Commit f497115d authored by NeilBrown's avatar NeilBrown Committed by Greg Kroah-Hartman
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staging: lustre: simplify capability dropping. 



Lustre has a 'squash credentials' concept similar to the "anon_uid"
for nfsd.  When accessing a file with squashed credentials, we
need to also drop capabilities.
Linux has cap_drop_fs_set() and cap_drop_nfsd_set().  Rather than
taking a completely different approach, this patch changes lustre
to use this same cap_drop_*_set() approach.

With this change we also drop CAP_MKNOD and CAP_MAC_OVERRIDE
which are probably appropriate, and don't drop
CAP_SYS_ADMIN or CAP_SYS_BOOT which should be irrelevant for
file permission checking

Calling both cap_drop_*_set() seems a bit clumsy, but gets
the job done.

Signed-off-by: default avatarNeilBrown <neilb@suse.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 63fd7d04

drivers/staging/lustre/include/linux/libcfs/curproc.h

+0 −10
Original line number Diff line number Diff line
@@ -50,16 +50,6 @@ 


typedef u32 cfs_cap_t;



#define CFS_CAP_FS_MASK (BIT(CAP_CHOWN) |		\

			 BIT(CAP_DAC_OVERRIDE) |	\

			 BIT(CAP_DAC_READ_SEARCH) |	\

			 BIT(CAP_FOWNER) |		\

			 BIT(CAP_FSETID) |		\

			 BIT(CAP_LINUX_IMMUTABLE) | \

			 BIT(CAP_SYS_ADMIN) |	\

			 BIT(CAP_SYS_BOOT) |	\

			 BIT(CAP_SYS_RESOURCE))



static inline cfs_cap_t cfs_curproc_cap_pack(void)

{

	/* cfs_cap_t is only the first word of kernel_cap_t */

drivers/staging/lustre/lustre/llite/file.c

+3 −5
Original line number Diff line number Diff line
@@ -3050,7 +3050,6 @@ int ll_inode_permission(struct inode *inode, int mask) 
	const struct cred *old_cred = NULL;

	struct cred *cred = NULL;

	bool squash_id = false;

	cfs_cap_t cap;

	int rc = 0;



	if (mask & MAY_NOT_BLOCK)
@@ -3094,10 +3093,9 @@ int ll_inode_permission(struct inode *inode, int mask) 


		cred->fsuid = make_kuid(&init_user_ns, squash->rsi_uid);

		cred->fsgid = make_kgid(&init_user_ns, squash->rsi_gid);

		for (cap = 0; cap < sizeof(cfs_cap_t) * 8; cap++) {

			if ((1 << cap) & CFS_CAP_FS_MASK)

				cap_lower(cred->cap_effective, cap);

		}

		cred->cap_effective = cap_drop_nfsd_set(cred->cap_effective);

		cred->cap_effective = cap_drop_fs_set(cred->cap_effective);



		old_cred = override_creds(cred);

	}