1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
2
3 #include <fcntl.h>
4 #include <sys/stat.h>
5 #include <sys/types.h>
6 #include <sys/xattr.h>
7
8 #include "chown-recursive.h"
9 #include "dirent-util.h"
10 #include "fd-util.h"
11 #include "fs-util.h"
12 #include "macro.h"
13 #include "stdio-util.h"
14 #include "strv.h"
15 #include "user-util.h"
16
chown_one(int fd,const struct stat * st,uid_t uid,gid_t gid,mode_t mask)17 static int chown_one(
18 int fd,
19 const struct stat *st,
20 uid_t uid,
21 gid_t gid,
22 mode_t mask) {
23
24 int r;
25
26 assert(fd >= 0);
27 assert(st);
28
29 /* We change ACLs through the /proc/self/fd/%i path, so that we have a stable reference that works
30 * with O_PATH. */
31
32 /* Drop any ACL if there is one */
33 FOREACH_STRING(n, "system.posix_acl_access", "system.posix_acl_default")
34 if (removexattr(FORMAT_PROC_FD_PATH(fd), n) < 0)
35 if (!IN_SET(errno, ENODATA, EOPNOTSUPP, ENOSYS, ENOTTY))
36 return -errno;
37
38 r = fchmod_and_chown(fd, st->st_mode & mask, uid, gid);
39 if (r < 0)
40 return r;
41
42 return 1;
43 }
44
chown_recursive_internal(int fd,const struct stat * st,uid_t uid,gid_t gid,mode_t mask)45 static int chown_recursive_internal(
46 int fd,
47 const struct stat *st,
48 uid_t uid,
49 gid_t gid,
50 mode_t mask) {
51
52 _cleanup_closedir_ DIR *d = NULL;
53 bool changed = false;
54 int r;
55
56 assert(fd >= 0);
57 assert(st);
58
59 d = fdopendir(fd);
60 if (!d) {
61 safe_close(fd);
62 return -errno;
63 }
64
65 FOREACH_DIRENT_ALL(de, d, return -errno) {
66 _cleanup_close_ int path_fd = -1;
67 struct stat fst;
68
69 if (dot_or_dot_dot(de->d_name))
70 continue;
71
72 /* Let's pin the child inode we want to fix now with an O_PATH fd, so that it cannot be swapped out
73 * while we manipulate it. */
74 path_fd = openat(dirfd(d), de->d_name, O_PATH|O_CLOEXEC|O_NOFOLLOW);
75 if (path_fd < 0)
76 return -errno;
77
78 if (fstat(path_fd, &fst) < 0)
79 return -errno;
80
81 if (S_ISDIR(fst.st_mode)) {
82 int subdir_fd;
83
84 /* Convert it to a "real" (i.e. non-O_PATH) fd now */
85 subdir_fd = fd_reopen(path_fd, O_RDONLY|O_CLOEXEC|O_NOATIME);
86 if (subdir_fd < 0)
87 return subdir_fd;
88
89 r = chown_recursive_internal(subdir_fd, &fst, uid, gid, mask); /* takes possession of subdir_fd even on failure */
90 if (r < 0)
91 return r;
92 if (r > 0)
93 changed = true;
94 } else {
95 r = chown_one(path_fd, &fst, uid, gid, mask);
96 if (r < 0)
97 return r;
98 if (r > 0)
99 changed = true;
100 }
101 }
102
103 r = chown_one(dirfd(d), st, uid, gid, mask);
104 if (r < 0)
105 return r;
106
107 return r > 0 || changed;
108 }
109
path_chown_recursive(const char * path,uid_t uid,gid_t gid,mode_t mask)110 int path_chown_recursive(
111 const char *path,
112 uid_t uid,
113 gid_t gid,
114 mode_t mask) {
115
116 _cleanup_close_ int fd = -1;
117 struct stat st;
118
119 fd = open(path, O_RDONLY|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
120 if (fd < 0)
121 return -errno;
122
123 if (!uid_is_valid(uid) && !gid_is_valid(gid) && FLAGS_SET(mask, 07777))
124 return 0; /* nothing to do */
125
126 if (fstat(fd, &st) < 0)
127 return -errno;
128
129 /* Let's take a shortcut: if the top-level directory is properly owned, we don't descend into the
130 * whole tree, under the assumption that all is OK anyway. */
131 if ((!uid_is_valid(uid) || st.st_uid == uid) &&
132 (!gid_is_valid(gid) || st.st_gid == gid) &&
133 ((st.st_mode & ~mask & 07777) == 0))
134 return 0;
135
136 return chown_recursive_internal(TAKE_FD(fd), &st, uid, gid, mask); /* we donate the fd to the call, regardless if it succeeded or failed */
137 }
138
fd_chown_recursive(int fd,uid_t uid,gid_t gid,mode_t mask)139 int fd_chown_recursive(
140 int fd,
141 uid_t uid,
142 gid_t gid,
143 mode_t mask) {
144
145 int duplicated_fd = -1;
146 struct stat st;
147
148 /* Note that the slightly different order of fstat() and the checks here and in
149 * path_chown_recursive(). That's because when we open the directory ourselves we can specify
150 * O_DIRECTORY and we always want to ensure we are operating on a directory before deciding whether
151 * the operation is otherwise redundant. */
152
153 if (fstat(fd, &st) < 0)
154 return -errno;
155
156 if (!S_ISDIR(st.st_mode))
157 return -ENOTDIR;
158
159 if (!uid_is_valid(uid) && !gid_is_valid(gid) && FLAGS_SET(mask, 07777))
160 return 0; /* nothing to do */
161
162 /* Shortcut, as above */
163 if ((!uid_is_valid(uid) || st.st_uid == uid) &&
164 (!gid_is_valid(gid) || st.st_gid == gid) &&
165 ((st.st_mode & ~mask & 07777) == 0))
166 return 0;
167
168 /* Let's duplicate the fd here, as opendir() wants to take possession of it and close it afterwards */
169 duplicated_fd = fcntl(fd, F_DUPFD_CLOEXEC, 3);
170 if (duplicated_fd < 0)
171 return -errno;
172
173 return chown_recursive_internal(duplicated_fd, &st, uid, gid, mask); /* fd donated even on failure */
174 }
175