3 files changed, 71 insertions, 91 deletions

diff --git a/src/firejail/firejail.h b/src/firejail/firejail.h
index 13b7b9523..a6924b830 100644
--- a/src/firejail/firejail.h
+++ b/src/firejail/firejail.h
@@ -567,7 +567,7 @@ typedef struct {
 // mountinfo.c
 MountData *get_last_mount(void);
 int get_mount_id(int fd);
-char **build_mount_array(const int mount_id, const char *path);
+char **build_mount_array(const int mountid, const char *path);
 
 // fs_var.c
 void fs_var_log(void);  // mounting /var/log
diff --git a/src/firejail/fs.c b/src/firejail/fs.c
index 0b9a38035..9c1b889ed 100644
--- a/src/firejail/fs.c
+++ b/src/firejail/fs.c
@@ -654,12 +654,13 @@ static void fs_remount_rec(const char *path, OPERATION op) {
 
         // build array with all mount points that need to get remounted
         char **arr = build_mount_array(mountid, path);
-        assert(arr);
+        if (!arr)
+                return;
         // remount
-        char **tmp = arr;
-        while (*tmp) {
-                fs_remount_simple(*tmp, op);
-                free(*tmp++);
+        int i;
+        for (i = 0; arr[i]; i++) {
+                fs_remount_simple(arr[i], op);
+                free(arr[i]);
         }
         free(arr);
 }
diff --git a/src/firejail/mountinfo.c b/src/firejail/mountinfo.c
index 304f80eee..ee437e10b 100644
--- a/src/firejail/mountinfo.c
+++ b/src/firejail/mountinfo.c
@@ -33,43 +33,38 @@ static MountData mdata;
 
 
 // Convert octal escape sequence to decimal value
-static int read_oct(const char *path) {
-        int dec = 0;
-        int digit, i;
-        // there are always exactly three octal digits
-        for (i = 1; i < 4; i++) {
-                digit = *(path + i);
-                if (digit < '0' || digit > '7') {
-                        fprintf(stderr, "Error: cannot read /proc/self/mountinfo\n");
-                        exit(1);
-                }
-                dec = (dec << 3) + (digit - '0');
-        }
-        return dec;
+static unsigned read_oct(char *s) {
+        assert(s[0] == '\\');
+        s++;
+
+        int i;
+        for (i = 0; i < 3; i++)
+                assert(s[i] >= '0' && s[i] <= '7');
+
+        return ((s[0] - '0') << 6 |
+                (s[1] - '0') << 3 |
+                (s[2] - '0') << 0);
 }
 
 // Restore empty spaces in pathnames extracted from /proc/self/mountinfo
 static void unmangle_path(char *path) {
-        char *p = strchr(path, '\\');
-        if (p && read_oct(p) == ' ') {
-                *p = ' ';
-                int i = 3;
-                do {
-                        p++;
-                        if (*(p + i) == '\\' && read_oct(p + i) == ' ') {
-                                *p = ' ';
-                                i += 3;
-                        }
-                        else
-                                *p = *(p + i);
-                } while (*p);
-        }
+        char *r = strchr(path, '\\');
+        if (!r)
+                return;
+
+        char *w = r;
+        do {
+                while (*r == '\\') {
+                        *w++ = read_oct(r);
+                        r += 4;
+                }
+                *w++ = *r;
+        } while (*r++);
 }
 
 // Parse a line from /proc/self/mountinfo,
 // the function does an exit(1) if anything goes wrong.
 static void parse_line(char *line, MountData *output) {
-        assert(line && output);
         memset(output, 0, sizeof(*output));
         // extract mount id, filesystem name, directory and filesystem types
         // examples:
@@ -87,8 +82,6 @@ static void parse_line(char *line, MountData *output) {
         char *ptr = strtok(line, " ");
         if (!ptr)
                 goto errexit;
-        if (ptr != line)
-                goto errexit;
         output->mountid = atoi(ptr);
         int cnt = 1;
 
@@ -109,10 +102,9 @@ static void parse_line(char *line, MountData *output) {
         ptr = strtok(NULL, " ");
         if (!ptr)
                 goto errexit;
-        output->fstype = ptr++;
+        output->fstype = ptr;
 
-
-        if (output->mountid == 0 ||
+        if (output->mountid < 0 ||
             output->fsname == NULL ||
             output->dir == NULL ||
             output->fstype == NULL)
@@ -195,9 +187,9 @@ static int get_mount_id_from_fdinfo(int fd) {
         char buf[MAX_BUF];
         while (fgets(buf, MAX_BUF, fp)) {
                 if (strncmp(buf, "mnt_id:", 7) == 0) {
-                        if (sscanf(buf + 7, "%d", &rv) != 1)
-                                goto errexit;
-                        break;
+                        if (sscanf(buf + 7, "%d", &rv) == 1)
+                                break;
+                        goto errexit;
                 }
         }
 
@@ -219,62 +211,50 @@ int get_mount_id(int fd) {
 
 // Check /proc/self/mountinfo if path contains any mounts points.
 // Returns an array that can be iterated over for recursive remounting.
-char **build_mount_array(const int mount_id, const char *path) {
+char **build_mount_array(const int mountid, const char *path) {
         assert(path);
 
-        // open /proc/self/mountinfo
         FILE *fp = fopen("/proc/self/mountinfo", "re");
         if (!fp) {
                 fprintf(stderr, "Error: cannot read /proc/self/mountinfo\n");
                 exit(1);
         }
 
-        // array to be returned
-        size_t cnt = 0;
+        // try to find line with mount id
+        int found = 0;
+        MountData mntp;
+        char line[MAX_BUF];
+        while (fgets(line, MAX_BUF, fp)) {
+                parse_line(line, &mntp);
+                if (mntp.mountid == mountid) {
+                        found = 1;
+                        break;
+                }
+        }
+
+        if (!found) {
+                fclose(fp);
+                return NULL;
+        }
+
+        // allocate array
         size_t size = 32;
         char **rv = malloc(size * sizeof(*rv));
         if (!rv)
                 errExit("malloc");
 
-        // read /proc/self/mountinfo
-        size_t pathlen = strlen(path);
-        char buf[MAX_BUF];
-        MountData mntp;
-        int found = 0;
+        // add directory itself
+        size_t cnt = 0;
+        rv[cnt] = strdup(path);
+        if (rv[cnt] == NULL)
+                errExit("strdup");
 
-        if (fgets(buf, MAX_BUF, fp) == NULL) {
-                fprintf(stderr, "Error: cannot read /proc/self/mountinfo\n");
-                exit(1);
-        }
-        do {
-                parse_line(buf, &mntp);
-                // find mount point with mount id
-                if (!found) {
-                        if (mntp.mountid == mount_id) {
-                                // give up if mount id has been reassigned,
-                                // don't remount blacklisted path
-                                if (strncmp(mntp.dir, path, strlen(mntp.dir)) ||
-                                    strstr(mntp.fsname, "firejail.ro.dir") ||
-                                    strstr(mntp.fsname, "firejail.ro.file"))
-                                            break;
-
-                                rv[cnt] = strdup(path);
-                                if (rv[cnt] == NULL)
-                                        errExit("strdup");
-                                cnt++;
-                                found = 1;
-                                continue;
-                        }
-                        continue;
-                }
-                // from here on add all mount points below path,
-                // don't remount blacklisted paths
-                if (strncmp(mntp.dir, path, pathlen) == 0 &&
-                    mntp.dir[pathlen] == '/' &&
-                    strstr(mntp.fsname, "firejail.ro.dir") == NULL &&
-                    strstr(mntp.fsname, "firejail.ro.file") == NULL) {
-
-                        if (cnt == size) {
+        // and add all following mountpoints contained in this directory
+        size_t pathlen = strlen(path);
+        while (fgets(line, MAX_BUF, fp)) {
+                parse_line(line, &mntp);
+                if (strncmp(mntp.dir, path, pathlen) == 0 && mntp.dir[pathlen] == '/') {
+                        if (++cnt == size) {
                                 size *= 2;
                                 rv = realloc(rv, size * sizeof(*rv));
                                 if (!rv)
@@ -283,18 +263,17 @@ char **build_mount_array(const int mount_id, const char *path) {
                         rv[cnt] = strdup(mntp.dir);
                         if (rv[cnt] == NULL)
                                 errExit("strdup");
-                        cnt++;
                 }
-        } while (fgets(buf, MAX_BUF, fp));
+        }
+        fclose(fp);
 
-        if (cnt == size) {
-                size++;
+        // end of array
+        if (++cnt == size) {
+                ++size;
                 rv = realloc(rv, size * sizeof(*rv));
                 if (!rv)
                         errExit("realloc");
         }
-        rv[cnt] = NULL; // end of the array
-
-        fclose(fp);
+        rv[cnt] = NULL;
         return rv;
 }