rootdev: Don't try to access /dev/block.android-wear-n-preview-3android-wear-n-preview-1android-n-preview-4android-n-preview-3android-n-preview-2android-n-preview-1android-cts_7.1_r1android-cts-7.1_r9android-cts-7.1_r8android-cts-7.1_r7android-cts-7.1_r6android-cts-7.1_r5android-cts-7.1_r4android-cts-7.1_r3android-cts-7.1_r29android-cts-7.1_r28android-cts-7.1_r27android-cts-7.1_r26android-cts-7.1_r25android-cts-7.1_r24android-cts-7.1_r23android-cts-7.1_r22android-cts-7.1_r21android-cts-7.1_r20android-cts-7.1_r2android-cts-7.1_r19android-cts-7.1_r18android-cts-7.1_r17android-cts-7.1_r16android-cts-7.1_r15android-cts-7.1_r14android-cts-7.1_r13android-cts-7.1_r12android-cts-7.1_r11android-cts-7.1_r10android-cts-7.1_r1android-cts-7.0_r9android-cts-7.0_r8android-cts-7.0_r7android-cts-7.0_r6android-cts-7.0_r5android-cts-7.0_r4android-cts-7.0_r33android-cts-7.0_r32android-cts-7.0_r31android-cts-7.0_r30android-cts-7.0_r3android-cts-7.0_r29android-cts-7.0_r28android-cts-7.0_r27android-cts-7.0_r26android-cts-7.0_r25android-cts-7.0_r24android-cts-7.0_r23android-cts-7.0_r22android-cts-7.0_r21android-cts-7.0_r20android-cts-7.0_r2android-cts-7.0_r19android-cts-7.0_r18android-cts-7.0_r17android-cts-7.0_r16android-cts-7.0_r15android-cts-7.0_r14android-cts-7.0_r13android-cts-7.0_r12android-cts-7.0_r11android-cts-7.0_r10android-cts-7.0_r1android-7.1.2_r9android-7.1.2_r8android-7.1.2_r6android-7.1.2_r5android-7.1.2_r4android-7.1.2_r39android-7.1.2_r38android-7.1.2_r37android-7.1.2_r36android-7.1.2_r33android-7.1.2_r32android-7.1.2_r30android-7.1.2_r3android-7.1.2_r29android-7.1.2_r28android-7.1.2_r27android-7.1.2_r25android-7.1.2_r24android-7.1.2_r23android-7.1.2_r2android-7.1.2_r19android-7.1.2_r18android-7.1.2_r17android-7.1.2_r16android-7.1.2_r15android-7.1.2_r14android-7.1.2_r13android-7.1.2_r12android-7.1.2_r11android-7.1.2_r10android-7.1.2_r1android-7.1.1_r9android-7.1.1_r8android-7.1.1_r7android-7.1.1_r61android-7.1.1_r60android-7.1.1_r6android-7.1.1_r59android-7.1.1_r58android-7.1.1_r57android-7.1.1_r56android-7.1.1_r55android-7.1.1_r54android-7.1.1_r53android-7.1.1_r52android-7.1.1_r51android-7.1.1_r50android-7.1.1_r49android-7.1.1_r48android-7.1.1_r47android-7.1.1_r46android-7.1.1_r45android-7.1.1_r44android-7.1.1_r43android-7.1.1_r42android-7.1.1_r41android-7.1.1_r40android-7.1.1_r4android-7.1.1_r39android-7.1.1_r38android-7.1.1_r35android-7.1.1_r33android-7.1.1_r32android-7.1.1_r31android-7.1.1_r3android-7.1.1_r28android-7.1.1_r27android-7.1.1_r26android-7.1.1_r25android-7.1.1_r24android-7.1.1_r23android-7.1.1_r22android-7.1.1_r21android-7.1.1_r20android-7.1.1_r2android-7.1.1_r17android-7.1.1_r16android-7.1.1_r15android-7.1.1_r14android-7.1.1_r13android-7.1.1_r12android-7.1.1_r11android-7.1.1_r10android-7.1.1_r1android-7.1.0_r7android-7.1.0_r6android-7.1.0_r5android-7.1.0_r4android-7.1.0_r3android-7.1.0_r2android-7.1.0_r1android-7.0.0_r9android-7.0.0_r8android-7.0.0_r7android-7.0.0_r6android-7.0.0_r5android-7.0.0_r4android-7.0.0_r36android-7.0.0_r35android-7.0.0_r34android-7.0.0_r33android-7.0.0_r32android-7.0.0_r31android-7.0.0_r30android-7.0.0_r3android-7.0.0_r29android-7.0.0_r28android-7.0.0_r27android-7.0.0_r24android-7.0.0_r21android-7.0.0_r19android-7.0.0_r17android-7.0.0_r15android-7.0.0_r14android-7.0.0_r13android-7.0.0_r12android-7.0.0_r11android-7.0.0_r10android-7.0.0_r1nougat-releasenougat-mr2.3-releasenougat-mr2.2-releasenougat-mr2.1-releasenougat-mr2-security-releasenougat-mr2-releasenougat-mr2-pixel-releasenougat-mr2-devnougat-mr1.8-releasenougat-mr1.7-releasenougat-mr1.6-releasenougat-mr1.5-releasenougat-mr1.4-releasenougat-mr1.3-releasenougat-mr1.2-releasenougat-mr1.1-releasenougat-mr1-volantis-releasenougat-mr1-security-releasenougat-mr1-releasenougat-mr1-flounder-releasenougat-mr1-devnougat-mr1-cts-releasenougat-mr0.5-releasenougat-dr1-releasenougat-devnougat-cts-releasenougat-bugfix-releasebrillo-m9-releasebrillo-m9-devbrillo-m8-releasebrillo-m8-devbrillo-m7-releasebrillo-m7-mr-devbrillo-m7-devbrillo-m10-releasebrillo-m10-dev

When the device used to back a path is found in /sys/block, rootdev will
double check that /dev/block/<device name> exists and that the dev_t
matches the one in /sys/block/.
On Android, the manufacturer can add an SELinux context for that device
node which will prevent core daemons from accessing it, failing the call
to rootdev.

To avoid this, rootdev should return the device node path without trying
to access it.

This CL also enable building with Clang to ensure we use the strictest
compiler possible.

BUG: 24143423
BUG: 24267261
TEST: metricsd starts and find the main disk without any SELinux denial.
TEST: builds with clang and -Werror.

Change-Id: Icfe64695c28277d4c8eb9c89de1e13a767a703b8

1 files changed, 6 insertions, 8 deletions

diff --git a/rootdev.c b/rootdev.c
index f0de1ff..e4c6d55 100644
--- a/rootdev.c
+++ b/rootdev.c
@@ -343,9 +343,8 @@ int rootdev_create_devices(const char *name, dev_t dev, bool symlink) {
 }
 
 int rootdev_get_path(char *path, size_t size, const char *device,
-                     dev_t dev, const char *dev_path) {
+                     const char *dev_path) {
   int path_len;
-  struct stat dev_statbuf;
 
   if (!dev_path)
     dev_path = kDefaultDevPath;
@@ -357,11 +356,10 @@ int rootdev_get_path(char *path, size_t size, const char *device,
   if (path_len != strlen(dev_path) + 1 + strlen(device))
     return -1;
 
-  if (stat(path, &dev_statbuf) != 0)
-    return 1;
-
-  if (dev && dev != dev_statbuf.st_rdev)
-    return 2;
+  // TODO(bsimonnet): We should check that |path| exists and is the right
+  // device. We don't do this currently as OEMs can add custom SELinux rules
+  // which may prevent us from accessing this.
+  // See b/24267261.
 
   return 0;
 }
@@ -397,7 +395,7 @@ int rootdev_wrapper(char *path, size_t size,
     rootdev_strip_partition(devname, size);
   }
 
-  res = rootdev_get_path(path, size, devname, *dev, dev_path);
+  res = rootdev_get_path(path, size, devname, dev_path);
 
   return res;
 }