diff options
| author | Masami Hiramatsu <mhiramat@kernel.org> | 2016-05-28 15:15:13 (GMT) |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2016-05-30 16:15:01 (GMT) |
| commit | 11870d714a1b744a0225e90b0b395346357defe9 (patch) | |
| tree | b0cabbde5a55ad879ec9505710bef357a385239c /tools/perf/util/symbol.c | |
| parent | dcd1e2a7ba63710843d559f1570628321e62223e (diff) | |
| download | linux-11870d714a1b744a0225e90b0b395346357defe9.tar.xz | |
perf symbols: Introduce filename__readable to check readability
Introduce filename__readable to check readability by opening the file
directly. Since the access(R_OK) just checks the readability based on
real UID/GID, it is ignored that the effective UID/GID and capabilities
for some special file (e.g. /proc/kcore).
filename__readable() directly opens given file with O_RDONLY so that the
kernel checks it by effective UID/GID and capabilities.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Hemant Kumar <hemant@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20160528151513.16098.97576.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/symbol.c')
| -rw-r--r-- | tools/perf/util/symbol.c | 32 |
1 files changed, 22 insertions, 10 deletions
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c index 54c4ff2..a469346 100644 --- a/tools/perf/util/symbol.c +++ b/tools/perf/util/symbol.c @@ -1641,6 +1641,20 @@ static int find_matching_kcore(struct map *map, char *dir, size_t dir_sz) return ret; } +/* + * Use open(O_RDONLY) to check readability directly instead of access(R_OK) + * since access(R_OK) only checks with real UID/GID but open() use effective + * UID/GID and actual capabilities (e.g. /proc/kcore requires CAP_SYS_RAWIO). + */ +static bool filename__readable(const char *file) +{ + int fd = open(file, O_RDONLY); + if (fd < 0) + return false; + close(fd); + return true; +} + static char *dso__find_kallsyms(struct dso *dso, struct map *map) { u8 host_build_id[BUILD_ID_SIZE]; @@ -1668,7 +1682,6 @@ static char *dso__find_kallsyms(struct dso *dso, struct map *map) /* Use /proc/kallsyms if possible */ if (is_host) { DIR *d; - int fd; /* If no cached kcore go with /proc/kallsyms */ d = opendir(path); @@ -1677,16 +1690,15 @@ static char *dso__find_kallsyms(struct dso *dso, struct map *map) closedir(d); /* - * Do not check the build-id cache, until we know we cannot use - * /proc/kcore. + * Do not check the build-id cache, unless we know we cannot use + * /proc/kcore or module maps don't match to /proc/kallsyms. + * To check readability of /proc/kcore, do not use access(R_OK) + * since /proc/kcore requires CAP_SYS_RAWIO to read and access + * can't check it. */ - fd = open("/proc/kcore", O_RDONLY); - if (fd != -1) { - close(fd); - /* If module maps match go with /proc/kallsyms */ - if (!validate_kcore_addresses("/proc/kallsyms", map)) - goto proc_kallsyms; - } + if (filename__readable("/proc/kcore") && + !validate_kcore_addresses("/proc/kallsyms", map)) + goto proc_kallsyms; /* Find kallsyms in build-id cache with kcore */ if (!find_matching_kcore(map, path, sizeof(path))) |