-[SNTFileInfo initWithEndpointSecurityFile:error:] stat after open

Source/common/BUILD

@@ -449,7 +449,7 @@ objc_library(
 
 santa_unit_test(
     name = "SNTFileInfoTest",
-    srcs = ["SNTFileInfoTest.m"],
+    srcs = ["SNTFileInfoTest.mm"],
     resources = [
         "testdata/32bitplist",
         "testdata/bad_pagezero",
@@ -459,7 +459,10 @@ santa_unit_test(
         "testdata/BundleExample.app/**",
         "testdata/DirectoryBundle/**",
     ]),
-    deps = [":SNTFileInfo"],
+    deps = [
+        ":SNTFileInfo",
+        ":TestUtils",
+    ],
 )
 
 santa_unit_test(

Source/common/SNTFileInfo.m

@@ -67,26 +67,6 @@ @implementation SNTFileInfo
 extern NSString *const NSURLQuarantinePropertiesKey WEAK_IMPORT_ATTRIBUTE;
 
 - (instancetype)initWithResolvedPath:(NSString *)path error:(NSError **)error {
-  struct stat fileStat;
-  if (path.length) {
-    lstat(path.UTF8String, &fileStat);
-  }
-  return [self initWithResolvedPath:path stat:&fileStat error:error];
-}
-
-- (instancetype)initWithEndpointSecurityFile:(const es_file_t *)esFile error:(NSError **)error {
-  return [self initWithResolvedPath:@(esFile->path.data) stat:&esFile->stat error:error];
-}
-
-- (instancetype)initWithResolvedPath:(NSString *)path
-                                stat:(const struct stat *)fileStat
-                               error:(NSError **)error {
-  if (!fileStat) {
-    // This is a programming error. Bail.
-    LOGE(@"NULL stat buffer unsupported");
-    exit(EXIT_FAILURE);
-  }
-
   self = [super init];
   if (self) {
     _path = path;
@@ -100,39 +80,50 @@ - (instancetype)initWithResolvedPath:(NSString *)path
       return nil;
     }
 
-    if (!((S_IFMT & fileStat->st_mode) == S_IFREG)) {
+    int fd = open([_path UTF8String], O_RDONLY | O_CLOEXEC);
+    if (fd < 0) {
       if (error) {
-        NSString *errStr = [NSString stringWithFormat:@"Non regular file: %s", strerror(errno)];
+        NSString *errStr = [NSString stringWithFormat:@"Unable to open file: %s", strerror(errno)];
         *error = [NSError errorWithDomain:@"com.google.santa.fileinfo"
-                                     code:290
+                                     code:280
                                  userInfo:@{NSLocalizedDescriptionKey : errStr}];
       }
       return nil;
     }
+    _fileHandle = [[NSFileHandle alloc] initWithFileDescriptor:fd closeOnDealloc:YES];
 
-    _fileSize = fileStat->st_size;
-    _vnode = (SantaVnode){.fsid = fileStat->st_dev, .fileid = fileStat->st_ino};
-
-    if (_fileSize == 0) return nil;
-
-    if (fileStat->st_uid != 0) {
-      struct passwd *pwd = getpwuid(fileStat->st_uid);
-      if (pwd) {
-        _fileOwnerHomeDir = @(pwd->pw_dir);
+    struct stat fileStat;
+    if (fstat(fd, &fileStat) == -1) {
+      if (error) {
+        NSString *errStr = [NSString stringWithFormat:@"Unable to stat file: %s", strerror(errno)];
+        *error = [NSError errorWithDomain:@"com.google.santa.fileinfo"
+                                     code:281
+                                 userInfo:@{NSLocalizedDescriptionKey : errStr}];
       }
+      return nil;
     }
 
-    int fd = open([_path UTF8String], O_RDONLY | O_CLOEXEC);
-    if (fd < 0) {
+    if (!((S_IFMT & fileStat.st_mode) == S_IFREG)) {
       if (error) {
-        NSString *errStr = [NSString stringWithFormat:@"Unable to open file: %s", strerror(errno)];
+        NSString *errStr = [NSString stringWithFormat:@"Non regular file: %s", strerror(errno)];
         *error = [NSError errorWithDomain:@"com.google.santa.fileinfo"
-                                     code:280
+                                     code:290
                                  userInfo:@{NSLocalizedDescriptionKey : errStr}];
       }
       return nil;
     }
-    _fileHandle = [[NSFileHandle alloc] initWithFileDescriptor:fd closeOnDealloc:YES];
+
+    _fileSize = fileStat.st_size;
+    _vnode = (SantaVnode){.fsid = fileStat.st_dev, .fileid = fileStat.st_ino};
+
+    if (_fileSize == 0) return nil;
+
+    if (fileStat.st_uid != 0) {
+      struct passwd *pwd = getpwuid(fileStat.st_uid);
+      if (pwd) {
+        _fileOwnerHomeDir = @(pwd->pw_dir);
+      }
+    }
   }
 
   return self;
@@ -156,6 +147,21 @@ - (instancetype)initWithPath:(NSString *)path error:(NSError **)error {
   return self;
 }
 
+- (instancetype)initWithEndpointSecurityFile:(const es_file_t *)esFile error:(NSError **)error {
+  SNTFileInfo *fi = [self initWithResolvedPath:@(esFile->path.data) error:error];
+  if (fi.vnode.fsid != esFile->stat.st_dev || fi.vnode.fileid != esFile->stat.st_ino ||
+      fi.fileSize != esFile->stat.st_size) {
+    if (error) {
+      NSString *errStr = @"ES stat mismatch";
+      *error = [NSError errorWithDomain:@"com.google.santa.fileinfo"
+                                   code:261
+                               userInfo:@{NSLocalizedDescriptionKey : errStr}];
+    }
+    return nil;
+  }
+  return fi;
+}
+
 - (instancetype)initWithPath:(NSString *)path {
   return [self initWithPath:path error:NULL];
 }

Source/common/SNTFileInfoTest.m → Source/common/SNTFileInfoTest.mm

@@ -13,6 +13,8 @@
 ///    limitations under the License.
 
 #import <XCTest/XCTest.h>
+#include <sys/stat.h>
+#include "Source/common/TestUtils.h"
 
 #import "Source/common/SNTFileInfo.h"
 
@@ -250,4 +252,21 @@ - (void)testEmbeddedInfoPlist {
   XCTAssertNotNil([sut infoPlist]);
 }
 
+- (void)testWithEndpointSecurityFile {
+  struct stat sb;
+  XCTAssertEqual(stat("/usr/bin/yes", &sb), 0);
+  es_file_t file = MakeESFile("/usr/bin/yes", sb);
+  NSError *error;
+  SNTFileInfo *sut = [[SNTFileInfo alloc] initWithEndpointSecurityFile:&file error:&error];
+  XCTAssertNotNil(sut);
+}
+
+- (void)testWithEndpointSecurityFileError {
+  // The constructed ES stat will not match `/usr/bin/yes` on disk stat values.
+  es_file_t file = MakeESFile("/usr/bin/yes");
+  NSError *error;
+  SNTFileInfo *sut = [[SNTFileInfo alloc] initWithEndpointSecurityFile:&file error:&error];
+  XCTAssertNil(sut);
+}
+
 @end