From 3a68810cd6ac23f7107491ab6e1fbd565ed52bf0 Mon Sep 17 00:00:00 2001

From: Lennart Poettering <lennart@poettering.net>

Date: Wed, 8 Apr 2015 22:35:52 +0200

Subject: [PATCH] tmpfiles: rework file attribute code

- Stick to one type for the flags field: unsigned. This appears to be

  what the kernel uses, and there's no point in using something else.

- compress the flags array by avoiding sparse entries

- extend some error messages to not use abbreviated words

- avoid TTOCTTOU issues by invoking fstat() after open() when applying

  file flags

- add explanation why we need to check the file type with fstat().

- don't needlessly abbreviate "attribute" as "attrib", in particually as

  "chattr" abbreviates it as "attr" rather than "attrib".

(cherry picked from commit 88ec4dfa289cd97496dbb9670365a3d4be13d41c)

Conflicts:

	src/tmpfiles/tmpfiles.c

Related: #1299714

---

 src/tmpfiles/tmpfiles.c | 207 ++++++++++++++++++++++++++----------------------

 1 file changed, 114 insertions(+), 93 deletions(-)

diff --git a/src/tmpfiles/tmpfiles.c b/src/tmpfiles/tmpfiles.c

index c8c56c722..800e620bc 100644

--- a/src/tmpfiles/tmpfiles.c

+++ b/src/tmpfiles/tmpfiles.c

@@ -92,8 +92,8 @@ typedef enum ItemType {

         RELABEL_PATH = 'z',

         RECURSIVE_RELABEL_PATH = 'Z',

         ADJUST_MODE = 'm', /* legacy, 'z' is identical to this */

-        SET_ATTRIB = 'h',

-        RECURSIVE_SET_ATTRIB = 'H',

+        SET_ATTRIBUTE = 'h',

+        RECURSIVE_SET_ATTRIBUTE = 'H',

 } ItemType;

 typedef struct Item {

@@ -112,15 +112,15 @@ typedef struct Item {

         usec_t age;

         dev_t major_minor;

-        unsigned long attrib_value;

-        unsigned long attrib_mask;

+        unsigned attribute_value;

+        unsigned attribute_mask;

         bool uid_set:1;

         bool gid_set:1;

         bool mode_set:1;

         bool age_set:1;

         bool mask_perms:1;

-        bool attrib_set:1;

+        bool attribute_set:1;

         bool keep_first_level:1;

@@ -823,123 +823,144 @@ static int path_set_acls(Item *item, const char *path) {

         return r;

 }

-#define ALL_ATTRIBS          \

-        FS_NOATIME_FL      | \

-        FS_SYNC_FL         | \

-        FS_DIRSYNC_FL      | \

-        FS_APPEND_FL       | \

-        FS_COMPR_FL        | \

-        FS_NODUMP_FL       | \

-        FS_EXTENT_FL       | \

-        FS_IMMUTABLE_FL    | \

-        FS_JOURNAL_DATA_FL | \

-        FS_SECRM_FL        | \

-        FS_UNRM_FL         | \

-        FS_NOTAIL_FL       | \

-        FS_TOPDIR_FL       | \

-        FS_NOCOW_FL

-

-static int get_attrib_from_arg(Item *item) {

-        static const unsigned attributes[] = {

-                [(uint8_t)'A'] = FS_NOATIME_FL,      /* do not update atime */

-                [(uint8_t)'S'] = FS_SYNC_FL,         /* Synchronous updates */

-                [(uint8_t)'D'] = FS_DIRSYNC_FL,      /* dirsync behaviour (directories only) */

-                [(uint8_t)'a'] = FS_APPEND_FL,       /* writes to file may only append */

-                [(uint8_t)'c'] = FS_COMPR_FL,        /* Compress file */

-                [(uint8_t)'d'] = FS_NODUMP_FL,       /* do not dump file */

-                [(uint8_t)'e'] = FS_EXTENT_FL,       /* Top of directory hierarchies*/

-                [(uint8_t)'i'] = FS_IMMUTABLE_FL,    /* Immutable file */

-                [(uint8_t)'j'] = FS_JOURNAL_DATA_FL, /* Reserved for ext3 */

-                [(uint8_t)'s'] = FS_SECRM_FL,        /* Secure deletion */

-                [(uint8_t)'u'] = FS_UNRM_FL,         /* Undelete */

-                [(uint8_t)'t'] = FS_NOTAIL_FL,       /* file tail should not be merged */

-                [(uint8_t)'T'] = FS_TOPDIR_FL,       /* Top of directory hierarchies*/

-                [(uint8_t)'C'] = FS_NOCOW_FL,        /* Do not cow file */

+#define ATTRIBUTES_ALL                          \

+        (FS_NOATIME_FL      |                   \

+         FS_SYNC_FL         |                   \

+         FS_DIRSYNC_FL      |                   \

+         FS_APPEND_FL       |                   \

+         FS_COMPR_FL        |                   \

+         FS_NODUMP_FL       |                   \

+         FS_EXTENT_FL       |                   \

+         FS_IMMUTABLE_FL    |                   \

+         FS_JOURNAL_DATA_FL |                   \

+         FS_SECRM_FL        |                   \

+         FS_UNRM_FL         |                   \

+         FS_NOTAIL_FL       |                   \

+         FS_TOPDIR_FL       |                   \

+         FS_NOCOW_FL)

+

+static int get_attribute_from_arg(Item *item) {

+

+        static const struct {

+                char character;

+                unsigned value;

+        } attributes[] = {

+                { 'A', FS_NOATIME_FL },      /* do not update atime */

+                { 'S', FS_SYNC_FL },         /* Synchronous updates */

+                { 'D', FS_DIRSYNC_FL },      /* dirsync behaviour (directories only) */

+                { 'a', FS_APPEND_FL },       /* writes to file may only append */

+                { 'c', FS_COMPR_FL },        /* Compress file */

+                { 'd', FS_NODUMP_FL },       /* do not dump file */

+                { 'e', FS_EXTENT_FL },       /* Top of directory hierarchies*/

+                { 'i', FS_IMMUTABLE_FL },    /* Immutable file */

+                { 'j', FS_JOURNAL_DATA_FL }, /* Reserved for ext3 */

+                { 's', FS_SECRM_FL },        /* Secure deletion */

+                { 'u', FS_UNRM_FL },         /* Undelete */

+                { 't', FS_NOTAIL_FL },       /* file tail should not be merged */

+                { 'T', FS_TOPDIR_FL },       /* Top of directory hierarchies*/

+                { 'C', FS_NOCOW_FL },        /* Do not cow file */

         };

-        char *p = item->argument;

+

         enum {

                 MODE_ADD,

                 MODE_DEL,

                 MODE_SET

         } mode = MODE_ADD;

-        unsigned long value = 0, mask = 0;

-        if (!p) {

-                log_error("\"%s\": setting ATTR need an argument", item->path);

-                return -EINVAL;

-        }

+        unsigned value = 0, mask = 0;

+        const char *p;

-        if (*p == '+') {

-                mode = MODE_ADD;

-                p++;

-        } else if (*p == '-') {

-                mode = MODE_DEL;

-                p++;

-        } else  if (*p == '=') {

-                mode = MODE_SET;

-                p++;

+        assert(item);

+

+        p = item->argument;

+        if (p) {

+                if (*p == '+') {

+                        mode = MODE_ADD;

+                        p++;

+                } else if (*p == '-') {

+                        mode = MODE_DEL;

+                        p++;

+                } else  if (*p == '=') {

+                        mode = MODE_SET;

+                        p++;

+                }

         }

-        if (!*p && mode != MODE_SET) {

-                log_error("\"%s\": setting ATTR: argument is empty", item->path);

+        if (isempty(p) && mode != MODE_SET) {

+                log_error("Setting file attribute on '%s' needs an attribute specification.", item->path);

                 return -EINVAL;

         }

-        for (; *p ; p++) {

-                if ((uint8_t)*p > ELEMENTSOF(attributes) || attributes[(uint8_t)*p] == 0) {

-                        log_error("\"%s\": setting ATTR: unknown attr '%c'", item->path, *p);

+

+        for (; p && *p ; p++) {

+                unsigned i, v;

+

+                for (i = 0; i < ELEMENTSOF(attributes); i++)

+                        if (*p == attributes[i].character)

+                                break;

+

+                if (i >= ELEMENTSOF(attributes)) {

+                        log_error("Unknown file attribute '%c' on '%s'.", *p, item->path);

                         return -EINVAL;

                 }

+

+                v = attributes[i].value;

+

                 if (mode == MODE_ADD || mode == MODE_SET)

-                        value |= attributes[(uint8_t)*p];

+                        value |= v;

                 else

-                        value &= ~attributes[(uint8_t)*p];

-                mask |= attributes[(uint8_t)*p];

+                        value &= ~v;

+

+                mask |= v;

         }

         if (mode == MODE_SET)

-                mask |= ALL_ATTRIBS;

+                mask |= ATTRIBUTES_ALL;

-        assert(mask);

+        assert(mask != 0);

-        item->attrib_mask = mask;

-        item->attrib_value = value;

-        item->attrib_set = true;

+        item->attribute_mask = mask;

+        item->attribute_value = value;

+        item->attribute_set = true;

         return 0;

-

 }

-static int path_set_attrib(Item *item, const char *path) {

+static int path_set_attribute(Item *item, const char *path) {

         _cleanup_close_ int fd = -1;

-        int r;

-        unsigned f;

         struct stat st;

+        unsigned f;

+        int r;

-        /* do nothing */

-        if (item->attrib_mask == 0 || !item->attrib_set)

-                return 0;

-        /*

-         * It is OK to ignore an lstat() error, because the error

-         * will be catch by the open() below anyway

-         */

-        if (lstat(path, &st) == 0 &&

-            !S_ISREG(st.st_mode) && !S_ISDIR(st.st_mode)) {

+        if (!item->attribute_set || item->attribute_mask == 0)

                 return 0;

-        }

         fd = open(path, O_RDONLY|O_NONBLOCK|O_CLOEXEC);

         if (fd < 0)

-                return log_error_errno(errno, "Cannot open \"%s\": %m", path);

+                return log_error_errno(errno, "Cannot open '%s': %m", path);

-        f = item->attrib_value & item->attrib_mask;

+        if (fstat(fd, &st) < 0)

+                return log_error_errno(errno, "Cannot stat '%s': %m", path);

+

+        /* Issuing the file attribute ioctls on device nodes is not

+         * safe, as that will be delivered to the drivers, not the

+         * file system containing the device node. */

+        if (!S_ISREG(st.st_mode) && !S_ISDIR(st.st_mode)) {

+                log_error("Setting file flags is only supported on regular files and directories, cannot set on '%s'.", path);

+                return -EINVAL;

+        }

+

+        f = item->attribute_value & item->attribute_mask;

+

+        /* Mask away directory-specific flags */

         if (!S_ISDIR(st.st_mode))

                 f &= ~FS_DIRSYNC_FL;

-        r = change_attr_fd(fd, f, item->attrib_mask);

+

+        r = chattr_fd(fd, f, item->attribute_mask);

         if (r < 0)

-                return log_error_errno(errno,

-                        "Cannot set attrib for \"%s\", value=0x%08lx, mask=0x%08lx: %m",

-                        path, item->attrib_value, item->attrib_mask);

+                return log_error_errno(r,

+                        "Cannot set file attribute for '%s', value=0x%08x, mask=0x%08x: %m",

+                        path, item->attribute_value, item->attribute_mask);

         return 0;

 }

@@ -1394,14 +1415,14 @@ static int create_item(Item *i) {

                         return r;

                 break;

-        case SET_ATTRIB:

-                r = glob_item(i, path_set_attrib, false);

+        case SET_ATTRIBUTE:

+                r = glob_item(i, path_set_attribute, false);

                 if (r < 0)

                         return r;

                 break;

-        case RECURSIVE_SET_ATTRIB:

-                r = glob_item(i, path_set_attrib, true);

+        case RECURSIVE_SET_ATTRIBUTE:

+                r = glob_item(i, path_set_attribute, true);

                 if (r < 0)

                         return r;

                 break;

@@ -1851,13 +1872,13 @@ static int parse_line(const char *fname, unsigned line, const char *buffer) {

                         return r;

                 break;

-        case SET_ATTRIB:

-        case RECURSIVE_SET_ATTRIB:

+        case SET_ATTRIBUTE:

+        case RECURSIVE_SET_ATTRIBUTE:

                 if (!i.argument) {

-                        log_error("[%s:%u] Set attrib requires argument.", fname, line);

+                        log_error("[%s:%u] Set file attribute requires argument.", fname, line);

                         return -EBADMSG;

                 }

-                r = get_attrib_from_arg(&i);

+                r = get_attribute_from_arg(&i);

                 if (r < 0)

                         return r;

                 break;