[systemd-devel] [PATCH] ima-setup: write policy one line at a time

[Zbigniew Jędrzejewski-Szmek]

ima_write_policy() expects data to be written as one or more
rules, no more than PAGE_SIZE at a time. Easiest way to ensure
that we are not splitting rules is to read and write on line at
a time.

https://bugzilla.redhat.com/show_bug.cgi?id=1226948
---
 src/core/ima-setup.c | 39 +++++++++++++++++----------------------
 1 file changed, 17 insertions(+), 22 deletions(-)

diff --git a/src/core/ima-setup.c b/src/core/ima-setup.c
index 4d8b638115..5b3d16cd31 100644
--- a/src/core/ima-setup.c
+++ b/src/core/ima-setup.c
@@ -23,9 +23,6 @@
 
 #include <unistd.h>
 #include <errno.h>
-#include <fcntl.h>
-#include <sys/stat.h>
-#include <sys/mman.h>
 
 #include "ima-setup.h"
 #include "util.h"
@@ -36,20 +33,19 @@
 #define IMA_POLICY_PATH "/etc/ima/ima-policy"
 
 int ima_setup(void) {
-        int r = 0;
-
 #ifdef HAVE_IMA
-        _cleanup_close_ int policyfd = -1, imafd = -1;
-        struct stat st;
-        char *policy;
+        _cleanup_fclose_ FILE *input = NULL;
+        _cleanup_close_ int imafd = -1;
+        char line[LINE_MAX];
+        unsigned lineno = 0;
 
         if (access(IMA_SECFS_DIR, F_OK) < 0) {
                 log_debug("IMA support is disabled in the kernel, ignoring.");
                 return 0;
         }
 
-        policyfd = open(IMA_POLICY_PATH, O_RDONLY|O_CLOEXEC);
-        if (policyfd < 0) {
+        input = fopen(IMA_POLICY_PATH, "re");
+        if (!input) {
                 log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_WARNING, errno,
                                "Failed to open the IMA custom policy file "IMA_POLICY_PATH", ignoring: %m");
                 return 0;
@@ -66,20 +62,19 @@ int ima_setup(void) {
                 return 0;
         }
 
-        if (fstat(policyfd, &st) < 0)
-                return log_error_errno(errno, "Failed to fstat "IMA_POLICY_PATH": %m");
+        FOREACH_LINE(line, input,
+                     return log_error_errno(errno, "Failed to read the IMA custom policy file "IMA_POLICY_PATH": %m")) {
+                size_t len;
 
-        policy = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, policyfd, 0);
-        if (policy == MAP_FAILED)
-                return log_error_errno(errno, "Failed to mmap "IMA_POLICY_PATH": %m");
+                len = strlen(line);
+                lineno++;
 
-        r = loop_write(imafd, policy, (size_t) st.st_size, false);
-        if (r < 0)
-                log_error_errno(r, "Failed to load the IMA custom policy file "IMA_POLICY_PATH": %m");
-        else
-                log_info("Successfully loaded the IMA custom policy "IMA_POLICY_PATH".");
+                if (len > 0 && write(imafd, line, len) < 0)
+                        return log_error_errno(errno, "Failed to load the IMA custom policy file "IMA_POLICY_PATH"%u: %m",
+                                               lineno);
+        }
 
-        munmap(policy, st.st_size);
+        log_info("Successfully loaded the IMA custom policy "IMA_POLICY_PATH".");
 #endif /* HAVE_IMA */
-        return r;
+        return 0;
 }
-- 
2.1.0