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Linux/fs/xfs/xfs_acl.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * Copyright (c) 2008, Christoph Hellwig
  4  * All Rights Reserved.
  5  */
  6 #include "xfs.h"
  7 #include "xfs_format.h"
  8 #include "xfs_log_format.h"
  9 #include "xfs_trans_resv.h"
 10 #include "xfs_mount.h"
 11 #include "xfs_inode.h"
 12 #include "xfs_acl.h"
 13 #include "xfs_attr.h"
 14 #include "xfs_trace.h"
 15 #include <linux/slab.h>
 16 #include <linux/xattr.h>
 17 #include <linux/posix_acl_xattr.h>
 18 
 19 
 20 /*
 21  * Locking scheme:
 22  *  - all ACL updates are protected by inode->i_mutex, which is taken before
 23  *    calling into this file.
 24  */
 25 
 26 STATIC struct posix_acl *
 27 xfs_acl_from_disk(
 28         const struct xfs_acl    *aclp,
 29         int                     len,
 30         int                     max_entries)
 31 {
 32         struct posix_acl_entry *acl_e;
 33         struct posix_acl *acl;
 34         const struct xfs_acl_entry *ace;
 35         unsigned int count, i;
 36 
 37         if (len < sizeof(*aclp))
 38                 return ERR_PTR(-EFSCORRUPTED);
 39         count = be32_to_cpu(aclp->acl_cnt);
 40         if (count > max_entries || XFS_ACL_SIZE(count) != len)
 41                 return ERR_PTR(-EFSCORRUPTED);
 42 
 43         acl = posix_acl_alloc(count, GFP_KERNEL);
 44         if (!acl)
 45                 return ERR_PTR(-ENOMEM);
 46 
 47         for (i = 0; i < count; i++) {
 48                 acl_e = &acl->a_entries[i];
 49                 ace = &aclp->acl_entry[i];
 50 
 51                 /*
 52                  * The tag is 32 bits on disk and 16 bits in core.
 53                  *
 54                  * Because every access to it goes through the core
 55                  * format first this is not a problem.
 56                  */
 57                 acl_e->e_tag = be32_to_cpu(ace->ae_tag);
 58                 acl_e->e_perm = be16_to_cpu(ace->ae_perm);
 59 
 60                 switch (acl_e->e_tag) {
 61                 case ACL_USER:
 62                         acl_e->e_uid = xfs_uid_to_kuid(be32_to_cpu(ace->ae_id));
 63                         break;
 64                 case ACL_GROUP:
 65                         acl_e->e_gid = xfs_gid_to_kgid(be32_to_cpu(ace->ae_id));
 66                         break;
 67                 case ACL_USER_OBJ:
 68                 case ACL_GROUP_OBJ:
 69                 case ACL_MASK:
 70                 case ACL_OTHER:
 71                         break;
 72                 default:
 73                         goto fail;
 74                 }
 75         }
 76         return acl;
 77 
 78 fail:
 79         posix_acl_release(acl);
 80         return ERR_PTR(-EINVAL);
 81 }
 82 
 83 STATIC void
 84 xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
 85 {
 86         const struct posix_acl_entry *acl_e;
 87         struct xfs_acl_entry *ace;
 88         int i;
 89 
 90         aclp->acl_cnt = cpu_to_be32(acl->a_count);
 91         for (i = 0; i < acl->a_count; i++) {
 92                 ace = &aclp->acl_entry[i];
 93                 acl_e = &acl->a_entries[i];
 94 
 95                 ace->ae_tag = cpu_to_be32(acl_e->e_tag);
 96                 switch (acl_e->e_tag) {
 97                 case ACL_USER:
 98                         ace->ae_id = cpu_to_be32(xfs_kuid_to_uid(acl_e->e_uid));
 99                         break;
100                 case ACL_GROUP:
101                         ace->ae_id = cpu_to_be32(xfs_kgid_to_gid(acl_e->e_gid));
102                         break;
103                 default:
104                         ace->ae_id = cpu_to_be32(ACL_UNDEFINED_ID);
105                         break;
106                 }
107 
108                 ace->ae_perm = cpu_to_be16(acl_e->e_perm);
109         }
110 }
111 
112 struct posix_acl *
113 xfs_get_acl(struct inode *inode, int type)
114 {
115         struct xfs_inode *ip = XFS_I(inode);
116         struct posix_acl *acl = NULL;
117         struct xfs_acl *xfs_acl;
118         unsigned char *ea_name;
119         int error;
120         int len;
121 
122         trace_xfs_get_acl(ip);
123 
124         switch (type) {
125         case ACL_TYPE_ACCESS:
126                 ea_name = SGI_ACL_FILE;
127                 break;
128         case ACL_TYPE_DEFAULT:
129                 ea_name = SGI_ACL_DEFAULT;
130                 break;
131         default:
132                 BUG();
133         }
134 
135         /*
136          * If we have a cached ACLs value just return it, not need to
137          * go out to the disk.
138          */
139         len = XFS_ACL_MAX_SIZE(ip->i_mount);
140         xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
141         if (!xfs_acl)
142                 return ERR_PTR(-ENOMEM);
143 
144         error = xfs_attr_get(ip, ea_name, (unsigned char *)xfs_acl,
145                                                         &len, ATTR_ROOT);
146         if (error) {
147                 /*
148                  * If the attribute doesn't exist make sure we have a negative
149                  * cache entry, for any other error assume it is transient.
150                  */
151                 if (error != -ENOATTR)
152                         acl = ERR_PTR(error);
153         } else  {
154                 acl = xfs_acl_from_disk(xfs_acl, len,
155                                         XFS_ACL_MAX_ENTRIES(ip->i_mount));
156         }
157         kmem_free(xfs_acl);
158         return acl;
159 }
160 
161 int
162 __xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
163 {
164         struct xfs_inode *ip = XFS_I(inode);
165         unsigned char *ea_name;
166         int error;
167 
168         switch (type) {
169         case ACL_TYPE_ACCESS:
170                 ea_name = SGI_ACL_FILE;
171                 break;
172         case ACL_TYPE_DEFAULT:
173                 if (!S_ISDIR(inode->i_mode))
174                         return acl ? -EACCES : 0;
175                 ea_name = SGI_ACL_DEFAULT;
176                 break;
177         default:
178                 return -EINVAL;
179         }
180 
181         if (acl) {
182                 struct xfs_acl *xfs_acl;
183                 int len = XFS_ACL_MAX_SIZE(ip->i_mount);
184 
185                 xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
186                 if (!xfs_acl)
187                         return -ENOMEM;
188 
189                 xfs_acl_to_disk(xfs_acl, acl);
190 
191                 /* subtract away the unused acl entries */
192                 len -= sizeof(struct xfs_acl_entry) *
193                          (XFS_ACL_MAX_ENTRIES(ip->i_mount) - acl->a_count);
194 
195                 error = xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl,
196                                 len, ATTR_ROOT);
197 
198                 kmem_free(xfs_acl);
199         } else {
200                 /*
201                  * A NULL ACL argument means we want to remove the ACL.
202                  */
203                 error = xfs_attr_remove(ip, ea_name, ATTR_ROOT);
204 
205                 /*
206                  * If the attribute didn't exist to start with that's fine.
207                  */
208                 if (error == -ENOATTR)
209                         error = 0;
210         }
211 
212         if (!error)
213                 set_cached_acl(inode, type, acl);
214         return error;
215 }
216 
217 static int
218 xfs_set_mode(struct inode *inode, umode_t mode)
219 {
220         int error = 0;
221 
222         if (mode != inode->i_mode) {
223                 struct iattr iattr;
224 
225                 iattr.ia_valid = ATTR_MODE | ATTR_CTIME;
226                 iattr.ia_mode = mode;
227                 iattr.ia_ctime = current_time(inode);
228 
229                 error = xfs_setattr_nonsize(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
230         }
231 
232         return error;
233 }
234 
235 int
236 xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
237 {
238         umode_t mode;
239         bool set_mode = false;
240         int error = 0;
241 
242         if (!acl)
243                 goto set_acl;
244 
245         error = -E2BIG;
246         if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
247                 return error;
248 
249         if (type == ACL_TYPE_ACCESS) {
250                 error = posix_acl_update_mode(inode, &mode, &acl);
251                 if (error)
252                         return error;
253                 set_mode = true;
254         }
255 
256  set_acl:
257         error =  __xfs_set_acl(inode, acl, type);
258         if (error)
259                 return error;
260 
261         /*
262          * We set the mode after successfully updating the ACL xattr because the
263          * xattr update can fail at ENOSPC and we don't want to change the mode
264          * if the ACL update hasn't been applied.
265          */
266         if (set_mode)
267                 error = xfs_set_mode(inode, mode);
268 
269         return error;
270 }
271 

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