timestamp: error out if fstat and lstat st_ino and st_dev are not the same

diff --git a/timestamp.c b/timestamp.c
index 0d8f9c3b9dbf413f61b7a7aadb82025e19429c64..baa713e0d59d1bf4887e50fa6a1e51460db8a22b 100644 (file)
--- a/timestamp.c
+++ b/timestamp.c
@@ -198,14 +198,21 @@ timestamp_name()
 static int
 opentsdir()
 {
 static int
 opentsdir()
 {

-       struct stat st;
+       struct stat st, stl;

        int fd;
        int isnew;
 
        int fd;
        int isnew;
 

-       fd = -1;

        isnew = 0;
 
        isnew = 0;
 

+

 reopen:
 reopen:

+       if (lstat(TIMESTAMP_DIR, &stl) == -1) {
+               if (!(errno == ENOENT && isnew == 0))
+                       err(1, "lstat: %s", TIMESTAMP_DIR);
+       } else if ((stl.st_mode & S_IFMT) != S_IFDIR) {
+               errx(1, "%s: not a directory", TIMESTAMP_DIR);
+       }
+

        if ((fd = open(TIMESTAMP_DIR, O_RDONLY | O_DIRECTORY)) == -1) {
                if (errno == ENOENT && isnew == 0) {
                        if (mkdir(TIMESTAMP_DIR, (S_IRUSR|S_IWUSR|S_IXUSR)) != 0)
        if ((fd = open(TIMESTAMP_DIR, O_RDONLY | O_DIRECTORY)) == -1) {
                if (errno == ENOENT && isnew == 0) {
                        if (mkdir(TIMESTAMP_DIR, (S_IRUSR|S_IWUSR|S_IXUSR)) != 0)


@@ -221,8 +228,9 @@ recheck:
        if (fstat(fd, &st) == -1)
                err(1, "fstatat");
 
        if (fstat(fd, &st) == -1)
                err(1, "fstatat");
 

-       if ((st.st_mode & S_IFMT) != S_IFDIR)
-               errx(1, "timestamp directory is not a directory");
+       if (stl.st_ino != st.st_ino || stl.st_dev != st.st_dev)
+               errx(1, "timestamp directory lstat and fstat are different files");
+

        if ((st.st_mode & (S_IWGRP|S_IRGRP|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH)) != 0)
                errx(1, "timestamp directory has wrong permissions");
 
        if ((st.st_mode & (S_IWGRP|S_IRGRP|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH)) != 0)
                errx(1, "timestamp directory has wrong permissions");
 


@@ -310,7 +318,7 @@ timestamp_set(int fd, int secs)
 int
 timestamp_open(int *valid, int secs)
 {
 int
 timestamp_open(int *valid, int secs)
 {

-       struct stat st;
+       struct stat st, stl;

        int dirfd, fd;
        gid_t gid;
        const char *name;
        int dirfd, fd;
        gid_t gid;
        const char *name;


@@ -322,20 +330,36 @@ timestamp_open(int *valid, int secs)
        if ((dirfd = opentsdir()) == -1)
                errx(1, "opentsdir");
 
        if ((dirfd = opentsdir()) == -1)
                errx(1, "opentsdir");
 

+       if (fstatat(dirfd, name, &stl, AT_SYMLINK_NOFOLLOW) == -1) {
+               if (errno != ENOENT)
+                       err(1, "fstatat");
+       } else if ((stl.st_mode & S_IFMT) != S_IFREG) {
+               errx(1, "timestamp: not a regular file");
+       }
+

        if ((fd = openat(dirfd, name, (O_RDWR), (S_IRUSR|S_IWUSR))) == -1)
                if (errno != ENOENT)
                        err(1, "open timestamp file");
 
        if ((fd = openat(dirfd, name, (O_RDWR), (S_IRUSR|S_IWUSR))) == -1)
                if (errno != ENOENT)
                        err(1, "open timestamp file");
 

-       if (fd == -1) {
+       /*
+        * If the file was opened, check if fstat and lstat results are
+        * the same file.
+        * If the file doesn't exist and we create it with O_CREAT|O_EXCL,
+        * it is already known that the file is a regular file.
+        */
+       if (fd != -1) {
+               if (fstat(fd, &st) == -1)
+                       err(1, "stat");
+               if (stl.st_ino != st.st_ino || stl.st_dev != st.st_dev)
+                       errx(1, "timestamp file lstat and fstat are different files");
+       } else {

                if ((fd = openat(dirfd, name, (O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW),
                    (S_IRUSR|S_IWUSR))) == -1)
                        err(1, "open timestamp file");
                if ((fd = openat(dirfd, name, (O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW),
                    (S_IRUSR|S_IWUSR))) == -1)
                        err(1, "open timestamp file");

+               if (fstat(fd, &st) == -1)
+                       err(1, "stat");

        }
 
        }
 

-       if (fstat(fd, &st) == -1)
-               err(1, "stat");
-       if ((st.st_mode & S_IFMT) != S_IFREG)
-               errx(1, "timestamp is not a regular file");

        if ((st.st_mode & (S_IWGRP|S_IRGRP|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH)) != 0)
                errx(1, "timestamp file has wrong permissions");
 
        if ((st.st_mode & (S_IWGRP|S_IRGRP|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH)) != 0)
                errx(1, "timestamp file has wrong permissions");