Commit b961144f authored by Amir Goldstein's avatar Amir Goldstein Committed by sanglipeng
Browse files

attr: add in_group_or_capable() 

stable inclusion
from stable-v5.10.176
commit 24378d6f748649060f4d0c3eea8a1efe5bccfd1d
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I87BGI

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=24378d6f748649060f4d0c3eea8a1efe5bccfd1d



--------------------------------

commit 11c2a870 upstream.

[backported to 5.10.y, prior to idmapped mounts]

In setattr_{copy,prepare}() we need to perform the same permission
checks to determine whether we need to drop the setgid bit or not.
Instead of open-coding it twice add a simple helper the encapsulates the
logic. We will reuse this helpers to make dropping the setgid bit during
write operations more consistent in a follow up patch.

Reviewed-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarChristian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarsanglipeng <sanglipeng1@jd.com>
parent ba337738

fs/attr.c

+5 −6
Original line number Diff line number Diff line
@@ -18,6 +18,8 @@ 
#include <linux/evm.h>

#include <linux/ima.h>



#include "internal.h"



static bool chown_ok(const struct inode *inode, kuid_t uid)

{

	if (uid_eq(current_fsuid(), inode->i_uid) &&
@@ -90,9 +92,8 @@ int setattr_prepare(struct dentry *dentry, struct iattr *attr) 
		if (!inode_owner_or_capable(inode))

			return -EPERM;

		/* Also check the setgid bit! */

		if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :

				inode->i_gid) &&

		    !capable_wrt_inode_uidgid(inode, CAP_FSETID))

		if (!in_group_or_capable(inode, (ia_valid & ATTR_GID) ?

						attr->ia_gid : inode->i_gid))

			attr->ia_mode &= ~S_ISGID;

	}
@@ -193,9 +194,7 @@ void setattr_copy(struct inode *inode, const struct iattr *attr) 
		inode->i_ctime = attr->ia_ctime;

	if (ia_valid & ATTR_MODE) {

		umode_t mode = attr->ia_mode;



		if (!in_group_p(inode->i_gid) &&

		    !capable_wrt_inode_uidgid(inode, CAP_FSETID))

		if (!in_group_or_capable(inode, inode->i_gid))

			mode &= ~S_ISGID;

		inode->i_mode = mode;

	}

fs/inode.c

+21 −4
Original line number Diff line number Diff line
@@ -2386,6 +2386,26 @@ int vfs_ioc_fssetxattr_check(struct inode *inode, const struct fsxattr *old_fa, 
}

EXPORT_SYMBOL(vfs_ioc_fssetxattr_check);



/**

 * in_group_or_capable - check whether caller is CAP_FSETID privileged

 * @inode:	inode to check

 * @gid:	the new/current gid of @inode

 *

 * Check wether @gid is in the caller's group list or if the caller is

 * privileged with CAP_FSETID over @inode. This can be used to determine

 * whether the setgid bit can be kept or must be dropped.

 *

 * Return: true if the caller is sufficiently privileged, false if not.

 */

bool in_group_or_capable(const struct inode *inode, kgid_t gid)

{

	if (in_group_p(gid))

		return true;

	if (capable_wrt_inode_uidgid(inode, CAP_FSETID))

		return true;

	return false;

}



/**

 * mode_strip_sgid - handle the sgid bit for non-directories

 * @dir: parent directory inode
@@ -2405,11 +2425,8 @@ umode_t mode_strip_sgid(const struct inode *dir, umode_t mode) 
		return mode;

	if (S_ISDIR(mode) || !dir || !(dir->i_mode & S_ISGID))

		return mode;

	if (in_group_p(dir->i_gid))

		return mode;

	if (capable_wrt_inode_uidgid(dir, CAP_FSETID))

	if (in_group_or_capable(dir, dir->i_gid))

		return mode;



	return mode & ~S_ISGID;

}

EXPORT_SYMBOL(mode_strip_sgid);

fs/internal.h

+1 −0
Original line number Diff line number Diff line
@@ -149,6 +149,7 @@ extern int vfs_open(const struct path *, struct file *); 
extern long prune_icache_sb(struct super_block *sb, struct shrink_control *sc);

extern void inode_add_lru(struct inode *inode);

extern int dentry_needs_remove_privs(struct dentry *dentry);

bool in_group_or_capable(const struct inode *inode, kgid_t gid);



/*

 * fs-writeback.c