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@ -1,345 +0,0 @@ |
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From 10e8001ad876d8cb3b5a17c7492e713bbc047975 Mon Sep 17 00:00:00 2001 |
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From: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> |
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Date: Thu, 28 Mar 2019 18:31:29 -0400 |
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Subject: [PATCH] Fix: getgrnam is not MT-Safe, use getgrnam_r |
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Running the test suite under a Yocto musl build resulted in musl |
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coredump due to double freeing. |
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We get the following backtraces: |
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0 a_crash () at ./arch/x86_64/atomic_arch.h:108 |
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1 unmap_chunk (self=<optimized out>) at src/malloc/malloc.c:515 |
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2 free (p=<optimized out>) at src/malloc/malloc.c:526 |
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3 0x00007f46d9dc3849 in __getgrent_a (f=f@entry=0x7f46d9d1f7e0, gr=gr@entry=0x7f46d9e24460 <gr>, line=line@entry=0x7f46d9e26058 <line>, size=size@entry=0x7f46d92db550, mem=mem@entry=0x7f46d9e26050 <mem>, nmem=nmem@entry=0x7f46d92db558, res=0x7f46d92db548) at src/passwd/getgrent_a.c:45 |
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4 0x00007f46d9dc2e6b in __getgr_a (name=0x487242 "tracing", gid=gid@entry=0, gr=gr@entry=0x7f46d9e24460 <gr>, buf=buf@entry=0x7f46d9e26058 <line>, size=size@entry=0x7f46d92db550, mem=mem@entry=0x7f46d9e26050 <mem>, nmem=0x7f46d92db558, res=0x7f46d92db548) at src/passwd/getgr_a.c:30 |
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5 0x00007f46d9dc3733 in getgrnam (name=<optimized out>) at src/passwd/getgrent.c:37 |
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6 0x0000000000460b29 in utils_get_group_id (name=<optimized out>) at ../../../lttng-tools-2.10.6/src/common/utils.c:1241 |
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7 0x000000000044ee69 in thread_manage_health (data=<optimized out>) at ../../../../lttng-tools-2.10.6/src/bin/lttng-sessiond/main.c:4115 |
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8 0x00007f46d9de1541 in start (p=<optimized out>) at src/thread/pthread_create.c:195 |
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9 0x00007f46d9dee661 in __clone () at src/thread/x86_64/clone.s:22 |
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From another run: |
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0 a_crash () at ./arch/x86_64/atomic_arch.h:108 |
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1 unmap_chunk (self=<optimized out>) at src/malloc/malloc.c:515 |
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2 free (p=<optimized out>) at src/malloc/malloc.c:526 |
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3 0x00007f5abc210849 in __getgrent_a (f=f@entry=0x7f5abc2733e0, gr=gr@entry=0x7f5abc271460 <gr>, line=line@entry=0x7f5abc273058 <line>, size=size@entry=0x7f5abaef5510, mem=mem@entry=0x7f5abc273050 <mem>, nmem=nmem@entry=0x7f5abaef5518, res=0x7f5abaef5508) at src/passwd/getgrent_a.c:45 |
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4 0x00007f5abc20fe6b in __getgr_a (name=0x487242 "tracing", gid=gid@entry=0, gr=gr@entry=0x7f5abc271460 <gr>, buf=buf@entry=0x7f5abc273058 <line>, size=size@entry=0x7f5abaef5510, mem=mem@entry=0x7f5abc273050 <mem>, nmem=0x7f5abaef5518, res=0x7f5abaef5508) at src/passwd/getgr_a.c:30 |
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5 0x00007f5abc210733 in getgrnam (name=<optimized out>) at src/passwd/getgrent.c:37 |
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6 0x0000000000460b29 in utils_get_group_id (name=<optimized out>) at ../../../lttng-tools-2.10.6/src/common/utils.c:1241 |
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7 0x000000000042dee4 in notification_channel_socket_create () at ../../../../lttng-tools-2.10.6/src/bin/lttng-sessiond/notification-thread.c:238 |
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8 init_thread_state (state=0x7f5abaef5560, handle=0x7f5abbf9be40) at ../../../../lttng-tools-2.10.6/src/bin/lttng-sessiond/notification-thread.c:375 |
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9 thread_notification (data=0x7f5abbf9be40) at ../../../../lttng-tools-2.10.6/src/bin/lttng-sessiond/notification-thread.c:495 |
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10 0x00007f5abc22e541 in start (p=<optimized out>) at src/thread/pthread_create.c:195 |
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11 0x00007f5abc23b661 in __clone () at src/thread/x86_64/clone.s:22 |
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The problem was easily reproducible (~6 crash on ~300 runs). A prototype fix |
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using mutex around the getgrnam yielded no crash in over 1000 runs. This |
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patch yielded the same results as the prototype fix. |
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Unfortunately we cannot rely on a mutex in liblttng-ctl since we cannot |
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enforce the locking for the application using the lib. |
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Use getgrnam_r instead. |
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The previous implementation of utils_get_group_id returned the gid of |
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the root group (0) on error/not found. lttng_check_tracing_group needs |
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to know if an error/not found occured, returning the root group is not |
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enough. We now return the gid via the passed parameter. The caller is |
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responsible for either defaulting to the root group or propagating the |
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error. |
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We also do not want to warn when used in liblttng-ctl context. We might |
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want to move the warning elsewhere in the future. For now, pass a bool |
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if we need to warn or not. |
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Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> |
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---
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src/bin/lttng-consumerd/health-consumerd.c | 10 ++- |
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src/bin/lttng-relayd/health-relayd.c | 20 ++++-- |
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src/bin/lttng-sessiond/main.c | 24 +++++-- |
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src/bin/lttng-sessiond/notification-thread.c | 10 ++- |
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src/common/utils.c | 75 +++++++++++++++++--- |
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src/common/utils.h | 4 +- |
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src/lib/lttng-ctl/lttng-ctl.c | 8 +-- |
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7 files changed, 122 insertions(+), 29 deletions(-) |
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diff --git a/src/bin/lttng-consumerd/health-consumerd.c b/src/bin/lttng-consumerd/health-consumerd.c
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index 1e2f31e4..6045401a 100644
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--- a/src/bin/lttng-consumerd/health-consumerd.c
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+++ b/src/bin/lttng-consumerd/health-consumerd.c
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@@ -184,8 +184,14 @@ void *thread_manage_health(void *data)
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is_root = !getuid(); |
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if (is_root) { |
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/* lttng health client socket path permissions */ |
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- ret = chown(health_unix_sock_path, 0,
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- utils_get_group_id(tracing_group_name));
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+ gid_t gid;
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+
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+ ret = utils_get_group_id(tracing_group_name, true, &gid);
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+ if (ret) {
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+ gid = 0; /* Default to root group. */
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+ }
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+
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+ ret = chown(health_unix_sock_path, 0, gid);
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if (ret < 0) { |
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ERR("Unable to set group on %s", health_unix_sock_path); |
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PERROR("chown"); |
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diff --git a/src/bin/lttng-relayd/health-relayd.c b/src/bin/lttng-relayd/health-relayd.c
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index ba996621..962e88c4 100644
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--- a/src/bin/lttng-relayd/health-relayd.c
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+++ b/src/bin/lttng-relayd/health-relayd.c
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@@ -105,8 +105,14 @@ static int create_lttng_rundir_with_perm(const char *rundir)
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int is_root = !getuid(); |
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if (is_root) { |
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- ret = chown(rundir, 0,
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- utils_get_group_id(tracing_group_name));
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+ gid_t gid;
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+
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+ ret = utils_get_group_id(tracing_group_name, true, &gid);
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+ if (ret) {
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+ gid = 0; /* Default to root group.*/
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+ }
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+
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+ ret = chown(rundir, 0, gid);
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if (ret < 0) { |
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ERR("Unable to set group on %s", rundir); |
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PERROR("chown"); |
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@@ -256,8 +262,14 @@ void *thread_manage_health(void *data)
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is_root = !getuid(); |
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if (is_root) { |
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/* lttng health client socket path permissions */ |
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- ret = chown(health_unix_sock_path, 0,
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- utils_get_group_id(tracing_group_name));
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+ gid_t gid;
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+
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+ ret = utils_get_group_id(tracing_group_name, true, &gid);
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+ if (ret) {
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+ gid = 0; /* Default to root group */
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+ }
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+
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+ ret = chown(health_unix_sock_path, 0, gid);
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if (ret < 0) { |
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ERR("Unable to set group on %s", health_unix_sock_path); |
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PERROR("chown"); |
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diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c
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index fa6fa483..49307064 100644
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--- a/src/bin/lttng-sessiond/main.c
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+++ b/src/bin/lttng-sessiond/main.c
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@@ -4112,8 +4112,14 @@ static void *thread_manage_health(void *data)
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if (is_root) { |
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/* lttng health client socket path permissions */ |
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- ret = chown(config.health_unix_sock_path.value, 0,
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- utils_get_group_id(config.tracing_group_name.value));
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+ gid_t gid;
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+
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+ ret = utils_get_group_id(config.tracing_group_name.value, true, &gid);
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+ if (ret) {
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+ gid = 0; /* Default to root group */
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+ }
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+
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+ ret = chown(config.health_unix_sock_path.value, 0, &gid);
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if (ret < 0) { |
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ERR("Unable to set group on %s", config.health_unix_sock_path.value); |
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PERROR("chown"); |
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@@ -5238,7 +5244,10 @@ static int set_permissions(char *rundir)
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int ret; |
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gid_t gid; |
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- gid = utils_get_group_id(config.tracing_group_name.value);
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+ ret = utils_get_group_id(config.tracing_group_name.value, true, &gid);
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+ if (ret) {
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+ gid = 0; /* Default to root group */
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+ }
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/* Set lttng run dir */ |
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ret = chown(rundir, 0, gid); |
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@@ -5349,7 +5358,14 @@ static int set_consumer_sockets(struct consumer_data *consumer_data)
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goto error; |
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} |
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if (is_root) { |
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- ret = chown(path, 0, utils_get_group_id(config.tracing_group_name.value));
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+ gid_t gid;
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+
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+ ret = utils_get_group_id(config.tracing_group_name.value, true, &gid);
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+ if (ret) {
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+ gid = 0; /* Default to root group */
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+ }
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+
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+ ret = chown(path, 0, gid);
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if (ret < 0) { |
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ERR("Unable to set group on %s", path); |
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PERROR("chown"); |
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diff --git a/src/bin/lttng-sessiond/notification-thread.c b/src/bin/lttng-sessiond/notification-thread.c
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index 92ac597f..18a264d9 100644
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--- a/src/bin/lttng-sessiond/notification-thread.c
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+++ b/src/bin/lttng-sessiond/notification-thread.c
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@@ -235,8 +235,14 @@ int notification_channel_socket_create(void)
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} |
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if (getuid() == 0) { |
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- ret = chown(sock_path, 0,
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- utils_get_group_id(config.tracing_group_name.value));
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+ gid_t gid;
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+
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+ ret = utils_get_group_id(config.tracing_group_name.value, true, &gid);
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+ if (ret) {
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+ gid = 0; /* Default to root group. */
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+ }
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+
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+ ret = chown(sock_path, 0, gid);
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if (ret) { |
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ERR("Failed to set the notification channel socket's group"); |
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ret = -1; |
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diff --git a/src/common/utils.c b/src/common/utils.c
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index c0bb031e..778bc00f 100644
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--- a/src/common/utils.c
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+++ b/src/common/utils.c
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@@ -1231,24 +1231,77 @@ size_t utils_get_current_time_str(const char *format, char *dst, size_t len)
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} |
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/* |
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- * Return the group ID matching name, else 0 if it cannot be found.
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+ * Return 0 on success and set *gid to the group_ID matching the passed name.
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+ * Else -1 if it cannot be found or an error occurred.
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*/ |
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LTTNG_HIDDEN |
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-gid_t utils_get_group_id(const char *name)
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+int utils_get_group_id(const char *name, bool warn, gid_t *gid)
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{ |
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- struct group *grp;
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+ static volatile int warn_once;
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- grp = getgrnam(name);
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- if (!grp) {
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- static volatile int warn_once;
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+ int ret;
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+ long sys_len;
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+ size_t len;
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+ struct group grp;
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+ struct group *result;
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+ char *buffer = NULL;
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- if (!warn_once) {
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- WARN("No tracing group detected");
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- warn_once = 1;
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+ /* Get the system limit if it exists */
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+ sys_len = sysconf(_SC_GETGR_R_SIZE_MAX);
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+ if (sys_len == -1) {
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+ len = 1024;
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+ } else {
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+ len = (size_t) sys_len;
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+ }
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+
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+ buffer = malloc(len);
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+ if (!buffer) {
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+ PERROR("getgrnam_r malloc");
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+ ret = -1;
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+ goto error;
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+ }
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+
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+ while ((ret = getgrnam_r(name, &grp, buffer, len, &result)) == ERANGE)
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+ {
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+ /* Buffer is not big enough, increase its size. */
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+ size_t new_len = 2 * len;
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+ char *new_buffer = NULL;
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+ if (new_len < len) {
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+ ERR("getgrnam_r buffer size overflow");
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+ ret = -1;
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+ goto error;
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+ }
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+ len = new_len;
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+ new_buffer = realloc(buffer, len);
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+ if (!new_buffer) {
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+ PERROR("getgrnam_r realloc");
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+ ret = -1;
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+ goto error;
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} |
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- return 0;
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+ buffer = new_buffer;
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+ }
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+ if (ret != 0) {
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+ PERROR("getgrnam_r");
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+ ret = -1;
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+ goto error;
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+ }
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+
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+ /* Group not found. */
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+ if (!result) {
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+ ret = -1;
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+ goto error;
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+ }
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+
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+ *gid = result->gr_gid;
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+ ret = 0;
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+
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+error:
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+ free(buffer);
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+ if (ret && warn && !warn_once) {
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+ WARN("No tracing group detected");
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+ warn_once = 1;
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} |
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- return grp->gr_gid;
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+ return ret;
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} |
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/* |
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diff --git a/src/common/utils.h b/src/common/utils.h
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index 18f19ef1..9c72431d 100644
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--- a/src/common/utils.h
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+++ b/src/common/utils.h
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@@ -22,6 +22,8 @@
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#include <unistd.h> |
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#include <stdint.h> |
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#include <getopt.h> |
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+#include <stdbool.h>
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+#include <sys/types.h>
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#define KIBI_LOG2 10 |
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#define MEBI_LOG2 20 |
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@@ -52,7 +54,7 @@ int utils_get_count_order_u64(uint64_t x);
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char *utils_get_home_dir(void); |
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char *utils_get_user_home_dir(uid_t uid); |
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size_t utils_get_current_time_str(const char *format, char *dst, size_t len); |
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-gid_t utils_get_group_id(const char *name);
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+int utils_get_group_id(const char *name, bool warn, gid_t *gid);
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char *utils_generate_optstring(const struct option *long_options, |
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size_t opt_count); |
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int utils_create_lock_file(const char *filepath); |
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diff --git a/src/lib/lttng-ctl/lttng-ctl.c b/src/lib/lttng-ctl/lttng-ctl.c
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index 2d84aad9..561b0bcf 100644
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--- a/src/lib/lttng-ctl/lttng-ctl.c
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+++ b/src/lib/lttng-ctl/lttng-ctl.c
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@@ -208,15 +208,13 @@ end:
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LTTNG_HIDDEN |
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int lttng_check_tracing_group(void) |
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{ |
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- struct group *grp_tracing; /* no free(). See getgrnam(3) */
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- gid_t *grp_list;
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+ gid_t *grp_list, tracing_gid;
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int grp_list_size, grp_id, i; |
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int ret = -1; |
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const char *grp_name = tracing_group; |
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/* Get GID of group 'tracing' */ |
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- grp_tracing = getgrnam(grp_name);
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- if (!grp_tracing) {
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+ if (utils_get_group_id(grp_name, false, &tracing_gid)) {
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/* If grp_tracing is NULL, the group does not exist. */ |
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goto end; |
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} |
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@@ -241,7 +239,7 @@ int lttng_check_tracing_group(void)
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} |
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for (i = 0; i < grp_list_size; i++) { |
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- if (grp_list[i] == grp_tracing->gr_gid) {
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+ if (grp_list[i] == tracing_gid) {
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ret = 1; |
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break; |
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} |
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--
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2.17.1 |
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