://lore.kernel.org/lkml/CALxfFW4BXhEwxR0Q5LSkg-8Vb4r2MONKCcUCVioehXQKr35eHg@mail.gmail.com/


because uid/gid parsing will fail before any assignment in most
filesystems.

Signed-off-by: default avatarEric Sandeen <sandeen@sandeen.net>
Link: https://lore.kernel.org/r/de859d0a-feb9-473d-a5e2-c195a3d47abb@redhat.com


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 104eef13

Documentation/filesystems/mount_api.rst

+7 −2
Original line number Diff line number Diff line
@@ -645,6 +645,8 @@ The members are as follows: 
	fs_param_is_blockdev	Blockdev path		* Needs lookup

	fs_param_is_path	Path			* Needs lookup

	fs_param_is_fd		File descriptor		result->int_32

	fs_param_is_uid		User ID (u32)           result->uid

	fs_param_is_gid		Group ID (u32)          result->gid

	=======================	=======================	=====================



     Note that if the value is of fs_param_is_bool type, fs_parse() will try
@@ -678,6 +680,8 @@ The members are as follows: 
	fsparam_bdev()		fs_param_is_blockdev

	fsparam_path()		fs_param_is_path

	fsparam_fd()		fs_param_is_fd

	fsparam_uid()		fs_param_is_uid

	fsparam_gid()		fs_param_is_gid

	=======================	===============================================



     all of which take two arguments, name string and option number - for
@@ -784,8 +788,9 @@ process the parameters it is given. 
     option number (which it returns).



     If successful, and if the parameter type indicates the result is a

     boolean, integer or enum type, the value is converted by this function and

     the result stored in result->{boolean,int_32,uint_32,uint_64}.

     boolean, integer, enum, uid, or gid type, the value is converted by this

     function and the result stored in

     result->{boolean,int_32,uint_32,uint_64,uid,gid}.



     If a match isn't initially made, the key is prefixed with "no" and no

     value is present then an attempt will be made to look up the key with the

fs/fs_parser.c

+34 −0
Original line number Diff line number Diff line
@@ -308,6 +308,40 @@ int fs_param_is_fd(struct p_log *log, const struct fs_parameter_spec *p, 
}

EXPORT_SYMBOL(fs_param_is_fd);



int fs_param_is_uid(struct p_log *log, const struct fs_parameter_spec *p,

		    struct fs_parameter *param, struct fs_parse_result *result)

{

	kuid_t uid;



	if (fs_param_is_u32(log, p, param, result) != 0)

		return fs_param_bad_value(log, param);



	uid = make_kuid(current_user_ns(), result->uint_32);

	if (!uid_valid(uid))

		return inval_plog(log, "Invalid uid '%s'", param->string);



	result->uid = uid;

	return 0;

}

EXPORT_SYMBOL(fs_param_is_uid);



int fs_param_is_gid(struct p_log *log, const struct fs_parameter_spec *p,

		    struct fs_parameter *param, struct fs_parse_result *result)

{

	kgid_t gid;



	if (fs_param_is_u32(log, p, param, result) != 0)

		return fs_param_bad_value(log, param);



	gid = make_kgid(current_user_ns(), result->uint_32);

	if (!gid_valid(gid))

		return inval_plog(log, "Invalid gid '%s'", param->string);



	result->gid = gid;

	return 0;

}

EXPORT_SYMBOL(fs_param_is_gid);



int fs_param_is_blockdev(struct p_log *log, const struct fs_parameter_spec *p,

		  struct fs_parameter *param, struct fs_parse_result *result)

{

include/linux/fs_parser.h

+5 −1
Original line number Diff line number Diff line
@@ -28,7 +28,7 @@ typedef int fs_param_type(struct p_log *, 
 */

fs_param_type fs_param_is_bool, fs_param_is_u32, fs_param_is_s32, fs_param_is_u64,

	fs_param_is_enum, fs_param_is_string, fs_param_is_blob, fs_param_is_blockdev,

	fs_param_is_path, fs_param_is_fd;

	fs_param_is_path, fs_param_is_fd, fs_param_is_uid, fs_param_is_gid;



/*

 * Specification of the type of value a parameter wants.
@@ -57,6 +57,8 @@ struct fs_parse_result { 
		int		int_32;		/* For spec_s32/spec_enum */

		unsigned int	uint_32;	/* For spec_u32{,_octal,_hex}/spec_enum */

		u64		uint_64;	/* For spec_u64 */

		kuid_t		uid;

		kgid_t		gid;

	};

};
@@ -131,6 +133,8 @@ static inline bool fs_validate_description(const char *name, 
#define fsparam_bdev(NAME, OPT)	__fsparam(fs_param_is_blockdev, NAME, OPT, 0, NULL)

#define fsparam_path(NAME, OPT)	__fsparam(fs_param_is_path, NAME, OPT, 0, NULL)

#define fsparam_fd(NAME, OPT)	__fsparam(fs_param_is_fd, NAME, OPT, 0, NULL)

#define fsparam_uid(NAME, OPT) __fsparam(fs_param_is_uid, NAME, OPT, 0, NULL)

#define fsparam_gid(NAME, OPT) __fsparam(fs_param_is_gid, NAME, OPT, 0, NULL)



/* String parameter that allows empty argument */

#define fsparam_string_empty(NAME, OPT) \