From 595a93d716680715a751737ec2f87b06ea582763 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Mon, 13 Apr 2015 15:16:54 +0200
Subject: [PATCH] tmpfiles: don't follow symlinks when adjusting ACLs, fille
attributes, access modes or ownership
Cherry-picked from: 48b8aaa82724bc2d8440470f414fb0d2416f29c
Resolves: #1296288
---
src/tmpfiles/tmpfiles.c | 112 ++++++++++++++++++++++++++--------------
1 file changed, 74 insertions(+), 38 deletions(-)
diff --git a/src/tmpfiles/tmpfiles.c b/src/tmpfiles/tmpfiles.c
index d0e6567d8a..64c733aaa0 100644
--- a/src/tmpfiles/tmpfiles.c
+++ b/src/tmpfiles/tmpfiles.c
@@ -570,51 +570,69 @@ finish:
}
static int path_set_perms(Item *i, const char *path) {
+ _cleanup_close_ int fd = -1;
struct stat st;
- bool st_valid;
assert(i);
assert(path);
- st_valid = stat(path, &st) == 0;
+ /* We open the file with O_PATH here, to make the operation
+ * somewhat atomic. Also there's unfortunately no fchmodat()
+ * with AT_SYMLINK_NOFOLLOW, hence we emulate it here via
+ * O_PATH. */
+
+ fd = open(path, O_RDONLY|O_NOFOLLOW|O_CLOEXEC|O_PATH|O_NOATIME);
+ if (fd < 0)
+ return log_error_errno(errno, "Adjusting owner and mode for %s failed: %m", path);
+
+ if (fstatat(fd, "", &st, AT_EMPTY_PATH) < 0)
+ return log_error_errno(errno, "Failed to fstat() file %s: %m", path);
+
+ if (S_ISLNK(st.st_mode))
+ log_debug("Skipping mode an owner fix for symlink %s.", path);
+ else {
+ char fn[strlen("/proc/self/fd/") + DECIMAL_STR_MAX(int)];
+ xsprintf(fn, "/proc/self/fd/%i", fd);
- /* not using i->path directly because it may be a glob */
- if (i->mode_set) {
- mode_t m = i->mode;
+ /* not using i->path directly because it may be a glob */
+ if (i->mode_set) {
+ mode_t m = i->mode;
- if (i->mask_perms && st_valid) {
- if (!(st.st_mode & 0111))
- m &= ~0111;
- if (!(st.st_mode & 0222))
+ if (i->mask_perms) {
+ if (!(st.st_mode & 0111))
+ m &= ~0111;
+ if (!(st.st_mode & 0222))
m &= ~0222;
- if (!(st.st_mode & 0444))
- m &= ~0444;
- if (!S_ISDIR(st.st_mode))
- m &= ~07000; /* remove sticky/sgid/suid bit, unless directory */
- }
+ if (!(st.st_mode & 0444))
+ m &= ~0444;
+ if (!S_ISDIR(st.st_mode))
+ m &= ~07000; /* remove sticky/sgid/suid bit, unless directory */
+ }
- if (st_valid && m == (st.st_mode & 07777))
- log_debug("\"%s\" has right mode %o", path, st.st_mode);
- else {
- log_debug("chmod \"%s\" to mode %o", path, m);
- if (chmod(path, m) < 0)
- return log_error_errno(errno, "chmod(%s) failed: %m", path);
+ if (m == (st.st_mode & 07777))
+ log_debug("\"%s\" has right mode %o", path, st.st_mode);
+ else {
+ log_debug("chmod \"%s\" to mode %o", path, m);
+ if (chmod(fn, m) < 0)
+ return log_error_errno(errno, "chmod(%s) failed: %m", path);
+ }
}
- }
-
- if ((!st_valid || i->uid != st.st_uid || i->gid != st.st_gid) &&
- (i->uid_set || i->gid_set)) {
- log_debug("chown \"%s\" to "UID_FMT"."GID_FMT,
- path,
- i->uid_set ? i->uid : UID_INVALID,
- i->gid_set ? i->gid : GID_INVALID);
- if (chown(path,
- i->uid_set ? i->uid : UID_INVALID,
- i->gid_set ? i->gid : GID_INVALID) < 0)
+ if ((i->uid != st.st_uid || i->gid != st.st_gid) &&
+ (i->uid_set || i->gid_set)) {
+ log_debug("chown \"%s\" to "UID_FMT"."GID_FMT,
+ path,
+ i->uid_set ? i->uid : UID_INVALID,
+ i->gid_set ? i->gid : GID_INVALID);
+ if (chown(fn,
+ i->uid_set ? i->uid : UID_INVALID,
+ i->gid_set ? i->gid : GID_INVALID) < 0)
return log_error_errno(errno, "chown(%s) failed: %m", path);
+ }
}
+ fd = safe_close(fd);
+
return label_fix(path, false, false);
}
@@ -699,10 +717,10 @@ static int get_acls_from_arg(Item *item) {
}
#ifdef HAVE_ACL
-static int path_set_acl(const char *path, acl_type_t type, acl_t acl, bool modify) {
+static int path_set_acl(const char *path, const char *pretty, acl_type_t type, acl_t acl, bool modify) {
+ _cleanup_(acl_free_charpp) char *t = NULL;
_cleanup_(acl_freep) acl_t dup = NULL;
int r;
- _cleanup_(acl_free_charpp) char *t = NULL;
/* Returns 0 for success, positive error if already warned,
* negative error otherwise. */
@@ -728,16 +746,16 @@ static int path_set_acl(const char *path, acl_type_t type, acl_t acl, bool modif
return r;
t = acl_to_any_text(dup, NULL, ',', TEXT_ABBREVIATE);
- log_debug("\"%s\": setting %s ACL \"%s\"", path,
+ log_debug("Setting %s ACL %s on %s.",
type == ACL_TYPE_ACCESS ? "access" : "default",
- strna(t));
+ strna(t), pretty);
r = acl_set_file(path, type, dup);
if (r < 0)
return -log_error_errno(errno,
"Setting %s ACL \"%s\" on %s failed: %m",
type == ACL_TYPE_ACCESS ? "access" : "default",
- strna(t), path);
+ strna(t), pretty);
return 0;
}
@@ -746,14 +764,32 @@ static int path_set_acl(const char *path, acl_type_t type, acl_t acl, bool modif
static int path_set_acls(Item *item, const char *path) {
int r = 0;
#ifdef HAVE_ACL
+ char fn[strlen("/proc/self/fd/") + DECIMAL_STR_MAX(int)];
+ _cleanup_close_ int fd = -1;
+ struct stat st;
+
assert(item);
assert(path);
+ fd = open(path, O_RDONLY|O_NOFOLLOW|O_CLOEXEC|O_PATH|O_NOATIME);
+ if (fd < 0)
+ return log_error_errno(errno, "Adjusting ACL of %s failed: %m", path);
+
+ if (fstatat(fd, "", &st, AT_EMPTY_PATH) < 0)
+ return log_error_errno(errno, "Failed to fstat() file %s: %m", path);
+
+ if (S_ISLNK(st.st_mode)) {
+ log_debug("Skipping ACL fix for symlink %s.", path);
+ return 0;
+ }
+
+ xsprintf(fn, "/proc/self/fd/%i", fd);
+
if (item->acl_access)
- r = path_set_acl(path, ACL_TYPE_ACCESS, item->acl_access, item->force);
+ r = path_set_acl(fn, path, ACL_TYPE_ACCESS, item->acl_access, item->force);
if (r == 0 && item->acl_default)
- r = path_set_acl(path, ACL_TYPE_DEFAULT, item->acl_default, item->force);
+ r = path_set_acl(fn, path, ACL_TYPE_DEFAULT, item->acl_default, item->force);
if (r > 0)
return -r; /* already warned */