[trusty CVE-2016-7097 1/1] posix_acl: Clear SGID bit when setting file permissions
Juerg Haefliger
juerg.haefliger at canonical.com
Wed Sep 6 08:54:53 UTC 2017
From: Jan Kara <jack at suse.cz>
commit 073931017b49d9458aa351605b43a7e34598caef upstream.
When file permissions are modified via chmod(2) and the user is not in
the owning group or capable of CAP_FSETID, the setgid bit is cleared in
inode_change_ok(). Setting a POSIX ACL via setxattr(2) sets the file
permissions as well as the new ACL, but doesn't clear the setgid bit in
a similar way; this allows to bypass the check in chmod(2). Fix that.
References: CVE-2016-7097
Reviewed-by: Christoph Hellwig <hch at lst.de>
Reviewed-by: Jeff Layton <jlayton at redhat.com>
Signed-off-by: Jan Kara <jack at suse.cz>
Signed-off-by: Andreas Gruenbacher <agruenba at redhat.com>
[bwh: Backported to 3.16:
- Drop changes to orangefs
- Adjust context
- Update ext3 as well]
Signed-off-by: Ben Hutchings <ben at decadent.org.uk>
CVE-2016-7097
[juergh: Backported to 3.13:
- Drop changes to ceph
- Use capable() instead of capable_wrt_inode_uidgid()
- Update generic_acl.c as well
- In gfs2, jfs, and xfs, take care to avoid leaking the allocated ACL if
posix_acl_update_mode() determines it's not needed]
Signed-off-by: Juerg Haefliger <juerg.haefliger at canonical.com>
---
fs/9p/acl.c | 40 +++++++++++++++++-----------------------
fs/btrfs/acl.c | 6 ++----
fs/ext2/acl.c | 12 ++++--------
fs/ext3/acl.c | 12 ++++--------
fs/ext4/acl.c | 12 ++++--------
fs/f2fs/acl.c | 6 ++----
fs/generic_acl.c | 15 ++++++++-------
fs/gfs2/acl.c | 16 +++++++---------
fs/hfsplus/posix_acl.c | 4 ++--
fs/jffs2/acl.c | 9 ++++-----
fs/jfs/xattr.c | 6 ++++--
fs/ocfs2/acl.c | 9 +++------
fs/posix_acl.c | 30 ++++++++++++++++++++++++++++++
fs/reiserfs/xattr_acl.c | 8 ++------
fs/xfs/xfs_acl.c | 17 +++++++----------
include/linux/posix_acl.h | 1 +
16 files changed, 101 insertions(+), 102 deletions(-)
diff --git a/fs/9p/acl.c b/fs/9p/acl.c
index 7af425f53bee..9686c1f17653 100644
--- a/fs/9p/acl.c
+++ b/fs/9p/acl.c
@@ -320,32 +320,26 @@ static int v9fs_xattr_set_acl(struct dentry *dentry, const char *name,
case ACL_TYPE_ACCESS:
name = POSIX_ACL_XATTR_ACCESS;
if (acl) {
- umode_t mode = inode->i_mode;
- retval = posix_acl_equiv_mode(acl, &mode);
- if (retval < 0)
+ struct iattr iattr;
+
+ retval = posix_acl_update_mode(inode, &iattr.ia_mode, &acl);
+ if (retval)
goto err_out;
- else {
- struct iattr iattr;
- if (retval == 0) {
- /*
- * ACL can be represented
- * by the mode bits. So don't
- * update ACL.
- */
- acl = NULL;
- value = NULL;
- size = 0;
- }
- /* Updte the mode bits */
- iattr.ia_mode = ((mode & S_IALLUGO) |
- (inode->i_mode & ~S_IALLUGO));
- iattr.ia_valid = ATTR_MODE;
- /* FIXME should we update ctime ?
- * What is the following setxattr update the
- * mode ?
+ if (!acl) {
+ /*
+ * ACL can be represented
+ * by the mode bits. So don't
+ * update ACL.
*/
- v9fs_vfs_setattr_dotl(dentry, &iattr);
+ value = NULL;
+ size = 0;
}
+ iattr.ia_valid = ATTR_MODE;
+ /* FIXME should we update ctime ?
+ * What is the following setxattr update the
+ * mode ?
+ */
+ v9fs_vfs_setattr_dotl(dentry, &iattr);
}
break;
case ACL_TYPE_DEFAULT:
diff --git a/fs/btrfs/acl.c b/fs/btrfs/acl.c
index 0890c83643e9..d6d53e5e7945 100644
--- a/fs/btrfs/acl.c
+++ b/fs/btrfs/acl.c
@@ -118,11 +118,9 @@ static int btrfs_set_acl(struct btrfs_trans_handle *trans,
case ACL_TYPE_ACCESS:
name = POSIX_ACL_XATTR_ACCESS;
if (acl) {
- ret = posix_acl_equiv_mode(acl, &inode->i_mode);
- if (ret < 0)
+ ret = posix_acl_update_mode(inode, &inode->i_mode, &acl);
+ if (ret)
return ret;
- if (ret == 0)
- acl = NULL;
}
ret = 0;
break;
diff --git a/fs/ext2/acl.c b/fs/ext2/acl.c
index 110b6b371a4e..48c3c2d7d261 100644
--- a/fs/ext2/acl.c
+++ b/fs/ext2/acl.c
@@ -206,15 +206,11 @@ ext2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
case ACL_TYPE_ACCESS:
name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
if (acl) {
- error = posix_acl_equiv_mode(acl, &inode->i_mode);
- if (error < 0)
+ error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
+ if (error)
return error;
- else {
- inode->i_ctime = CURRENT_TIME_SEC;
- mark_inode_dirty(inode);
- if (error == 0)
- acl = NULL;
- }
+ inode->i_ctime = CURRENT_TIME_SEC;
+ mark_inode_dirty(inode);
}
break;
diff --git a/fs/ext3/acl.c b/fs/ext3/acl.c
index dbb5ad59a7fc..bb2f60a62d82 100644
--- a/fs/ext3/acl.c
+++ b/fs/ext3/acl.c
@@ -205,15 +205,11 @@ ext3_set_acl(handle_t *handle, struct inode *inode, int type,
case ACL_TYPE_ACCESS:
name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
if (acl) {
- error = posix_acl_equiv_mode(acl, &inode->i_mode);
- if (error < 0)
+ error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
+ if (error)
return error;
- else {
- inode->i_ctime = CURRENT_TIME_SEC;
- ext3_mark_inode_dirty(handle, inode);
- if (error == 0)
- acl = NULL;
- }
+ inode->i_ctime = CURRENT_TIME_SEC;
+ ext3_mark_inode_dirty(handle, inode);
}
break;
diff --git a/fs/ext4/acl.c b/fs/ext4/acl.c
index 39a54a0e9fe4..c844f1bfb451 100644
--- a/fs/ext4/acl.c
+++ b/fs/ext4/acl.c
@@ -211,15 +211,11 @@ ext4_set_acl(handle_t *handle, struct inode *inode, int type,
case ACL_TYPE_ACCESS:
name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
if (acl) {
- error = posix_acl_equiv_mode(acl, &inode->i_mode);
- if (error < 0)
+ error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
+ if (error)
return error;
- else {
- inode->i_ctime = ext4_current_time(inode);
- ext4_mark_inode_dirty(handle, inode);
- if (error == 0)
- acl = NULL;
- }
+ inode->i_ctime = ext4_current_time(inode);
+ ext4_mark_inode_dirty(handle, inode);
}
break;
diff --git a/fs/f2fs/acl.c b/fs/f2fs/acl.c
index d0fc287efeff..0eb2d66827ad 100644
--- a/fs/f2fs/acl.c
+++ b/fs/f2fs/acl.c
@@ -224,12 +224,10 @@ static int f2fs_set_acl(struct inode *inode, int type,
case ACL_TYPE_ACCESS:
name_index = F2FS_XATTR_INDEX_POSIX_ACL_ACCESS;
if (acl) {
- error = posix_acl_equiv_mode(acl, &inode->i_mode);
- if (error < 0)
+ error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
+ if (error)
return error;
set_acl_inode(fi, inode->i_mode);
- if (error == 0)
- acl = NULL;
}
break;
diff --git a/fs/generic_acl.c b/fs/generic_acl.c
index b3f3676796d3..67319f168b42 100644
--- a/fs/generic_acl.c
+++ b/fs/generic_acl.c
@@ -86,16 +86,17 @@ generic_acl_set(struct dentry *dentry, const char *name, const void *value,
if (error)
goto failed;
switch (type) {
- case ACL_TYPE_ACCESS:
- error = posix_acl_equiv_mode(acl, &inode->i_mode);
- if (error < 0)
+ case ACL_TYPE_ACCESS: {
+ struct posix_acl *saved_acl = acl;
+
+ error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
+ if (acl == NULL)
+ posix_acl_release(saved_acl);
+ if (error)
goto failed;
inode->i_ctime = CURRENT_TIME;
- if (error == 0) {
- posix_acl_release(acl);
- acl = NULL;
- }
break;
+ }
case ACL_TYPE_DEFAULT:
if (!S_ISDIR(inode->i_mode)) {
error = -EINVAL;
diff --git a/fs/gfs2/acl.c b/fs/gfs2/acl.c
index f69ac0af5496..015809a066b5 100644
--- a/fs/gfs2/acl.c
+++ b/fs/gfs2/acl.c
@@ -267,16 +267,14 @@ static int gfs2_xattr_system_set(struct dentry *dentry, const char *name,
goto out_release;
if (type == ACL_TYPE_ACCESS) {
- umode_t mode = inode->i_mode;
- error = posix_acl_equiv_mode(acl, &mode);
+ struct posix_acl *saved_acl = acl;
+ umode_t mode;
- if (error <= 0) {
- posix_acl_release(acl);
- acl = NULL;
-
- if (error < 0)
- return error;
- }
+ error = posix_acl_update_mode(inode, &mode, &acl);
+ if (error || acl == NULL)
+ posix_acl_release(saved_acl);
+ if (error)
+ return error;
error = gfs2_set_mode(inode, mode);
if (error)
diff --git a/fs/hfsplus/posix_acl.c b/fs/hfsplus/posix_acl.c
index b609cc14c72e..9f7cc491ffb1 100644
--- a/fs/hfsplus/posix_acl.c
+++ b/fs/hfsplus/posix_acl.c
@@ -72,8 +72,8 @@ static int hfsplus_set_posix_acl(struct inode *inode,
case ACL_TYPE_ACCESS:
xattr_name = POSIX_ACL_XATTR_ACCESS;
if (acl) {
- err = posix_acl_equiv_mode(acl, &inode->i_mode);
- if (err < 0)
+ err = posix_acl_update_mode(inode, &inode->i_mode, &acl);
+ if (err)
return err;
}
err = 0;
diff --git a/fs/jffs2/acl.c b/fs/jffs2/acl.c
index 223283c30111..9335b8d3cf52 100644
--- a/fs/jffs2/acl.c
+++ b/fs/jffs2/acl.c
@@ -243,9 +243,10 @@ static int jffs2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
case ACL_TYPE_ACCESS:
xprefix = JFFS2_XPREFIX_ACL_ACCESS;
if (acl) {
- umode_t mode = inode->i_mode;
- rc = posix_acl_equiv_mode(acl, &mode);
- if (rc < 0)
+ umode_t mode;
+
+ rc = posix_acl_update_mode(inode, &mode, &acl);
+ if (rc)
return rc;
if (inode->i_mode != mode) {
struct iattr attr;
@@ -257,8 +258,6 @@ static int jffs2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
if (rc < 0)
return rc;
}
- if (rc == 0)
- acl = NULL;
}
break;
case ACL_TYPE_DEFAULT:
diff --git a/fs/jfs/xattr.c b/fs/jfs/xattr.c
index d3472f4cd530..6910662a8bf5 100644
--- a/fs/jfs/xattr.c
+++ b/fs/jfs/xattr.c
@@ -693,9 +693,11 @@ static int can_set_system_xattr(struct inode *inode, const char *name,
return rc;
}
if (acl) {
- rc = posix_acl_equiv_mode(acl, &inode->i_mode);
+ struct posix_acl *dummy = acl;
+
+ rc = posix_acl_update_mode(inode, &inode->i_mode, &dummy);
posix_acl_release(acl);
- if (rc < 0) {
+ if (rc) {
printk(KERN_ERR
"posix_acl_equiv_mode returned %d\n",
rc);
diff --git a/fs/ocfs2/acl.c b/fs/ocfs2/acl.c
index b4f788e0ca31..b16bb5c70bc8 100644
--- a/fs/ocfs2/acl.c
+++ b/fs/ocfs2/acl.c
@@ -270,14 +270,11 @@ static int ocfs2_set_acl(handle_t *handle,
case ACL_TYPE_ACCESS:
name_index = OCFS2_XATTR_INDEX_POSIX_ACL_ACCESS;
if (acl) {
- umode_t mode = inode->i_mode;
- ret = posix_acl_equiv_mode(acl, &mode);
- if (ret < 0)
+ umode_t mode;
+ ret = posix_acl_update_mode(inode, &mode, &acl);
+ if (ret)
return ret;
else {
- if (ret == 0)
- acl = NULL;
-
ret = ocfs2_acl_set_mode(inode, di_bh,
handle, mode);
if (ret)
diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 3542f1f814e2..8161e5c9dc31 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -407,6 +407,36 @@ posix_acl_create(struct posix_acl **acl, gfp_t gfp, umode_t *mode_p)
}
EXPORT_SYMBOL(posix_acl_create);
+/**
+ * posix_acl_update_mode - update mode in set_acl
+ *
+ * Update the file mode when setting an ACL: compute the new file permission
+ * bits based on the ACL. In addition, if the ACL is equivalent to the new
+ * file mode, set *acl to NULL to indicate that no ACL should be set.
+ *
+ * As with chmod, clear the setgit bit if the caller is not in the owning group
+ * or capable of CAP_FSETID (see inode_change_ok).
+ *
+ * Called from set_acl inode operations.
+ */
+int posix_acl_update_mode(struct inode *inode, umode_t *mode_p,
+ struct posix_acl **acl)
+{
+ umode_t mode = inode->i_mode;
+ int error;
+
+ error = posix_acl_equiv_mode(*acl, &mode);
+ if (error < 0)
+ return error;
+ if (error == 0)
+ *acl = NULL;
+ if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
+ mode &= ~S_ISGID;
+ *mode_p = mode;
+ return 0;
+}
+EXPORT_SYMBOL(posix_acl_update_mode);
+
int
posix_acl_chmod(struct posix_acl **acl, gfp_t gfp, umode_t mode)
{
diff --git a/fs/reiserfs/xattr_acl.c b/fs/reiserfs/xattr_acl.c
index 06c04f73da65..a86ad7ec7957 100644
--- a/fs/reiserfs/xattr_acl.c
+++ b/fs/reiserfs/xattr_acl.c
@@ -288,13 +288,9 @@ reiserfs_set_acl(struct reiserfs_transaction_handle *th, struct inode *inode,
case ACL_TYPE_ACCESS:
name = POSIX_ACL_XATTR_ACCESS;
if (acl) {
- error = posix_acl_equiv_mode(acl, &inode->i_mode);
- if (error < 0)
+ error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
+ if (error)
return error;
- else {
- if (error == 0)
- acl = NULL;
- }
}
break;
case ACL_TYPE_DEFAULT:
diff --git a/fs/xfs/xfs_acl.c b/fs/xfs/xfs_acl.c
index 370eb3e121d1..89ac0522b38d 100644
--- a/fs/xfs/xfs_acl.c
+++ b/fs/xfs/xfs_acl.c
@@ -402,17 +402,14 @@ xfs_xattr_acl_set(struct dentry *dentry, const char *name,
goto out_release;
if (type == ACL_TYPE_ACCESS) {
- umode_t mode = inode->i_mode;
- error = posix_acl_equiv_mode(acl, &mode);
-
- if (error <= 0) {
- posix_acl_release(acl);
- acl = NULL;
-
- if (error < 0)
- return error;
- }
+ struct posix_acl *saved_acl = acl;
+ umode_t mode;
+ error = posix_acl_update_mode(inode, &mode, &acl);
+ if (error || acl == NULL)
+ posix_acl_release(saved_acl);
+ if (error)
+ return error;
error = xfs_set_mode(inode, mode);
if (error)
goto out_release;
diff --git a/include/linux/posix_acl.h b/include/linux/posix_acl.h
index 7931efe71175..2ae0bba45f12 100644
--- a/include/linux/posix_acl.h
+++ b/include/linux/posix_acl.h
@@ -90,6 +90,7 @@ extern struct posix_acl *posix_acl_from_mode(umode_t, gfp_t);
extern int posix_acl_equiv_mode(const struct posix_acl *, umode_t *);
extern int posix_acl_create(struct posix_acl **, gfp_t, umode_t *);
extern int posix_acl_chmod(struct posix_acl **, gfp_t, umode_t);
+extern int posix_acl_update_mode(struct inode *, umode_t *, struct posix_acl **);
extern struct posix_acl *get_posix_acl(struct inode *, int);
extern int set_posix_acl(struct inode *, int, struct posix_acl *);
--
2.14.1
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