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| -rw-r--r-- | module/zfs/zpl_xattr.c | 432 |
1 files changed, 432 insertions, 0 deletions
diff --git a/module/zfs/zpl_xattr.c b/module/zfs/zpl_xattr.c new file mode 100644 index 000000000..910500a72 --- /dev/null +++ b/module/zfs/zpl_xattr.c @@ -0,0 +1,432 @@ +/* + * CDDL HEADER START + * + * The contents of this file are subject to the terms of the + * Common Development and Distribution License (the "License"). + * You may not use this file except in compliance with the License. + * + * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE + * or http://www.opensolaris.org/os/licensing. + * See the License for the specific language governing permissions + * and limitations under the License. + * + * When distributing Covered Code, include this CDDL HEADER in each + * file and include the License file at usr/src/OPENSOLARIS.LICENSE. + * If applicable, add the following below this CDDL HEADER, with the + * fields enclosed by brackets "[]" replaced with your own identifying + * information: Portions Copyright [yyyy] [name of copyright owner] + * + * CDDL HEADER END + */ +/* + * Copyright (c) 2011, Lawrence Livermore National Security, LLC. + * + * Extended attributes (xattr) on Solaris are implemented as files + * which exist in a hidden xattr directory. These extended attributes + * can be accessed using the attropen() system call which opens + * the extended attribute. It can then be manipulated just like + * a standard file descriptor. This has a couple advantages such + * as practically no size limit on the file, and the extended + * attributes permissions may differ from those of the parent file. + * This interface is really quite clever, but it's also completely + * different than what is supported on Linux. + * + * Under Linux extended attributes are manipulated by the system + * calls getxattr(2), setxattr(2), and listxattr(2). They consider + * extended attributes to be name/value pairs where the name is a + * NULL terminated string. The name must also include one of the + * following name space prefixes: + * + * user - No restrictions and is available to user applications. + * trusted - Restricted to kernel and root (CAP_SYS_ADMIN) use. + * system - Used for access control lists (system.nfs4_acl, etc). + * security - Used by SELinux to store a files security context. + * + * This Linux interface is implemented internally using the more + * flexible Solaris style extended attributes. Every extended + * attribute is store as a file in a hidden directory associated + * with the parent file. This ensures on disk compatibility with + * zfs implementations on other platforms (Solaris, FreeBSD, MacOS). + * + * One consequence of this implementation is that when an extended + * attribute is manipulated an inode is created. This inode will + * exist in the Linux inode cache but there will be no associated + * entry in the dentry cache which references it. This is safe + * but it may result in some confusion. + * + * Longer term I would like to see the 'security.selinux' extended + * attribute moved to a SA. This should significantly improve + * performance on a SELinux enabled system by minimizing the + * number of seeks required to access a file. However, for now + * this xattr is still stored in a file because I'm pretty sure + * adding a new SA will break on-disk compatibility. + */ + + +#include <sys/zfs_vfsops.h> +#include <sys/zfs_vnops.h> +#include <sys/zfs_znode.h> +#include <sys/vfs.h> +#include <sys/zpl.h> + +typedef struct xattr_filldir { + size_t size; + size_t offset; + char *buf; + struct inode *inode; +} xattr_filldir_t; + +static int +zpl_xattr_filldir(void *arg, const char *name, int name_len, + loff_t offset, uint64_t objnum, unsigned int d_type) +{ + xattr_filldir_t *xf = arg; + + if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) + if (!(ITOZSB(xf->inode)->z_flags & ZSB_XATTR_USER)) + return (0); + + if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) + if (!capable(CAP_SYS_ADMIN)) + return (0); + + /* When xf->buf is NULL only calculate the required size. */ + if (xf->buf) { + if (xf->offset + name_len + 1 > xf->size) + return (-ERANGE); + + memcpy(xf->buf + xf->offset, name, name_len); + xf->buf[xf->offset + name_len] = '\0'; + } + + xf->offset += (name_len + 1); + + return (0); +} + +ssize_t +zpl_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size) +{ + struct inode *ip = dentry->d_inode; + struct inode *dxip = NULL; + loff_t pos = 3; /* skip '.', '..', and '.zfs' entries. */ + cred_t *cr; + int error; + xattr_filldir_t xf = { buffer_size, 0, buffer, ip }; + + cr = (cred_t *)get_current_cred(); + + /* Lookup the xattr directory */ + error = -zfs_lookup(ip, NULL, &dxip, LOOKUP_XATTR, cr, NULL, NULL); + if (error) { + if (error == -ENOENT) + error = 0; + + goto out; + } + + /* Fill provided buffer via zpl_zattr_filldir helper */ + error = -zfs_readdir(dxip, (void *)&xf, zpl_xattr_filldir, &pos, cr); + if (error) + goto out; + + error = xf.offset; +out: + if (dxip) + iput(dxip); + + put_cred(cr); + + return (error); +} + +static int +zpl_xattr_get(struct inode *ip, const char *name, void *buf, size_t size) +{ + struct inode *dxip = NULL; + struct inode *xip = NULL; + cred_t *cr; + int error; + + cr = (cred_t *)get_current_cred(); + + /* Lookup the xattr directory */ + error = -zfs_lookup(ip, NULL, &dxip, LOOKUP_XATTR, cr, NULL, NULL); + if (error) + goto out; + + /* Lookup a specific xattr name in the directory */ + error = -zfs_lookup(dxip, (char *)name, &xip, 0, cr, NULL, NULL); + if (error) + goto out; + + if (!size) { + error = i_size_read(xip); + goto out; + } + + error = zpl_read_common(xip, buf, size, 0, UIO_SYSSPACE, 0, cr); +out: + if (xip) + iput(xip); + + if (dxip) + iput(dxip); + + put_cred(cr); + + if (error == -ENOENT) + error = -ENODATA; + + return (error); +} + +static int +zpl_xattr_set(struct inode *ip, const char *name, const void *value, + size_t size, int flags) +{ + struct inode *dxip = NULL; + struct inode *xip = NULL; + vattr_t *vap = NULL; + cred_t *cr; + ssize_t wrote; + int error; + + cr = (cred_t *)get_current_cred(); + + /* Lookup the xattr directory and create it if required. */ + error = -zfs_lookup(ip, NULL, &dxip, LOOKUP_XATTR | CREATE_XATTR_DIR, + cr, NULL, NULL); + if (error) + goto out; + + /* + * Lookup a specific xattr name in the directory, two failure modes: + * XATTR_CREATE: fail if xattr already exists + * XATTR_REMOVE: fail if xattr does not exist + */ + error = -zfs_lookup(dxip, (char *)name, &xip, 0, cr, NULL, NULL); + if (error) { + if (error != -ENOENT) + goto out; + + if ((error == -ENOENT) && (flags & XATTR_REPLACE)) + goto out; + } else { + error = -EEXIST; + if (flags & XATTR_CREATE) + goto out; + } + error = 0; + + /* Remove a specific name xattr when value is set to NULL. */ + if (value == NULL) { + if (xip) + error = -zfs_remove(dxip, (char *)name, cr); + + goto out; + } + + /* Lookup failed create a new xattr. */ + if (xip == NULL) { + vap = kmem_zalloc(sizeof(vattr_t), KM_SLEEP); + vap->va_mode = S_IFREG | 0644; + vap->va_mask = ATTR_MODE; + vap->va_uid = current_fsuid(); + vap->va_gid = current_fsgid(); + + error = -zfs_create(dxip, (char *)name, vap, 0, 0644, &xip, + cr, 0, NULL); + if (error) + goto out; + } + + ASSERT(xip != NULL); + wrote = zpl_write_common(xip, value, size, 0, UIO_SYSSPACE, 0, cr); + if (wrote < 0) + error = wrote; + +out: + if (vap) + kmem_free(vap, sizeof(vattr_t)); + + if (xip) + iput(xip); + + if (dxip) + iput(dxip); + + put_cred(cr); + if (error == -ENOENT) + error = -ENODATA; + + ASSERT3S(error, <=, 0); + + return (error); +} + +static int +zpl_xattr_user_get(struct inode *ip, const char *name, + void *buffer, size_t size) +{ + char *xattr_name; + int error; + + if (strcmp(name, "") == 0) + return -EINVAL; + + if (!(ITOZSB(ip)->z_flags & ZSB_XATTR_USER)) + return -EOPNOTSUPP; + + xattr_name = kmem_asprintf("%s%s", XATTR_USER_PREFIX, name); + error = zpl_xattr_get(ip, xattr_name, buffer, size); + strfree(xattr_name); + + return (error); +} + +static int +zpl_xattr_user_set(struct inode *ip, const char *name, + const void *value, size_t size, int flags) +{ + char *xattr_name; + int error; + + if (strcmp(name, "") == 0) + return -EINVAL; + + if (!(ITOZSB(ip)->z_flags & ZSB_XATTR_USER)) + return -EOPNOTSUPP; + + xattr_name = kmem_asprintf("%s%s", XATTR_USER_PREFIX, name); + error = zpl_xattr_set(ip, xattr_name, value, size, flags); + strfree(xattr_name); + + return (error); +} + +struct xattr_handler zpl_xattr_user_handler = { + .prefix = XATTR_USER_PREFIX, + .get = zpl_xattr_user_get, + .set = zpl_xattr_user_set, +}; + +static int +zpl_xattr_trusted_get(struct inode *ip, const char *name, + void *buffer, size_t size) +{ + char *xattr_name; + int error; + + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + + if (strcmp(name, "") == 0) + return -EINVAL; + + xattr_name = kmem_asprintf("%s%s", XATTR_TRUSTED_PREFIX, name); + error = zpl_xattr_get(ip, xattr_name, buffer, size); + strfree(xattr_name); + + return (error); +} + +static int +zpl_xattr_trusted_set(struct inode *ip, const char *name, + const void *value, size_t size, int flags) +{ + char *xattr_name; + int error; + + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + + if (strcmp(name, "") == 0) + return -EINVAL; + + xattr_name = kmem_asprintf("%s%s", XATTR_TRUSTED_PREFIX, name); + error = zpl_xattr_set(ip, xattr_name, value, size, flags); + strfree(xattr_name); + + return (error); +} + +struct xattr_handler zpl_xattr_trusted_handler = { + .prefix = XATTR_TRUSTED_PREFIX, + .get = zpl_xattr_trusted_get, + .set = zpl_xattr_trusted_set, +}; + +static int +zpl_xattr_security_get(struct inode *ip, const char *name, + void *buffer, size_t size) +{ + char *xattr_name; + int error; + + if (strcmp(name, "") == 0) + return -EINVAL; + + xattr_name = kmem_asprintf("%s%s", XATTR_SECURITY_PREFIX, name); + error = zpl_xattr_get(ip, xattr_name, buffer, size); + strfree(xattr_name); + + return (error); +} + +static int +zpl_xattr_security_set(struct inode *ip, const char *name, + const void *value, size_t size, int flags) +{ + char *xattr_name; + int error; + + if (strcmp(name, "") == 0) + return -EINVAL; + + xattr_name = kmem_asprintf("%s%s", XATTR_SECURITY_PREFIX, name); + error = zpl_xattr_set(ip, xattr_name, value, size, flags); + strfree(xattr_name); + + return (error); +} + +int +zpl_xattr_security_init(struct inode *ip, struct inode *dip) +{ + int error; + size_t len; + void *value; + char *name; + + error = security_inode_init_security(ip, dip, &name, &value, &len); + if (error) { + if (error == -EOPNOTSUPP) + return 0; + + return (error); + } + + error = zpl_xattr_security_set(ip, name, value, len, 0); + + kfree(name); + kfree(value); + + return (error); +} + +struct xattr_handler zpl_xattr_security_handler = { + .prefix = XATTR_SECURITY_PREFIX, + .get = zpl_xattr_security_get, + .set = zpl_xattr_security_set, +}; + +struct xattr_handler *zpl_xattr_handlers[] = { + &zpl_xattr_security_handler, + &zpl_xattr_trusted_handler, + &zpl_xattr_user_handler, +#ifdef HAVE_POSIX_ACLS + &zpl_xattr_acl_access_handler, + &zpl_xattr_acl_default_handler, +#endif /* HAVE_POSIX_ACLS */ +}; |